WO2024154812A1 - Iron-based sintered alloy valve seat for internal combustion engines and method for producing same - Google Patents
Iron-based sintered alloy valve seat for internal combustion engines and method for producing same Download PDFInfo
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- WO2024154812A1 WO2024154812A1 PCT/JP2024/001385 JP2024001385W WO2024154812A1 WO 2024154812 A1 WO2024154812 A1 WO 2024154812A1 JP 2024001385 W JP2024001385 W JP 2024001385W WO 2024154812 A1 WO2024154812 A1 WO 2024154812A1
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 222
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- 229910052710 silicon Inorganic materials 0.000 claims abstract description 36
- 239000000203 mixture Substances 0.000 claims abstract description 35
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 23
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- 239000002356 single layer Substances 0.000 claims description 9
- 229910052802 copper Inorganic materials 0.000 claims description 8
- CWQXQMHSOZUFJS-UHFFFAOYSA-N molybdenum disulfide Chemical compound S=[Mo]=S CWQXQMHSOZUFJS-UHFFFAOYSA-N 0.000 claims description 8
- 229910052982 molybdenum disulfide Inorganic materials 0.000 claims description 8
- KWUUWVQMAVOYKS-UHFFFAOYSA-N iron molybdenum Chemical compound [Fe].[Fe][Mo][Mo] KWUUWVQMAVOYKS-UHFFFAOYSA-N 0.000 claims description 7
- CADICXFYUNYKGD-UHFFFAOYSA-N sulfanylidenemanganese Chemical compound [Mn]=S CADICXFYUNYKGD-UHFFFAOYSA-N 0.000 claims description 7
- 229910001182 Mo alloy Inorganic materials 0.000 claims description 5
- 238000001556 precipitation Methods 0.000 claims description 5
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- 239000000446 fuel Substances 0.000 description 6
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- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 4
- 229910017116 Fe—Mo Inorganic materials 0.000 description 3
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910001309 Ferromolybdenum Inorganic materials 0.000 description 2
- 229910017313 Mo—Co Inorganic materials 0.000 description 2
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
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Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/12—Metallic powder containing non-metallic particles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/05—Mixtures of metal powder with non-metallic powder
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/07—Alloys based on nickel or cobalt based on cobalt
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/02—Making ferrous alloys by powder metallurgy
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
Definitions
- the present invention relates to an iron-based sintered alloy valve seat for internal combustion engines and a manufacturing method thereof, and in particular to improving the wear resistance and radial crushing strength of valve seats for internal combustion engines that use gas fuels such as LPG, CNG, and hydrogen, as well as special fuels such as those containing ethanol.
- Valve seats are usually pressed into the cylinder head of an internal combustion engine, and serve to seal in the combustion gases and cool the valves. Valve seats are exposed to a variety of conditions, including being struck by the valves, wearing away due to sliding, being heated by the combustion gases, and being corroded by combustion products. For this reason, valve seats have traditionally been required to have excellent heat resistance and wear resistance, as well as low aggressiveness to prevent abrasion to the valves, which are the mating material.
- Patent Document 1 describes "an iron-based sintered alloy valve seat for internal combustion engines with excellent wear resistance.”
- the base phase is a hard single-phase structure in which fine carbides of 10 ⁇ m or less are precipitated, with a hardness of 550 HV or more.
- hard particles with a hardness of 650 to 1200 HV are dispersed in the base phase at an area ratio of 20 to 40%, and a diffusion phase is formed around the hard particles at an area ratio of 0.5 to 5%, or solid lubricant particles are further dispersed at an area ratio of 5% or less to create an iron-based sintered alloy valve seat with a structure.
- valve seat wears little, and a combination of a valve and a valve seat with excellent wear resistance can be realized.
- Patent Document 2 describes a valve seat made of an iron-based sintered alloy.
- the valve seat described in Patent Document 2 has a two-layer structure in which a valve seating side portion and a head seating side portion are sintered together.
- the valve seating side portion has a porosity of 10-25% by volume and a post-sintering density of 6.1-7.1 g/ cm3 , and is made of an iron-based sintered alloy material in which hard particles are dispersed in a matrix phase.
- the hard particles are particles made of one or more elements selected from C, Cr, Mo, Co, Si, Ni, S, and Fe, and are dispersed in the matrix phase by an area ratio of 5-40%.
- Patent Document 2 as the above-mentioned hard particles, Cr-Mo-Co based intermetallic compound particles, Ni-Cr-Mo-Co based intermetallic compound particles, Fe-Mo alloy particles, Fe-Ni-Mo-S based alloy particles, and Fe-Mo-Si based alloy particles are exemplified.
- Patent Document 3 proposes an iron-based sintered alloy valve seat.
- the iron-based sintered alloy valve seat described in Patent Document 3 is an iron-based sintered alloy valve seat in which hard particles are dispersed in the matrix phase, and the overall composition is, by mass%, Cr: 5.0-20.0%, Si: 0.4-2.0%, Ni: 2.0-6.0%, Mo: 5.0-25.0%, W: 0.1-5.0%, V: 0.5-5.0%, Nb: 1.0% or less, C: 0.5-1.5%, with the balance being Fe and unavoidable impurities.
- Fe-Mo-Si alloy particles as hard particles, which are, by mass%, Mo: 40.0-70.0%, Si: 0.4-2.0%, C: 0.1% or less, with the balance being Fe and unavoidable impurities.
- Patent Document 4 proposes a hard particle dispersion type iron-based sintered alloy.
- the hard particle dispersion type iron-based sintered alloy described in Patent Document 4 is an iron-based sintered alloy in which 3 to 20% of hard particles are dispersed and sintered based on the entire alloy in a matrix containing, by weight percentage, 0.4 to 2% Si, 2 to 12% Ni, 3 to 12% Mo, 0.5 to 5% Cr, 0.6 to 4% V, 0.1 to 3% Nb, 0.5 to 2% C, and the balance Fe.
- the dispersed hard particles contain 60 to 70% Mo, 0.3 to 1% B, and 0.1% or less C, with the balance being Fe.
- B When B is added to ferro-molybdenum-based hard particles, B improves the wettability of ferro-molybdenum, prevents the hard particles from falling off the matrix, and improves the adhesion between the matrix and the hard particles, thereby improving the thermal strength and mechanical strength of the sintered alloy.
- the iron-based sintered alloy valve seats described in Patent Documents 1 and 2 have problems such as low radial crushing strength, which makes them prone to cracking when pressed into a cylinder head, and particles easily falling off when they come into contact with the valve, resulting in reduced wear resistance. Furthermore, the iron-based sintered alloy valve seats described in Patent Documents 1 and 2 have low Young's modulus, which makes them prone to deformation, resulting in reduced sealing performance and the leakage of combustion gas.
- the dispersed iron-based hard particles do not contain Co, and therefore are more susceptible to cracking and chipping than conventional Co-based hard particles.
- the hard particles fall off from the matrix phase, and it has been found that there is a problem in that the desired wear resistance cannot be ensured, particularly in the harsh valve seat operating environments of recent years.
- the object of the present invention is to provide an iron-based sintered alloy valve seat for internal combustion engines that has excellent wear resistance and radial crushing strength even in the harsh environments in which valve seats are used these days.
- excellent radial crushing strength here refers to a radial crushing strength of 490 MPa or more obtained in accordance with the provisions of JIS Z 2507.
- the inventors first conducted an intensive study of various factors that affect the radial crushing strength. As a result, they discovered that the low "radial crushing strength" is due to the low compressibility of the iron-based powder used. In that case, carbides are already precipitated in the iron-based powder used, which increases the hardness of the powder particles, and the plastic deformation (compression) of the powder particles during compaction is insufficient. Therefore, it was thought that the element diffusion during sintering is also difficult to promote, and as a result, the interparticle bonding force is reduced.
- the present invention it was conceived to use an iron-based powder with a low carbon content as the iron-based powder for forming the matrix phase so that sufficient compaction can be achieved during compaction and sufficient plastic deformation can be applied to the powder particles.
- the carbon content of the iron-based powder is reduced too much, the amount of carbide is reduced and the wear resistance of the sintered body is reduced. Therefore, it was decided to increase the amount of graphite powder to prevent the carbon content of the sintered body from decreasing, and to use an iron-based powder with an increased amount of carbide-forming elements to increase the amount of carbide.
- the amount of fine carbide precipitated in the sintered body was significantly increased compared to conventional methods, and that the wear resistance and radial crushing strength were significantly improved.
- a valve seat press-fitted into a cylinder head of an internal combustion engine has a single-layer structure including a functional component-side layer, the functional component-side layer has a structure in which a matrix phase consisting of a fine carbide precipitate phase, a high alloy phase of 5.0 to 30.0% by area, hard particles of 10.0 to 40.0% by area, and solid lubricant particles of 0 to 4.0% by area are dispersed in the matrix phase;
- the hard particles are Si-Cr-Mo-based Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, in mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities; or Si-Cr-Mo-Ni-based Co-based intermetallic compound particles having a composition containing, in mass%, Si: 1.5 to 2.
- a valve seat press-fitted into a cylinder head of an internal combustion engine has a two-layer structure in which a functional member-side layer and a support member-side layer are sintered together, the functional component-side layer has a structure in which a matrix phase consisting of a fine carbide precipitate phase, a high alloy phase of 5.0 to 30.0% by area, hard particles of 10.0 to 40.0% by area, and solid lubricant particles of 0 to 4.0% by area are dispersed in the matrix phase;
- the hard particles are Si-Cr-Mo-based Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, in mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities; or Si-Cr-Mo-Ni-based Co-based intermetallic compound particles having a composition containing, in mass%, Si: 1.5 to 2.5%, Cr
- the valve seat made of an iron-based sintered alloy according to any one of [2] to [4], characterized in that the hardness improving particles are iron-molybdenum alloy particles.
- a method for producing a valve seat made of a single-layered iron-based sintered alloy according to [1] Predetermined amounts of iron-based powder, graphite powder, alloying element powder, hard particle powder, and/or solid lubricant powder are blended, mixed, and kneaded to obtain a mixed powder, and then The mixed powder is filled into a mold of a predetermined shape and pressed to form a green compact, and then The green compact is sintered in a protective atmosphere to produce a sintered body, which is then cut or ground to produce a valve seat having a desired shape.
- the iron-based powder contains, by mass%, C: 0.2 to 0.8%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 7.0% or less, Mo: 7.0% or less, V: 5.0% or less, W: 12.0% or less, or further contains Co: 12.0% or less, the balance being Fe and unavoidable impurities, and has a particle hardness of 170 to 280 HV in Vickers hardness; the iron-based powder is blended in an amount of 40.0 to 70.0% by mass with respect to the total amount of the mixed powder; the hard particle powder being Si-Cr-Mo Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, by mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities, or Si-Cr-Mo-Ni Co-based intermetallic compound particles having a composition containing, by mass%, Si: 1.5 to 2.5%,
- [8] A method for producing a two-layered iron-based sintered alloy valve seat according to [2], Predetermined amounts of iron-based powder, graphite powder, alloying element powder, hard particle powder, and/or solid lubricant powder are blended, mixed, and kneaded to obtain a mixed powder for a functional member side layer; Predetermined amounts of iron-based powder, graphite powder, or alloying element powder, hardness improving particles, and solid lubricant powder are blended, mixed, and kneaded to obtain a mixed powder for a support member side layer; The mixed powder for the functional member side layer and the mixed powder for the support member side layer are filled in this order into a die of a predetermined shape, and pressed to form a green compact.
- the green compact is then sintered in a protective atmosphere to form a two-layer sintered body in which the functional member side layer and the support member side layer are sintered together.
- the two-layer sintered body is then cut or further ground to produce a two-layer valve seat of a predetermined shape.
- the iron-based powder contains, by mass%, C: 0.2 to 0.8%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 7.0% or less, Mo: 7.0% or less, V: 5.0% or less, W: 12.0% or less, or further contains Co: 12.0% or less, the balance being Fe and unavoidable impurities, and has a particle hardness of 170 to 280 HV in Vickers hardness, and the iron-based powder is blended in an amount of 40.0 to 70.0% by mass with respect to the total amount of the mixed powder, the hard particle powder being Si-Cr-Mo Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, by mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities, or Si-Cr-Mo-Ni Co-based intermetallic compound particles having a composition containing,
- a method for producing an iron-based sintered alloy valve seat characterized in that the above-mentioned two-layer structure sintered body is obtained.
- the present invention makes it possible to manufacture iron-based sintered alloy valve seats for internal combustion engines that are excellent in both wear resistance and radial crushing strength, providing significant benefits to the industry.
- FIG. 1 is an explanatory diagram showing an overview of a rig testing machine.
- the valve seat of the present invention is an iron-based sintered alloy valve seat with a single-layer structure consisting of only a functional component layer, or an iron-based sintered alloy valve seat with a two-layer structure in which a functional component layer and a support component layer are sintered together.
- the functional component side layer has a matrix phase consisting of a fine carbide precipitate phase, and a structure in which 5.0-30.0% of a high alloy phase, 10.0-40.0% of hard particles, and 0-4.0% of solid lubricant particles are dispersed in the matrix phase, with the area ratio relative to the entire structure.
- the remainder other than the high alloy phase, hard particles, and solid lubricant particles is the matrix phase and pores.
- the pores are preferably impregnated with a thermosetting resin or an anaerobic resin. By impregnating and sealing the pores with a thermosetting resin or an anaerobic resin, the cutting and machinability are improved without a decrease in wear resistance, and the corrosion resistance can also be improved.
- the voids can also be calculated from the true density and the density of the functional component side layer.
- the base phase is a fine carbide precipitation phase.
- the fine carbide precipitation phase is a phase in which fine carbides with a particle size of 10 ⁇ m or less are precipitated, and is a hard phase with a Vickers hardness of 450 HV or more, preferably 650 HV or less.
- the presence of such a hard fine carbide precipitation phase strengthens the matrix, further improving its wear resistance. If the particle size of the carbides precipitated in the matrix phase exceeds 10 ⁇ m, the hardness and toughness of the matrix phase decrease, the aggressiveness against the mating member increases, and the radial crushing strength decreases.
- the high alloy phase dispersed in the matrix phase is an area where the alloying elements diffuse from the hard particles and added elements during sintering, resulting in a high alloy content.
- the high alloy phase has the effect of preventing hard particles from falling off, and preferably has a Vickers hardness of 170HV or more, and preferably 280HV or less.
- the high alloy phase must be present in an area ratio of 5.0% or more relative to the entire structure.
- the area ratio of the high alloy phase is set to be in the range of 5.0 to 30.0%, with a range of 10.0 to 20.0% being preferable.
- the hard particles to be dispersed are those having a Vickers hardness of 600 to 1200HV. If the hardness of the hard particles is less than 600HV, there is little effect in improving wear resistance. On the other hand, if the hardness exceeds 1200HV, it will lead to a decrease in machinability. For this reason, the hardness of the hard particles dispersed in the matrix phase is limited to the range of 600 to 1200HV on the Vickers hardness scale.
- hard particles having the above-mentioned hardness are dispersed in the matrix phase at an area ratio of 10.0 to 40.0% relative to the entire structure (including the matrix phase, hard particles, solid lubricant particles, and pores). If the amount of dispersed hard particles is less than 10.0%, the desired wear resistance cannot be ensured. On the other hand, if it exceeds 40.0%, the bonding strength with the matrix phase decreases, and wear resistance decreases. For this reason, the amount of dispersed hard particles in the matrix phase is limited to a range of 10.0 to 40.0% in area ratio.
- the hard particles preferably have the above hardness and an average particle size of 10 to 150 ⁇ m. If the average particle size of the hard particles is less than 10 ⁇ m, they are prone to over-diffusion during sintering, while if it exceeds 150 ⁇ m, the bonding strength with the matrix decreases and wear resistance decreases. For this reason, it is preferable to limit the average particle size of the hard particles dispersed in the matrix phase to the range of 10 to 150 ⁇ m. Note that "average particle size” here refers to the particle size D50 at which the cumulative distribution measured by the laser scattering method is 50%.
- the hard particles dispersed in the matrix phase are Si-Cr-Mo Co-based intermetallic compound particles having a composition, by mass%, of Si: 2.2-2.7%, Cr: 7.5-9.5%, Mo: 27.0-30.0%, with the balance being Co and unavoidable impurities, or Si-Cr-Mo-Ni Co-based intermetallic compound particles having a composition, by mass%, of Si: 1.5-2.5%, Cr: 24.0-26.0%, Mo: 23.0-26.0%, Ni: 9.5-11.0%, with the balance being Co and unavoidable impurities.
- Co-based intermetallic compound particles with the above composition as the dispersed hard particles, the diffusion of alloy elements becomes significant during sintering, making it easier to form a high alloy phase around the hard particles.
- solid lubricant particles may be further dispersed in the matrix phase at 4.0% or less. Dispersing the solid lubricant particles in the matrix phase improves machinability and lubricity. However, if the area ratio is more than 4.0%, the mechanical properties will be significantly deteriorated. For this reason, the area ratio of the solid lubricant particles is limited to the range of 0 to 4.0%.
- the solid lubricant particles are preferably one or two types selected from manganese sulfide MnS and molybdenum disulfide MoS2 .
- the functional member side layer of the valve seat of the present invention has a composition (base composition) consisting of a base phase, a high alloy phase, hard particles, and solid lubricant particles, the base portion containing, by mass%, C: 0.50-2.80%, one or more selected from Si: 1.80% or less, Mn: 2.50% or less, Cr: 3.00-11.00%, Mo: 3.00-17.00%, Ni: 1.00-8.50%, Co: 5.00-30.00%, V: 0.50-4.00%, W: 4.00-10.00%, and S: 0-2.00%, with the remainder being Fe and unavoidable impurities.
- base composition consisting of a base phase, a high alloy phase, hard particles, and solid lubricant particles, the base portion containing, by mass%, C: 0.50-2.80%, one or more selected from Si: 1.80% or less, Mn: 2.50% or less, Cr: 3.00-11.00%, Mo: 3.00-17.00%, Ni: 1.00-8.50%, Co: 5.00-30.00%, V
- C 0.50-2.80%
- C is an element necessary for adjusting the matrix phase to a specified hardness and structure, or for forming carbides, and is contained at 0.50% or more.
- the melting point drops and the sintering process becomes liquid phase sintering.
- the amount of precipitated carbides becomes too large, the number of pores increases, and the elongation properties and dimensional accuracy decrease.
- C is limited to the range of 0.50 to 2.80%, and preferably 0.90 to 1.70%.
- C is preferably 2.30 to 2.60%.
- Si 1.80% or less
- Silicon is an element contained mainly in hard particles and constitutes intermetallic compounds. It increases the hardness of the hard particles, increases the strength of the matrix, and improves wear resistance. For this reason, it is preferable to contain 0.20% or more of silicon. On the other hand, if the silicon content exceeds 1.80%, aggressiveness against the mating member increases. For this reason, it is preferable to limit the silicon content to 1.80% or less. It is more preferable to set the content to 0.50 to 1.00%.
- Mn 2.50% or less
- Mn is an element that increases the hardness of the matrix phase.
- a part of Mn is included in the matrix due to solid lubricant particles, and contributes to improving machinability. It is preferable to contain 0.05% or more.
- Mn content exceeds 2.50%, the hardness, toughness, and ductility of the matrix phase decrease. For this reason, it is preferable to limit Mn to 2.50% or less. More preferably, it is 0.20 to 1.60%.
- Cr 3.00-11.00% Cr dissolves in the matrix phase and forms carbides to increase the hardness of the matrix phase, and as a constituent element of intermetallic compounds, Cr contributes to increasing the hardness of hard particles, so the matrix should contain 3.00% or more of Cr.
- the Cr content exceeds 11.00%, the precipitation of Cr carbides in the matrix phase becomes excessive, making it difficult to make the carbides in the matrix phase fine. For this reason, it is preferable to limit the Cr content to the range of 3.00 to 11.00%. More preferably, it is 4.00 to 6.00%.
- Mo 3.00-17.00%
- Mo dissolves in the matrix phase and precipitates as carbides to increase the hardness of the matrix phase.
- Mo is an element that contributes to increasing the hardness of hard particles as a constituent element of intermetallic compounds, and it is preferable to contain 3.00% or more in the matrix.
- Mo is contained in excess of 17.00%, it becomes difficult to increase the density during powder molding, and moldability decreases. For this reason, it is preferable to limit Mo to the range of 3.00 to 17.00%. More preferably, it is 9.00 to 15.00%.
- Ni is an element that contributes to improving the strength and toughness of the matrix phase and further to the formation of a high alloy phase.
- Ni is an element that contributes to increasing the toughness of hard particles as a constituent element of intermetallic compounds, and it is preferable to contain 1.00% or more.
- the Ni content exceeds 8.50%, it is difficult to increase the density during powder molding, and the moldability is reduced. For this reason, it is preferable to limit Ni to the range of 1.00 to 8.50%. More preferably, it is 1.00 to 3.00%.
- Co 5.00-30.00%
- Co is mainly contained in the hard particles, forms an intermetallic compound, and increases the hardness of the hard particles, but diffuses into the matrix during sintering, contributes to the formation of a high alloy phase, and is further contained in the matrix phase, increases the strength of the matrix phase, especially its high-temperature strength, and further contributes to improving the toughness of the matrix phase. It is preferable for the matrix to contain 5.00% or more. On the other hand, if the Co content exceeds 30.00%, the wear resistance decreases. For this reason, it is preferable to limit Co to 5.00-30.00%. More preferably, it is 9.00-27.00%.
- V 0.50-4.00%
- V is an element that precipitates as fine carbides, increases the hardness of the matrix phase, and improves wear resistance, and is preferably contained at 0.50% or more.
- a V content of more than 4.00% reduces formability. For this reason, it is preferable to limit V to the range of 0.50 to 4.00%, and more preferably 1.00 to 3.00%.
- W 4.00-10.00%
- W is an element that precipitates as fine carbides, increases the hardness of the matrix phase, and improves wear resistance, and is preferably contained at 4.00% or more.
- a W content of more than 10.00% reduces formability. For this reason, it is preferable to limit W to the range of 4.00 to 10.00%, and more preferably 3.00 to 7.00%.
- S 0-2.00%
- S is an element contained in the solid lubricant particles and the matrix, which contributes to improving machinability, and can be contained as necessary. If the S content exceeds 2.00%, it leads to a decrease in toughness and ductility. For this reason, it is preferable to limit S to the range of 0 to 2.00%.
- the balance other than the above components consists of Fe and unavoidable impurities.
- P 0.10% or less is permissible.
- the functional member side layer of the two-layer structure is the same as the functional member side layer in the case of the single-layer structure described above.
- the support member side layer in the case of the two-layer structure need only be capable of holding the functional member side layer, and does not need to be particularly limited.
- the support member side layer is preferably made of an iron-based sintered alloy material having a structure in which a base phase, 0-4.0% by area of solid lubricant particles and 0-5.0% by area of hardness improving particles are dispersed in the base phase, and the base portion containing the base phase, solid lubricant particles and hardness improving particles contains, by mass%, C: 0.30-2.00%, Ni: 0-2.00%, Mo: 0-2.00%, Cu: 0-5.00%, Mn: 0-5.00%, and S: 0-2.00%, with the balance being Fe and unavoidable impurities.
- the matrix phase of the support member side layer is preferably pearlite.
- solid lubricant particles for improving machinability may be dispersed in the matrix phase as necessary.
- examples of solid lubricant particles include MnS, MoS2 , etc.
- the solid lubricant particles are preferably 0.3% or more in area ratio to the entire structure of the support member side layer. If the amount of dispersed solid lubricant particles is less than 0.3%, it is difficult to achieve the purpose of improving machinability. On the other hand, even if the amount of dispersed solid lubricant particles exceeds 4.0%, the effect is saturated and it is not possible to expect an effect commensurate with the amount dispersed. For this reason, the area ratio of the solid lubricant particles is preferably in the range of 0 to 4.0%.
- hardness improving particles may be dispersed in an area ratio of 0 to 5.0%.
- An example of hardness improving particles dispersed in the support member side layer is an iron-molybdenum (Fe-Mo) alloy. If the hardness improving particles are dispersed in an area ratio of more than 5.0%, the effect saturates, so if they are contained, the upper limit is set at 5.0%.
- the support member side layer has a structure in which solid lubricant particles and hardness improving particles are dispersed in the matrix phase as necessary.
- the remainder other than the matrix phase, solid lubricant particles, and hardness improving particles are pores.
- the pores are preferably impregnated with a thermosetting resin or anaerobic resin. By impregnating the pores with a thermosetting resin or anaerobic resin and sealing them, cutting and machinability are improved without a significant decrease in wear resistance. Sealing the pores is also expected to improve corrosion resistance.
- C is contained in an amount of 0.30% or more to ensure the desired strength. On the other hand, if it is contained in excess of 2.00%, the strength becomes too high and the toughness decreases. For this reason, it is preferable to limit C to the range of 0.30-2.00%. C is preferably 0.30-1.20%. When the pores are impregnated with resin, C is preferably 1.40-1.80%.
- the base portion of the support member side layer may contain Ni: 0-2.00%, Mo: 0-2.00%, Cu: 0-5.00%, Mn: 0-5.00%, and S: 0-2.00%.
- Ni, Mo, and Cu are elements that increase the matrix phase strength (hardness) of the support member side layer, and can be included as necessary.
- Ni, Mo, and Cu are included according to the desired strength, but if they exceed Ni: 2.00%, Mo: 2.00%, and Cu: 5.00%, respectively, the strength will be too high. Therefore, when included, it is preferable to limit the ranges of Ni: 2.00% or less, Mo: 2.00% or less, and Cu: 5.00% or less.
- a portion of Mo, Mn, and S are included in the matrix due to the dispersion of solid lubricant particles, but even if a large amount of solid lubricant particles are dispersed, the effect saturates and ductility decreases. Therefore, when included, it is preferable to limit Mn: 5.00% or less and S: 2.00% or less.
- the remainder other than the above components consists of Fe and unavoidable impurities.
- unavoidable impurities P: 0.10% or less is acceptable.
- iron-based powder, graphite powder, alloying element powder, hard particle powder, and/or solid lubricant particle powder are mixed in predetermined amounts so as to obtain the above-mentioned base composition, and then mixed and kneaded to obtain a mixed powder (mixed powder for the functional component side layer).
- the iron-based powder mixed into the mixed powder is a powder mixed to form a base phase, and in the present invention, it is an alloy steel powder that can form the base phase into a structure consisting of a fine carbide precipitate phase.
- An example of such an alloy steel powder is a powder whose composition conforms to the high-speed tool steel composition specified in JIS G 4403, but it goes without saying that it is not limited to this.
- the iron-based powder to be blended contains, by mass%, C: 0.2-0.8%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 7.0% or less, Mo: 7.0% or less, V: 5.0% or less, W: 12.0% or less, Co: 0-12.0%, with the remainder being Fe and unavoidable impurities, and has a particle hardness of 170-280 HV on the Vickers hardness scale.
- the iron-based powder blended in this invention is a powder with a high-speed steel composition with reduced C.
- the C content of the iron-based powder is less than 0.2%, the hardness of the powder particles will not decrease any further. On the other hand, if the C content exceeds 0.8%, the hardness of the powder particles will be too high, and the compressibility of the powder particles will decrease. For this reason, it is preferable to limit the C content of the iron-based powder to the range of 0.2 to 0.8%, and more preferably to 0.4 to 0.6%.
- Si 1.0% or less Silicon is an element that affects the flow of molten metal during powder production (atomized powder production). In order to obtain this effect, a silicon content of 0.3% or more is significant. On the other hand, if the silicon content exceeds 1.0%, the compressibility decreases. For this reason, it is preferable to limit the silicon content to 1.0% or less. Furthermore, it is more preferable to limit the silicon content to 0.5% or less.
- Mn 1.0% or less Mn acts as a deoxidizer and contributes to increasing strength (hardness). This effect is significant when the content is 0.10% or more. On the other hand, if the Mn content exceeds 1.0%, the oxygen concentration of the powder increases and the diffusibility during sintering decreases. In addition, the hardness increases and the compressibility decreases. For this reason, it is preferable to limit Mn to 1.0% or less.
- Cr 7.0% or less Cr is an element that forms carbides and has the effect of improving wear resistance. This effect is significant when the Cr content is 0.1% or more, but when the Cr content exceeds 7.0%, the toughness decreases. For this reason, it is preferable to limit the Cr content to 7.0% or less.
- Mo 7.0% or less
- Mo is an element that forms fine carbides and has the effect of improving wear resistance. This effect is prominent when the Mo content is 2.0% or more, but if it exceeds 7.0%, formability decreases. For this reason, it is preferable to limit Mo to 7.0% or less. Furthermore, it is more preferable to limit it to 2.0 to 5.0%.
- W 12.0% or less W is an element that forms fine carbides and has the effect of improving wear resistance. This effect is remarkable when the W content is 5.0% or more, but when it exceeds 12.0%, the formability decreases. For this reason, it is preferable to limit W to 12.0% or less.
- Co 12.0% or less may be contained as necessary.
- Cobalt 0-12.0% Co is an element that increases strength, especially high-temperature strength, and contributes to improving toughness as well as forming a high alloy phase, and is preferably contained at 10.0% or more as necessary. On the other hand, a Co content of more than 12.0% leads to a decrease in strength. Therefore, when Co is contained, it is preferable to limit it to 12.0% or less.
- the remainder of the steel other than the above components consists of Fe and unavoidable impurities.
- unavoidable impurities P: 0.03% or less and S: 0.02% or less are acceptable.
- P segregates at the austenite grain boundaries and promotes grain boundary embrittlement, so it is preferable to reduce it as much as possible. More preferably, it is 0.010% or less.
- S also exists in the steel as sulfide-based inclusions and impairs hot workability, so it is preferable to reduce it as much as possible. More preferably, it is 0.005% or less.
- the iron-based powder used in the present invention has a particle hardness of 170 to 280 HV. If the particle hardness is less than 170 HV, the hardness of the iron-based powder is too low, and the wear resistance of the sintered body decreases. On the other hand, if the particle hardness exceeds 280 HV, the compressibility decreases, and the radial crushing strength of the sintered body decreases. For this reason, the particle hardness of the iron-based powder to be blended is limited to 170 to 280 HV.
- the hard particle powder to be mixed in the mixed powder is a Si-Cr-Mo Co-based intermetallic compound particle powder or a Si-Cr-Mo-Ni Co-based intermetallic compound particle powder having the above-mentioned hardness and composition.
- such hard particle powder is mixed in an amount of 10.0 to 40.0% by mass relative to the total amount of the mixed powder.
- the hard particle powder to be mixed is preferably a particle powder with an average particle size of 10 to 150 ⁇ m. If the average particle size of the hard particles is less than 10 ⁇ m, they tend to diffuse during sintering and the desired wear resistance cannot be ensured. On the other hand, if the average particle size of the hard particles exceeds 150 ⁇ m, the bonding strength with the matrix decreases.
- the "average particle size” here means the particle size D50 at which the cumulative distribution measured by the laser scattering method is 50%.
- solid lubricant particles are mixed as necessary to improve machinability, processability, and lubricity.
- the solid lubricant particles are preferably MnS, MoS2 , etc.
- the amount of solid lubricant particles mixed is preferably 0 to 4.0% by mass based on the total amount of the mixed powder.
- the mixed powder contains a predetermined amount of the above-mentioned iron-based powder, hard particle powder, or solid lubricant particle powder, and further contains graphite powder and alloying element powder to obtain the above-mentioned matrix composition.
- the alloying element powder to be added include Ni powder and/or Co powder.
- the mixed powder may also contain a lubricant such as zinc stearate.
- the resulting mixed powder is then filled into a mold of the desired valve seat shape.
- the mixed powder is filled into a die, it is pressed with a press machine or the like to form a green compact having a valve seat shape.
- the pressing is preferably performed so that the density of the green compact is 6.6 g/ cm3 or more.
- the resulting green compact is then subjected to a sintering process to produce a sintered body.
- the sintering process is preferably carried out in a reducing atmosphere such as nitrogen, hydrogen gas, or ammonia decomposition gas at a heating temperature in the range of 1100-1200°C, and is maintained for 0.5 hours or more. If the heating temperature is less than 1100°C, sintering diffusion will be insufficient, while if it exceeds 1200°C, excessive diffusion will occur and wear resistance will decrease.
- the press working P-sintering process S process may be repeated multiple times (2P2S, etc.).
- valve seat single-layer structure
- thermosetting resin or anaerobic resin any known (commercially available) thermosetting resin or anaerobic resin can be used.
- a mixed powder for the support component side layer is also prepared.
- the mixed powder for the support member side layer is prepared by blending, mixing, and kneading a predetermined amount of iron-based powder, graphite powder, or alloying element powder, hardness improving particle powder, and solid lubricant powder so as to obtain the above-mentioned base composition, to obtain a mixed powder (mixed powder for the support member side layer).
- the iron-based powder is pure iron powder.
- the graphite powder is blended at 0.5 to 2.0% by mass based on the total amount of the mixed powder for the support member side layer.
- the alloying element powder is blended at 0 to 5.0% by mass based on the total amount of the mixed powder for the support member side layer.
- the alloying element powder is preferably Mo powder, Ni powder, or Cu powder.
- the hardness improving particle powder is iron-molybdenum (Fe-Mo) alloy particle powder, and the hardness improving particle powder is blended at 0 to 5.0% by mass based on the total amount of the mixed powder for the support member side layer.
- the solid lubricant powder is mixed in an amount of 0 to 4.0% by mass based on the total amount of the mixed powder for the support member side layer.
- the mixed powder may also contain a lubricant such as zinc stearate.
- the mixed powder for the functional member side layer and the mixed powder for the support member side layer are filled in this order and in the desired ratio into a mold of a specified shape.
- press processing is performed to form a green compact in the same manner as in the case of the single layer structure described above, and then the green compact is sintered in the same manner as in the case of the single layer structure described above to obtain a sintered body with a two-layer structure.
- the sintering process is preferably performed in a reducing atmosphere at a heating temperature of 1100 to 1200°C for 0.5 hours or more.
- the pressing process P-sintering process S process may be repeated multiple times (2P2S, etc.).
- the resulting two-layer sintered body is then processed by grinding, cutting, etc. to produce a two-layer valve seat (product) of the desired dimensions and shape.
- the resin impregnation process is preferably a process in which the valve seat is immersed in a liquid of thermosetting resin or anaerobic resin in a vacuum atmosphere, and then pressurized from atmospheric pressure to fully impregnate the resin into the pores, and then heated to harden the resin in the pores and seal them.
- the pores in the iron-based sintered alloy material are impregnated with thermosetting resin or anaerobic resin.
- the mixed powder for the functional component side layer and the mixed powder for the support component side layer were prepared.
- the mixed powders for the functional component side layers were prepared by mixing and kneading the iron-based powder for forming the matrix phase with graphite powder, alloying element powder, hard particle powder, and solid lubricant particle powder (MnS powder) in the amounts shown in Table 1.
- the iron-based powder used was high-speed tool steel powder with the composition and hardness shown in Table 2.
- the hard particle powder used was particle powder with the composition, hardness, and average particle size shown in Table 3.
- the mixed powders were mixed with 1 part by mass of zinc stearate per 100 parts by mass of the mixed powder as a lubricant.
- the mixed powder for the support member side layer (mixed powder No. 1A, No. 1B) was prepared by mixing and kneading iron-based powder for forming the matrix phase, graphite powder, or alloy element powder, hardness improvement particle powder, and solid lubricant particle powder in the amounts shown in Table 1.
- the iron-based powder used had the composition and hardness shown in Table 2.
- Iron-based powder No. c was pure iron powder.
- the hard particle powder used had the composition, hardness, and average particle size shown in Table 3.
- Hard particle powder No. h3 was a hardness improvement particle powder, an iron-molybdenum alloy particle powder.
- the mixed powder contained 1 part by mass of zinc stearate per 100 parts by mass of the mixed powder as a lubricant.
- the obtained mixed powder was filled into a die and pressed into a green compact having a predetermined valve seat shape by a press.
- the density of the obtained green compact was measured by Archimedes' method and was found to be 6.6 g/ cm3 or more.
- the obtained green compact was subjected to a sintering process.
- the compact was placed in a sintering furnace in a reducing atmosphere with a heating temperature of 1160°C (holding time: 6 hours) to produce a sintered compact.
- the obtained sintered body was further processed by cutting, polishing, etc. to produce an iron-based sintered alloy valve seat of the specified shape (outer diameter: 27 mm ⁇ x inner diameter 22 mm ⁇ x thickness 6 mm).
- valve seats were subjected to a resin impregnation process using anaerobic resin.
- the resin impregnation process involves immersing the valve seats in a liquid of the resin in a vacuum atmosphere, then increasing the pressure from atmospheric pressure to thoroughly impregnate the resin into the pores, and then heating the valve seats to harden the resin in the pores and seal them.
- the anaerobic resin used was a commercially available anaerobic resin.
- the obtained valve seat was subjected to chemical analysis, structure observation, hardness test, density test, wear test, and radial crushing strength test.
- the test methods were as follows. (1) Chemical Analysis Analytical samples were taken from each portion of the obtained valve seat, and the content of each component in each portion was analyzed by optical emission spectrometry to determine the composition of the sintered body matrix. (2) Structure observation The cross section perpendicular to the axial direction of the obtained valve seat was polished and etched (etchant: nital solution) to reveal the structure, and observed with an optical microscope (magnification: 200 times). The obtained structure photograph was used to identify the type of matrix structure, and the area ratio was determined by image analysis.
- the alloy diffuses around the hard particles to form a high alloy phase.
- the cross section perpendicular to the axial direction was polished and etched (etching solution: marble solution) to reveal the structure, which was then observed under an optical microscope (magnification: 200x) and the structure fraction (area fraction) was measured by image analysis.
- etching solution marble solution
- structure fraction area fraction
- (3) Hardness Test For the obtained valve seat, a cross section perpendicular to the axial direction was polished and etched (etchant: nital solution) to reveal the structure, and the Vickers hardness HV of the matrix phase was measured using a Vickers hardness tester (test force: 0.98 N (100 gf)).
- Test temperature 150°C, 250°C (seating side temperature)
- Test duration 12 hours
- Valve speed 20 rpm
- Impact load 700N
- Valve material Heat-resistant steel with nitride film (SUH35 surface hardness 1150HV)
- the wear ratio of the valve seat was calculated, taking the valve seat No. 1 (conventional example) as the standard (1.00).
- (6) Radial Crushing Strength Test The radial crushing strength of the obtained valve seat (functional component side layer only) was determined in accordance with the provisions of JIS Z 2507.
- the radial crushing strength ratio of the valve seat was calculated, taking the valve seat No. 1 (conventional example) as the standard (1.00).
- the radial crushing strength of the valve seat No. 1 (conventional example) was 490 MPa.
- all of the examples of the present invention have a higher sintered density in the functional component layer, a higher radial crushing strength ratio, improved radial crushing strength (functional component layer), and a lower wear ratio, improved wear resistance.
- the material for internal combustion engine valve seats of the present invention (iron-based sintered alloy material) is expected to contribute to improving the wear resistance of valve seats for internal combustion engines that use gas fuels such as LPG and CNG hydrogen, as well as special fuels containing ethanol.
- the examples of the present invention (valve seats No. 17 and No. 18) in which the pores were impregnated with resin have improved crushing strength and wear resistance compared to the conventional example (valve seat No. 1).
- the example of the present invention (valve seat No. 17) that was impregnated with resin exhibits the same radial crushing strength and wear resistance as the example of the present invention (valve seat No. 6) that was not impregnated with resin.
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Abstract
The present invention provides an iron-based sintered alloy valve seat. The present invention is a sintered body of an iron-based sintered alloy having a two-layer structure in which a functional-member-side layer and a support-member-side layer are integrally sintered. In the functional-member-side layer, dispersed in a base phase constituted by a fine carbide precipitated phase are: a high alloy phase, in an amount of 5.0-30.0% by area ratio; Si-Cr-Mo or Si-Cr-Mo-Ni Co-based intermetallic compound particles that have a Vickers hardness of 600-1,200 HV, in an amount of 10.0-40.0%; and solid lubricant particles in an amount of 0-4.0%. In the sintered body of the iron-based sintered alloy, a base part has a composition containing, in terms of mass%, 0.50-2.80% C, not more than 1.80% Si, not more than 2.50% Mn, 3.00-11.00% Cr, 3.00-17.00% Mo, 1.00-8.50% Ni, 5.00-30.00% Co, 0.50-4.00% V, 4.00-10.00% W, and 0-2.00% S. Thus, it is possible to provide a valve seat that has excellent radial crushing strength and excellent wear resistance as compared to conventional valve seats.
Description
本発明は、内燃機関用鉄基焼結合金製バルブシートおよびその製造方法に係り、とくに、ＬＰＧ、ＣＮＧ、水素等のガス燃料及びエタノール含有などの特殊燃料を使用する内燃機関用バルブシートの耐摩耗性向上、圧環強さの向上に関する。
The present invention relates to an iron-based sintered alloy valve seat for internal combustion engines and a manufacturing method thereof, and in particular to improving the wear resistance and radial crushing strength of valve seats for internal combustion engines that use gas fuels such as LPG, CNG, and hydrogen, as well as special fuels such as those containing ethanol.
バルブシートは、通常、内燃機関のシリンダーヘッドに圧入されて、燃焼ガスのシールとバルブを冷却する役割を担っている。バルブシートは、バルブによる叩かれ、すべりによる摩耗、燃焼ガスによる加熱、燃焼生成物による腐食等に晒される。そのため、従来からバルブシートには、耐熱性、耐摩耗性に優れること、相手材であるバルブを摩耗させないように相手攻撃性が低いことなどが要求されてきた。
Valve seats are usually pressed into the cylinder head of an internal combustion engine, and serve to seal in the combustion gases and cool the valves. Valve seats are exposed to a variety of conditions, including being struck by the valves, wearing away due to sliding, being heated by the combustion gases, and being corroded by combustion products. For this reason, valve seats have traditionally been required to have excellent heat resistance and wear resistance, as well as low aggressiveness to prevent abrasion to the valves, which are the mating material.
このような要求に対し、例えば特許文献１には、「耐摩耗性に優れた内燃機関用鉄基焼結合金製バルブシート」が記載されている。特許文献１に記載された技術では、基地相を10μm以下の微細炭化物が析出した550HV以上の硬さを有する微細炭化物析出相である硬質な単相組織としている。そして、該基地相中に650～1200HVの硬さを有する硬質粒子を面積率で20～40％分散させ、硬質粒子の周りに拡散相を面積率で0.5～5％形成し、あるいはさらに固体潤滑剤粒子を面積率で5％以下分散させた組織を有する鉄基焼結合金製バルブシートとしている。これにより、厳しい摩耗環境であるガス燃料等の特殊燃料を使用する環境下の内燃機関において、高フェース面硬さバルブを使用しても、バルブシートの摩耗は少なく、耐摩耗性に優れたバルブとバルブシートの組合せが実現できるとしている。
In response to such demands, for example, Patent Document 1 describes "an iron-based sintered alloy valve seat for internal combustion engines with excellent wear resistance." In the technology described in Patent Document 1, the base phase is a hard single-phase structure in which fine carbides of 10 μm or less are precipitated, with a hardness of 550 HV or more. In addition, hard particles with a hardness of 650 to 1200 HV are dispersed in the base phase at an area ratio of 20 to 40%, and a diffusion phase is formed around the hard particles at an area ratio of 0.5 to 5%, or solid lubricant particles are further dispersed at an area ratio of 5% or less to create an iron-based sintered alloy valve seat with a structure. As a result, even if a valve with a high face hardness is used in an internal combustion engine in an environment using special fuels such as gas fuel, which is a severe wear environment, the valve seat wears little, and a combination of a valve and a valve seat with excellent wear resistance can be realized.
また、特許文献２には、鉄基焼結合金製バルブシートが記載されている。特許文献２に記載されたバルブシートは、バルブ着座側部とヘッド着座側部とが一体で焼結された二層構造を有するバルブシートである。バルブ着座側部は、体積率で10～25％の気孔率と6.1～7.1g/cm3の焼結後密度とを有し、基地相中に硬質粒子を分散させた鉄基焼結合金材からなるとしている。硬質粒子は、C、Cr、Mo、Co、Si、Ni、S、Feのうちから選ばれた１種または２種以上の元素からなる粒子であり、基地相中に面積率で5～40％分散している。基地相と硬質粒子を含む基地部の組成は、質量％で、Ni：2.0～23.0％、Cr：0.4～15.0％、Mo：3.0～15.0％、Cu：0.2～3.0％、Co：3.0～15.0％、V：0.1～0.5％、Mn：0.1～0.5％、W：0.2～6.0％、C：0.8～2.0％、Si：0.1～1.0％、S：0.1～1.0％のうちから選ばれた１種または２種以上を合計で10.0～40.0％含有し、残部Feおよび不可避的不純物からなる組成を有するとしている。なお、特許文献２には、上記した硬質粒子として、Cr－Mo－Co系金属間化合物粒子、Ni－Cr－Mo－Co系金属間化合物粒子、Fe－Mo合金粒子、Fe－Ni－Mo－S系合金粒子、Fe－Mo－Si系合金粒子が例示されている。
Patent Document 2 describes a valve seat made of an iron-based sintered alloy. The valve seat described in Patent Document 2 has a two-layer structure in which a valve seating side portion and a head seating side portion are sintered together. The valve seating side portion has a porosity of 10-25% by volume and a post-sintering density of 6.1-7.1 g/ cm3 , and is made of an iron-based sintered alloy material in which hard particles are dispersed in a matrix phase. The hard particles are particles made of one or more elements selected from C, Cr, Mo, Co, Si, Ni, S, and Fe, and are dispersed in the matrix phase by an area ratio of 5-40%. The composition of the matrix phase and the matrix portion including the hard particles is, in mass%, comprised of one or more elements selected from Ni: 2.0-23.0%, Cr: 0.4-15.0%, Mo: 3.0-15.0%, Cu: 0.2-3.0%, Co: 3.0-15.0%, V: 0.1-0.5%, Mn: 0.1-0.5%, W: 0.2-6.0%, C: 0.8-2.0%, Si: 0.1-1.0%, S: 0.1-1.0%, totalling 10.0-40.0%, with the remainder being Fe and unavoidable impurities. In addition, in Patent Document 2, as the above-mentioned hard particles, Cr-Mo-Co based intermetallic compound particles, Ni-Cr-Mo-Co based intermetallic compound particles, Fe-Mo alloy particles, Fe-Ni-Mo-S based alloy particles, and Fe-Mo-Si based alloy particles are exemplified.
また、特許文献３には、鉄基焼結合金製バルブシートが提案されている。特許文献３に記載された鉄基焼結合金製バルブシートは、基地相中に硬質粒子が分散し、全体の組成が、質量％で、Cr：5.0～20.0％、Si：0.4～2.0％、Ni：2.0～6.0％、Mo：5.0～25.0％、W：0.1～5.0％、V：0.5～5.0％、Nb：1.0％以下、C：0.5～1.5％、を含み、残部Fe及び不可避的不純物からなる組成を有する鉄基焼結合金製バルブシートである。特許文献３に記載された鉄基焼結合金製バルブシートでは、硬質粒子として、質量％で、Mo：40.0～70.0％、Si：0.4～2.0％、C：0.1％以下を含み、残部Feおよび不可避的不純物からなるFe－Mo－Si合金粒子を用いることが好ましいとしている。
Also, Patent Document 3 proposes an iron-based sintered alloy valve seat. The iron-based sintered alloy valve seat described in Patent Document 3 is an iron-based sintered alloy valve seat in which hard particles are dispersed in the matrix phase, and the overall composition is, by mass%, Cr: 5.0-20.0%, Si: 0.4-2.0%, Ni: 2.0-6.0%, Mo: 5.0-25.0%, W: 0.1-5.0%, V: 0.5-5.0%, Nb: 1.0% or less, C: 0.5-1.5%, with the balance being Fe and unavoidable impurities. In the iron-based sintered alloy valve seat described in Patent Document 3, it is preferable to use Fe-Mo-Si alloy particles as hard particles, which are, by mass%, Mo: 40.0-70.0%, Si: 0.4-2.0%, C: 0.1% or less, with the balance being Fe and unavoidable impurities.
また、特許文献４には、硬質粒子分散型鉄基焼結合金が提案されている。特許文献４に記載された硬質粒子分散型鉄基焼結合金は、重量百分率で、Si：0.4～2％、Ni：2～12％、Mo：3～12％、Cr：0.5～5％、V：0.6～4％、Nb：0.1～3％、C：0.5～2％、および残部Feを含む基地中に、合金全体を基準として3～20％の硬質粒子が分散されて焼結された鉄基焼結合金である。分散する硬質粒子はMo：60～70％、B：0.3～1％、C：0.1％以下を含み、残部Feを含む硬質粒子である。フェロモリブデン系硬質粒子にBを添加すると、Bは、フェロモリブデンの濡れ性を向上し、硬質粒子の基地からの脱落を防止し、基地と硬質粒子との密着性が向上し、焼結合金の熱的強度、機械的強度を向上できるとしている。
Also, Patent Document 4 proposes a hard particle dispersion type iron-based sintered alloy. The hard particle dispersion type iron-based sintered alloy described in Patent Document 4 is an iron-based sintered alloy in which 3 to 20% of hard particles are dispersed and sintered based on the entire alloy in a matrix containing, by weight percentage, 0.4 to 2% Si, 2 to 12% Ni, 3 to 12% Mo, 0.5 to 5% Cr, 0.6 to 4% V, 0.1 to 3% Nb, 0.5 to 2% C, and the balance Fe. The dispersed hard particles contain 60 to 70% Mo, 0.3 to 1% B, and 0.1% or less C, with the balance being Fe. When B is added to ferro-molybdenum-based hard particles, B improves the wettability of ferro-molybdenum, prevents the hard particles from falling off the matrix, and improves the adhesion between the matrix and the hard particles, thereby improving the thermal strength and mechanical strength of the sintered alloy.
特許文献１、２に記載されたバルブシートでは、基地相の高温強度や靭性の向上や、耐摩耗性の向上に寄与するとして、基地相や硬質粒子に多量のCoを含有させることが好ましいとしている。
In the valve seats described in Patent Documents 1 and 2, it is preferable to include a large amount of Co in the base phase and hard particles, as this contributes to improving the high-temperature strength and toughness of the base phase and improving wear resistance.
しかしながら、特許文献１、２に記載された鉄基焼結合金製バルブシートでは、圧環強さが低く、シリンダヘッドへの圧入に際し、割れが発生しやすく、また、バルブと接触するに際し、粒子が脱落しやすくなり、耐摩耗性が低下するなどの問題があった。また、特許文献１、２に記載された鉄基焼結合金製バルブシートではヤング率が低く変形しやすくなり、シール性が低下し、燃焼ガスが漏れるという問題もあった。
However, the iron-based sintered alloy valve seats described in Patent Documents 1 and 2 have problems such as low radial crushing strength, which makes them prone to cracking when pressed into a cylinder head, and particles easily falling off when they come into contact with the valve, resulting in reduced wear resistance.
Furthermore, the iron-based sintered alloy valve seats described in Patent Documents 1 and 2 have low Young's modulus, which makes them prone to deformation, resulting in reduced sealing performance and the leakage of combustion gas.
また、特許文献３、４に記載された技術では、分散させた鉄基硬質粒子がCoを含有しないことから、従来のCo基硬質粒子より割れ、欠けを生じやすい。そのため、基地相から硬質粒子が脱落し、とくに、近年の厳しいバルブシート使用環境下では、所望の耐摩耗性を確保できないという問題があることを知見した。
In addition, in the technology described in Patent Documents 3 and 4, the dispersed iron-based hard particles do not contain Co, and therefore are more susceptible to cracking and chipping than conventional Co-based hard particles. As a result, the hard particles fall off from the matrix phase, and it has been found that there is a problem in that the desired wear resistance cannot be ensured, particularly in the harsh valve seat operating environments of recent years.
本発明は、近年の厳しいバルブシート使用環境下においても、耐摩耗性に優れるうえ、圧環強さにも優れた、内燃機関用鉄基焼結合金製バルブシートを提供することを目的とする。なお、ここでいう「圧環強さに優れた」とは、JIS Z 2507 の規定に準拠して得られた圧環強さが490MPa以上である場合をいうものとする。
The object of the present invention is to provide an iron-based sintered alloy valve seat for internal combustion engines that has excellent wear resistance and radial crushing strength even in the harsh environments in which valve seats are used these days. Note that "excellent radial crushing strength" here refers to a radial crushing strength of 490 MPa or more obtained in accordance with the provisions of JIS Z 2507.
本発明者らは、上記した目的を達成するため、まず、圧環強さに影響する各種要因について、鋭意検討した。その結果、低い「圧環強さ」は、使用した鉄系粉末の圧縮性が低いことに起因するという知見を得た。その場合、使用した鉄系粉末では炭化物が粉末中ですでに析出し、粉末粒子の硬さが高くなり、圧粉成形時に、粉末粒子の塑性変形（圧縮）が不十分となり、そのため、焼結処理時の元素拡散も促進されにくく、結果として粒子間結合力が低下すると考えた。そこで、本発明では、圧粉成形時に十分な圧粉成形が可能で粉末粒子へ十分な塑性変形が付加できるように、基地相形成用の鉄系粉末として、炭素量の低い鉄系粉末を使用することに想到した。しかし、鉄系粉末の炭素量を低減しすぎると、炭化物量が少なくなり、焼結体の耐摩耗性が低下する。そのため、黒鉛粉末配合量を増加して、焼結体の炭素量が低下しないように配慮するとともに、炭化物量の増加のため、炭化物形成元素量を増加させた鉄系粉末を用いることとした。これより、焼結体における微細炭化物の析出量が、従来より著しく増加し、耐摩耗性、圧環強さが顕著に向上することを知見した。
In order to achieve the above-mentioned object, the inventors first conducted an intensive study of various factors that affect the radial crushing strength. As a result, they discovered that the low "radial crushing strength" is due to the low compressibility of the iron-based powder used. In that case, carbides are already precipitated in the iron-based powder used, which increases the hardness of the powder particles, and the plastic deformation (compression) of the powder particles during compaction is insufficient. Therefore, it was thought that the element diffusion during sintering is also difficult to promote, and as a result, the interparticle bonding force is reduced. Therefore, in the present invention, it was conceived to use an iron-based powder with a low carbon content as the iron-based powder for forming the matrix phase so that sufficient compaction can be achieved during compaction and sufficient plastic deformation can be applied to the powder particles. However, if the carbon content of the iron-based powder is reduced too much, the amount of carbide is reduced and the wear resistance of the sintered body is reduced. Therefore, it was decided to increase the amount of graphite powder to prevent the carbon content of the sintered body from decreasing, and to use an iron-based powder with an increased amount of carbide-forming elements to increase the amount of carbide. As a result, it was found that the amount of fine carbide precipitated in the sintered body was significantly increased compared to conventional methods, and that the wear resistance and radial crushing strength were significantly improved.
また、本発明では、適正量のNiとあるいはさらにCoを、基地中に含有させることにより、焼結の進行が顕著に促進され、耐摩耗性の低下もなく、圧環強さが向上することを知見した。
Furthermore, in the present invention, it was discovered that by incorporating an appropriate amount of Ni and/or Co into the matrix, the progress of sintering is significantly accelerated, and the radial crushing strength is improved without any decrease in wear resistance.
本発明は、かかる知見に基づき、さらに検討を加えて完成されたものである。すなわち、本発明の要旨は次のとおりである。
［１］内燃機関のシリンダーヘッドに圧入されるバルブシートであって、
該バルブシートが機能部材側層からなる単層構造を有し、
前記機能部材側層が、微細炭化物析出相からなる基地相と、該基地相中に面積率で、5.0～30.0％の高合金相と、10.0～40.0％の硬質粒子と、さらに0～4.0％の固体潤滑剤粒子を分散させてなる組織を有し、
前記硬質粒子が、ビッカース硬さで600～1200HVの硬さを有し、質量％で、Si：2.2～2.7％、Cr：7.5～9.5％、Mo：27.0～30.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo系Co基金属間化合物粒子またはSi：1.5～2.5％、Cr：24.0～26.0％、Mo：23.0～26.0％、Ni：9.5～11.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo－Ni系Co基金属間化合物粒子であり、
前記基地相、前記硬質粒子および前記固体潤滑剤粒子を含む基地部が、質量％で、C：0.50～2.80％を含み、さらに、Si：1.80％以下、Mn：2.50％以下、Cr：3.00～11.00％、Mo：3.00～17.00％、Ni：1.00～8.50％、Co：5.00～30.00％、V：0.50～4.00％、W：4.00～10.00％のうちから選ばれた１種または２種以上、およびS：0～2.00％を含有し、残部Feおよび不可避的不純物からなる基地部組成を有する鉄基焼結合金材からなり、
前記バルブシートの密度が6.6～7.4g/cm3であることを特徴とする内燃機関用鉄基焼結合金製バルブシート。
[２]内燃機関のシリンダーヘッドに圧入されるバルブシートであって、
該バルブシートが機能部材側層と支持部材側層とが一体で焼結された二層構造を有し、
前記機能部材側層が、微細炭化物析出相からなる基地相と、該基地相中に面積率で、5.0～30.0％の高合金相と、10.0～40.0％の硬質粒子と、さらに0～4.0％の固体潤滑剤粒子を分散させてなる組織を有し、
前記硬質粒子が、ビッカース硬さで600～1200HVの硬さを有し、質量％で、Si：2.2～2.7％、Cr：7.5～9.5％、Mo：27.0～30.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo系Co基金属間化合物粒子またはSi：1.5～2.5％、Cr：24.0～26.0％、Mo：23.0～26.0％、Ni：9.5～11.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo－Ni系Co基金属間化合物粒子であり、
前記基地相、前記硬質粒子および前記固体潤滑剤粒子を含む基地部が、質量％で、C：0.50～2.80％を含み、さらに、Si：1.80％以下、Mn：2.50％以下、Cr：3.00～11.00％、Mo：3.00～17.00％、Ni：1.00～8.50％、Co：5.00～30.00％、V：0.50～4.00％、W：4.00～10.00％のうちから選ばれた１種または２種以上、およびS：0～2.00％を含有し、残部Feおよび不可避的不純物からなる基地部組成を有し、
前記支持部材側層が、パーライトからなる基地相と、該基地相中に、面積率で0～4.0％の固体潤滑剤粒子および0～5.0％の硬度改善粒子を分散させてなる組織と、さらに前記基地相、前記固体潤滑剤粒子および前記硬度改善粒子を含む基地部が、質量％で、C：0.30～2.00％を含み、さらに、Ni：0～2.00％、Mo：0～2.00％、Cu：0～5.00％、Mn：0～5.00％およびS：0～2.00％を含有し、残部Feおよび不可避的不純物からなる組成と、を有する鉄基焼結合金材からなり、
前記バルブシートの密度が6.7～7.4g/cm3であることを特徴とする内燃機関用鉄基焼結合金製バルブシート。
［３］前記微細炭化物析出相は、粒径10μm以下の微細炭化物が析出し、ビッカース硬さで450～650HVの硬さを有する相であることを特徴とする[１]または[２]に記載の内燃機関用鉄基焼結合金製バルブシート。
［４］前記固体潤滑剤粒子が、硫化マンガンMnS、二硫化モリブデンMoS2のうちから選ばれた１種または２種であることを特徴とする[１]ないし[３]のいずれか一つに記載の内燃機関用鉄基焼結合金製バルブシート。
［５］前記硬度改善粒子が、鉄―モリブデン合金粒子であることを特徴とする[２]ないし［４］のいずれか一つに記載の鉄基焼結合金製バルブシート。
［６］前記鉄基焼結合金材の空孔には、熱硬化性樹脂または嫌気性樹脂が含浸されてなることを特徴とする［１］ないし［５］のいずれか一つに記載の内燃機関用鉄基焼結合金製バルブシート。
［７］［１］に記載の単層構造の鉄基焼結合金製バルブシートの製造方法であって、
鉄系粉末と、黒鉛粉末と、合金元素粉末と、硬質粒子粉末と、あるいはさらに固体潤滑剤粉末とを所定量配合し、混合、混錬して、混合粉としたのち、
前記混合粉を所定形状の金型に充填しプレス加工を施して圧粉体とし、ついで、
前記圧粉体に保護雰囲気中で焼結処理を施し焼結体としたのち、切削加工あるいはさらに研削加工を施して、所定形状のバルブシートを製造するに当たり、
前記鉄系粉末を、質量％で、C：0.2～0.8％、Si：1.0％以下、Mn：1.0％以下、Cr：7.0％以下、Mo：7.0％以下、V：5.0％以下、W：12.0％以下を含有し、あるいはさらにCo：12.0％以下を含有し、残部Feおよび不可避的不純物からなる組成を有し、ビッカース硬さで170～280HVの粒子硬さを有する鉄系粉末とし、該鉄系粉末を、前記混合粉全量に対する質量％で、40.0～70.0％配合し、
前記硬質粒子粉末を、ビッカース硬さで600～1200HVの硬さを有し、質量％で、Si：2.2～2.7％、Cr：7.5～9.5％、Mo：27.0～30.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo系Co基金属間化合物粒子またはSi：1.5～2.5％、Cr：24.0～26.0％、Mo：23.0～26.0％、Ni：9.5～11.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo－Ni系Co基金属間化合物粒子とし、該硬質粒子粉末を、前記混合粉全量に対する質量％で、10.0～40.0％配合し、
前記黒鉛粉末を、前記混合粉全量に対する質量％で、0.5～2.0％配合し、
前記合金元素粉末を、前記混合粉全量に対する質量％で、合計0～7.0％配合し、さらに、前記固体潤滑剤粉末を、前記混合粉全量に対する質量％で、0～4.0％配合し、
前記プレス加工を、前記圧粉体の密度が、密度:6.6/cm3以上となるように施し、
前記焼結処理を、焼結温度：1100～1200℃で行う処理として、前記焼結体を得ることを特徴とする鉄基焼結合金製バルブシートの製造方法。
［８］［２］に記載の二層構造の鉄基焼結合金製バルブシートの製造方法であって、
鉄系粉末と、黒鉛粉末と、合金元素粉末と、硬質粒子粉末と、あるいはさらに固体潤滑剤粉末とを所定量配合し、混合、混錬して、機能部材側層用混合粉とし、
鉄系粉末と、黒鉛粉末と、あるいはさらに合金元素粉末と、硬度改善粒子と、固体潤滑剤粉末とを所定量配合し、混合、混錬して、支持部材側層用混合粉とし、
前記機能部材側層用混合粉と前記支持部材側層用混合粉とをその順に、所定形状の金型に充填し、プレス加工を施して圧粉体とし、ついで、前記圧粉体に保護雰囲気中で焼結処理を施し、機能部材側層と支持部材側層とが一体で焼結された二層構造の焼結体としたのち、切削加工あるいはさらに研削加工を施して、所定形状の二層構造のバルブシートを製造するに当たり、
前記機能部材側層用混合粉では、前記鉄系粉末を、質量％で、C：0.2～0.8％、Si：1.0％以下、Mn：1.0％以下、Cr：7.0％以下、Mo：7.0％以下、V：5.0％以下、W：12.0％以下を含有し、あるいはさらにCo：12.0％以下を含有し、残部Feおよび不可避的不純物からなる組成を有し、ビッカース硬さで170～280HVの粒子硬さを有する鉄系粉末とし、該鉄系粉末を、前記混合粉全量に対する質量％で、40.0～70.0％配合し、
前記硬質粒子粉末を、ビッカース硬さで600～1200HVの硬さを有し、質量％で、Si：2.2～2.7％、Cr：7.5～9.5％、Mo：27.0～30.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo系Co基金属間化合物粒子またはSi：1.5～2.5％、Cr：24.0～26.0％、Mo：23.0～26.0％、Ni：9.5～11.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo－Ni系Co基金属間化合物粒子とし、該硬質粒子粉末を、前記混合粉全量に対する質量％で、10～40％配合し、
前記黒鉛粉末を、前記混合粉全量に対する質量％で、0.5～2.0％配合し、前記合金元素粉末を、前記混合粉全量に対する質量％で合計で、0～7.0％配合し、さらに、前記固体潤滑剤粒子粉末を、前記混合粉全量に対する質量％で、0～4.0％配合し、
前記支持部材側層用混合粉では、前記鉄系粉末を純鉄粉とし、前記黒鉛粉末を、前記支持部材側層用混合粉全量に対する質量％で、0.5～2.0％配合し、前記合金元素粉末を、前記支持部材側層用混合粉全量に対する質量％で、合計で0～5.0％配合し、前記硬度改善粒子粉末を鉄－モリブデン合金粒子粉末として、該硬度改善粒子粉末を前記支持部材側層用混合粉全量に対する質量％で、0～5.0％配合し、前記固体潤滑剤粉末を、前記支持部材側層用混合粉全量に対する質量％で、0～4.0％配合し、
前記プレス加工を、前記圧粉体の密度が、密度:6.6g/cm3以上となるように施し、
前記焼結処理を、焼結温度：1100～1200℃で行う処理として、
前記二層構造の焼結体とすることを特徴とする鉄基焼結合金製バルブシートの製造方法。
［９］前記焼結処理後に、さらに熱硬化性樹脂または嫌気性樹脂を含浸する樹脂含浸処理を施すことを特徴とする［７］または［８］に記載の鉄基焼結合金製バルブシートの製造方法。 The present invention has been completed based on these findings and through further investigation.
[1] A valve seat press-fitted into a cylinder head of an internal combustion engine,
the valve seat has a single-layer structure including a functional component-side layer,
the functional component-side layer has a structure in which a matrix phase consisting of a fine carbide precipitate phase, a high alloy phase of 5.0 to 30.0% by area, hard particles of 10.0 to 40.0% by area, and solid lubricant particles of 0 to 4.0% by area are dispersed in the matrix phase;
the hard particles are Si-Cr-Mo-based Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, in mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities; or Si-Cr-Mo-Ni-based Co-based intermetallic compound particles having a composition containing, in mass%, Si: 1.5 to 2.5%, Cr: 24.0 to 26.0%, Mo: 23.0 to 26.0%, Ni: 9.5 to 11.0%, with the balance being Co and unavoidable impurities;
the matrix portion including the matrix phase, the hard particles, and the solid lubricant particles is an iron-based sintered alloy material having a matrix composition containing, in mass %, C: 0.50 to 2.80%, one or more selected from Si: 1.80% or less, Mn: 2.50% or less, Cr: 3.00 to 11.00%, Mo: 3.00 to 17.00%, Ni: 1.00 to 8.50%, Co: 5.00 to 30.00%, V: 0.50 to 4.00%, W: 4.00 to 10.00%, and S: 0 to 2.00%, with the balance being Fe and unavoidable impurities;
An iron-based sintered alloy valve seat for an internal combustion engine, characterized in that the density of the valve seat is 6.6 to 7.4 g/ cm3 .
[2] A valve seat press-fitted into a cylinder head of an internal combustion engine,
the valve seat has a two-layer structure in which a functional member-side layer and a support member-side layer are sintered together,
the functional component-side layer has a structure in which a matrix phase consisting of a fine carbide precipitate phase, a high alloy phase of 5.0 to 30.0% by area, hard particles of 10.0 to 40.0% by area, and solid lubricant particles of 0 to 4.0% by area are dispersed in the matrix phase;
the hard particles are Si-Cr-Mo-based Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, in mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities; or Si-Cr-Mo-Ni-based Co-based intermetallic compound particles having a composition containing, in mass%, Si: 1.5 to 2.5%, Cr: 24.0 to 26.0%, Mo: 23.0 to 26.0%, Ni: 9.5 to 11.0%, with the balance being Co and unavoidable impurities;
the matrix portion including the matrix phase, the hard particles, and the solid lubricant particles contains, in mass %, C: 0.50 to 2.80%, one or more selected from Si: 1.80% or less, Mn: 2.50% or less, Cr: 3.00 to 11.00%, Mo: 3.00 to 17.00%, Ni: 1.00 to 8.50%, Co: 5.00 to 30.00%, V: 0.50 to 4.00%, W: 4.00 to 10.00%, and S: 0 to 2.00%, with the balance being Fe and unavoidable impurities;
the support member side layer is made of an iron-based sintered alloy material having a structure in which a matrix phase made of pearlite, 0-4.0% by area of solid lubricant particles and 0-5.0% by area of hardness improver particles are dispersed in the matrix phase, and the matrix portion containing the matrix phase, the solid lubricant particles and the hardness improver particles contains, by mass %, C: 0.30-2.00%, Ni: 0-2.00%, Mo: 0-2.00%, Cu: 0-5.00%, Mn: 0-5.00%, and S: 0-2.00%, with the balance being Fe and unavoidable impurities;
An iron-based sintered alloy valve seat for an internal combustion engine, characterized in that the density of the valve seat is 6.7 to 7.4 g/ cm3 .
[3] The valve seat made of an iron-based sintered alloy for an internal combustion engine according to [1] or [2], characterized in that the fine carbide precipitate phase is a phase in which fine carbides having a grain size of 10 μm or less are precipitated and has a Vickers hardness of 450 to 650 HV.
[4] The valve seat made of an iron-based sintered alloy for an internal combustion engine according to any one of [1] to [3], characterized in that the solid lubricant particles are one or two types selected from manganese sulfide (MnS) and molybdenum disulfide (MoS2).
[5] The valve seat made of an iron-based sintered alloy according to any one of [2] to [4], characterized in that the hardness improving particles are iron-molybdenum alloy particles.
[6] The iron-based sintered alloy valve seat for an internal combustion engine according to any one of [1] to [5], characterized in that the pores of the iron-based sintered alloy material are impregnated with a thermosetting resin or an anaerobic resin.
[7] A method for producing a valve seat made of a single-layered iron-based sintered alloy according to [1],
Predetermined amounts of iron-based powder, graphite powder, alloying element powder, hard particle powder, and/or solid lubricant powder are blended, mixed, and kneaded to obtain a mixed powder, and then
The mixed powder is filled into a mold of a predetermined shape and pressed to form a green compact, and then
The green compact is sintered in a protective atmosphere to produce a sintered body, which is then cut or ground to produce a valve seat having a desired shape.
the iron-based powder contains, by mass%, C: 0.2 to 0.8%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 7.0% or less, Mo: 7.0% or less, V: 5.0% or less, W: 12.0% or less, or further contains Co: 12.0% or less, the balance being Fe and unavoidable impurities, and has a particle hardness of 170 to 280 HV in Vickers hardness; the iron-based powder is blended in an amount of 40.0 to 70.0% by mass with respect to the total amount of the mixed powder;
the hard particle powder being Si-Cr-Mo Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, by mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities, or Si-Cr-Mo-Ni Co-based intermetallic compound particles having a composition containing, by mass%, Si: 1.5 to 2.5%, Cr: 24.0 to 26.0%, Mo: 23.0 to 26.0%, Ni: 9.5 to 11.0%, with the balance being Co and unavoidable impurities, the hard particle powder being blended in an amount of 10.0 to 40.0% by mass with respect to the total amount of the mixed powder;
The graphite powder is blended in an amount of 0.5 to 2.0% by mass relative to the total amount of the mixed powder,
The alloy element powder is blended in a total amount of 0 to 7.0% by mass with respect to the total amount of the mixed powder, and the solid lubricant powder is blended in a total amount of 0 to 4.0% by mass with respect to the total amount of the mixed powder,
The press working is performed so that the density of the powder compact is 6.6/ cm3 or more,
The method for producing an iron-based sintered alloy valve seat is characterized in that the sintering process is carried out at a sintering temperature of 1100 to 1200°C to obtain the sintered body.
[8] A method for producing a two-layered iron-based sintered alloy valve seat according to [2],
Predetermined amounts of iron-based powder, graphite powder, alloying element powder, hard particle powder, and/or solid lubricant powder are blended, mixed, and kneaded to obtain a mixed powder for a functional member side layer;
Predetermined amounts of iron-based powder, graphite powder, or alloying element powder, hardness improving particles, and solid lubricant powder are blended, mixed, and kneaded to obtain a mixed powder for a support member side layer;
The mixed powder for the functional member side layer and the mixed powder for the support member side layer are filled in this order into a die of a predetermined shape, and pressed to form a green compact. The green compact is then sintered in a protective atmosphere to form a two-layer sintered body in which the functional member side layer and the support member side layer are sintered together. The two-layer sintered body is then cut or further ground to produce a two-layer valve seat of a predetermined shape.
In the mixed powder for the functional component side layer, the iron-based powder contains, by mass%, C: 0.2 to 0.8%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 7.0% or less, Mo: 7.0% or less, V: 5.0% or less, W: 12.0% or less, or further contains Co: 12.0% or less, the balance being Fe and unavoidable impurities, and has a particle hardness of 170 to 280 HV in Vickers hardness, and the iron-based powder is blended in an amount of 40.0 to 70.0% by mass with respect to the total amount of the mixed powder,
the hard particle powder being Si-Cr-Mo Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, by mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities, or Si-Cr-Mo-Ni Co-based intermetallic compound particles having a composition containing, by mass%, Si: 1.5 to 2.5%, Cr: 24.0 to 26.0%, Mo: 23.0 to 26.0%, Ni: 9.5 to 11.0%, with the balance being Co and unavoidable impurities, the hard particle powder being blended in an amount of 10 to 40% by mass with respect to the total amount of the mixed powder;
The graphite powder is blended in an amount of 0.5 to 2.0% by mass based on the total amount of the mixed powder, the alloy element powders are blended in an amount of 0 to 7.0% by mass based on the total amount of the mixed powder, and the solid lubricant particle powder is blended in an amount of 0 to 4.0% by mass based on the total amount of the mixed powder,
In the mixed powder for the support member side layer, the iron-based powder is pure iron powder, the graphite powder is blended in an amount of 0.5 to 2.0% by mass based on the total amount of the mixed powder for the support member side layer, the alloy element powder is blended in a total amount of 0 to 5.0% by mass based on the total amount of the mixed powder for the support member side layer, the hardness improving particle powder is iron-molybdenum alloy particle powder, the hardness improving particle powder is blended in an amount of 0 to 5.0% by mass based on the total amount of the mixed powder for the support member side layer, and the solid lubricant powder is blended in an amount of 0 to 4.0% by mass based on the total amount of the mixed powder for the support member side layer,
The press working is performed so that the density of the powder compact is 6.6 g/ cm3 or more,
The sintering process is carried out at a sintering temperature of 1100 to 1200°C.
A method for producing an iron-based sintered alloy valve seat, characterized in that the above-mentioned two-layer structure sintered body is obtained.
[9] The method for producing an iron-based sintered alloy valve seat according to [7] or [8], further comprising the step of carrying out a resin impregnation treatment for impregnating a thermosetting resin or an anaerobic resin after the sintering treatment.
［１］内燃機関のシリンダーヘッドに圧入されるバルブシートであって、
該バルブシートが機能部材側層からなる単層構造を有し、
前記機能部材側層が、微細炭化物析出相からなる基地相と、該基地相中に面積率で、5.0～30.0％の高合金相と、10.0～40.0％の硬質粒子と、さらに0～4.0％の固体潤滑剤粒子を分散させてなる組織を有し、
前記硬質粒子が、ビッカース硬さで600～1200HVの硬さを有し、質量％で、Si：2.2～2.7％、Cr：7.5～9.5％、Mo：27.0～30.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo系Co基金属間化合物粒子またはSi：1.5～2.5％、Cr：24.0～26.0％、Mo：23.0～26.0％、Ni：9.5～11.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo－Ni系Co基金属間化合物粒子であり、
前記基地相、前記硬質粒子および前記固体潤滑剤粒子を含む基地部が、質量％で、C：0.50～2.80％を含み、さらに、Si：1.80％以下、Mn：2.50％以下、Cr：3.00～11.00％、Mo：3.00～17.00％、Ni：1.00～8.50％、Co：5.00～30.00％、V：0.50～4.00％、W：4.00～10.00％のうちから選ばれた１種または２種以上、およびS：0～2.00％を含有し、残部Feおよび不可避的不純物からなる基地部組成を有する鉄基焼結合金材からなり、
前記バルブシートの密度が6.6～7.4g/cm3であることを特徴とする内燃機関用鉄基焼結合金製バルブシート。
[２]内燃機関のシリンダーヘッドに圧入されるバルブシートであって、
該バルブシートが機能部材側層と支持部材側層とが一体で焼結された二層構造を有し、
前記機能部材側層が、微細炭化物析出相からなる基地相と、該基地相中に面積率で、5.0～30.0％の高合金相と、10.0～40.0％の硬質粒子と、さらに0～4.0％の固体潤滑剤粒子を分散させてなる組織を有し、
前記硬質粒子が、ビッカース硬さで600～1200HVの硬さを有し、質量％で、Si：2.2～2.7％、Cr：7.5～9.5％、Mo：27.0～30.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo系Co基金属間化合物粒子またはSi：1.5～2.5％、Cr：24.0～26.0％、Mo：23.0～26.0％、Ni：9.5～11.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo－Ni系Co基金属間化合物粒子であり、
前記基地相、前記硬質粒子および前記固体潤滑剤粒子を含む基地部が、質量％で、C：0.50～2.80％を含み、さらに、Si：1.80％以下、Mn：2.50％以下、Cr：3.00～11.00％、Mo：3.00～17.00％、Ni：1.00～8.50％、Co：5.00～30.00％、V：0.50～4.00％、W：4.00～10.00％のうちから選ばれた１種または２種以上、およびS：0～2.00％を含有し、残部Feおよび不可避的不純物からなる基地部組成を有し、
前記支持部材側層が、パーライトからなる基地相と、該基地相中に、面積率で0～4.0％の固体潤滑剤粒子および0～5.0％の硬度改善粒子を分散させてなる組織と、さらに前記基地相、前記固体潤滑剤粒子および前記硬度改善粒子を含む基地部が、質量％で、C：0.30～2.00％を含み、さらに、Ni：0～2.00％、Mo：0～2.00％、Cu：0～5.00％、Mn：0～5.00％およびS：0～2.00％を含有し、残部Feおよび不可避的不純物からなる組成と、を有する鉄基焼結合金材からなり、
前記バルブシートの密度が6.7～7.4g/cm3であることを特徴とする内燃機関用鉄基焼結合金製バルブシート。
［３］前記微細炭化物析出相は、粒径10μm以下の微細炭化物が析出し、ビッカース硬さで450～650HVの硬さを有する相であることを特徴とする[１]または[２]に記載の内燃機関用鉄基焼結合金製バルブシート。
［４］前記固体潤滑剤粒子が、硫化マンガンMnS、二硫化モリブデンMoS2のうちから選ばれた１種または２種であることを特徴とする[１]ないし[３]のいずれか一つに記載の内燃機関用鉄基焼結合金製バルブシート。
［５］前記硬度改善粒子が、鉄―モリブデン合金粒子であることを特徴とする[２]ないし［４］のいずれか一つに記載の鉄基焼結合金製バルブシート。
［６］前記鉄基焼結合金材の空孔には、熱硬化性樹脂または嫌気性樹脂が含浸されてなることを特徴とする［１］ないし［５］のいずれか一つに記載の内燃機関用鉄基焼結合金製バルブシート。
［７］［１］に記載の単層構造の鉄基焼結合金製バルブシートの製造方法であって、
鉄系粉末と、黒鉛粉末と、合金元素粉末と、硬質粒子粉末と、あるいはさらに固体潤滑剤粉末とを所定量配合し、混合、混錬して、混合粉としたのち、
前記混合粉を所定形状の金型に充填しプレス加工を施して圧粉体とし、ついで、
前記圧粉体に保護雰囲気中で焼結処理を施し焼結体としたのち、切削加工あるいはさらに研削加工を施して、所定形状のバルブシートを製造するに当たり、
前記鉄系粉末を、質量％で、C：0.2～0.8％、Si：1.0％以下、Mn：1.0％以下、Cr：7.0％以下、Mo：7.0％以下、V：5.0％以下、W：12.0％以下を含有し、あるいはさらにCo：12.0％以下を含有し、残部Feおよび不可避的不純物からなる組成を有し、ビッカース硬さで170～280HVの粒子硬さを有する鉄系粉末とし、該鉄系粉末を、前記混合粉全量に対する質量％で、40.0～70.0％配合し、
前記硬質粒子粉末を、ビッカース硬さで600～1200HVの硬さを有し、質量％で、Si：2.2～2.7％、Cr：7.5～9.5％、Mo：27.0～30.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo系Co基金属間化合物粒子またはSi：1.5～2.5％、Cr：24.0～26.0％、Mo：23.0～26.0％、Ni：9.5～11.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo－Ni系Co基金属間化合物粒子とし、該硬質粒子粉末を、前記混合粉全量に対する質量％で、10.0～40.0％配合し、
前記黒鉛粉末を、前記混合粉全量に対する質量％で、0.5～2.0％配合し、
前記合金元素粉末を、前記混合粉全量に対する質量％で、合計0～7.0％配合し、さらに、前記固体潤滑剤粉末を、前記混合粉全量に対する質量％で、0～4.0％配合し、
前記プレス加工を、前記圧粉体の密度が、密度:6.6/cm3以上となるように施し、
前記焼結処理を、焼結温度：1100～1200℃で行う処理として、前記焼結体を得ることを特徴とする鉄基焼結合金製バルブシートの製造方法。
［８］［２］に記載の二層構造の鉄基焼結合金製バルブシートの製造方法であって、
鉄系粉末と、黒鉛粉末と、合金元素粉末と、硬質粒子粉末と、あるいはさらに固体潤滑剤粉末とを所定量配合し、混合、混錬して、機能部材側層用混合粉とし、
鉄系粉末と、黒鉛粉末と、あるいはさらに合金元素粉末と、硬度改善粒子と、固体潤滑剤粉末とを所定量配合し、混合、混錬して、支持部材側層用混合粉とし、
前記機能部材側層用混合粉と前記支持部材側層用混合粉とをその順に、所定形状の金型に充填し、プレス加工を施して圧粉体とし、ついで、前記圧粉体に保護雰囲気中で焼結処理を施し、機能部材側層と支持部材側層とが一体で焼結された二層構造の焼結体としたのち、切削加工あるいはさらに研削加工を施して、所定形状の二層構造のバルブシートを製造するに当たり、
前記機能部材側層用混合粉では、前記鉄系粉末を、質量％で、C：0.2～0.8％、Si：1.0％以下、Mn：1.0％以下、Cr：7.0％以下、Mo：7.0％以下、V：5.0％以下、W：12.0％以下を含有し、あるいはさらにCo：12.0％以下を含有し、残部Feおよび不可避的不純物からなる組成を有し、ビッカース硬さで170～280HVの粒子硬さを有する鉄系粉末とし、該鉄系粉末を、前記混合粉全量に対する質量％で、40.0～70.0％配合し、
前記硬質粒子粉末を、ビッカース硬さで600～1200HVの硬さを有し、質量％で、Si：2.2～2.7％、Cr：7.5～9.5％、Mo：27.0～30.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo系Co基金属間化合物粒子またはSi：1.5～2.5％、Cr：24.0～26.0％、Mo：23.0～26.0％、Ni：9.5～11.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo－Ni系Co基金属間化合物粒子とし、該硬質粒子粉末を、前記混合粉全量に対する質量％で、10～40％配合し、
前記黒鉛粉末を、前記混合粉全量に対する質量％で、0.5～2.0％配合し、前記合金元素粉末を、前記混合粉全量に対する質量％で合計で、0～7.0％配合し、さらに、前記固体潤滑剤粒子粉末を、前記混合粉全量に対する質量％で、0～4.0％配合し、
前記支持部材側層用混合粉では、前記鉄系粉末を純鉄粉とし、前記黒鉛粉末を、前記支持部材側層用混合粉全量に対する質量％で、0.5～2.0％配合し、前記合金元素粉末を、前記支持部材側層用混合粉全量に対する質量％で、合計で0～5.0％配合し、前記硬度改善粒子粉末を鉄－モリブデン合金粒子粉末として、該硬度改善粒子粉末を前記支持部材側層用混合粉全量に対する質量％で、0～5.0％配合し、前記固体潤滑剤粉末を、前記支持部材側層用混合粉全量に対する質量％で、0～4.0％配合し、
前記プレス加工を、前記圧粉体の密度が、密度:6.6g/cm3以上となるように施し、
前記焼結処理を、焼結温度：1100～1200℃で行う処理として、
前記二層構造の焼結体とすることを特徴とする鉄基焼結合金製バルブシートの製造方法。
［９］前記焼結処理後に、さらに熱硬化性樹脂または嫌気性樹脂を含浸する樹脂含浸処理を施すことを特徴とする［７］または［８］に記載の鉄基焼結合金製バルブシートの製造方法。 The present invention has been completed based on these findings and through further investigation.
[1] A valve seat press-fitted into a cylinder head of an internal combustion engine,
the valve seat has a single-layer structure including a functional component-side layer,
the functional component-side layer has a structure in which a matrix phase consisting of a fine carbide precipitate phase, a high alloy phase of 5.0 to 30.0% by area, hard particles of 10.0 to 40.0% by area, and solid lubricant particles of 0 to 4.0% by area are dispersed in the matrix phase;
the hard particles are Si-Cr-Mo-based Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, in mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities; or Si-Cr-Mo-Ni-based Co-based intermetallic compound particles having a composition containing, in mass%, Si: 1.5 to 2.5%, Cr: 24.0 to 26.0%, Mo: 23.0 to 26.0%, Ni: 9.5 to 11.0%, with the balance being Co and unavoidable impurities;
the matrix portion including the matrix phase, the hard particles, and the solid lubricant particles is an iron-based sintered alloy material having a matrix composition containing, in mass %, C: 0.50 to 2.80%, one or more selected from Si: 1.80% or less, Mn: 2.50% or less, Cr: 3.00 to 11.00%, Mo: 3.00 to 17.00%, Ni: 1.00 to 8.50%, Co: 5.00 to 30.00%, V: 0.50 to 4.00%, W: 4.00 to 10.00%, and S: 0 to 2.00%, with the balance being Fe and unavoidable impurities;
An iron-based sintered alloy valve seat for an internal combustion engine, characterized in that the density of the valve seat is 6.6 to 7.4 g/ cm3 .
[2] A valve seat press-fitted into a cylinder head of an internal combustion engine,
the valve seat has a two-layer structure in which a functional member-side layer and a support member-side layer are sintered together,
the functional component-side layer has a structure in which a matrix phase consisting of a fine carbide precipitate phase, a high alloy phase of 5.0 to 30.0% by area, hard particles of 10.0 to 40.0% by area, and solid lubricant particles of 0 to 4.0% by area are dispersed in the matrix phase;
the hard particles are Si-Cr-Mo-based Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, in mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities; or Si-Cr-Mo-Ni-based Co-based intermetallic compound particles having a composition containing, in mass%, Si: 1.5 to 2.5%, Cr: 24.0 to 26.0%, Mo: 23.0 to 26.0%, Ni: 9.5 to 11.0%, with the balance being Co and unavoidable impurities;
the matrix portion including the matrix phase, the hard particles, and the solid lubricant particles contains, in mass %, C: 0.50 to 2.80%, one or more selected from Si: 1.80% or less, Mn: 2.50% or less, Cr: 3.00 to 11.00%, Mo: 3.00 to 17.00%, Ni: 1.00 to 8.50%, Co: 5.00 to 30.00%, V: 0.50 to 4.00%, W: 4.00 to 10.00%, and S: 0 to 2.00%, with the balance being Fe and unavoidable impurities;
the support member side layer is made of an iron-based sintered alloy material having a structure in which a matrix phase made of pearlite, 0-4.0% by area of solid lubricant particles and 0-5.0% by area of hardness improver particles are dispersed in the matrix phase, and the matrix portion containing the matrix phase, the solid lubricant particles and the hardness improver particles contains, by mass %, C: 0.30-2.00%, Ni: 0-2.00%, Mo: 0-2.00%, Cu: 0-5.00%, Mn: 0-5.00%, and S: 0-2.00%, with the balance being Fe and unavoidable impurities;
An iron-based sintered alloy valve seat for an internal combustion engine, characterized in that the density of the valve seat is 6.7 to 7.4 g/ cm3 .
[3] The valve seat made of an iron-based sintered alloy for an internal combustion engine according to [1] or [2], characterized in that the fine carbide precipitate phase is a phase in which fine carbides having a grain size of 10 μm or less are precipitated and has a Vickers hardness of 450 to 650 HV.
[4] The valve seat made of an iron-based sintered alloy for an internal combustion engine according to any one of [1] to [3], characterized in that the solid lubricant particles are one or two types selected from manganese sulfide (MnS) and molybdenum disulfide (MoS2).
[5] The valve seat made of an iron-based sintered alloy according to any one of [2] to [4], characterized in that the hardness improving particles are iron-molybdenum alloy particles.
[6] The iron-based sintered alloy valve seat for an internal combustion engine according to any one of [1] to [5], characterized in that the pores of the iron-based sintered alloy material are impregnated with a thermosetting resin or an anaerobic resin.
[7] A method for producing a valve seat made of a single-layered iron-based sintered alloy according to [1],
Predetermined amounts of iron-based powder, graphite powder, alloying element powder, hard particle powder, and/or solid lubricant powder are blended, mixed, and kneaded to obtain a mixed powder, and then
The mixed powder is filled into a mold of a predetermined shape and pressed to form a green compact, and then
The green compact is sintered in a protective atmosphere to produce a sintered body, which is then cut or ground to produce a valve seat having a desired shape.
the iron-based powder contains, by mass%, C: 0.2 to 0.8%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 7.0% or less, Mo: 7.0% or less, V: 5.0% or less, W: 12.0% or less, or further contains Co: 12.0% or less, the balance being Fe and unavoidable impurities, and has a particle hardness of 170 to 280 HV in Vickers hardness; the iron-based powder is blended in an amount of 40.0 to 70.0% by mass with respect to the total amount of the mixed powder;
the hard particle powder being Si-Cr-Mo Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, by mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities, or Si-Cr-Mo-Ni Co-based intermetallic compound particles having a composition containing, by mass%, Si: 1.5 to 2.5%, Cr: 24.0 to 26.0%, Mo: 23.0 to 26.0%, Ni: 9.5 to 11.0%, with the balance being Co and unavoidable impurities, the hard particle powder being blended in an amount of 10.0 to 40.0% by mass with respect to the total amount of the mixed powder;
The graphite powder is blended in an amount of 0.5 to 2.0% by mass relative to the total amount of the mixed powder,
The alloy element powder is blended in a total amount of 0 to 7.0% by mass with respect to the total amount of the mixed powder, and the solid lubricant powder is blended in a total amount of 0 to 4.0% by mass with respect to the total amount of the mixed powder,
The press working is performed so that the density of the powder compact is 6.6/ cm3 or more,
The method for producing an iron-based sintered alloy valve seat is characterized in that the sintering process is carried out at a sintering temperature of 1100 to 1200°C to obtain the sintered body.
[8] A method for producing a two-layered iron-based sintered alloy valve seat according to [2],
Predetermined amounts of iron-based powder, graphite powder, alloying element powder, hard particle powder, and/or solid lubricant powder are blended, mixed, and kneaded to obtain a mixed powder for a functional member side layer;
Predetermined amounts of iron-based powder, graphite powder, or alloying element powder, hardness improving particles, and solid lubricant powder are blended, mixed, and kneaded to obtain a mixed powder for a support member side layer;
The mixed powder for the functional member side layer and the mixed powder for the support member side layer are filled in this order into a die of a predetermined shape, and pressed to form a green compact. The green compact is then sintered in a protective atmosphere to form a two-layer sintered body in which the functional member side layer and the support member side layer are sintered together. The two-layer sintered body is then cut or further ground to produce a two-layer valve seat of a predetermined shape.
In the mixed powder for the functional component side layer, the iron-based powder contains, by mass%, C: 0.2 to 0.8%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 7.0% or less, Mo: 7.0% or less, V: 5.0% or less, W: 12.0% or less, or further contains Co: 12.0% or less, the balance being Fe and unavoidable impurities, and has a particle hardness of 170 to 280 HV in Vickers hardness, and the iron-based powder is blended in an amount of 40.0 to 70.0% by mass with respect to the total amount of the mixed powder,
the hard particle powder being Si-Cr-Mo Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, by mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities, or Si-Cr-Mo-Ni Co-based intermetallic compound particles having a composition containing, by mass%, Si: 1.5 to 2.5%, Cr: 24.0 to 26.0%, Mo: 23.0 to 26.0%, Ni: 9.5 to 11.0%, with the balance being Co and unavoidable impurities, the hard particle powder being blended in an amount of 10 to 40% by mass with respect to the total amount of the mixed powder;
The graphite powder is blended in an amount of 0.5 to 2.0% by mass based on the total amount of the mixed powder, the alloy element powders are blended in an amount of 0 to 7.0% by mass based on the total amount of the mixed powder, and the solid lubricant particle powder is blended in an amount of 0 to 4.0% by mass based on the total amount of the mixed powder,
In the mixed powder for the support member side layer, the iron-based powder is pure iron powder, the graphite powder is blended in an amount of 0.5 to 2.0% by mass based on the total amount of the mixed powder for the support member side layer, the alloy element powder is blended in a total amount of 0 to 5.0% by mass based on the total amount of the mixed powder for the support member side layer, the hardness improving particle powder is iron-molybdenum alloy particle powder, the hardness improving particle powder is blended in an amount of 0 to 5.0% by mass based on the total amount of the mixed powder for the support member side layer, and the solid lubricant powder is blended in an amount of 0 to 4.0% by mass based on the total amount of the mixed powder for the support member side layer,
The press working is performed so that the density of the powder compact is 6.6 g/ cm3 or more,
The sintering process is carried out at a sintering temperature of 1100 to 1200°C.
A method for producing an iron-based sintered alloy valve seat, characterized in that the above-mentioned two-layer structure sintered body is obtained.
[9] The method for producing an iron-based sintered alloy valve seat according to [7] or [8], further comprising the step of carrying out a resin impregnation treatment for impregnating a thermosetting resin or an anaerobic resin after the sintering treatment.
本発明によれば、耐摩耗性に優れるうえ、圧環強さにも優れた内燃機関用鉄基焼結合金製バルブシートを製造でき、産業上格段の効果を奏する。
The present invention makes it possible to manufacture iron-based sintered alloy valve seats for internal combustion engines that are excellent in both wear resistance and radial crushing strength, providing significant benefits to the industry.
本発明バルブシートは、機能部材側層のみの単層構造の鉄基焼結合金製バルブシートであるか、または機能部材側層と支持部材側層とを一体的に焼結した二層構造の鉄基焼結合金製バルブシートである。
The valve seat of the present invention is an iron-based sintered alloy valve seat with a single-layer structure consisting of only a functional component layer, or an iron-based sintered alloy valve seat with a two-layer structure in which a functional component layer and a support component layer are sintered together.
まず、機能部材側層について説明する。
First, we will explain the functional component side layer.
機能部材側層は、微細炭化物析出相からなる基地相と、該基地相中に、組織全体に対する面積率で、5.0～30.0％の高合金相、10.0～40.0％の硬質粒子および0～4.0％の固体潤滑剤粒子をそれぞれ分散させた組織を有する。なお、高合金相、硬質粒子および固体潤滑剤粒子以外の残部は、基地相および空孔である。なお、空孔には、熱硬化性樹脂または嫌気性樹脂を含浸させることが好ましい。空孔に、熱硬化性樹脂または嫌気性樹脂を含浸させ、封孔することにより、耐摩耗性の低下を伴うことなく、切削性、被削性が向上するとともに、耐食性の向上も期待できる。
空孔は真密度、機能部材側層の密度から計算でも求めることができる。 The functional component side layer has a matrix phase consisting of a fine carbide precipitate phase, and a structure in which 5.0-30.0% of a high alloy phase, 10.0-40.0% of hard particles, and 0-4.0% of solid lubricant particles are dispersed in the matrix phase, with the area ratio relative to the entire structure. The remainder other than the high alloy phase, hard particles, and solid lubricant particles is the matrix phase and pores. The pores are preferably impregnated with a thermosetting resin or an anaerobic resin. By impregnating and sealing the pores with a thermosetting resin or an anaerobic resin, the cutting and machinability are improved without a decrease in wear resistance, and the corrosion resistance can also be improved.
The voids can also be calculated from the true density and the density of the functional component side layer.
空孔は真密度、機能部材側層の密度から計算でも求めることができる。 The functional component side layer has a matrix phase consisting of a fine carbide precipitate phase, and a structure in which 5.0-30.0% of a high alloy phase, 10.0-40.0% of hard particles, and 0-4.0% of solid lubricant particles are dispersed in the matrix phase, with the area ratio relative to the entire structure. The remainder other than the high alloy phase, hard particles, and solid lubricant particles is the matrix phase and pores. The pores are preferably impregnated with a thermosetting resin or an anaerobic resin. By impregnating and sealing the pores with a thermosetting resin or an anaerobic resin, the cutting and machinability are improved without a decrease in wear resistance, and the corrosion resistance can also be improved.
The voids can also be calculated from the true density and the density of the functional component side layer.
基地相は、微細炭化物析出相とする。
The base phase is a fine carbide precipitation phase.
微細炭化物析出相は、粒径：10μm以下の微細炭化物が析出した相であり、ビッカース硬さで450HV以上好ましくは650HV以下の硬さを有する硬質な相である。このような硬質の微細炭化物析出相の存在により、基地が強化でき、耐摩耗性がより向上する。基地相中に析出する炭化物の粒径が、10μmを超えて大きくなると、基地相の硬さ、靭性が低下し相手攻撃性が増加し、圧環強さが低下する。
The fine carbide precipitation phase is a phase in which fine carbides with a particle size of 10 μm or less are precipitated, and is a hard phase with a Vickers hardness of 450 HV or more, preferably 650 HV or less. The presence of such a hard fine carbide precipitation phase strengthens the matrix, further improving its wear resistance. If the particle size of the carbides precipitated in the matrix phase exceeds 10 μm, the hardness and toughness of the matrix phase decrease, the aggressiveness against the mating member increases, and the radial crushing strength decreases.
基地相中に分散する高合金相は、焼結時に、硬質粒子や添加元素から合金元素が拡散し合金量が高くなった領域である。高合金相は、とくに硬質粒子の脱落を防止する作用を有し、ビッカース硬さで170HV以上好ましくは280HV以下の硬さを有することが好ましい。高合金相は、上記した作用を得るために、組織全体に対する面積率で、5.0％以上の含有を必要とする。一方、30.0％を超えて高合金相を含有すると、バルブシートの強度が低下する。このため、高合金相は、面積率で、5.0～30.0％の範囲とした。なお、好ましくは10.0～20.0％である。
The high alloy phase dispersed in the matrix phase is an area where the alloying elements diffuse from the hard particles and added elements during sintering, resulting in a high alloy content. The high alloy phase has the effect of preventing hard particles from falling off, and preferably has a Vickers hardness of 170HV or more, and preferably 280HV or less. In order to obtain the above-mentioned effect, the high alloy phase must be present in an area ratio of 5.0% or more relative to the entire structure. On the other hand, if the high alloy phase is present in an amount exceeding 30.0%, the strength of the valve seat decreases. For this reason, the area ratio of the high alloy phase is set to be in the range of 5.0 to 30.0%, with a range of 10.0 to 20.0% being preferable.
分散する硬質粒子は、ビッカース硬さで600～1200HVの硬さを有する硬質粒子とする。硬質粒子の硬さが、600HV未満では、耐摩耗性の向上効果が少ない。一方、1200HVを超えて高くなると、被削性の低下を招く。このため、基地相中に分散させる硬質粒子の硬さはビッカース硬さで600～1200HVの範囲に限定した。
The hard particles to be dispersed are those having a Vickers hardness of 600 to 1200HV. If the hardness of the hard particles is less than 600HV, there is little effect in improving wear resistance. On the other hand, if the hardness exceeds 1200HV, it will lead to a decrease in machinability. For this reason, the hardness of the hard particles dispersed in the matrix phase is limited to the range of 600 to 1200HV on the Vickers hardness scale.
本発明では、上記した硬さの硬質粒子を基地相中に、組織全体（基地相、硬質粒子、固体潤滑剤粒子、空孔を含む）に対する面積率で、10.0～40.0％分散させる。硬質粒子の分散量が10.0％未満では、所望の耐摩耗性を確保できない。一方、40.0％を超えると、基地相との結合力が低下し、耐摩耗性が低下する。このため、基地相中に分散させる硬質粒子の分散量は面積率で、10.0～40.0％の範囲に限定した。
In the present invention, hard particles having the above-mentioned hardness are dispersed in the matrix phase at an area ratio of 10.0 to 40.0% relative to the entire structure (including the matrix phase, hard particles, solid lubricant particles, and pores). If the amount of dispersed hard particles is less than 10.0%, the desired wear resistance cannot be ensured. On the other hand, if it exceeds 40.0%, the bonding strength with the matrix phase decreases, and wear resistance decreases. For this reason, the amount of dispersed hard particles in the matrix phase is limited to a range of 10.0 to 40.0% in area ratio.
なお、硬質粒子は、上記硬さを有し、平均粒径：10～150μmの粒子とすることが好ましい。硬質粒子の平均粒径が10μm未満では、焼結時に過拡散しやすく、一方、150μmを超えて大きくなると、基地との結合力が低下し、耐摩耗性が低下する。このため、基地相中に分散させる硬質粒子の平均粒径は10～150μmの範囲に限定することが好ましい。なお、ここでいう「平均粒径」は、レーザ散乱法で測定した累積分布が50％となる粒径D50を意味する。
The hard particles preferably have the above hardness and an average particle size of 10 to 150 μm. If the average particle size of the hard particles is less than 10 μm, they are prone to over-diffusion during sintering, while if it exceeds 150 μm, the bonding strength with the matrix decreases and wear resistance decreases. For this reason, it is preferable to limit the average particle size of the hard particles dispersed in the matrix phase to the range of 10 to 150 μm. Note that "average particle size" here refers to the particle size D50 at which the cumulative distribution measured by the laser scattering method is 50%.
そして、本発明で、基地相中に分散させる硬質粒子は、質量％で、Si：2.2～2.7％、Cr：7.5～9.5％、Mo：27.0～30.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo系Co基金属間化合物粒子またはSi：1.5～2.5％、Cr：24.0～26.0％、Mo：23.0～26.0％、Ni：9.5～11.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo－Ni系Co基金属間化合物粒子とする。分散する硬質粒子を上記した組成のCo基金属間化合物粒子とすることにより、焼結時に合金元素の拡散が顕著となり、硬質粒子の周囲に高合金相を形成しやすくなる。
In the present invention, the hard particles dispersed in the matrix phase are Si-Cr-Mo Co-based intermetallic compound particles having a composition, by mass%, of Si: 2.2-2.7%, Cr: 7.5-9.5%, Mo: 27.0-30.0%, with the balance being Co and unavoidable impurities, or Si-Cr-Mo-Ni Co-based intermetallic compound particles having a composition, by mass%, of Si: 1.5-2.5%, Cr: 24.0-26.0%, Mo: 23.0-26.0%, Ni: 9.5-11.0%, with the balance being Co and unavoidable impurities. By using Co-based intermetallic compound particles with the above composition as the dispersed hard particles, the diffusion of alloy elements becomes significant during sintering, making it easier to form a high alloy phase around the hard particles.
また、本発明バルブシートの機能部材側層では、さらに基地相中に固体潤滑剤粒子を4.0％以下分散させてもよい。基地相中に固体潤滑剤粒子を分散させることにより、被削性、潤滑性が向上する。しかし、面積率で4.0％を超えて分散させると、機械的特性の低下が著しくなる。このため、固体潤滑剤粒子は、面積率で0～4.0％の範囲に限定した。なお、固体潤滑剤粒子は、硫化マンガンMnS、二硫化モリブデンMoS2のうちから選ばれた１種または２種とすることが好ましい。
In addition, in the functional component side layer of the valve seat of the present invention, solid lubricant particles may be further dispersed in the matrix phase at 4.0% or less. Dispersing the solid lubricant particles in the matrix phase improves machinability and lubricity. However, if the area ratio is more than 4.0%, the mechanical properties will be significantly deteriorated. For this reason, the area ratio of the solid lubricant particles is limited to the range of 0 to 4.0%. The solid lubricant particles are preferably one or two types selected from manganese sulfide MnS and molybdenum disulfide MoS2 .
また、本発明バルブシートの機能部材側層は、基地相、高合金相、硬質粒子および固体潤滑剤粒子を含む基地部が、質量％で、C：0.50～2.80％を含み、さらに、Si：1.80％以下、Mn：2.50％以下、Cr：3.00～11.00％、Mo：3.00～17.00％、Ni：1.00～8.50％、Co：5.00～30.00％、V：0.50～4.00％、W：4.00～10.00％のうちから選ばれた１種または２種以上、およびS：0～2.00％を含有し、残部Feおよび不可避的不純物からなる組成（基地部組成）を有する。
In addition, the functional member side layer of the valve seat of the present invention has a composition (base composition) consisting of a base phase, a high alloy phase, hard particles, and solid lubricant particles, the base portion containing, by mass%, C: 0.50-2.80%, one or more selected from Si: 1.80% or less, Mn: 2.50% or less, Cr: 3.00-11.00%, Mo: 3.00-17.00%, Ni: 1.00-8.50%, Co: 5.00-30.00%, V: 0.50-4.00%, W: 4.00-10.00%, and S: 0-2.00%, with the remainder being Fe and unavoidable impurities.
つぎに、機能部材側層の基地部組成における限定理由について説明する。なお、以下、組成における質量％は、単に％で記す。
Next, we will explain the reasons for limiting the composition of the base part of the functional component side layer. Note that hereafter, mass % in the composition will simply be expressed as %.
C：0.50～2.80％
Cは、基地相を所定の硬さ、組織に調整するため、あるいは炭化物を形成するために必要な元素であり、0.50％以上含有させる。一方、2.80％を超えて含有すると、融点が低下し、焼結処理が液相焼結となる。液相焼結となると、析出炭化物量が多くなりすぎ、また、空孔の数が増加し、伸び特性、寸法精度が低下する。このため、Cは0.50～2.80％の範囲に限定した。なお、好ましくは0.90～1.70％である。空孔に樹脂含浸させた場合は、Cは好ましくは2.30～2.60％である。 C: 0.50-2.80%
C is an element necessary for adjusting the matrix phase to a specified hardness and structure, or for forming carbides, and is contained at 0.50% or more. On the other hand, if it is contained at more than 2.80%, the melting point drops and the sintering process becomes liquid phase sintering. When it becomes liquid phase sintering, the amount of precipitated carbides becomes too large, the number of pores increases, and the elongation properties and dimensional accuracy decrease. For this reason, C is limited to the range of 0.50 to 2.80%, and preferably 0.90 to 1.70%. When the pores are impregnated with resin, C is preferably 2.30 to 2.60%.
Cは、基地相を所定の硬さ、組織に調整するため、あるいは炭化物を形成するために必要な元素であり、0.50％以上含有させる。一方、2.80％を超えて含有すると、融点が低下し、焼結処理が液相焼結となる。液相焼結となると、析出炭化物量が多くなりすぎ、また、空孔の数が増加し、伸び特性、寸法精度が低下する。このため、Cは0.50～2.80％の範囲に限定した。なお、好ましくは0.90～1.70％である。空孔に樹脂含浸させた場合は、Cは好ましくは2.30～2.60％である。 C: 0.50-2.80%
C is an element necessary for adjusting the matrix phase to a specified hardness and structure, or for forming carbides, and is contained at 0.50% or more. On the other hand, if it is contained at more than 2.80%, the melting point drops and the sintering process becomes liquid phase sintering. When it becomes liquid phase sintering, the amount of precipitated carbides becomes too large, the number of pores increases, and the elongation properties and dimensional accuracy decrease. For this reason, C is limited to the range of 0.50 to 2.80%, and preferably 0.90 to 1.70%. When the pores are impregnated with resin, C is preferably 2.30 to 2.60%.
Si：1.80％以下
Siは、主として硬質粒子に含まれ、金属間化合物を構成する元素で、硬質粒子の硬さを増加させるとともに、基地強度を増加させ耐摩耗性を向上させる。このためには、Siは0.20％以上含有することが好ましい。一方、1.80％を超えてSiを含有すると、相手攻撃性が増加する。このようなことから、Siは1.80％以下に限定することが好ましい。なお、より好ましくは0.50～1.00％である。 Si: 1.80% or less Silicon is an element contained mainly in hard particles and constitutes intermetallic compounds. It increases the hardness of the hard particles, increases the strength of the matrix, and improves wear resistance. For this reason, it is preferable to contain 0.20% or more of silicon. On the other hand, if the silicon content exceeds 1.80%, aggressiveness against the mating member increases. For this reason, it is preferable to limit the silicon content to 1.80% or less. It is more preferable to set the content to 0.50 to 1.00%.
Siは、主として硬質粒子に含まれ、金属間化合物を構成する元素で、硬質粒子の硬さを増加させるとともに、基地強度を増加させ耐摩耗性を向上させる。このためには、Siは0.20％以上含有することが好ましい。一方、1.80％を超えてSiを含有すると、相手攻撃性が増加する。このようなことから、Siは1.80％以下に限定することが好ましい。なお、より好ましくは0.50～1.00％である。 Si: 1.80% or less Silicon is an element contained mainly in hard particles and constitutes intermetallic compounds. It increases the hardness of the hard particles, increases the strength of the matrix, and improves wear resistance. For this reason, it is preferable to contain 0.20% or more of silicon. On the other hand, if the silicon content exceeds 1.80%, aggressiveness against the mating member increases. For this reason, it is preferable to limit the silicon content to 1.80% or less. It is more preferable to set the content to 0.50 to 1.00%.
Mn：2.50％以下
Mnは、基地相の硬さを増加させる元素であり、またMnの一部は固体潤滑剤粒子に起因して基地部に含まれ、被削性向上に寄与する元素であり、0.05％以上含有することが好ましい。一方、Mnを2.50％超えて含有すると基地相硬さ、靭性、延性が低下する。このため、Mnは2.50％以下に限定することが好ましい。なお、より好ましくは0.20～1.60％である。 Mn: 2.50% or less Mn is an element that increases the hardness of the matrix phase. A part of Mn is included in the matrix due to solid lubricant particles, and contributes to improving machinability. It is preferable to contain 0.05% or more. On the other hand, if the Mn content exceeds 2.50%, the hardness, toughness, and ductility of the matrix phase decrease. For this reason, it is preferable to limit Mn to 2.50% or less. More preferably, it is 0.20 to 1.60%.
Mnは、基地相の硬さを増加させる元素であり、またMnの一部は固体潤滑剤粒子に起因して基地部に含まれ、被削性向上に寄与する元素であり、0.05％以上含有することが好ましい。一方、Mnを2.50％超えて含有すると基地相硬さ、靭性、延性が低下する。このため、Mnは2.50％以下に限定することが好ましい。なお、より好ましくは0.20～1.60％である。 Mn: 2.50% or less Mn is an element that increases the hardness of the matrix phase. A part of Mn is included in the matrix due to solid lubricant particles, and contributes to improving machinability. It is preferable to contain 0.05% or more. On the other hand, if the Mn content exceeds 2.50%, the hardness, toughness, and ductility of the matrix phase decrease. For this reason, it is preferable to limit Mn to 2.50% or less. More preferably, it is 0.20 to 1.60%.
Cr：3.00～11.00％
Crは、基地相に固溶し、また炭化物を形成して基地相の硬さを増加させるとともに、Crは金属間化合物の構成元素として硬質粒子の硬さ増加に寄与する元素であり、基地部として3.00％以上含有する。一方、Crを11.00％を超えて含有すると、基地相中にCr炭化物の析出が過多となり、基地相中の炭化物を微細な炭化物とすることが難しくなる。このため、Crは3.00～11.00％の範囲に限定することが好ましい。なお、より好ましくは4.00～6.00％である。 Cr: 3.00-11.00%
Cr dissolves in the matrix phase and forms carbides to increase the hardness of the matrix phase, and as a constituent element of intermetallic compounds, Cr contributes to increasing the hardness of hard particles, so the matrix should contain 3.00% or more of Cr. On the other hand, if the Cr content exceeds 11.00%, the precipitation of Cr carbides in the matrix phase becomes excessive, making it difficult to make the carbides in the matrix phase fine. For this reason, it is preferable to limit the Cr content to the range of 3.00 to 11.00%. More preferably, it is 4.00 to 6.00%.
Crは、基地相に固溶し、また炭化物を形成して基地相の硬さを増加させるとともに、Crは金属間化合物の構成元素として硬質粒子の硬さ増加に寄与する元素であり、基地部として3.00％以上含有する。一方、Crを11.00％を超えて含有すると、基地相中にCr炭化物の析出が過多となり、基地相中の炭化物を微細な炭化物とすることが難しくなる。このため、Crは3.00～11.00％の範囲に限定することが好ましい。なお、より好ましくは4.00～6.00％である。 Cr: 3.00-11.00%
Cr dissolves in the matrix phase and forms carbides to increase the hardness of the matrix phase, and as a constituent element of intermetallic compounds, Cr contributes to increasing the hardness of hard particles, so the matrix should contain 3.00% or more of Cr. On the other hand, if the Cr content exceeds 11.00%, the precipitation of Cr carbides in the matrix phase becomes excessive, making it difficult to make the carbides in the matrix phase fine. For this reason, it is preferable to limit the Cr content to the range of 3.00 to 11.00%. More preferably, it is 4.00 to 6.00%.
Mo：3.00～17.00％
Moは、基地相に固溶して、また炭化物として析出して基地相硬さを増加させ、さらにMoは金属間化合物の構成元素として硬質粒子の硬さ増加に寄与する元素であり、基地部として3.00％以上含有することが好ましい。一方、Moを17.00％を超えて含有すると、粉末成形時の密度が増加しにくく、成形性が低下する。このため、Moは3.00～17.00％の範囲に限定することが好ましい。なお、より好ましくは9.00～15.00％である。 Mo: 3.00-17.00%
Mo dissolves in the matrix phase and precipitates as carbides to increase the hardness of the matrix phase. Furthermore, Mo is an element that contributes to increasing the hardness of hard particles as a constituent element of intermetallic compounds, and it is preferable to contain 3.00% or more in the matrix. On the other hand, if Mo is contained in excess of 17.00%, it becomes difficult to increase the density during powder molding, and moldability decreases. For this reason, it is preferable to limit Mo to the range of 3.00 to 17.00%. More preferably, it is 9.00 to 15.00%.
Moは、基地相に固溶して、また炭化物として析出して基地相硬さを増加させ、さらにMoは金属間化合物の構成元素として硬質粒子の硬さ増加に寄与する元素であり、基地部として3.00％以上含有することが好ましい。一方、Moを17.00％を超えて含有すると、粉末成形時の密度が増加しにくく、成形性が低下する。このため、Moは3.00～17.00％の範囲に限定することが好ましい。なお、より好ましくは9.00～15.00％である。 Mo: 3.00-17.00%
Mo dissolves in the matrix phase and precipitates as carbides to increase the hardness of the matrix phase. Furthermore, Mo is an element that contributes to increasing the hardness of hard particles as a constituent element of intermetallic compounds, and it is preferable to contain 3.00% or more in the matrix. On the other hand, if Mo is contained in excess of 17.00%, it becomes difficult to increase the density during powder molding, and moldability decreases. For this reason, it is preferable to limit Mo to the range of 3.00 to 17.00%. More preferably, it is 9.00 to 15.00%.
Ni：1.00～8.50％
Niは、基地相の強度、靭性の向上、さらには高合金相の生成に寄与する元素であり、また、Niは金属間化合物の構成元素として硬質粒子の靭性増加にも寄与する元素であり、1.00％以上含有することが好ましい。一方、8.50％を超えるNiの含有は、粉末成形時の密度が増加しにくく、成形性を低下させる。このため、Niは1.00～8.50％の範囲に限定することが好ましい。なお、より好ましくは1.00～3.00％である。 Ni: 1.00-8.50%
Ni is an element that contributes to improving the strength and toughness of the matrix phase and further to the formation of a high alloy phase. In addition, Ni is an element that contributes to increasing the toughness of hard particles as a constituent element of intermetallic compounds, and it is preferable to contain 1.00% or more. On the other hand, if the Ni content exceeds 8.50%, it is difficult to increase the density during powder molding, and the moldability is reduced. For this reason, it is preferable to limit Ni to the range of 1.00 to 8.50%. More preferably, it is 1.00 to 3.00%.
Niは、基地相の強度、靭性の向上、さらには高合金相の生成に寄与する元素であり、また、Niは金属間化合物の構成元素として硬質粒子の靭性増加にも寄与する元素であり、1.00％以上含有することが好ましい。一方、8.50％を超えるNiの含有は、粉末成形時の密度が増加しにくく、成形性を低下させる。このため、Niは1.00～8.50％の範囲に限定することが好ましい。なお、より好ましくは1.00～3.00％である。 Ni: 1.00-8.50%
Ni is an element that contributes to improving the strength and toughness of the matrix phase and further to the formation of a high alloy phase. In addition, Ni is an element that contributes to increasing the toughness of hard particles as a constituent element of intermetallic compounds, and it is preferable to contain 1.00% or more. On the other hand, if the Ni content exceeds 8.50%, it is difficult to increase the density during powder molding, and the moldability is reduced. For this reason, it is preferable to limit Ni to the range of 1.00 to 8.50%. More preferably, it is 1.00 to 3.00%.
Co：5.00～30.00％
Coは、主として、硬質粒子中に含まれ、金属間化合物を構成し、硬質粒子の硬さを高めるが、焼結時に基地中に拡散し、高合金相の形成に寄与し、さらに基地相に含まれ、基地相の強度、とくに高温強度を増加させ、さらに基地相の靭性向上に寄与する元素である。基地部として、5.00％以上含有することが好ましい。一方、30.00％を超えるCoの含有は、耐摩耗性が低下する。このため、Coは5.00～30.00％に限定することが好ましい。なお、より好ましくは9.00～27.00％である。 Co: 5.00-30.00%
Co is mainly contained in the hard particles, forms an intermetallic compound, and increases the hardness of the hard particles, but diffuses into the matrix during sintering, contributes to the formation of a high alloy phase, and is further contained in the matrix phase, increases the strength of the matrix phase, especially its high-temperature strength, and further contributes to improving the toughness of the matrix phase. It is preferable for the matrix to contain 5.00% or more. On the other hand, if the Co content exceeds 30.00%, the wear resistance decreases. For this reason, it is preferable to limit Co to 5.00-30.00%. More preferably, it is 9.00-27.00%.
Coは、主として、硬質粒子中に含まれ、金属間化合物を構成し、硬質粒子の硬さを高めるが、焼結時に基地中に拡散し、高合金相の形成に寄与し、さらに基地相に含まれ、基地相の強度、とくに高温強度を増加させ、さらに基地相の靭性向上に寄与する元素である。基地部として、5.00％以上含有することが好ましい。一方、30.00％を超えるCoの含有は、耐摩耗性が低下する。このため、Coは5.00～30.00％に限定することが好ましい。なお、より好ましくは9.00～27.00％である。 Co: 5.00-30.00%
Co is mainly contained in the hard particles, forms an intermetallic compound, and increases the hardness of the hard particles, but diffuses into the matrix during sintering, contributes to the formation of a high alloy phase, and is further contained in the matrix phase, increases the strength of the matrix phase, especially its high-temperature strength, and further contributes to improving the toughness of the matrix phase. It is preferable for the matrix to contain 5.00% or more. On the other hand, if the Co content exceeds 30.00%, the wear resistance decreases. For this reason, it is preferable to limit Co to 5.00-30.00%. More preferably, it is 9.00-27.00%.
V：0.50～4.00％
Vは、微細炭化物として析出し、基地相の硬さを増加させて、耐摩耗性を向上させる元素であり、0.50％以上含有することが好ましい。一方、4.00％を超えるVの含有は、成形性を低下させる。このため、Vは0.50～4.00％の範囲に限定することが好ましい。なお、より好ましくは1.00～3.00％である。 V: 0.50-4.00%
V is an element that precipitates as fine carbides, increases the hardness of the matrix phase, and improves wear resistance, and is preferably contained at 0.50% or more. On the other hand, a V content of more than 4.00% reduces formability. For this reason, it is preferable to limit V to the range of 0.50 to 4.00%, and more preferably 1.00 to 3.00%.
Vは、微細炭化物として析出し、基地相の硬さを増加させて、耐摩耗性を向上させる元素であり、0.50％以上含有することが好ましい。一方、4.00％を超えるVの含有は、成形性を低下させる。このため、Vは0.50～4.00％の範囲に限定することが好ましい。なお、より好ましくは1.00～3.00％である。 V: 0.50-4.00%
V is an element that precipitates as fine carbides, increases the hardness of the matrix phase, and improves wear resistance, and is preferably contained at 0.50% or more. On the other hand, a V content of more than 4.00% reduces formability. For this reason, it is preferable to limit V to the range of 0.50 to 4.00%, and more preferably 1.00 to 3.00%.
W：4.00～10.00％
Wは、微細炭化物として析出し、基地相の硬さを増加させて、耐摩耗性を向上させる元素であり、4.00％以上含有することが好ましい。一方、10.00％を超えるWの含有は、成形性を低下させる。このため、Wは4.00～10.00％の範囲に限定することが好ましい。なお、より好ましくは3.00～7.00％である。 W: 4.00-10.00%
W is an element that precipitates as fine carbides, increases the hardness of the matrix phase, and improves wear resistance, and is preferably contained at 4.00% or more. On the other hand, a W content of more than 10.00% reduces formability. For this reason, it is preferable to limit W to the range of 4.00 to 10.00%, and more preferably 3.00 to 7.00%.
Wは、微細炭化物として析出し、基地相の硬さを増加させて、耐摩耗性を向上させる元素であり、4.00％以上含有することが好ましい。一方、10.00％を超えるWの含有は、成形性を低下させる。このため、Wは4.00～10.00％の範囲に限定することが好ましい。なお、より好ましくは3.00～7.00％である。 W: 4.00-10.00%
W is an element that precipitates as fine carbides, increases the hardness of the matrix phase, and improves wear resistance, and is preferably contained at 4.00% or more. On the other hand, a W content of more than 10.00% reduces formability. For this reason, it is preferable to limit W to the range of 4.00 to 10.00%, and more preferably 3.00 to 7.00%.
基地部では、上記した成分のうちから選ばれた１種または２種以上を含有できる。また、基地部では、上記した成分以外に、S：0～2.0％を含有できる。
The base part can contain one or more of the components listed above. In addition to the components listed above, the base part can also contain S: 0-2.0%.
S：0～2.00％
Sは、固体潤滑剤粒子に含有され、基地部に含まれ、被削性向上に寄与する元素であり、必要に応じて含有できる。Sが2.00％を超えて含有されると、靭性、延性の低下に繋がる。このため、Sは0～2.00％の範囲に限定することが好ましい。 S: 0-2.00%
S is an element contained in the solid lubricant particles and the matrix, which contributes to improving machinability, and can be contained as necessary. If the S content exceeds 2.00%, it leads to a decrease in toughness and ductility. For this reason, it is preferable to limit S to the range of 0 to 2.00%.
Sは、固体潤滑剤粒子に含有され、基地部に含まれ、被削性向上に寄与する元素であり、必要に応じて含有できる。Sが2.00％を超えて含有されると、靭性、延性の低下に繋がる。このため、Sは0～2.00％の範囲に限定することが好ましい。 S: 0-2.00%
S is an element contained in the solid lubricant particles and the matrix, which contributes to improving machinability, and can be contained as necessary. If the S content exceeds 2.00%, it leads to a decrease in toughness and ductility. For this reason, it is preferable to limit S to the range of 0 to 2.00%.
上記した成分以外の残部は、Feおよび不可避的不純物からなる。なお、不可避的不純物としては、P：0.10％以下が許容できる。
The balance other than the above components consists of Fe and unavoidable impurities. As for unavoidable impurities, P: 0.10% or less is permissible.
つぎに、本発明バルブシートを二層構造とした場合の支持部材側層について説明する。なお、二層構造の機能部材側層は、上記した単層構造の場合の機能部材側層と同じとする。そして、二層構造とした場合の支持部材側層は、機能部材側層を保持できるものであればよく、とくに限定する必要はない。
Next, the support member side layer when the valve seat of the present invention has a two-layer structure will be described. The functional member side layer of the two-layer structure is the same as the functional member side layer in the case of the single-layer structure described above. The support member side layer in the case of the two-layer structure need only be capable of holding the functional member side layer, and does not need to be particularly limited.
なお、支持部材側層としては、基地相と、該基地相中に面積率で0～4.0％の固体潤滑剤粒子および面積率で0～5.0％の硬度改善粒子を分散させてなる組織と、さらに基地相、固体潤滑剤粒子および硬度改善粒子を含む基地部が、質量％で、C：0.30～2.00％を含み、さらに、Ni：0～2.00％、Mo：0～2.00％、Cu：0～5.00％、Mn：0～5.00％およびS：0～2.00％を含有し、残部Feおよび不可避的不純物からなる組成と、を有する鉄基焼結合金材からなることが好ましい。
The support member side layer is preferably made of an iron-based sintered alloy material having a structure in which a base phase, 0-4.0% by area of solid lubricant particles and 0-5.0% by area of hardness improving particles are dispersed in the base phase, and the base portion containing the base phase, solid lubricant particles and hardness improving particles contains, by mass%, C: 0.30-2.00%, Ni: 0-2.00%, Mo: 0-2.00%, Cu: 0-5.00%, Mn: 0-5.00%, and S: 0-2.00%, with the balance being Fe and unavoidable impurities.
なお、支持部材側層の基地相はパーライトとすることが好ましい。
The matrix phase of the support member side layer is preferably pearlite.
また、基地相中には、必要に応じて被削性を向上させる固体潤滑剤粒子を分散させてもよい。固体潤滑剤粒子としては、MnS、MoS2等が例示できる。分散させる場合は、固体潤滑剤粒子は、支持部材側層の組織全体に対する面積率で、0.3％以上とすることが好ましい。固体潤滑剤粒子の分散量が0.3％未満では被削性向上の目的を達成できにくい。一方、固体潤滑剤粒子を4.0％超えて分散させても、効果が飽和し、分散量に見合う効果が期待できなくなる。このため、固体潤滑剤粒子は面積率で0～4.0％の範囲とすることが好ましい。
In addition, solid lubricant particles for improving machinability may be dispersed in the matrix phase as necessary. Examples of solid lubricant particles include MnS, MoS2 , etc. When dispersed, the solid lubricant particles are preferably 0.3% or more in area ratio to the entire structure of the support member side layer. If the amount of dispersed solid lubricant particles is less than 0.3%, it is difficult to achieve the purpose of improving machinability. On the other hand, even if the amount of dispersed solid lubricant particles exceeds 4.0%, the effect is saturated and it is not possible to expect an effect commensurate with the amount dispersed. For this reason, the area ratio of the solid lubricant particles is preferably in the range of 0 to 4.0%.
また、支持部材側層の基地相中には、基地相の強度を増加させるために、硬度改善粒子を面積率で0～5.0％分散させてもよい。支持部材側層中に分散させる硬度改善粒子としては、鉄－モリブデン（Fe－Mo）合金が例示できる。硬度改善粒子を面積率で5.0％を超えて分散させても効果が飽和するため、含有する場合は、5.0％を上限とした。
In addition, in order to increase the strength of the matrix phase in the support member side layer, hardness improving particles may be dispersed in an area ratio of 0 to 5.0%. An example of hardness improving particles dispersed in the support member side layer is an iron-molybdenum (Fe-Mo) alloy. If the hardness improving particles are dispersed in an area ratio of more than 5.0%, the effect saturates, so if they are contained, the upper limit is set at 5.0%.
支持部材側層では、基地相中に、必要に応じて、固体潤滑剤粒子、硬度改善粒子を分散させた組織を有する。基地相、固体潤滑剤粒子、硬度改善粒子以外の残部は、空孔である。なお、空孔には、機能部材側層と同様に、熱硬化性樹脂または嫌気樹脂を含浸させることが好ましい。空孔に熱硬化性樹脂または嫌気樹脂を含浸させ、封孔することにより、耐摩耗性の著しい低下を伴うことなく、切削性、被削性が向上する。また、封孔により、耐食性の向上が期待できる。
The support member side layer has a structure in which solid lubricant particles and hardness improving particles are dispersed in the matrix phase as necessary. The remainder other than the matrix phase, solid lubricant particles, and hardness improving particles are pores. As with the functional member side layer, the pores are preferably impregnated with a thermosetting resin or anaerobic resin. By impregnating the pores with a thermosetting resin or anaerobic resin and sealing them, cutting and machinability are improved without a significant decrease in wear resistance. Sealing the pores is also expected to improve corrosion resistance.
支持部材側層の基地部組成の限定理由について、説明する。
The reasons for limiting the base composition of the support member side layer are explained below.
Cは、所望の強度を確保するために、0.30％以上含有させる。一方、2.00％を超えて含有すると、強度が高くなりすぎて靭性が低下する。このため、Cは0.30～2.00％の範囲に限定することが好ましい。Cは好ましくは0.30～1.20％である。空孔に樹脂含浸させた場合は、Cは好ましくは1.40～1.80％である。なお、支持部材側層の基地部は、上記したC以外に、Ni：0～2.00％、Mo：0～2.00％、Cu：0～5.00％、Mn：0～5.00％およびS：0～2.00％を含有してもよい。
C is contained in an amount of 0.30% or more to ensure the desired strength. On the other hand, if it is contained in excess of 2.00%, the strength becomes too high and the toughness decreases. For this reason, it is preferable to limit C to the range of 0.30-2.00%. C is preferably 0.30-1.20%. When the pores are impregnated with resin, C is preferably 1.40-1.80%. In addition to the above C, the base portion of the support member side layer may contain Ni: 0-2.00%, Mo: 0-2.00%, Cu: 0-5.00%, Mn: 0-5.00%, and S: 0-2.00%.
Ni、Mo、Cuは、支持部材側層の基地相強度（硬さ）を増加させる元素であり、必要に応じて、含有できる。Ni、Mo、Cuは、所望の強度に応じて含有するが、Ni：2.00％、Mo：2.00％、Cu：5.00％、をそれぞれ超えて含有すると、強度が高くなりすぎる。そのため、含有する場合には、Ni：2.00％以下、Mo：2.00％以下、Cu：5.00％以下の範囲に限定することが好ましい。また、Moの一部およびMn、Sは、固体潤滑剤粒子の分散に起因して基地部に含有されるが、固体潤滑剤粒子を多量に分散させても、効果が飽和し、延性が低下する。このため、含有する場合には、Mn：5.00％以下、S：2.00％以下に限定することが好ましい。
Ni, Mo, and Cu are elements that increase the matrix phase strength (hardness) of the support member side layer, and can be included as necessary. Ni, Mo, and Cu are included according to the desired strength, but if they exceed Ni: 2.00%, Mo: 2.00%, and Cu: 5.00%, respectively, the strength will be too high. Therefore, when included, it is preferable to limit the ranges of Ni: 2.00% or less, Mo: 2.00% or less, and Cu: 5.00% or less. In addition, a portion of Mo, Mn, and S are included in the matrix due to the dispersion of solid lubricant particles, but even if a large amount of solid lubricant particles are dispersed, the effect saturates and ductility decreases. Therefore, when included, it is preferable to limit Mn: 5.00% or less and S: 2.00% or less.
上記した成分以外の残部は、Feおよび不可避的不純物からなる。不可避的不純物としては、P：0.10％以下が許容できる。
The remainder other than the above components consists of Fe and unavoidable impurities. As for unavoidable impurities, P: 0.10% or less is acceptable.
つぎに、本発明鉄基焼結合金製バルブシートの製造方法について説明する。
Next, we will explain the manufacturing method for the iron-based sintered alloy valve seat of the present invention.
本発明の単層構造の鉄基焼結合金製バルブシートの製造方法では、まず、鉄系粉末と、黒鉛粉末と、合金元素粉末と、硬質粒子粉末と、あるいはさらに固体潤滑剤粒子粉末とを、上記した基地部組成となるように所定量配合し、混合、混錬して、混合粉（機能部材側層用混合粉）とする。
In the manufacturing method of the single-layered iron-based sintered alloy valve seat of the present invention, first, iron-based powder, graphite powder, alloying element powder, hard particle powder, and/or solid lubricant particle powder are mixed in predetermined amounts so as to obtain the above-mentioned base composition, and then mixed and kneaded to obtain a mixed powder (mixed powder for the functional component side layer).
混合粉（機能部材側層用混合粉）に配合する鉄系粉末は、基地相を形成するために配合する粉末であり、本発明では基地相を微細炭化物析出相からなる組織とすることができる合金鋼粉末とする。そのような合金鋼粉末としては、JIS G 4403に規定される高速度工具鋼組成に準じた組成の粉末が例示できるが、それに限定されないことは言うまでもない。
The iron-based powder mixed into the mixed powder (mixed powder for the functional component side layer) is a powder mixed to form a base phase, and in the present invention, it is an alloy steel powder that can form the base phase into a structure consisting of a fine carbide precipitate phase. An example of such an alloy steel powder is a powder whose composition conforms to the high-speed tool steel composition specified in JIS G 4403, but it goes without saying that it is not limited to this.
配合する鉄系粉末は、質量％で、C：0.2～0.8％、Si：1.0％以下、Mn：1.0％以下、Cr：7.0％以下、Mo：7.0％以下、V：5.0％以下、W：12.0％以下、Co：0～12.0％を含有し、残部Feおよび不可避的不純物からなる組成を有し、ビッカース硬さで170～280HVの粒子硬さを有する鉄系粉末とする。本発明で配合する鉄系粉末は、Cを低減した高速度鋼組成の粉末とする。
The iron-based powder to be blended contains, by mass%, C: 0.2-0.8%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 7.0% or less, Mo: 7.0% or less, V: 5.0% or less, W: 12.0% or less, Co: 0-12.0%, with the remainder being Fe and unavoidable impurities, and has a particle hardness of 170-280 HV on the Vickers hardness scale. The iron-based powder blended in this invention is a powder with a high-speed steel composition with reduced C.
まず、鉄系粉末の組成限定理由について説明する。以下、組成における質量％は、単に％と記す。
First, we will explain the reasons for limiting the composition of the iron-based powder. Hereafter, mass% in the composition will simply be written as %.
C：0.2～0.8％
Cが0.2％未満では、それ以上の粉末粒子の硬さ低下が認められなくなる。一方、Cが0.8％を超えると、粉末粒子の硬さが高くなりすぎて、粉末粒子の圧縮性が低下する。このため、鉄系粉末のC含有量は0.2～0.8％の範囲に限定することが好ましい。なお、より好ましくは0.4～0.6％である。
C: 0.2-0.8%
If the C content is less than 0.2%, the hardness of the powder particles will not decrease any further. On the other hand, if the C content exceeds 0.8%, the hardness of the powder particles will be too high, and the compressibility of the powder particles will decrease. For this reason, it is preferable to limit the C content of the iron-based powder to the range of 0.2 to 0.8%, and more preferably to 0.4 to 0.6%.
Si：1.0％以下
Siは、粉末製造時（アトマイズ粉製造時）、湯流れに影響する元素である。このような効果を得るためには、0.3％以上のSi含有で顕著となる。一方、1.0％を超えてSiを含有すると圧縮性が低下する。このため、Siは、1.0％以下に限定することが好ましい。なお、より好ましくは0.5％以下である。 Si: 1.0% or less Silicon is an element that affects the flow of molten metal during powder production (atomized powder production). In order to obtain this effect, a silicon content of 0.3% or more is significant. On the other hand, if the silicon content exceeds 1.0%, the compressibility decreases. For this reason, it is preferable to limit the silicon content to 1.0% or less. Furthermore, it is more preferable to limit the silicon content to 0.5% or less.
Siは、粉末製造時（アトマイズ粉製造時）、湯流れに影響する元素である。このような効果を得るためには、0.3％以上のSi含有で顕著となる。一方、1.0％を超えてSiを含有すると圧縮性が低下する。このため、Siは、1.0％以下に限定することが好ましい。なお、より好ましくは0.5％以下である。 Si: 1.0% or less Silicon is an element that affects the flow of molten metal during powder production (atomized powder production). In order to obtain this effect, a silicon content of 0.3% or more is significant. On the other hand, if the silicon content exceeds 1.0%, the compressibility decreases. For this reason, it is preferable to limit the silicon content to 1.0% or less. Furthermore, it is more preferable to limit the silicon content to 0.5% or less.
Mn：1.0％以下
Mnは、脱酸剤として作用するとともに、強度（硬さ）増加に寄与する。このような効果は、0.10％以上の含有で顕著となる。一方、1.0％を超えてMnを含有すると、粉末の酸素濃度が高くなり、焼結時の拡散性が低下する。また、硬さが高くなり圧縮性が低下する。このため、Mnは1.0％以下に限定することが好ましい。 Mn: 1.0% or less Mn acts as a deoxidizer and contributes to increasing strength (hardness). This effect is significant when the content is 0.10% or more. On the other hand, if the Mn content exceeds 1.0%, the oxygen concentration of the powder increases and the diffusibility during sintering decreases. In addition, the hardness increases and the compressibility decreases. For this reason, it is preferable to limit Mn to 1.0% or less.
Mnは、脱酸剤として作用するとともに、強度（硬さ）増加に寄与する。このような効果は、0.10％以上の含有で顕著となる。一方、1.0％を超えてMnを含有すると、粉末の酸素濃度が高くなり、焼結時の拡散性が低下する。また、硬さが高くなり圧縮性が低下する。このため、Mnは1.0％以下に限定することが好ましい。 Mn: 1.0% or less Mn acts as a deoxidizer and contributes to increasing strength (hardness). This effect is significant when the content is 0.10% or more. On the other hand, if the Mn content exceeds 1.0%, the oxygen concentration of the powder increases and the diffusibility during sintering decreases. In addition, the hardness increases and the compressibility decreases. For this reason, it is preferable to limit Mn to 1.0% or less.
Cr：7.0％以下
Crは、炭化物を形成し、耐摩耗性を向上する効果を有する元素である。このような効果は、0.1％以上のCrの含有で顕著となるが、7.0％を超えて含有すると、靭性が低下する。このため、Crは7.0％以下に限定することが好ましい。 Cr: 7.0% or less Cr is an element that forms carbides and has the effect of improving wear resistance. This effect is significant when the Cr content is 0.1% or more, but when the Cr content exceeds 7.0%, the toughness decreases. For this reason, it is preferable to limit the Cr content to 7.0% or less.
Crは、炭化物を形成し、耐摩耗性を向上する効果を有する元素である。このような効果は、0.1％以上のCrの含有で顕著となるが、7.0％を超えて含有すると、靭性が低下する。このため、Crは7.0％以下に限定することが好ましい。 Cr: 7.0% or less Cr is an element that forms carbides and has the effect of improving wear resistance. This effect is significant when the Cr content is 0.1% or more, but when the Cr content exceeds 7.0%, the toughness decreases. For this reason, it is preferable to limit the Cr content to 7.0% or less.
Mo：7.0％以下
Moは、微細炭化物を形成し、耐摩耗性を向上する効果を有する元素である。このような効果は、2.0％以上のMoの含有で顕著となるが、7.0％を超えて含有すると、成形性が低下する。このため、Moは7.0％以下に限定することが好ましい。なお、より好ましくは2.0～5.0％である。 Mo: 7.0% or less Mo is an element that forms fine carbides and has the effect of improving wear resistance. This effect is prominent when the Mo content is 2.0% or more, but if it exceeds 7.0%, formability decreases. For this reason, it is preferable to limit Mo to 7.0% or less. Furthermore, it is more preferable to limit it to 2.0 to 5.0%.
Moは、微細炭化物を形成し、耐摩耗性を向上する効果を有する元素である。このような効果は、2.0％以上のMoの含有で顕著となるが、7.0％を超えて含有すると、成形性が低下する。このため、Moは7.0％以下に限定することが好ましい。なお、より好ましくは2.0～5.0％である。 Mo: 7.0% or less Mo is an element that forms fine carbides and has the effect of improving wear resistance. This effect is prominent when the Mo content is 2.0% or more, but if it exceeds 7.0%, formability decreases. For this reason, it is preferable to limit Mo to 7.0% or less. Furthermore, it is more preferable to limit it to 2.0 to 5.0%.
V：5.0％以下
Vは、微細炭化物を形成し、耐摩耗性を向上する効果を有する元素である。このような効果は、2.0％以上のVの含有で顕著となるが、5.0％を超えて含有すると、成形性が低下する。このため、Vは5.0％以下に限定することが好ましい。なお、より好ましくは2.0～4.0％である。 V: 5.0% or less V is an element that forms fine carbides and has the effect of improving wear resistance. This effect is prominent when the V content is 2.0% or more, but if the V content exceeds 5.0%, formability decreases. For this reason, it is preferable to limit V to 5.0% or less. Furthermore, it is more preferable to limit it to 2.0 to 4.0%.
Vは、微細炭化物を形成し、耐摩耗性を向上する効果を有する元素である。このような効果は、2.0％以上のVの含有で顕著となるが、5.0％を超えて含有すると、成形性が低下する。このため、Vは5.0％以下に限定することが好ましい。なお、より好ましくは2.0～4.0％である。 V: 5.0% or less V is an element that forms fine carbides and has the effect of improving wear resistance. This effect is prominent when the V content is 2.0% or more, but if the V content exceeds 5.0%, formability decreases. For this reason, it is preferable to limit V to 5.0% or less. Furthermore, it is more preferable to limit it to 2.0 to 4.0%.
W：12.0％以下
Wは、微細炭化物を形成し、耐摩耗性を向上する効果を有する元素である。このような効果は、5.0％以上のWの含有で顕著となるが、12.0％を超えて含有すると、成形性が低下する。このため、Wは12.0％以下に限定することが好ましい。 W: 12.0% or less W is an element that forms fine carbides and has the effect of improving wear resistance. This effect is remarkable when the W content is 5.0% or more, but when it exceeds 12.0%, the formability decreases. For this reason, it is preferable to limit W to 12.0% or less.
Wは、微細炭化物を形成し、耐摩耗性を向上する効果を有する元素である。このような効果は、5.0％以上のWの含有で顕著となるが、12.0％を超えて含有すると、成形性が低下する。このため、Wは12.0％以下に限定することが好ましい。 W: 12.0% or less W is an element that forms fine carbides and has the effect of improving wear resistance. This effect is remarkable when the W content is 5.0% or more, but when it exceeds 12.0%, the formability decreases. For this reason, it is preferable to limit W to 12.0% or less.
上記した成分以外に、さらに必要に応じてCo：12.0％以下を含有してもよい。
In addition to the above components, Co: 12.0% or less may be contained as necessary.
Co：0～12.0％
Coは、強度、とくに高温強度を増加させ、さらに靭性の向上に寄与するとともに、高合金相の形成に寄与する元素であり、必要に応じて10.0％以上含有することが好ましい。一方、12.0％を超えるCoの含有は、強度の低下を招く。このため、Coは含有する場合には、12.0％以下に限定することが好ましい。 Cobalt: 0-12.0%
Co is an element that increases strength, especially high-temperature strength, and contributes to improving toughness as well as forming a high alloy phase, and is preferably contained at 10.0% or more as necessary. On the other hand, a Co content of more than 12.0% leads to a decrease in strength. Therefore, when Co is contained, it is preferable to limit it to 12.0% or less.
Coは、強度、とくに高温強度を増加させ、さらに靭性の向上に寄与するとともに、高合金相の形成に寄与する元素であり、必要に応じて10.0％以上含有することが好ましい。一方、12.0％を超えるCoの含有は、強度の低下を招く。このため、Coは含有する場合には、12.0％以下に限定することが好ましい。 Cobalt: 0-12.0%
Co is an element that increases strength, especially high-temperature strength, and contributes to improving toughness as well as forming a high alloy phase, and is preferably contained at 10.0% or more as necessary. On the other hand, a Co content of more than 12.0% leads to a decrease in strength. Therefore, when Co is contained, it is preferable to limit it to 12.0% or less.
上記した成分以外の残部は、Feおよび不可避的不純物からなる。不可避的不純物としては、P：0.03％以下、S：0.02％以下が許容できる。Pは、オーステナイト粒界に偏析して粒界脆性を促進するため、できるだけ低減することが好ましい。なお、より好ましくは0.010％以下である。また、Sは、鋼中では硫化物系介在物として存在し、熱間加工性を阻害するため、できるだけ低減することが望ましい。なお、より好ましくは0.005％以下である。
The remainder of the steel other than the above components consists of Fe and unavoidable impurities. As unavoidable impurities, P: 0.03% or less and S: 0.02% or less are acceptable. P segregates at the austenite grain boundaries and promotes grain boundary embrittlement, so it is preferable to reduce it as much as possible. More preferably, it is 0.010% or less. S also exists in the steel as sulfide-based inclusions and impairs hot workability, so it is preferable to reduce it as much as possible. More preferably, it is 0.005% or less.
粒子硬さ：170～280HV
本発明で使用する鉄系粉末は、170～280HVの粒子硬さを有する粉末とする。粒子硬さが170HV未満では、鉄系粉末の硬さが低くなり過ぎて焼結体としての耐摩耗性が低下する。一方、280HVを超えて粒子硬さが高くなると、圧縮性が低下し、焼結体としての圧環強さが低下する。このため、配合する鉄系粉末の粒子硬さは170～280HVに限定した。 Particle hardness: 170-280HV
The iron-based powder used in the present invention has a particle hardness of 170 to 280 HV. If the particle hardness is less than 170 HV, the hardness of the iron-based powder is too low, and the wear resistance of the sintered body decreases. On the other hand, if the particle hardness exceeds 280 HV, the compressibility decreases, and the radial crushing strength of the sintered body decreases. For this reason, the particle hardness of the iron-based powder to be blended is limited to 170 to 280 HV.
本発明で使用する鉄系粉末は、170～280HVの粒子硬さを有する粉末とする。粒子硬さが170HV未満では、鉄系粉末の硬さが低くなり過ぎて焼結体としての耐摩耗性が低下する。一方、280HVを超えて粒子硬さが高くなると、圧縮性が低下し、焼結体としての圧環強さが低下する。このため、配合する鉄系粉末の粒子硬さは170～280HVに限定した。 Particle hardness: 170-280HV
The iron-based powder used in the present invention has a particle hardness of 170 to 280 HV. If the particle hardness is less than 170 HV, the hardness of the iron-based powder is too low, and the wear resistance of the sintered body decreases. On the other hand, if the particle hardness exceeds 280 HV, the compressibility decreases, and the radial crushing strength of the sintered body decreases. For this reason, the particle hardness of the iron-based powder to be blended is limited to 170 to 280 HV.
また、混合粉中に配合する硬質粒子粉末は、上記した硬さ、組成を有するSi－Cr－Mo系Co基金属間化合物粒子粉末またはSi－Cr－Mo－Ni系Co基金属間化合物粒子粉末とする。本発明では、このような硬質粒子粉末を、混合粉全量に対する質量％で、10.0～40.0％配合する。なお、配合する硬質粒子粉末は、平均粒径が10～150μmの粒子粉末とすることが好ましい。硬質粒子の平均粒径が10μm未満では、焼結時に拡散しやすく、所望の耐摩耗性が確保できない。一方、硬質粒子の平均粒径が150μmを超えると、基地との結合力が低下する。なお、ここでいう「平均粒径」は、レーザ散乱法で測定した累積分布が50％となる粒径D50を意味する。
The hard particle powder to be mixed in the mixed powder is a Si-Cr-Mo Co-based intermetallic compound particle powder or a Si-Cr-Mo-Ni Co-based intermetallic compound particle powder having the above-mentioned hardness and composition. In the present invention, such hard particle powder is mixed in an amount of 10.0 to 40.0% by mass relative to the total amount of the mixed powder. The hard particle powder to be mixed is preferably a particle powder with an average particle size of 10 to 150 μm. If the average particle size of the hard particles is less than 10 μm, they tend to diffuse during sintering and the desired wear resistance cannot be ensured. On the other hand, if the average particle size of the hard particles exceeds 150 μm, the bonding strength with the matrix decreases. Note that the "average particle size" here means the particle size D50 at which the cumulative distribution measured by the laser scattering method is 50%.
また、固体潤滑剤粒子は、被削性、加工性、潤滑性を向上させるために、必要に応じて配合する。固体潤滑剤粒子としては、MnS、MoS2等とすることが好ましい。固体潤滑剤粒子粉末の配合量は、混合粉全量に対する質量％で、0～4.0％とすることが好ましい。
In addition, solid lubricant particles are mixed as necessary to improve machinability, processability, and lubricity. The solid lubricant particles are preferably MnS, MoS2 , etc. The amount of solid lubricant particles mixed is preferably 0 to 4.0% by mass based on the total amount of the mixed powder.
なお、混合粉には、上記した鉄系粉末、硬質粒子粉末、あるいはさらに固体潤滑剤粒子粉末を所定量配合し、さらに上記した基地部組成となるように、黒鉛粉末、合金元素粉末を配合することはいうまでもない。配合する合金元素粉末としては、Ni粉末、あるいはさらにCo粉末が例示できる。なお、混合粉には、ステアリン酸亜鉛等の潤滑剤を配合しても良い。
It goes without saying that the mixed powder contains a predetermined amount of the above-mentioned iron-based powder, hard particle powder, or solid lubricant particle powder, and further contains graphite powder and alloying element powder to obtain the above-mentioned matrix composition. Examples of the alloying element powder to be added include Ni powder and/or Co powder. The mixed powder may also contain a lubricant such as zinc stearate.
上記したように、鉄系粉末に、さらに黒鉛粉末と、合金元素粉末と、硬質粒子粉末と、あるいはさらに固体潤滑剤粒子粉末とを所定量配合し、混合、混錬して混合粉とする。
As described above, the iron-based powder is mixed with a predetermined amount of graphite powder, alloying element powder, hard particle powder, and/or solid lubricant particle powder, and then mixed and kneaded to produce a mixed powder.
得られた混合粉を、ついで、所定のバルブシート形状の金型に充填する。
The resulting mixed powder is then filled into a mold of the desired valve seat shape.
混合粉を金型に充填した後、プレス加工機等でプレス加工し、バルブシート形状の圧粉体とする。なお、プレス加工は、圧粉体の密度が6.6g/cm3以上となるように調整することが好ましい。
After the mixed powder is filled into a die, it is pressed with a press machine or the like to form a green compact having a valve seat shape. Note that the pressing is preferably performed so that the density of the green compact is 6.6 g/ cm3 or more.
得られた圧粉体に、ついで、焼結処理を施し、焼結体とする。
The resulting green compact is then subjected to a sintering process to produce a sintered body.
焼結処理は、窒素、水素ガス等やアンモニア分解ガス等の還元雰囲気中で、加熱温度：1100～1200℃の温度範囲で、0.5hr以上保持する処理とすることが好ましい。加熱温度が1100℃未満では、焼結拡散が不足し、一方、1200℃超えでは、過拡散となり、耐摩耗性が低下する。なお、プレス加工Ｐ－焼結処理Ｓ工程は複数回繰り返す工程（２Ｐ２Ｓ等）としてもよい。
The sintering process is preferably carried out in a reducing atmosphere such as nitrogen, hydrogen gas, or ammonia decomposition gas at a heating temperature in the range of 1100-1200°C, and is maintained for 0.5 hours or more. If the heating temperature is less than 1100°C, sintering diffusion will be insufficient, while if it exceeds 1200°C, excessive diffusion will occur and wear resistance will decrease. The press working P-sintering process S process may be repeated multiple times (2P2S, etc.).
得られた焼結体に研削・切削等の加工を施して、所望の寸法形状のバルブシート（単層構造）とする。
The resulting sintered body is then processed by grinding, cutting, etc. to produce a valve seat (single-layer structure) of the desired dimensions and shape.
なお、上記した焼結処理後に、好ましくは研削・切削等の加工を施して得られたバルブシート（製品）に、樹脂含浸処理を施すことが好ましい。樹脂含浸処理は、真空雰囲気中で、バルブシートを熱硬化性樹脂または嫌気性樹脂の液体中に浸漬したのち、大気圧からさらに加圧して、空孔中に樹脂を十分に含浸させたのち、加熱して空孔中内の樹脂を硬化させて封孔する処理とすることが好ましい。なお、使用する熱硬化性樹脂、嫌気性樹脂は公知（市販）のものがいずれも適用できる。
After the above-mentioned sintering process, it is preferable to carry out a resin impregnation process on the valve seat (product) obtained by processing, such as grinding and cutting. The resin impregnation process is preferably carried out by immersing the valve seat in a liquid of thermosetting resin or anaerobic resin in a vacuum atmosphere, then applying additional pressure from atmospheric pressure to sufficiently impregnate the resin into the pores, and then heating the resin in the pores to harden and seal them. Any known (commercially available) thermosetting resin or anaerobic resin can be used.
つぎに、本発明の二層構造の鉄基焼結合金製バルブシートの製造方法では、上記した混合粉（機能部材側層用混合粉）に加えて、さらに支持部材側層用混合粉を用意する。
Next, in the manufacturing method of the two-layered iron-based sintered alloy valve seat of the present invention, in addition to the mixed powder described above (mixed powder for the functional component side layer), a mixed powder for the support component side layer is also prepared.
支持部材側層用混合粉は、鉄系粉末と、黒鉛粉末と、あるいはさらに合金元素粉末と、硬度改善粒子粉末と、固体潤滑剤粉末とを、上記した基地部組成となるように、所定量配合し、混合、混錬して、混合粉（支持部材側層用混合粉）とする。支持部材側層用混合粉では、鉄系粉末を純鉄粉とする。黒鉛粉末は、支持部材側層用混合粉全量に対する質量％で、0.5～2.0％配合する。合金元素粉末は、支持部材側層用混合粉全量に対する質量％で、合計で0～5.0％配合する。配合する合金元素粉末としては、Mo粉末、Ni粉末、Cu粉末とすることが好ましい。硬度改善粒子粉末は鉄－モリブデン（Fe－Mo）合金粒子粉末として、該硬度改善粒子粉末を支持部材側層用混合粉全量に対する質量％で、0～5.0％配合する。固体潤滑剤粉末は、前記支持部材側層用混合粉全量に対する質量％で、0～4.0％配合する。また、混合粉には、ステアリン酸亜鉛等の潤滑剤を配合しても良い。
The mixed powder for the support member side layer is prepared by blending, mixing, and kneading a predetermined amount of iron-based powder, graphite powder, or alloying element powder, hardness improving particle powder, and solid lubricant powder so as to obtain the above-mentioned base composition, to obtain a mixed powder (mixed powder for the support member side layer). In the mixed powder for the support member side layer, the iron-based powder is pure iron powder. The graphite powder is blended at 0.5 to 2.0% by mass based on the total amount of the mixed powder for the support member side layer. The alloying element powder is blended at 0 to 5.0% by mass based on the total amount of the mixed powder for the support member side layer. The alloying element powder is preferably Mo powder, Ni powder, or Cu powder. The hardness improving particle powder is iron-molybdenum (Fe-Mo) alloy particle powder, and the hardness improving particle powder is blended at 0 to 5.0% by mass based on the total amount of the mixed powder for the support member side layer. The solid lubricant powder is mixed in an amount of 0 to 4.0% by mass based on the total amount of the mixed powder for the support member side layer. The mixed powder may also contain a lubricant such as zinc stearate.
そして、機能部材側層用混合粉と支持部材側層用混合粉をこの順に、所望の比率で、所定形状の金型に充填する。金型に充填した後に、上記した単層構造の場合と同じように、プレス加工を施して圧粉体とし、ついで圧粉体に、上記した単層構造の場合と同じように、焼結処理を施し二層構造の焼結体を得る。焼結処理は、単層構造の場合と同様に、還元雰囲気中で、加熱温度：1100～1200℃の温度範囲で、0.5hr以上保持する処理とすることが好ましい。加熱温度が1100℃未満では、焼結拡散が不足し、一方、1200℃超えでは、過拡散となり、耐摩耗性が低下する。なお、プレス加工Ｐ－焼結処理Ｓ工程は複数回繰り返す工程（２Ｐ２Ｓ等）としてもよい。
Then, the mixed powder for the functional member side layer and the mixed powder for the support member side layer are filled in this order and in the desired ratio into a mold of a specified shape. After filling the mold, press processing is performed to form a green compact in the same manner as in the case of the single layer structure described above, and then the green compact is sintered in the same manner as in the case of the single layer structure described above to obtain a sintered body with a two-layer structure. As in the case of the single layer structure, the sintering process is preferably performed in a reducing atmosphere at a heating temperature of 1100 to 1200°C for 0.5 hours or more. If the heating temperature is less than 1100°C, sintering diffusion will be insufficient, while if it exceeds 1200°C, excessive diffusion will occur and wear resistance will decrease. The pressing process P-sintering process S process may be repeated multiple times (2P2S, etc.).
得られた二層構造の焼結体に研削・切削等の加工を施して、所望の寸法形状の二層構造のバルブシート（製品）とする。
The resulting two-layer sintered body is then processed by grinding, cutting, etc. to produce a two-layer valve seat (product) of the desired dimensions and shape.
なお、上記した焼結処理後に、好ましくは研削・切削等の加工を施して得られた２層構造のバルブシート（製品）に、樹脂含浸処理を施すことが好ましい。樹脂含浸処理は、真空雰囲気中で、熱硬化性樹脂または嫌気性樹脂の液体中にバルブシートを浸漬したのち、大気圧から加圧して、空孔中に樹脂を十分に含浸したのち、加熱して空孔内の樹脂を硬化させて封孔する処理とすることが好ましい。樹脂含浸処理により、鉄基焼結合金材（機能部材側層および支持部材側層、または機能部材側層）の空孔には熱硬化性樹脂または嫌気性樹脂が含浸される。
After the above-mentioned sintering process, it is preferable to perform a resin impregnation process on the valve seat (product) with a two-layer structure obtained by processing such as grinding and cutting. The resin impregnation process is preferably a process in which the valve seat is immersed in a liquid of thermosetting resin or anaerobic resin in a vacuum atmosphere, and then pressurized from atmospheric pressure to fully impregnate the resin into the pores, and then heated to harden the resin in the pores and seal them. By the resin impregnation process, the pores in the iron-based sintered alloy material (the functional member side layer and the support member side layer, or the functional member side layer) are impregnated with thermosetting resin or anaerobic resin.
以下、実施例に基づき、さらに本発明について説明する。
The present invention will be further explained below based on examples.
まず、機能部材側層用混合粉および支持部材側層用混合粉を用意した。
First, the mixed powder for the functional component side layer and the mixed powder for the support component side layer were prepared.
機能部材側層用混合粉（混合粉No.A～No.N）は、基地相形成用の鉄系粉末に、黒鉛粉末、合金元素粉末、硬質粒子粉末、固体潤滑剤粒子粉末（MnS粉末）を、表１に示す配合量となるように調整し、混合、混錬して混合粉とした。なお、使用した鉄系粉末は、表２に示す組成、硬さの高速度工具鋼系粉末とした。また、使用した硬質粒子粉末は、表３に示す組成、硬さ、平均粒径の粒子粉末とした。なお、混合粉には潤滑剤として、混合粉100質量部に対しステアリン酸亜鉛を1質量部配合した。
The mixed powders for the functional component side layers (mixed powders No. A to No. N) were prepared by mixing and kneading the iron-based powder for forming the matrix phase with graphite powder, alloying element powder, hard particle powder, and solid lubricant particle powder (MnS powder) in the amounts shown in Table 1. The iron-based powder used was high-speed tool steel powder with the composition and hardness shown in Table 2. The hard particle powder used was particle powder with the composition, hardness, and average particle size shown in Table 3. The mixed powders were mixed with 1 part by mass of zinc stearate per 100 parts by mass of the mixed powder as a lubricant.
また、支持部材側層用混合粉（混合粉No.1A、No.1B）は、基地相形成用の鉄系粉末と、黒鉛粉末と、あるいはさらに合金元素粉末と硬度改善粒子粉末と固体潤滑剤粒子粉末と、を表１に示す配合量となるように調整し、混合、混錬して混合粉とした。なお、使用した鉄系粉末は表２に示す組成、硬さの粉末とした。鉄系粉末No.ｃは純鉄粉である。また、使用した硬質粒子粉末は、表３に示す組成、硬さ、平均粒径の粒子粉末とした。硬質粒子粉末No.h3は、硬度改善粒子粉末で、鉄―モリブデン合金粒子粉末である。なお、混合粉には潤滑剤として、混合粉100質量部に対しステアリン酸亜鉛を1質量部配合した。また、一部のバルブシートでは、機能部材側層のみの単層構造とした。
The mixed powder for the support member side layer (mixed powder No. 1A, No. 1B) was prepared by mixing and kneading iron-based powder for forming the matrix phase, graphite powder, or alloy element powder, hardness improvement particle powder, and solid lubricant particle powder in the amounts shown in Table 1. The iron-based powder used had the composition and hardness shown in Table 2. Iron-based powder No. c was pure iron powder. The hard particle powder used had the composition, hardness, and average particle size shown in Table 3. Hard particle powder No. h3 was a hardness improvement particle powder, an iron-molybdenum alloy particle powder. The mixed powder contained 1 part by mass of zinc stearate per 100 parts by mass of the mixed powder as a lubricant. Some valve seats had a single-layer structure with only the functional member side layer.
得られた混合粉を、金型に充填し、プレス加工機で所定のバルブシート形状の圧粉体とした。得られた圧粉体について、アルキメデス法で密度を測定したが、6.6g/cm3以上であった。
The obtained mixed powder was filled into a die and pressed into a green compact having a predetermined valve seat shape by a press. The density of the obtained green compact was measured by Archimedes' method and was found to be 6.6 g/ cm3 or more.
ついで、得られた圧粉体に、焼結処理を施した。焼結処理は、還元雰囲気中で、加熱温度：1160℃とした焼結炉に装入し（保持時間：6hr）、焼結体とした。
Then, the obtained green compact was subjected to a sintering process. The compact was placed in a sintering furnace in a reducing atmosphere with a heating temperature of 1160°C (holding time: 6 hours) to produce a sintered compact.
得られた焼結体に、さらに切削、研磨等の加工を施して、所定形状（外径：27mmΦ×内径22mmΦ×厚さ6mm）の鉄基焼結合金製バルブシートとした。
The obtained sintered body was further processed by cutting, polishing, etc. to produce an iron-based sintered alloy valve seat of the specified shape (outer diameter: 27 mmΦ x inner diameter 22 mmΦ x thickness 6 mm).
なお、得られたバルブシートの一部について、さらに、嫌気性樹脂を用いて樹脂含浸処理を施した。樹脂含浸処理は、真空雰囲気中で、バルブシートを当該樹脂の液体中に浸漬したのち、大気圧からさらに加圧して、空孔に樹脂を十分に含浸させ、さらに加熱して空孔内の樹脂を硬化させて、封孔する処理とした。なお、使用した嫌気性樹脂は、市販の嫌気性樹脂とした。
Furthermore, some of the obtained valve seats were subjected to a resin impregnation process using anaerobic resin. The resin impregnation process involves immersing the valve seats in a liquid of the resin in a vacuum atmosphere, then increasing the pressure from atmospheric pressure to thoroughly impregnate the resin into the pores, and then heating the valve seats to harden the resin in the pores and seal them. The anaerobic resin used was a commercially available anaerobic resin.
ついで、得られたバルブシートについて、化学分析、組織観察、硬さ試験、密度試験、摩耗試験、圧環強さ試験を実施した。試験方法は次の通りとした。
（１）化学分析
得られたバルブシートの各部位から分析用試料を採取し、発光分析法により、各部位における各成分の含有量を分析し、焼結体基地部の組成を求めた。
（２）組織観察
得られたバルブシートについて、軸方向に垂直な断面を研磨し、腐食（腐食液：ナイタール液）して組織を現出し、光学顕微鏡（倍率：200倍）で観察した。得られた組織写真を用いて、基地相組織の種類を特定し、画像解析により面積率を求めた。また、走査型電子顕微鏡（倍率：2000倍）を用いて、基地相中に析出した炭化物について観察し、炭化物の粒径を測定した。炭化物粒径の最大径が10μm以下であることを確認し、基地相が微細炭化物析出相であるとした。炭化物粒径（長辺長さ）の最大径が10μmを超える場合には、単に炭化物析出相とした。 Next, the obtained valve seat was subjected to chemical analysis, structure observation, hardness test, density test, wear test, and radial crushing strength test. The test methods were as follows.
(1) Chemical Analysis Analytical samples were taken from each portion of the obtained valve seat, and the content of each component in each portion was analyzed by optical emission spectrometry to determine the composition of the sintered body matrix.
(2) Structure observation The cross section perpendicular to the axial direction of the obtained valve seat was polished and etched (etchant: nital solution) to reveal the structure, and observed with an optical microscope (magnification: 200 times). The obtained structure photograph was used to identify the type of matrix structure, and the area ratio was determined by image analysis. In addition, a scanning electron microscope (magnification: 2000 times) was used to observe the carbides precipitated in the matrix phase and measure the grain size of the carbides. It was confirmed that the maximum diameter of the carbide grain size was 10 μm or less, and the matrix phase was determined to be a fine carbide precipitate phase. When the maximum diameter of the carbide grain size (long side length) exceeded 10 μm, it was simply determined to be a carbide precipitate phase.
（１）化学分析
得られたバルブシートの各部位から分析用試料を採取し、発光分析法により、各部位における各成分の含有量を分析し、焼結体基地部の組成を求めた。
（２）組織観察
得られたバルブシートについて、軸方向に垂直な断面を研磨し、腐食（腐食液：ナイタール液）して組織を現出し、光学顕微鏡（倍率：200倍）で観察した。得られた組織写真を用いて、基地相組織の種類を特定し、画像解析により面積率を求めた。また、走査型電子顕微鏡（倍率：2000倍）を用いて、基地相中に析出した炭化物について観察し、炭化物の粒径を測定した。炭化物粒径の最大径が10μm以下であることを確認し、基地相が微細炭化物析出相であるとした。炭化物粒径（長辺長さ）の最大径が10μmを超える場合には、単に炭化物析出相とした。 Next, the obtained valve seat was subjected to chemical analysis, structure observation, hardness test, density test, wear test, and radial crushing strength test. The test methods were as follows.
(1) Chemical Analysis Analytical samples were taken from each portion of the obtained valve seat, and the content of each component in each portion was analyzed by optical emission spectrometry to determine the composition of the sintered body matrix.
(2) Structure observation The cross section perpendicular to the axial direction of the obtained valve seat was polished and etched (etchant: nital solution) to reveal the structure, and observed with an optical microscope (magnification: 200 times). The obtained structure photograph was used to identify the type of matrix structure, and the area ratio was determined by image analysis. In addition, a scanning electron microscope (magnification: 2000 times) was used to observe the carbides precipitated in the matrix phase and measure the grain size of the carbides. It was confirmed that the maximum diameter of the carbide grain size was 10 μm or less, and the matrix phase was determined to be a fine carbide precipitate phase. When the maximum diameter of the carbide grain size (long side length) exceeded 10 μm, it was simply determined to be a carbide precipitate phase.
また、硬質粒子の周辺には、合金が拡散し高合金相が形成されている。軸方向に垂直な断面を研磨し、腐食（腐食液：マーブル液）して組織を現出し、光学顕微鏡（倍率：200倍）で観察し、画像解析により組織分率（面積率）を測定した。
（３）硬さ試験
得られたバルブシートについて、軸方向に垂直な断面を研磨し、腐食（腐食液：ナイタール液）して組織を現出し、ビッカース硬度計（試験力：0.98N(100gf)）を用いて、基地相のビッカース硬さHVを測定した。
（４）密度試験
得られたバルブシート（機能部材側層のみ、支持部材側層のみおよび二層構造）について、アルキメデス法を用いて密度（焼結体密度）を測定した。
（５）摩耗試験
得られたバルブシートについて、図１に示すリグ試験機を用いて、次に示す試験条件で摩耗試験を実施した。 In addition, the alloy diffuses around the hard particles to form a high alloy phase. The cross section perpendicular to the axial direction was polished and etched (etching solution: marble solution) to reveal the structure, which was then observed under an optical microscope (magnification: 200x) and the structure fraction (area fraction) was measured by image analysis.
(3) Hardness Test For the obtained valve seat, a cross section perpendicular to the axial direction was polished and etched (etchant: nital solution) to reveal the structure, and the Vickers hardness HV of the matrix phase was measured using a Vickers hardness tester (test force: 0.98 N (100 gf)).
(4) Density Test The density (sintered body density) of the obtained valve seats (functional member side layer only, support member side layer only, and two-layer structure) was measured by Archimedes' method.
(5) Wear Test A wear test was carried out on the obtained valve seat using a rig tester shown in FIG. 1 under the test conditions shown below.
（３）硬さ試験
得られたバルブシートについて、軸方向に垂直な断面を研磨し、腐食（腐食液：ナイタール液）して組織を現出し、ビッカース硬度計（試験力：0.98N(100gf)）を用いて、基地相のビッカース硬さHVを測定した。
（４）密度試験
得られたバルブシート（機能部材側層のみ、支持部材側層のみおよび二層構造）について、アルキメデス法を用いて密度（焼結体密度）を測定した。
（５）摩耗試験
得られたバルブシートについて、図１に示すリグ試験機を用いて、次に示す試験条件で摩耗試験を実施した。 In addition, the alloy diffuses around the hard particles to form a high alloy phase. The cross section perpendicular to the axial direction was polished and etched (etching solution: marble solution) to reveal the structure, which was then observed under an optical microscope (magnification: 200x) and the structure fraction (area fraction) was measured by image analysis.
(3) Hardness Test For the obtained valve seat, a cross section perpendicular to the axial direction was polished and etched (etchant: nital solution) to reveal the structure, and the Vickers hardness HV of the matrix phase was measured using a Vickers hardness tester (test force: 0.98 N (100 gf)).
(4) Density Test The density (sintered body density) of the obtained valve seats (functional member side layer only, support member side layer only, and two-layer structure) was measured by Archimedes' method.
(5) Wear Test A wear test was carried out on the obtained valve seat using a rig tester shown in FIG. 1 under the test conditions shown below.
試験温度：150℃、250℃（着座側温度）
試験時間：12hr
カム回転数：3000rpm
バルブ回転数：20rpm
衝撃荷重：700N
バルブ材質：窒化膜付き耐熱鋼（SUH35表面硬さ1150HV）
試験後、試験片（バルブシート）の摩耗量を測定した。得られた摩耗量から、バルブシートNo.1（従来例）を基準（1.00）とし、当該バルブシートの摩耗比を算出した。
（６）圧環強さ試験
得られたバルブシート（機能部材側層のみ）について、JIS Z 2507の規定に準拠して、圧環強さを求めた。得られた圧環強さから、バルブシートNo.1（従来例）を基準（1.00）とし、当該バルブシート（機能部材側層）の圧環強さ比を算出した。なお、バルブシートNo.1（従来例）の圧環強さは490MPaであった。 Test temperature: 150℃, 250℃ (seating side temperature)
Test duration: 12 hours
Cam rotation speed: 3000 rpm
Valve speed: 20 rpm
Impact load: 700N
Valve material: Heat-resistant steel with nitride film (SUH35 surface hardness 1150HV)
After the test, the amount of wear of the test piece (valve seat) was measured. From the amount of wear obtained, the wear ratio of the valve seat was calculated, taking the valve seat No. 1 (conventional example) as the standard (1.00).
(6) Radial Crushing Strength Test The radial crushing strength of the obtained valve seat (functional component side layer only) was determined in accordance with the provisions of JIS Z 2507. From the radial crushing strength obtained, the radial crushing strength ratio of the valve seat (functional component side layer) was calculated, taking the valve seat No. 1 (conventional example) as the standard (1.00). The radial crushing strength of the valve seat No. 1 (conventional example) was 490 MPa.
試験時間：12hr
カム回転数：3000rpm
バルブ回転数：20rpm
衝撃荷重：700N
バルブ材質：窒化膜付き耐熱鋼（SUH35表面硬さ1150HV）
試験後、試験片（バルブシート）の摩耗量を測定した。得られた摩耗量から、バルブシートNo.1（従来例）を基準（1.00）とし、当該バルブシートの摩耗比を算出した。
（６）圧環強さ試験
得られたバルブシート（機能部材側層のみ）について、JIS Z 2507の規定に準拠して、圧環強さを求めた。得られた圧環強さから、バルブシートNo.1（従来例）を基準（1.00）とし、当該バルブシート（機能部材側層）の圧環強さ比を算出した。なお、バルブシートNo.1（従来例）の圧環強さは490MPaであった。 Test temperature: 150℃, 250℃ (seating side temperature)
Test duration: 12 hours
Cam rotation speed: 3000 rpm
Valve speed: 20 rpm
Impact load: 700N
Valve material: Heat-resistant steel with nitride film (SUH35 surface hardness 1150HV)
After the test, the amount of wear of the test piece (valve seat) was measured. From the amount of wear obtained, the wear ratio of the valve seat was calculated, taking the valve seat No. 1 (conventional example) as the standard (1.00).
(6) Radial Crushing Strength Test The radial crushing strength of the obtained valve seat (functional component side layer only) was determined in accordance with the provisions of JIS Z 2507. From the radial crushing strength obtained, the radial crushing strength ratio of the valve seat (functional component side layer) was calculated, taking the valve seat No. 1 (conventional example) as the standard (1.00). The radial crushing strength of the valve seat No. 1 (conventional example) was 490 MPa.
得られた結果を表４および表５に示す。
The results are shown in Tables 4 and 5.
本発明例はいずれも、従来例（バルブシートNo.1）に比べて、機能部材側層の焼結体密度が高くなり、さらに圧環強さ比が高く圧環強さ（機能部材側層）が向上し、また、摩耗比が低く、耐摩耗性が向上している。なお、本発明の内燃機関用バルブシート用材料（鉄基焼結合金材）は、ＬＰＧ、ＣＮＧ水素等のガス燃料、及びエタノール含有の特殊燃料を使用する内燃機関用バルブシートの耐摩耗性向上に寄与することが期待できる。
Compared to the conventional example (Valve Seat No. 1), all of the examples of the present invention have a higher sintered density in the functional component layer, a higher radial crushing strength ratio, improved radial crushing strength (functional component layer), and a lower wear ratio, improved wear resistance. The material for internal combustion engine valve seats of the present invention (iron-based sintered alloy material) is expected to contribute to improving the wear resistance of valve seats for internal combustion engines that use gas fuels such as LPG and CNG hydrogen, as well as special fuels containing ethanol.
また、空孔への樹脂含浸処理を施された本発明例（バルブシートNo.17、No.18）は、従来例（バルブシートNo.1）に比べて圧壊強さが向上し、耐摩耗性が向上している。樹脂含浸処理を施された本発明例（バルブシートNo.17）は、樹脂含浸処理なしの本発明例（バルブシートNo.6）と同等の圧環強さ、耐摩耗性を示している。樹脂含浸処理による封孔により、圧壊強さ、耐摩耗性の低下を伴うことなく、耐食性の向上が期待できる。
In addition, the examples of the present invention (valve seats No. 17 and No. 18) in which the pores were impregnated with resin have improved crushing strength and wear resistance compared to the conventional example (valve seat No. 1). The example of the present invention (valve seat No. 17) that was impregnated with resin exhibits the same radial crushing strength and wear resistance as the example of the present invention (valve seat No. 6) that was not impregnated with resin. By sealing the pores with resin impregnation, it is expected that corrosion resistance will be improved without a decrease in crushing strength or wear resistance.
１ バルブシート
２ シリンダブロック相当材
３ 加熱手段
４ バルブ 1Valve seat 2 Cylinder block equivalent material 3 Heating means 4 Valve
２ シリンダブロック相当材
３ 加熱手段
４ バルブ 1
Claims (9)
- 内燃機関のシリンダーヘッドに圧入されるバルブシートであって、
該バルブシートが機能部材側層からなる単層構造を有し、
前記機能部材側層が、微細炭化物析出相からなる基地相と、該基地相中に面積率で、5.0～30.0％の高合金相と、10.0～40.0％の硬質粒子と、さらに0～4.0％の固体潤滑剤粒子を分散させてなる組織を有し、
前記硬質粒子が、ビッカース硬さで600～1200HVの硬さを有し、質量％で、Si：2.2～2.7％、Cr：7.5～9.5％、Mo：27.0～30.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo系Co基金属間化合物粒子またはSi：1.5～2.5％、Cr：24.0～26.0％、Mo：23.0～26.0％、Ni：9.5～11.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo－Ni系Co基金属間化合物粒子であり、
前記基地相、前記硬質粒子および前記固体潤滑剤粒子を含む基地部が、質量％で、C：0.50～2.80％を含み、さらに、Si：1.80％以下、Mn：2.50％以下、Cr：3.00～11.00％、Mo：3.00～17.00％、Ni：1.00～8.50％、Co：5.00～30.00％、V：0.50～4.00％、W：4.00～10.00％のうちから選ばれた１種または２種以上、およびS：0～2.00％を含有し、残部Feおよび不可避的不純物からなる基地部組成を有する鉄基焼結合金材からなり、
前記バルブシートの密度が6.6～7.4g/cm3であることを特徴とする内燃機関用鉄基焼結合金製バルブシート。 A valve seat press-fitted into a cylinder head of an internal combustion engine,
the valve seat has a single-layer structure including a functional component-side layer,
the functional component-side layer has a structure in which a matrix phase consisting of a fine carbide precipitate phase, a high alloy phase of 5.0 to 30.0% by area, hard particles of 10.0 to 40.0% by area, and solid lubricant particles of 0 to 4.0% by area are dispersed in the matrix phase;
the hard particles are Si-Cr-Mo-based Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, in mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities; or Si-Cr-Mo-Ni-based Co-based intermetallic compound particles having a composition containing, in mass%, Si: 1.5 to 2.5%, Cr: 24.0 to 26.0%, Mo: 23.0 to 26.0%, Ni: 9.5 to 11.0%, with the balance being Co and unavoidable impurities;
the matrix portion including the matrix phase, the hard particles, and the solid lubricant particles is an iron-based sintered alloy material having a matrix composition containing, in mass %, C: 0.50 to 2.80%, one or more selected from Si: 1.80% or less, Mn: 2.50% or less, Cr: 3.00 to 11.00%, Mo: 3.00 to 17.00%, Ni: 1.00 to 8.50%, Co: 5.00 to 30.00%, V: 0.50 to 4.00%, W: 4.00 to 10.00%, and S: 0 to 2.00%, with the balance being Fe and unavoidable impurities;
An iron-based sintered alloy valve seat for an internal combustion engine, characterized in that the density of the valve seat is 6.6 to 7.4 g/ cm3 . - 内燃機関のシリンダーヘッドに圧入されるバルブシートであって、
該バルブシートが機能部材側層と支持部材側層とが一体で焼結された二層構造を有し、
前記機能部材側層が、微細炭化物析出相からなる基地相と、該基地相中に面積率で、5.0～30.0％の高合金相と、10.0～40.0％の硬質粒子と、さらに0～4.0％の固体潤滑剤粒子を分散させてなる組織を有し、
前記硬質粒子が、ビッカース硬さで600～1200HVの硬さを有し、質量％で、Si：2.2～2.7％、Cr：7.5～9.5％、Mo：27.0～30.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo系Co基金属間化合物粒子またはSi：1.5～2.5％、Cr：24.0～26.0％、Mo：23.0～26.0％、Ni：9.5～11.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo－Ni系Co基金属間化合物粒子であり、
前記基地相、前記硬質粒子および前記固体潤滑剤粒子を含む基地部が、質量％で、C：0.50～2.80％を含み、さらに、Si：1.80％以下、Mn：2.50％以下、Cr：3.00～11.00％、Mo：3.00～17.00％、Ni：1.00～8.50％、Co：5.00～30.00％、V：0.50～4.00％、W：4.00～10.00％のうちから選ばれた１種または２種以上、およびS：0～2.00％を含有し、残部Feおよび不可避的不純物からなる基地部組成を有し、
前記支持部材側層が、パーライトからなる基地相と、該基地相中に、面積率で0～4.0％の固体潤滑剤粒子および0～5.0％の硬度改善粒子を分散させてなる組織と、さらに前記基地相、前記固体潤滑剤粒子および前記硬度改善粒子を含む基地部が、質量％で、C：0.30～2.00％を含み、さらに、Ni：0～2.00％、Mo：0～2.00％、Cu：0～5.00％、Mn：0～5.00％およびS：0～2.00％を含有し、残部Feおよび不可避的不純物からなる組成と、を有する鉄基焼結合金材からなり、
前記バルブシートの密度が6.7～7.4g/cm3であることを特徴とする内燃機関用鉄基焼結合金製バルブシート。 A valve seat press-fitted into a cylinder head of an internal combustion engine,
the valve seat has a two-layer structure in which a functional member-side layer and a support member-side layer are sintered together,
the functional component-side layer has a structure in which a matrix phase consisting of a fine carbide precipitate phase, a high alloy phase of 5.0 to 30.0% by area, hard particles of 10.0 to 40.0% by area, and solid lubricant particles of 0 to 4.0% by area are dispersed in the matrix phase;
the hard particles are Si-Cr-Mo-based Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, in mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities; or Si-Cr-Mo-Ni-based Co-based intermetallic compound particles having a composition containing, in mass%, Si: 1.5 to 2.5%, Cr: 24.0 to 26.0%, Mo: 23.0 to 26.0%, Ni: 9.5 to 11.0%, with the balance being Co and unavoidable impurities;
the matrix portion including the matrix phase, the hard particles, and the solid lubricant particles contains, in mass %, C: 0.50 to 2.80%, one or more selected from Si: 1.80% or less, Mn: 2.50% or less, Cr: 3.00 to 11.00%, Mo: 3.00 to 17.00%, Ni: 1.00 to 8.50%, Co: 5.00 to 30.00%, V: 0.50 to 4.00%, W: 4.00 to 10.00%, and S: 0 to 2.00%, with the balance being Fe and unavoidable impurities;
the support member side layer is made of an iron-based sintered alloy material having a structure in which a matrix phase made of pearlite, 0-4.0% by area of solid lubricant particles and 0-5.0% by area of hardness improver particles are dispersed in the matrix phase, and the matrix portion containing the matrix phase, the solid lubricant particles and the hardness improver particles contains, by mass %, C: 0.30-2.00%, Ni: 0-2.00%, Mo: 0-2.00%, Cu: 0-5.00%, Mn: 0-5.00%, and S: 0-2.00%, with the balance being Fe and unavoidable impurities;
An iron-based sintered alloy valve seat for an internal combustion engine, characterized in that the density of the valve seat is 6.7 to 7.4 g/ cm3 . - 前記微細炭化物析出相は、粒径10μm以下の微細炭化物が析出し、ビッカース硬さで450～650HVの硬さを有する相であることを特徴とする請求項１または２に記載の内燃機関用鉄基焼結合金製バルブシート。 The iron-based sintered alloy valve seat for internal combustion engines according to claim 1 or 2, characterized in that the fine carbide precipitation phase is a phase in which fine carbides having a grain size of 10 μm or less are precipitated and has a Vickers hardness of 450 to 650 HV.
- 前記固体潤滑剤粒子が、硫化マンガンMnS、二硫化モリブデンMoS2のうちから選ばれた１種または２種であることを特徴とする請求項１ないし３のいずれか一項に記載の内燃機関用鉄基焼結合金製バルブシート。 4. The valve seat made of an iron-based sintered alloy for an internal combustion engine according to claim 1, wherein the solid lubricant particles are one or two types selected from the group consisting of manganese sulfide (MnS) and molybdenum disulfide (MoS2 ) .
- 前記硬度改善粒子が、鉄―モリブデン合金粒子であることを特徴とする請求項２ないし４のいずれか一項に記載の鉄基焼結合金製バルブシート。 The iron-based sintered alloy valve seat according to any one of claims 2 to 4, characterized in that the hardness improving particles are iron-molybdenum alloy particles.
- 前記鉄基焼結合金材の空孔には、熱硬化性樹脂または嫌気性樹脂が含浸されてなることを特徴とする請求項１ないし５のいずれか一項に記載の内燃機関用鉄基焼結合金製バルブシート。 The iron-based sintered alloy valve seat for an internal combustion engine according to any one of claims 1 to 5, characterized in that the pores of the iron-based sintered alloy material are impregnated with a thermosetting resin or an anaerobic resin.
- 請求項１に記載の単層構造の鉄基焼結合金製バルブシートの製造方法であって、
鉄系粉末と、黒鉛粉末と、合金元素粉末と、硬質粒子粉末と、あるいはさらに固体潤滑剤粉末とを所定量配合し、混合、混錬して、混合粉としたのち、
前記混合粉を所定形状の金型に充填しプレス加工を施して圧粉体とし、ついで、
前記圧粉体に保護雰囲気中で焼結処理を施し焼結体としたのち、切削加工あるいはさらに研削加工を施して、所定形状のバルブシートを製造するに当たり、
前記鉄系粉末を、質量％で、C：0.2～0.8％、Si：1.0％以下、Mn：1.0％以下、Cr：7.0％以下、Mo：7.0％以下、V：5.0％以下、W：12.0％以下を含有し、あるいはさらにCo：12.0％以下を含有し、残部Feおよび不可避的不純物からなる組成を有し、ビッカース硬さで170～280HVの粒子硬さを有する鉄系粉末とし、該鉄系粉末を、前記混合粉全量に対する質量％で、40.0～70.0％配合し、
前記硬質粒子粉末を、ビッカース硬さで600～1200HVの硬さを有し、質量％で、Si：2.2～2.7％、Cr：7.5～9.5％、Mo：27.0～30.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo系Co基金属間化合物粒子またはSi：1.5～2.5％、Cr：24.0～26.0％、Mo：23.0～26.0％、Ni：9.5～11.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo－Ni系Co基金属間化合物粒子とし、該硬質粒子粉末を、前記混合粉全量に対する質量％で、10.0～40.0％配合し、
前記黒鉛粉末を、前記混合粉全量に対する質量％で、0.5～2.0％配合し、
前記合金元素粉末を、前記混合粉全量に対する質量％で、合計0～7.0％配合し、さらに、前記固体潤滑剤粉末を、前記混合粉全量に対する質量％で、0～4.0％配合し、
前記プレス加工を、前記圧粉体の密度が、密度:6.6/cm3以上となるように施し、
前記焼結処理を、焼結温度：1100～1200℃で行う処理として、前記焼結体を得ることを特徴とする鉄基焼結合金製バルブシートの製造方法。 A method for producing the single-layered iron-based sintered alloy valve seat according to claim 1, comprising the steps of:
Predetermined amounts of iron-based powder, graphite powder, alloying element powder, hard particle powder, and/or solid lubricant powder are blended, mixed, and kneaded to obtain a mixed powder, and then
The mixed powder is filled into a mold of a predetermined shape and pressed to form a green compact, and then
The green compact is sintered in a protective atmosphere to produce a sintered body, which is then cut or ground to produce a valve seat having a desired shape.
the iron-based powder contains, by mass%, C: 0.2 to 0.8%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 7.0% or less, Mo: 7.0% or less, V: 5.0% or less, W: 12.0% or less, or further contains Co: 12.0% or less, the balance being Fe and unavoidable impurities, and has a particle hardness of 170 to 280 HV in Vickers hardness; the iron-based powder is blended in an amount of 40.0 to 70.0% by mass with respect to the total amount of the mixed powder;
the hard particle powder being Si-Cr-Mo Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, by mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities, or Si-Cr-Mo-Ni Co-based intermetallic compound particles having a composition containing, by mass%, Si: 1.5 to 2.5%, Cr: 24.0 to 26.0%, Mo: 23.0 to 26.0%, Ni: 9.5 to 11.0%, with the balance being Co and unavoidable impurities, the hard particle powder being blended in an amount of 10.0 to 40.0% by mass with respect to the total amount of the mixed powder;
The graphite powder is blended in an amount of 0.5 to 2.0% by mass relative to the total amount of the mixed powder,
The alloy element powder is blended in a total amount of 0 to 7.0% by mass with respect to the total amount of the mixed powder, and the solid lubricant powder is blended in a total amount of 0 to 4.0% by mass with respect to the total amount of the mixed powder,
The press working is performed so that the density of the powder compact is 6.6/ cm3 or more,
The method for producing an iron-based sintered alloy valve seat is characterized in that the sintering process is carried out at a sintering temperature of 1100 to 1200°C to obtain the sintered body. - 請求項２に記載の二層構造の鉄基焼結合金製バルブシートの製造方法であって、
鉄系粉末と、黒鉛粉末と、合金元素粉末と、硬質粒子粉末と、あるいはさらに固体潤滑剤粉末とを所定量配合し、混合、混錬して、機能部材側層用混合粉とし、
鉄系粉末と、黒鉛粉末と、あるいはさらに合金元素粉末と、硬度改善粒子と、固体潤滑剤粉末とを所定量配合し、混合、混錬して、支持部材側層用混合粉とし、
前記機能部材側層用混合粉と前記支持部材側層用混合粉とをその順に、所定形状の金型に充填し、プレス加工を施して圧粉体とし、ついで、前記圧粉体に保護雰囲気中で焼結処理を施し、機能部材側層と支持部材側層とが一体で焼結された二層構造の焼結体としたのち、切削加工あるいはさらに研削加工を施して、所定形状の二層構造のバルブシートを製造するに当たり、
前記機能部材側層用混合粉では、前記鉄系粉末を、質量％で、C：0.2～0.8％、Si：1.0％以下、Mn：1.0％以下、Cr：7.0％以下、Mo：7.0％以下、V：5.0％以下、W：12.0％以下を含有し、あるいはさらにCo：12.0％以下を含有し、残部Feおよび不可避的不純物からなる組成を有し、ビッカース硬さで170～280HVの粒子硬さを有する鉄系粉末とし、該鉄系粉末を、前記混合粉全量に対する質量％で、40.0～70.0％配合し、
前記硬質粒子粉末を、ビッカース硬さで600～1200HVの硬さを有し、質量％で、Si：2.2～2.7％、Cr：7.5～9.5％、Mo：27.0～30.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo系Co基金属間化合物粒子またはSi：1.5～2.5％、Cr：24.0～26.0％、Mo：23.0～26.0％、Ni：9.5～11.0％を含み、残部Coおよび不可避的不純物からなる組成を有するSi－Cr－Mo－Ni系Co基金属間化合物粒子とし、該硬質粒子粉末を、前記混合粉全量に対する質量％で、10～40％配合し、
前記黒鉛粉末を、前記混合粉全量に対する質量％で、0.5～2.0％配合し、前記合金元素粉末を、前記混合粉全量に対する質量％で合計で、0～7.0％配合し、さらに、前記固体潤滑剤粉末を、前記混合粉全量に対する質量％で、0～4.0％配合し、
前記支持部材側層用混合粉では、前記鉄系粉末を純鉄粉とし、前記黒鉛粉末を、前記支持部材側層用混合粉全量に対する質量％で、0.5～2.0％配合し、前記合金元素粉末を、前記支持部材側層用混合粉全量に対する質量％で、合計で0～5.0％配合し、前記硬度改善粒子粉末を鉄－モリブデン合金粒子粉末として、該硬度改善粒子粉末を前記支持部材側層用混合粉全量に対する質量％で、0～5.0％配合し、前記固体潤滑剤粉末を、前記支持部材側層用混合粉全量に対する質量％で、0～4.0％配合し、
前記プレス加工を、前記圧粉体の密度が、密度:6.6g/cm3以上となるように施し、
前記焼結処理を、焼結温度：1100～1200℃で行う処理として、
前記二層構造の焼結体とすることを特徴とする鉄基焼結合金製バルブシートの製造方法。 A method for manufacturing the two-layered iron-based sintered alloy valve seat according to claim 2, comprising the steps of:
Predetermined amounts of iron-based powder, graphite powder, alloying element powder, hard particle powder, and/or solid lubricant powder are blended, mixed, and kneaded to obtain a mixed powder for a functional member side layer;
Predetermined amounts of iron-based powder, graphite powder, or alloying element powder, hardness improving particles, and solid lubricant powder are blended, mixed, and kneaded to obtain a mixed powder for a support member side layer;
The mixed powder for the functional member side layer and the mixed powder for the support member side layer are filled in this order into a die of a predetermined shape, and pressed to form a green compact. The green compact is then sintered in a protective atmosphere to form a two-layer sintered body in which the functional member side layer and the support member side layer are sintered together. The two-layer sintered body is then cut or further ground to produce a two-layer valve seat of a predetermined shape.
In the mixed powder for the functional component side layer, the iron-based powder contains, by mass%, C: 0.2 to 0.8%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 7.0% or less, Mo: 7.0% or less, V: 5.0% or less, W: 12.0% or less, or further contains Co: 12.0% or less, the balance being Fe and unavoidable impurities, and has a particle hardness of 170 to 280 HV in Vickers hardness, and the iron-based powder is blended in an amount of 40.0 to 70.0% by mass with respect to the total amount of the mixed powder,
the hard particle powder being Si-Cr-Mo Co-based intermetallic compound particles having a Vickers hardness of 600 to 1200 HV and containing, by mass%, Si: 2.2 to 2.7%, Cr: 7.5 to 9.5%, Mo: 27.0 to 30.0%, with the balance being Co and unavoidable impurities, or Si-Cr-Mo-Ni Co-based intermetallic compound particles having a composition containing, by mass%, Si: 1.5 to 2.5%, Cr: 24.0 to 26.0%, Mo: 23.0 to 26.0%, Ni: 9.5 to 11.0%, with the balance being Co and unavoidable impurities, the hard particle powder being blended in an amount of 10 to 40% by mass with respect to the total amount of the mixed powder;
The graphite powder is blended in an amount of 0.5 to 2.0% by mass relative to the total amount of the mixed powder, the alloy element powders are blended in an amount of 0 to 7.0% by mass relative to the total amount of the mixed powder, and the solid lubricant powder is blended in an amount of 0 to 4.0% by mass relative to the total amount of the mixed powder,
In the mixed powder for the support member side layer, the iron-based powder is pure iron powder, the graphite powder is blended in an amount of 0.5 to 2.0% by mass based on the total amount of the mixed powder for the support member side layer, the alloy element powder is blended in a total amount of 0 to 5.0% by mass based on the total amount of the mixed powder for the support member side layer, the hardness improving particle powder is iron-molybdenum alloy particle powder, the hardness improving particle powder is blended in an amount of 0 to 5.0% by mass based on the total amount of the mixed powder for the support member side layer, and the solid lubricant powder is blended in an amount of 0 to 4.0% by mass based on the total amount of the mixed powder for the support member side layer,
The press working is performed so that the density of the powder compact is 6.6 g/ cm3 or more,
The sintering process is carried out at a sintering temperature of 1100 to 1200°C.
A method for producing an iron-based sintered alloy valve seat, characterized in that the above-mentioned two-layer structure sintered body is obtained. - 前記焼結処理後に、さらに加熱硬化型樹脂または嫌気性樹脂を含浸する樹脂含浸処理を施すことを特徴とする請求項７または８に記載の鉄基焼結合金製バルブシートの製造方法。 The method for manufacturing an iron-based sintered alloy valve seat according to claim 7 or 8, characterized in that after the sintering process, a resin impregnation process is further carried out to impregnate the valve seat with a thermosetting resin or an anaerobic resin.
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|---|---|---|---|---|
| JP2006299404A (en) * | 2005-03-23 | 2006-11-02 | Nippon Piston Ring Co Ltd | Valve seat material made from iron-based sintered alloy for internal combustion engine |
| JP2007064165A (en) * | 2005-09-02 | 2007-03-15 | Nippon Piston Ring Co Ltd | Combination of valve and valve seat for internal combustion engine |
| WO2014119720A1 (en) * | 2013-01-31 | 2014-08-07 | 日本ピストンリング株式会社 | Highly wear-resistant valve seat for use in internal combustion engine and manufacturing method therefor |
| JP2018090900A (en) * | 2016-11-28 | 2018-06-14 | 日本ピストンリング株式会社 | Iron-based sintered allot valve seat for internal combustion engine having excellent wear resistance and assemblage of valve seat and valve |
| WO2019221106A1 (en) * | 2018-05-15 | 2019-11-21 | 日本ピストンリング株式会社 | Iron-based sintered alloy valve seat for internal combustion engine |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006299404A (en) * | 2005-03-23 | 2006-11-02 | Nippon Piston Ring Co Ltd | Valve seat material made from iron-based sintered alloy for internal combustion engine |
| JP2007064165A (en) * | 2005-09-02 | 2007-03-15 | Nippon Piston Ring Co Ltd | Combination of valve and valve seat for internal combustion engine |
| WO2014119720A1 (en) * | 2013-01-31 | 2014-08-07 | 日本ピストンリング株式会社 | Highly wear-resistant valve seat for use in internal combustion engine and manufacturing method therefor |
| JP2018090900A (en) * | 2016-11-28 | 2018-06-14 | 日本ピストンリング株式会社 | Iron-based sintered allot valve seat for internal combustion engine having excellent wear resistance and assemblage of valve seat and valve |
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