JP4736920B2 - Sliding material - Google Patents

Description

  The present invention relates to a sliding material that can be used for an engine block, a hydraulic pump, a compressor component, a bearing, and the like in which a part of the surface is a sliding surface.

  Generally, sliding materials are indispensable for various machines that perform reciprocating, rotational movement, and the like. For example, various sliding materials are used for engines and compressors.

  Generally, on the sliding surface, it is desirable that the sliding surface is a mirror surface in order to reduce the amount of wear due to friction. However, if the sliding surface is a mirror surface, the mirror-finished metals can be kept low when they are rubbed together via oil, but a certain amount of heat is generated, which may cause seizure. Therefore, a sliding surface with an appropriate surface roughness or a surface treatment such as plating that improves the sliding characteristics of the surface is required for each application. .

  Among them, several methods for modifying the surface by shot blasting have been studied depending on the purpose because they can be processed even after the sliding material is formed as a sliding member and can be applied with residual stress by compression.

  For example, in order to suppress wear of a sliding counterpart material, Patent Document 1 discloses shot injection using shot grains on a polished surface obtained by performing surface polishing of a machine part in which a large amount of hard particles such as metal carbide is dispersed. Disclosed is a method of removing an edge caused by burrs or the like on a polished surface (rounding, scraping, or missing a tip portion) by applying a treatment. It is disclosed that the wear of the mating member during sliding can be effectively suppressed by removing the edge.

Further, Patent Document 2 discloses a slide of a sliding member made of a powder aluminum alloy containing silicon, manganese, and magnesium, in which hard particles that are one or more kinds of iron-based hard particles and ceramic particles having a hardness lower than that of alumina are dispersed. Disclosed is a powder aluminum alloy sliding member in which a large number of recesses are formed by shot blasting using fine particles coated with either nickel or tin on the moving surface and either a nickel coating or a tin coating is formed. Yes. Numerous recesses serve as oil reservoirs and can secure the oil retaining function of the sliding surface. Also, a nickel or tin coating is formed on the surface of the aluminum alloy that easily adheres, making it difficult to wear and prevent scuffing. It is disclosed that it can be improved, and that the sliding surface is work-hardened by applying fine particles to the sliding surface, so that the wear resistance is improved accordingly.
Japanese Patent Laid-Open No. 11-207622 JP 2003-13163 A

  However, the characteristics required for the sliding surface vary depending on the intended sliding component. The method of modifying the surface by shot blasting has been studied as shown in the above-mentioned patent document depending on the purpose, but there is a sliding material that can further modify the sliding characteristics to meet the requirements of sliding parts. It has been demanded.

  Many sliding parts have a specified surface roughness in order to reduce the amount of wear during sliding.

  For example, the surface roughness (Rz) required for a bore in an engine is determined, and it is required to improve the sliding characteristics within the surface roughness.

  The shot injection process in Patent Document 1 is used for removing burrs, and the amount of wear is reduced by changing the Sm value (average peak interval) without changing the surface roughness (Rz) much. In Patent Document 2, the surface roughness is increased by a factor of five by performing shot blasting.

  The present invention has been made in view of such circumstances, and the surface sliding characteristics are improved according to the requirements of the sliding parts without changing the surface roughness of the sliding material by shot blasting. An object of the present invention is to provide a sliding material that can be used.

  Accordingly, the present inventors have intensively studied to solve this problem, and as a result of repeated trial and error, shot blasting of metal particles that are softer than the metal substrate and have a smaller coefficient of friction on the sliding surface of the metal substrate. As a result, it was discovered that the sliding characteristics of the sliding surface can be improved without mechanically increasing the surface roughness by mechanically forming a part of the metal particles on the sliding surface of the metal substrate. The present invention has been completed.

That is, in the sliding material of the present invention, the second metal substrate softer than the first metal substrate is cast into the first metal substrate, and both the first metal substrate and the second metal substrate are formed on the sliding surface. The metal base material, which is a composite material with exposed metal, and the sliding surface of the metal base material are softer than the first metal base material, harder than the second metal base material, and more friction than the first metal base material. by shot-blasting the small metal particles coefficients, and deposit metal that is mechanically deposited to the surface of the first metal substrate so as to cover at least 8% or more of the sliding surfaces, was closed, the first metal the substrate is a porous metal substrate, and the porous metal substrate, a second metal substrate, characterized that you have exposed to the sliding surface present on the porous metal substrate in the pores. It is preferable that the concave portion is formed on the surface of the second metal substrate by or shot blasting.

The first metal substrate is an iron-based porous material, the second metal substrate, aluminum is any one of an aluminum alloy, magnesium or magnesium alloy, metallic particles, zinc, tin, It is preferable to contain at least one of gold, copper and magnesium.

In particular, the second metal substrate is preferably an aluminum alloy, and the metal particles are preferably zinc .

  The processing conditions for the shot blasting are preferably the following conditions.

  Metal particle size: 150 μm or more and 750 μm or less, air pressure: 0.1 MPa or more and 0.3 MPa or less, spray distance: 50 mm or more and 150 mm or less, projection time: 5 seconds or more and 45 seconds or less.

By small shot blasting the metal particles and the friction coefficient softer than the first gold Shokumotozai the sliding surface of the gold Shokumotozai, first gold Shokumotozai mechanically alloyed some metallic particles (Mechanical alloying) and mechanically attached. Metal particles softer than the first metal substrate do not roughen the surface of the first metal substrate.

With or Chakukinzoku is appears as a characteristic surface properties of metal particles deposited by covering the at least eight percent of the sliding surface of the metal substrate, the sliding characteristics of the sliding surface is modified. Further, the friction coefficient of the sliding surface can be reduced by mechanically adhering metal particles having a smaller friction coefficient than the first metal substrate to the sliding surface. In addition, the metal base material is formed by casting a second metal base material softer than the first metal base material in the first metal base material, and exposing both the first metal base material and the second metal base material on the sliding surface. Composite material. By using a composite material, the sliding member has the advantages of both metals.

Or gold Shokumotozai has iron, iron alloy, the porous metal substrate, and aluminum, aluminum alloy, by being selected from the magnesium or magnesium alloy, excellent strength lightweight.

Also metallic particles, zinc, tin, gold, by containing at least one of copper and magnesium, the sliding characteristics of the sliding surface by the characteristics with soft respective metal than the first metal substrate is improved Is done.

Also metallic particles and softer than the first gold Shokumotozai, by being harder than the second metal substrate, when shot blasting the metallic particles, metallic particles of the second gold Shokumotozai the sliding table surface can be formed a recess is mechanically deposited on the sliding surface of且one first gold Shokumotozai. Therefore the sliding table surface of the composite der Rukin Shokumotozai can improve the sliding properties modified with sliding surfaces of the metal substrate.

The first gold Shokumotozai especially is iron-based porous material, the second gold Shokumotozai is an aluminum alloy, it is preferred that the metal particles is zinc. A metal base material in which an aluminum alloy is cast in an iron-based porous material and the iron-based porous material and aluminum alloy are exposed on the sliding surface is lighter than an iron-based material and has a higher strength and sliding than an aluminum alloy alone. Excellent as a moving material.

  In addition, by making the metal particles softer than iron and harder than aluminum alloy, the aluminum alloy surface can be recessed by shot blasting of zinc, but the surface of the iron-based porous material is not scratched, so the sliding material The surface roughness (Rz) of the sliding surface is not increased too much.

  Zinc that is softer than the iron-based porous material mechanically adheres to the surface of the iron-based porous material. Since zinc has a smaller friction coefficient than iron-based porous materials, the adhesion coefficient of zinc can lower the friction coefficient of the surface of the iron-based porous material, which in turn can reduce the friction coefficient of the entire sliding surface. Can be reduced. Therefore, the surface characteristics can be adjusted by adjusting the ratio of the iron-based porous material and the aluminum alloy.

  Moreover, the processing conditions of the said shot blasting are the said conditions, A metal particle can be appropriately made to adhere to a metal base material appropriately.

  The sliding material of the present invention has a metal substrate and an attached metal.

  Further, the adhered metal covers at least 8% or more of the sliding surface of the base material by shot blasting metal particles that are softer and have a smaller friction coefficient than the metallic base material on the sliding surface of the metal base material. It is mechanically attached to the surface.

  If the metal base material in this invention is a base material which consists of a metal used as a sliding material, there will be no limitation in particular. Examples thereof include iron-based metals, aluminum-based metals, and magnesium-based metals.

  In particular, those containing an iron-based metal as the metal substrate are preferred in terms of strength. For example, iron, an iron-based alloy, an iron-based porous material, and a composite material in which aluminum, an aluminum alloy, magnesium, or a magnesium alloy is cast into an iron-based porous material can be given.

  In addition, the metal substrate is preferably a composite material in which the first porous metal substrate is cast with a second metal substrate that is softer than the first porous metal substrate. For example, a composite material in which the first porous metal substrate is an iron-based metal and the second metal substrate is an aluminum-based metal, the first porous metal substrate is an iron-based metal, and the second metal substrate is magnesium. Examples of the composite material are metal based metals.

  In particular, it is preferable that the metal base material is a composite material in which an aluminum alloy is cast into an iron-based porous material because the base material is lightweight and excellent in strength.

  The shape of the metal substrate is not particularly limited and is adapted to the use as a sliding member. For example, the sliding material of the present invention can be used for an engine block, a hydraulic pump, a compressor component, a bearing, etc., part of which is a sliding surface.

  The metal particles in the present invention are not particularly limited as long as they are softer than the metal substrate used and have a small friction coefficient. For example, aluminum, zinc, tin, gold, copper, magnesium and nickel may be used as the metal particles.

  Further, the metal particles may be the same metal as all the particles, or may be a metal whose surface is coated with another metal. In that case, any metal may be used as long as it is softer than the metal substrate used by the coated metal, has a small friction coefficient, and has a low melting point.

  When the metal substrate is a composite material, the metal particles are preferably softer than the first porous metal substrate and harder than the second metal substrate. For example, when the first porous metal substrate is an iron-based metal and the second metal substrate is an aluminum-based metal, the metal particles are preferably zinc, copper, tin, or the like.

  The particle size of the metal particles is preferably 150 μm or more and 750 μm or less. When the particle diameter is within this range, it is easy to be deposited on the sliding surface by shot blasting on the sliding surface.

  The metal particles are mechanically attached to the sliding surface by shot blasting. The metal particles are mechanically attached to the metal substrate by mechanical alloying. Since the metal particles are softer than the metal substrate, the surface of the metal substrate is not roughened, and the surface roughness (Rz) of the metal substrate is not so increased.

  When the metal substrate is a composite material, the metal particles are mechanically attached and formed on the sliding surface of the first porous metal substrate that is harder than itself. In addition, the metal particles can form a recess on the sliding surface of the second metal substrate which is softer than itself. The concave portion becomes an oil reservoir on a sliding surface with lubricating oil or the like, and can further improve the sliding characteristics.

  Further, the adhered metal covers at least 8% or more of the sliding surface of the substrate. By covering at least 8% or more of the sliding surface, the characteristics of the attached metal particles appear as surface characteristics, and the sliding characteristics of the sliding surface are improved.

  Further, the friction coefficient of the sliding surface can be reduced by mechanically adhering metal particles having a friction coefficient smaller than that of the metal substrate to the sliding surface.

  In particular, when the metal substrate is a composite material obtained by casting an iron-based porous material with an aluminum alloy, the metal particles are preferably zinc.

  The shape of the iron-based porous material is not particularly limited. For example, a cylindrical shape, a ring shape, a plate shape, or a disk shape may be used.

  The iron-based porous material desirably has a porosity of 12% to 50%. If it is a porous material with the porosity of this range, it will become a sliding material with favorable adhesiveness and intensity | strength with an aluminum alloy.

  Further, the iron-based porous material may be used for the entire sliding member, or may be used for a part of the periphery of the sliding surface.

  The aluminum alloy can contain Cu, Si, Mg, Zn, Fe, Mn, Ni, Sn, and Ti.

  For example, JIS standard A2000 series and ADC12, AC8A, AC4C, AC2B etc. are mentioned as an aluminum alloy.

  The method for producing a composite material in which an aluminum alloy is cast into an iron-based porous material is a normal casting method, and is not particularly limited.

  For example, it is placed in a mold of a predetermined shape at a position where the iron-based porous material is exposed on the sliding surface so as to have a predetermined shape according to the purpose, and the aluminum alloy is cast at a predetermined pressure and a predetermined temperature. The porous alloy material is cast and the aluminum alloy is cast into the pores of the porous material.

  Then, it cools at predetermined temperature and takes out a sliding material from a type | mold.

  Next, honing is performed on the sliding surface of the sliding material taken out of the mold. By performing the honing process, the sliding surface becomes a surface on which both the iron-based porous material surface and the aluminum alloy surface exist.

  Next, shot blasting is performed on the sliding surface subjected to the honing process under the following conditions.

  Shot grain material: Zinc, Shot grain size: 150 μm or more and 750 μm or less, Air pressure: 0.1 MPa or more and 0.3 MPa or less, Injection distance: 50 mm or more and 150 mm or less, Projection time: 5 seconds or more and 45 seconds or less.

  The above conditions are conditions under which zinc can be mechanically deposited on the surface of the iron-based porous material without damaging the iron-based porous material.

  Therefore, the sliding member has a low coefficient of friction because zinc is mechanically adhered to the surface of the iron-based porous material without newly scratching the sliding surface of the iron-based porous material. And good sliding characteristics.

  Further, since the shot blasting process can be partially performed on the necessary surface, the process can be easily performed at a lower cost than the electrolytic corrosion process conventionally performed.

  Below, the test example of a sliding member is demonstrated. As a test example, a metal base material obtained by casting an aluminum alloy in an iron-based porous material was used. FIG. 1 is a partial explanatory view (cross-sectional view) of a manufacturing method of a sliding member of a test example.

  A cylindrical iron-based porous sintered body 1 having a porosity of 18%, which is an iron-based porous material, was prepared. Pure iron (KIP440B) was used as the material of the iron-based porous sintered body 1. The iron-based porous sintered body 1 has a cylindrical shape with a diameter of 86 mm, a height of 160 mm, and a cylinder with a thickness of 5 mm.

  As shown in FIG. 1, the iron-based porous sintered body 1 was placed on a die 2 of a cylinder block so that the iron-based porous sintered body 1 faces a sliding surface. The mold 2 is a cylinder block mold and has a cylindrical shape as shown in FIG.

  An aluminum alloy (ADC12) was poured into the mold 2 from the outer peripheral surface side and the bottom surface of the iron-based porous sintered body 1. The casting conditions at this time were a molten metal temperature of 680 ° C., a mold temperature of 250 ° C., preheating of the iron-based porous sintered body 1 at 800 ° C., and a molten metal pressure of 83 MPa.

  In this way, the molten aluminum alloy was cast from the outer peripheral surface side and the bottom surface of the iron-based porous sintered body 1 to the inside. The sliding inner peripheral surface of the cylinder bore 3 obtained in this way was honed with a honing machine.

  Using the cylinder bore 3 manufactured as described above, shot blasting was performed under various conditions, and the surface was observed.

  The shot blasting process was performed using the shot blasting device 4 on the inner surface of the cylinder which is the sliding surface of the cylinder bore 3. The shot blasting device used was made by Shinto Brater.

  Table 1 shows the shot blasting conditions implemented. FIG. 2 shows an EPMA mapping image (EPMA: electron probe microanalyzer) of the sliding inner peripheral surface of some cylinder bores subjected to shot blasting under the conditions shown in Table 1.

  In FIG. EPMA mapping of the surface of what used zinc as a metal particle which is 8 (description No.2-4) was described. EPMA was performed using EPMA-1600 manufactured by Shimadzu Corporation. The upper left diagram of FIG. 2 shows element distribution images of each composition metal, and the upper right, lower right, and lower left diagrams show element distribution images of aluminum, zinc, and iron, respectively. Each of the four figures maps the same location. In the upper left figure, each metal composition is mapped. A metal having a high specific gravity is described in white, and a light metal is described in black. In this case, black represents an aluminum alloy, white represents zinc, and whitish gray represents iron.

  Similarly, the upper right figure shows an element distribution image of aluminum, and the white part in the upper right figure shows aluminum. The lower left figure shows an iron element distribution image, and the white part shows iron. The lower right figure shows an element distribution image of zinc, and the white portion shows zinc.

  It can be seen from FIG. 4 that zinc is attached not to aluminum but to the iron portion.

  The surface roughness of each sample performed under each shot blasting condition was measured with a contact-type surface roughness meter and listed in the column of Rz (μm) in Table 1.

  No. in Table 1 No. 1 (description No. 0) (hereinafter, No. will be described using the description No.) is a honing process performed by a honing machine and shot blasting is not performed.

  Description No. in Table 1 No. 1 was shot blasting under the conditions shown in Table 1 with alumina abrasive grains # 80 (manufactured by Shinto Brater Co., Ltd., product number AF80 having a center particle size of about 190 μm (particle size range 150 to 212 μm) As shown in Table 1, the surface roughness (Rz) is as large as 16.9 μm.

  Description No. in Table 1 2, 2-1 and 2-2 are shot particles shown in Table 1 where the shot particles are steel (manufactured by Shinto Brater Co., Ltd., product number SB-3, center particle size of about 300 μm (particle size range: 180 to 500 μm)). The shot blasting process is performed.

  Since steel shot particles are used, the surface of both the aluminum alloy and the iron-based porous sintered material is scraped as a whole by shot blasting, and as shown in Table 1, the surface roughness Rz is 8.8 μm or more. It was a big value.

  Description No. in Table 1 Nos. 3, 2-3, and 2-4 are shot particles of zinc (made by Shinto Brater Co., Ltd., product number AD-4, center particle size of about 400 μm (particle size range 297 to 710 μm)). The shot blasting process is performed.

  As shown in Table 1, the surface roughness was as small as less than 5 μm. Zinc shot particles are harder than aluminum alloys and softer than iron-based porous sintered materials, so that the surface roughness (Rz) was not increased so much that the aluminum alloy portion could be selectively cut without damaging iron. Conceivable.

  A sliding experiment was performed using each cylinder bore sample prepared under the above conditions.

In the sliding experiment, a piston ring (nitrided SUS) is used as the material to be slid, and using a reciprocating sliding tester, stroke / speed: 40 mm · 500 cpm, load: 3 kgf, maximum surface pressure Hertz stress: 20 kgf / mm ² A sliding test was performed under the condition of a test temperature of 70 ° C., and a friction coefficient before baking and a baking time (minute) were measured. As the lubricating oil, E / G oil for CC class diesel, application: 0.13 mg / cm ² was used.

  Table 2 shows the friction coefficient and seizure time of each sample before seizure. FIG. 3 shows a graph comparing the surface roughness (Rz) and the seizing time (minutes), and FIG. 4 shows a graph comparing the surface roughness (Rz) and the friction coefficient before seizure.

  For the sliding test, the sample description No. 0, 1, 3, 2-3, 2-4.

  Description No. which is not shot blasted. The sample No. 0 had a surface roughness (Rz) of 0.7 μm and was burned in a short time of 0.15 minutes in the sliding test. Moreover, the friction coefficient before baking was as high as 0.64.

  Further, description No. in which shot blasting was performed using alumina. Sample No. 1 has a high surface roughness (Rz) of 16.9 μm. Description No. Sample No. 1 had a seizure time of 29 minutes in the sliding test, and the coefficient of friction before seizure was 0.3.

  On the other hand, description No. in which shot blasting was performed using zinc. Samples 3, 3, 2-3, and 4 have a surface roughness (Rz) of 2 to 5 μm. Description No. In the samples 3, 2, 3 and 2-4, although the Rz was low, the burn-in time was significantly improved as compared with the other samples. In addition, the coefficient of friction before baking was lower than that of other samples.

  In the sample using zinc as shot particles, the friction coefficient could be reduced by the adhesion and formation of zinc on the surface of the iron-based sintered body without damaging the surface of the iron-based sintered body and increasing the surface roughness. It is done. For this reason, it is considered that the friction coefficient of the entire sample can be reduced in the sliding test, and thereby the seizing time can be extended.

  In addition, there was an effect when the adhesion area of zinc calculated from EPMA mapping was 8% or more.

  As described above, the sliding member can adhere 8% or more of a low friction coefficient metal to a metal surface having a large friction coefficient on the sliding surface, thereby reducing low friction without increasing the surface roughness. By having a coefficient, a sliding member that improves sliding characteristics can be obtained.

The partial explanatory view (sectional drawing) of the manufacturing method of the sliding member of a test example is shown. The EPMA mapping image of the internal peripheral surface of the sliding member of the test example of this invention is represented. The graph which compared surface roughness (Rz) and image sticking time (minutes) is shown. The graph which compared surface roughness (Rz) and the friction coefficient before image sticking is shown.

Explanation of symbols

1. Iron-based porous sintered body, 2, mold, 3, cylinder bore, 4, shot blasting device.

Claims (5)

A composite material in which a second metal base material softer than the first metal base material is cast into the first metal base material, and both the first metal base material and the second metal base material are exposed on a sliding surface. A metal substrate,
Shot blasting metal particles that are softer than the first metal substrate, harder than the second metal substrate, and have a smaller friction coefficient than the first metal substrate on the sliding surface of the metal substrate. An attached metal mechanically adhered to the surface of the first metal base so as to cover at least 8% or more of the sliding surface;
Have a first metal substrate is a porous metal substrate, and the porous metal substrate, said second metal substrate and said slide that are present in the pores of the porous metal substrate sliding material characterized that you have exposed on the surface. The first metal substrate is an iron-based porous material, and the second metal substrate is any one of aluminum, an aluminum alloy, magnesium, or a magnesium alloy,
The sliding material according to claim 1 , wherein the metal particles include at least one of zinc, tin, gold, copper, and magnesium. The sliding material according to claim 2 , wherein the second metal substrate is an aluminum alloy, and the metal particles are zinc. The sliding material according to any one of claims 1 to 3 , wherein the processing conditions for the shot blasting are the following conditions.
Metal particle size: 150 μm or more and 750 μm or less Air pressure: 0.1 MPa or more and 0.3 MPa or less Injection distance: 50 mm or more and 150 mm or less Projection time: 5 seconds or more and 45 seconds or less Sliding material according to any one of claims 1 to 4, the recess on the surface of the second metal substrate is formed by the shot blasting.

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