JPH0472892B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a combination of two members that come into contact with each other and slide relative to each other, and more specifically, one member is a composite material reinforced with alumina-silica fibers containing mullite crystals. This relates to a combination of two members, one made of steel and the other made of steel. BACKGROUND OF THE INVENTION Special mechanical properties are often required in parts of the components and members of various machines. For example, in automobile engines, as demands for engine performance become higher, members such as pistons not only have excellent specific strength and rigidity, but also require that their sliding surfaces have excellent wear resistance. It has become a strong requirement to be present. As a means of improving the specific strength and abrasion resistance of such members, attempts have been made to construct them from composite materials in which various inorganic fibers are used as reinforcement materials and metals such as aluminum alloys are used as a matrix. ing. As one of such fiber-reinforced metal composite materials, a patent application filed in 1983 filed by the same applicant as the present applicant
In No. 034172, a fiber-reinforced metal composite material using alumina-silica fibers containing mullite crystals as a reinforcing material and an aluminum alloy or the like as a matrix has already been proposed. It is possible to improve the specific strength, abrasion resistance, etc. of a member made of the above materials, and it is also possible to obtain a composite material that is less expensive than a composite material using alumina fiber or the like as a reinforcing material. Problems to be Solved by the Invention However, in a combination of two members that are in contact with each other and slide relative to each other, when one of the members is made of the fiber-reinforced metal composite material as described above, Depending on the material of the other member, the wear of the other member increases significantly, and therefore, they cannot be used as a combination of sliding members that abut each other and slide relative to each other. The present inventors proposed a combination of two members that come into contact with each other and slide relative to each other, one of which is reinforced with alumina-silica fibers containing mullite crystals, which have excellent strength and rigidity and are inexpensive. In order to minimize the amount of wear of both parts in a combination of parts made of fiber-reinforced metal composite material with a metal matrix such as aluminum alloy and the other part made of steel. for,
As a result of conducting various experimental studies on the appropriate combination of materials and properties, it was found that each material must have specific characteristics and properties. The present invention is based on the knowledge obtained as a result of the above-mentioned experimental research conducted by the inventors of the present invention, and is based on the findings that one member is reinforced with alumina-silica fibers containing mullite crystals and is made of a metal such as an aluminum alloy as a matrix. It is a combination of two members made of fiber-reinforced metal composite material and the other member made of steel, which abut each other and slide relatively. The object is to provide a combination of two members with improved wear characteristics on sliding surfaces. Means for Solving the Problems According to the present invention, this object is achieved by combining a first member and a second member that abut each other and slide relatively, so that at least one of the first members The sliding surface portion for the second member is 35 to 65 wt%
It has a composition of Al ₂ O ₃ , 65 to 35 wt% SiO ₂ , and the balance is 10 wt% or less of other metal oxides, and the amount of mullite crystals is
Alumina-silica fibers containing 15 wt% or more of alumina-silica fibers, in which the content of non-fibrous particles with a particle size of 150 μ or more contained in the aggregate is 5 wt% or less, are used as reinforcement materials, and aluminum, magnesium, It is composed of a composite material with a matrix of metals selected from the group consisting of tin, copper, lead, zinc, and alloys containing these as main components, and a volume percentage of alumina-silica fibers of 0.5% or more,
This is achieved by a combination of members characterized in that at least the sliding surface of the second member relative to the first member is made of steel having a hardness Hv (10Kg) of 200 or more. Effects and Effects of the Invention According to the present invention, the composite material constituting the sliding surface portion of the first member includes a predetermined amount of mullite crystals, which is much cheaper, harder, and more stable than alumina fibers, etc. volume ratio due to alumina-silica fiber containing
At 0.5% or more, the matrix metal is strengthened, and the content of giant hard non-fibrous particles with a particle size of 150μ or more is suppressed to 5wt% or less, and the sliding surface of the second member has a hardness of Hv (10Kg). ) is made of over 200 steel, so it is a combination of two parts that touch each other and slide relative to each other, and the sliding surfaces of both parts relative to each other have excellent wear resistance. Therefore, it is possible to minimize the amount of wear on the respective sliding surfaces of both members, and to avoid abnormal wear caused by falling particles.Moreover, one of the members has a specific strength of It is possible to obtain a combination of members with excellent mechanical properties such as rigidity and machinability. Generally, alumina-silica fibers are broadly classified into alumina fibers and alumina-silica fibers in terms of their composition and manufacturing method. So-called alumina fibers with an Al ₂ O ₃ content of 70 wt% or more and a SiO ₂ content of 30 wt% or less are made into fibers using a mixture of a viscous organic solution and an inorganic salt of aluminum, and then heated at high temperatures. Since it is produced by oxidative roasting, it has excellent performance as a reinforcing fiber, but is very expensive. On the other hand, _{the Al2O3} content is 35~65wt% and the _SiO2 content is
So-called alumina-silica fiber, which has a content of 35 to 65 wt%, is produced by melting a mixture of alumina and silica in an electric furnace or the like, and then blowing the melt, since the mixture of alumina and silica has a lower melting point than that of alumina. It is produced relatively inexpensively and in large quantities by making it into fibers using a spinning method. especially
Al ₂ O ₃ content is 65wt% or more and SiO ₂ content is
If it is less than 35wt%, the melting point of the mixture of alumina and silica will be too high and the viscosity of the melt will be low; on the other hand, if the Al ₂ O ₃ content is less than 35wt% and the SiO ₂ content is more than 65wt% It is difficult to apply these inexpensive manufacturing methods to these methods because the appropriate viscosity required for blowing and spinning cannot be obtained.
In addition, CaO, MgO,
_Na2O , _Fe2O3 , _{Cr2O3 , ZrO2} , _{TiO2 ,} PbO,
_SnO2 , ZnO, _MoO3 , NiO, _K2O , _MnO2 ,
Metal oxides such as B ₂ O ₃ , V ₂ O ₅ , CuO, CoCO ₄ may be added. According to the results of experimental research conducted by the inventors, these components
It was recognized that it is preferable to suppress the content to 10 wt% or less. Therefore, the composition of the alumina-silica fiber as a reinforcing material in the member combination of the present invention is
35~65wt% _{Al2O3 ,} 65~35wt% _SiO2 , balance 10wt
% or less of other metal oxides. Alumina-silica fibers produced by a blowing method or a spinning method are amorphous fibers, and the hardness of the fibers is about Hv700. When such amorphous alumina-silica fibers are heated to a temperature of 950° C. or higher, mullite crystals are precipitated, increasing the hardness of the fibers. According to the results of experimental research conducted by the inventors of the present invention, the hardness of the fiber increases rapidly when the amount of mullite crystals is about 15wt%, and when the amount of mullite crystals is about 19wt%.
%, the hardness of the fibers was approximately Hv1000, and it was observed that even if the amount of mullite crystals was increased beyond this, the hardness of the fibers did not increase significantly. The wear resistance and strength of metals reinforced with alumina-silica fibers containing mullite crystals correspond well to the hardness of the alumina-silica fibers themselves, and when the amount of mullite crystals is 15wt% or more, especially 19wt% or more. Composite materials with excellent wear resistance and strength can be obtained. Therefore, in the member combination of the present invention, the amount of mullite crystals in the alumina-silica fibers is 15 wt% or more, preferably 19 wt% or more. In addition, in the production of alumina-silica fibers by a blowing method etc., a large amount of non-fiber particles are inevitably produced at the same time as fibers, and therefore a relatively large amount of non-fiber particles are produced in the alumina-silica fiber aggregate. Contains particles. In order to improve the properties of alumina-silica fibers, when the fibers are heat-treated to precipitate mullite crystals, the non-fibrous particles also crystallize into mullite and harden. According to the results of experimental research conducted by the inventors of the present application, large particles, particularly those with a particle size exceeding 150μ, deteriorate the mechanical properties and workability of composite materials, causing a decrease in the strength of composite materials.
Furthermore, particles falling off may cause problems such as abnormal wear on the mating material. Therefore, in the member combination of the present invention, the content of non-fibrous particles with a particle size of 150μ or more contained in the alumina-silica fiber aggregate is 5wt% or less, particularly 2wt%.
It can be further suppressed to 1wt% or less. Furthermore, according to the results of experimental research conducted by the inventors of the present application, alumina-silica fibers containing mullite crystals having the above-mentioned excellent properties are used as reinforcing fibers, and aluminum, magnesium, copper, zinc,
In composite materials whose matrix metals are lead, tin, and alloys containing these as main components, alumina
Even when the volume fraction of silica fibers is about 0.5%, the wear resistance of the composite material is significantly improved, and even if the volume fraction of alumina-silica fibers is increased further, the amount of wear on the mating material does not increase significantly. Therefore, in the member combination of the present invention, the volume percentage of alumina-silica fibers is set to be 0.5% or more, particularly 1% or more, and even 2% or more. In order to obtain a composite material for one member in the combination of members of the present invention, which has excellent mechanical properties such as strength and wear resistance, and also has excellent friction and wear characteristics against the mating member, According to the results of experimental studies conducted by the inventors of the present invention, alumina-silica fibers containing mullite crystals have an average fiber diameter of 1.5 to 5.0μ and an average fiber length of 20μ to 3mm in the case of short fibers. However, in the case of long fibers, it has been found that it is preferable to have a fiber diameter of 3 to 30μ. The combination of members according to the present invention may be applied to combinations of members of various mechanical devices, such as a cylinder piston, a piston ring and a piston of an automobile engine. DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be explained in detail below by way of example embodiments with reference to the accompanying figures. Example 1 Alumina-silica fiber manufactured by Isolite Babkotsu Fireproofing Co., Ltd. (trade name "Kaowool", nominal composition: 51wt% Al ₂ O ₃ , 49wt% SiO ₂ ) was subjected to grain removal treatment to remove the particles contained in the fiber aggregate. After reducing the content of particles with a particle size of 150μ or more to 0.4wt%, the fiber aggregates are heat-treated at various high temperatures to produce fibers with various amounts of mullite crystals as shown in Table 1 below. Formed fibers.

[Table] Next, each of the above-mentioned alumina-silica fibers was dispersed in colloidal silica, the colloidal silica was stirred, and the colloidal silica in which the alumina-silica fibers were uniformly dispersed was formed by vacuum forming as shown in Fig. 1. 80×80× as shown
Form a 20 mm fiber forming body 1 and heat it at 600°C.
The individual alumina-silica fibers 2 were bonded with silica by firing. In this case, the first
As shown in the figure, the individual alumina-silica fibers 2 were oriented randomly in the x-y plane and stacked in the z-direction. Next, as shown in FIG. 2, the fiber molded body 1 is placed in the mold cavity 4 of the mold 3,
A molten metal 5 of aluminum alloy (JIS standard AC8A) at 730°C is poured into the mold cavity, and the molten metal is heated to 1500°C by a plunger 6 that fits into the mold 3.
The pressure is increased to Kg/cm ² and the pressurized state is maintained until the molten metal 5 is completely solidified. Thus, as shown in FIG. is cast, and the solidified body is further heat treated.
T ₇ was applied, and composite materials 1' with alumina-silica fibers as reinforcing fibers and aluminum alloy as a matrix were cut out from each solidified body, and hardness test pieces and block test pieces for wear tests were machined from these composite materials. Created by. After polishing the test surface of the hardness test piece thus formed, the Vickers hardness of the alumina-silica fiber was measured. However, since the size of the fiber itself is very small with an average fiber diameter of 2.9μ, the hardness of non-fibrous particles with a relatively large particle size that can be measured is measured, and that value is used to determine the alumina-silica fiber. hardness. The measurement results are shown in FIG. 4, where the horizontal axis represents the amount of mullite crystals in the alumina-silica fibers and the vertical axis represents the hardness of the alumina-silica fibers. From this Figure 4, the hardness of alumina-silica fiber is low in the range of about 10wt% or less, but increases significantly when the mullite crystal content exceeds about 15wt%, and when the mullite crystal content exceeds about 20wt%. It can be seen that the value is almost constant. Next, the above-mentioned block test pieces were sequentially set in a friction and wear tester, and the bearing steel (JIS standard
Contact with the outer circumferential surface of a cylindrical test piece made of quenched and tempered material (hardness Hv630) of SUJ2), and apply lubricating oil (cathle motor oil 5W-30) at room temperature (20℃) to the contact area of the test piece. Contact surface pressure 20 while supplying
A wear test was conducted by rotating a cylindrical test piece ^for 1 hour at a sliding speed of 0.3 m/sec and a sliding speed of 0.3 m/sec. The test surface of the block test piece in this abrasion test was a plane perpendicular to the xy plane shown in FIG. The results of the wear test are shown in Figure 5. Furthermore, in Figure 5,
The upper half represents the wear amount (wear scar depth μ) of the block test piece, and the lower half represents the wear amount (wear loss mg) of the cylindrical test piece that is the mating member. From Figure 5, when bearing steel is used as the mating member, the wear amount of the block test piece does not substantially change in the range where the amount of mullite crystals in the alumina-silica fiber is from 0 to 11 wt%. First, in the range of 11 to 19 wt% mullite crystal content, it decreases significantly as the mullite crystal content increases, and the mullite crystal content decreases.
In contrast, the wear amount of the cylindrical test piece remains essentially constant regardless of the amount of mullite crystals in the alumina-silica fibers. I understand. The relationship between the amount of mullite crystals in Fig. 5 and the wear amount of the block test piece is similar to that of the alumina crystal shown in Fig. 4.
This corresponds to the relationship between the hardness of silica fibers and the amount of mullite crystals, and from these figures 4 and 5, it is clear that a member made of a composite material with alumina-silica fibers as reinforcing fibers and aluminum alloy as a matrix. In order to reduce both the amount of wear and the amount of wear of the steel mating member on which the abrasion slides, it is preferable that the alumina-silica fiber is a crystalline alumina-silica fiber containing mullite crystals. -The amount of mullite crystals in silica fiber is
It can be seen that the content is preferably 15 wt% or more, and more preferably 19 wt% or more. Example 2 From Example 1 above, it was found that the amount of mullite crystals in the alumina-silica fibers is preferably 15 wt% or more, so what is the appropriate value for the volume percentage of the alumina-silica fibers? A wear test was conducted with the mullite crystal content of the alumina-silica fiber set at 62 wt%. First, alumina-silica fibers with a nominal composition of 55wt% Al ₂ O ₃ and 45wt% SiO ₂ are subjected to degranulation treatment to reduce the amount of particles with a particle size of 150μ or more to 0.2%.
After that, heat treatment reduces the amount of mullite crystals to 62wt.
%. The alumina-silica fibers treated as described above and copper alloy (Cu
-10wt%Sn) powder was weighed, a small amount of ethanol was added thereto, and the mixture was mixed using a stirrer for about 30 minutes. After drying the mixture thus obtained at 80°C for 5 hours, a predetermined amount of the mixture was filled into a mold having a cavity with cross-sectional dimensions of 15.02 x 6.52 mm, and the mixture was punched to a density of 4000 kg/cm. It was molded into a plate by compressing it at a pressure of ² . Next, each plate was heated at 770℃ for 30 minutes in a batch-type sintering furnace set in an atmosphere of decomposed ammonia gas (dew point -30℃).
A composite material was produced by sintering by heating for a minute and gradually cooling in a cooling zone in a sintering furnace.

[Table] Block test pieces for friction and wear tests were formed from the composite material thus obtained, and bearing steel (JIS standard SUJ2, hardness:
A wear test was conducted using a cylindrical specimen made of Hv710) as the mating member. The results of this wear test are shown in FIG. In FIG. 6, the upper half represents the wear amount (wear scar depth μ) of the block test piece, and the lower half represents the wear amount (wear loss mg) of the cylindrical test piece, which is the mating member. Figure 6 shows that the amount of wear of a composite material reinforced with alumina-silica fibers containing mullite crystals is significantly reduced even when the volume fraction of alumina-silica fibers is about 0.5%, and the wear resistance of the composite material is significantly reduced. In order to ensure that the volume ratio of alumina-silica fiber is 0.5%
From the above, it can be seen that it is particularly preferable that the content is 1.0% or more, and more preferably 2.0% or more. Furthermore, it can be seen that the amount of wear on the mating member does not substantially increase even if the volume fraction of alumina-silica fiber is increased to 0.5% or more. Abrasion tests similar to those in Example 2 above using the volume fraction of alumina-silica fibers as a parameter were conducted on block specimens made of composite materials whose matrix metals were aluminum alloys, magnesium alloys, zinc alloys, lead alloys, and tin alloys. The results obtained showed a similar tendency to the results shown in FIG. 6. Example 3 From Example 2 above, it was found that the volume fraction of alumina-silica fibers is preferably 0.5% or more, so it is appropriate to have any properties of the steel constituting the other member. The abrasion test was conducted on the alumina-silica fiber volume percentage of 6.9%.
I set it to . A fiber molded body was formed from the alumina-silica fibers shown in Table 3 below (the chemical composition is the nominal composition) in the same manner as in Example 1 above, and the fiber molded body was used as a reinforcing material. A composite material with an alloy (JIS standard AC8A) as a matrix is cast using a high-pressure casting method (water temperature 730℃, pressure applied to the molten metal 1500℃).
Kg/cm ² ), and after _T7 heat treatment for each composite material, the size is 16 x 6 x 10 mm, and a block test using one side (16 x 10 mm) as the test surface. Pieces _C1 to _C6 were created. Also, as a comparative example,
A block specimen C ₀ of the same dimensions made only of aluminum alloy (JIS standard AC8A), and amorphous alumina-silica fibers (55wt% Al ₂ O ₃ , 45wt% SiO) with an average fiber diameter of 3.0 μ and an average fiber length of 3 mm. ₂ ) A block specimen _C7 of the same size was prepared from a composite material consisting of a fiber molded body with a fiber volume fraction of 6.5% as a reinforcing material and an aluminum alloy (JIS standard AC8A) as a matrix.

[Table] These test pieces were sequentially set in the LFW friction and wear tester, and the mating parts, which were 35 mm in outer diameter, 30 mm in inner diameter,
Contact with the outer peripheral surface of a steel cylindrical specimen with a width of 10 mm,
While supplying room temperature lubricating oil (castle motor oil 5W-30) to the contact parts of these test pieces,
A wear test was conducted by rotating a cylindrical test piece ^for 1 hour at a sliding speed of 0.3 m/sec and a sliding speed of 0.3 m/sec. In this wear test, the hardness of the cylindrical test piece was
Hv (10Kg) was set to various values, and combinations of block test pieces and cylindrical test pieces shown in Table 4 below C ₀ ~
Tests were conducted on _C7 .

【table】

[Table] Figure 7 shows the results of the above wear test. The 7th
In the figure, the upper half represents the wear amount (wear scar depth μ) of the block test piece, and the lower half represents the wear amount (wear loss mg) of the cylindrical test piece, which is the mating material. Symbols C ₀ to C ₇ correspond to test piece combinations C ₀ to _{C 7} in Table 4 above, respectively. From this Figure 7, the wear amount of the block test piece is
Block test piece made only of aluminum alloy
Except for C ₀ and block specimen C ₇ , in which the reinforcing fibers are amorphous alumina-silica fibers, they are very small and there is almost no difference depending on the material and hardness of the steel used as the mating material. Regardless of the material, the wear amount of a cylindrical test piece as a material is determined by the hardness Hv (10
It can be seen that the value is small when Kg) is 200 or more, preferably 250 or more. Example 4 A fiber molded body made of alumina-silica fibers shown in Table 5 below (chemical composition is nominal composition) was formed in the same manner as in Example 1, and the fiber molded body was reinforced. Magnesium alloy (JIS
A composite material using standard MDC1-A) as a matrix is cast using high-pressure casting method (water temperature 700℃, pressure applied to the molten metal).
1500Kg/cm ² ), and a block test piece _D1 having the same dimensions as in Example 3 above was prepared.
In addition, as a comparative example, magnesium alloy (JIS standard
A block test piece _D0 of the same size was prepared consisting only of MDC1-A). These block test pieces were subjected to the same wear test as in Example 3 above. However, in this case, the cylindrical test piece serving as the mating material was made of stainless steel (JIS standard SUS420J2), and the test was conducted for 30 minutes with the surface pressure set at 5 kg/mm ² .

[Table] The results of this wear test are shown in Figure 8. This eighth
From the figure, even if the matrix is a magnesium alloy, if the volume fraction of the alumina-silica fibers, the amount of mullite crystals in the alumina-silica fibers, and the hardness of the steel are within the scope of the present invention, the block test can be carried out. It can be seen that the wear amount of both the blank and the cylindrical specimen is very small. In addition, a wear test similar to the wear test in this example was carried out when the matrix was copper alloy, tin alloy, lead alloy.
A block test piece cut out from a composite material formed in the same manner except that it was made of zinc alloy was also tested, and the results showed that the volume percentage of alumina-silica fiber, the alumina-silica fiber It was found that when the amount of mullite crystals and the hardness of the steel fall within the range of the present invention, the amount of wear of both the block test piece and the cylindrical test piece becomes a very small value. From the results of the above-mentioned examples, it is clear that the combination of two members that come into contact with each other and slide relative to each other, one of which is reinforced with alumina-silica fibers containing mullite crystals, and made of aluminum alloy, etc. In a combination of two parts, such as one made of a composite material with a metal matrix and the other part made of steel, the composite material making up one part weighs 35 to 65wt. % _{Al2O3 ,} 65~
An alumina-silica fiber having a composition of 35wt% SiO ₂ and the balance 10wt% or less of other metal oxides, and a mullite crystal content of 15wt% or more, and non-silica fibers with a particle size of 150μ or more contained in the aggregate. Aluminum, magnesium, tin,
A composite material in which the matrix is a metal selected from the group consisting of copper, lead, zinc, and alloys containing these as main components, and the volume percentage of alumina-silica fibers is 0.5% or more, and constitutes the other member. The hardness of steel Hv (10Kg) is 200 or more, and even 250
It can be seen that the above steel is preferable. Although the present invention has been described above in detail with reference to several embodiments, the present invention is not limited to these embodiments, and various other embodiments are possible within the scope of the present invention. It will be clear to those skilled in the art that

[Brief explanation of the drawing]

Figure 1 is an illustration showing the fiber orientation state of a fiber molded body made of alumina-silica fibers containing mullite crystals, Figure 2 is an illustration showing the manufacturing process of a composite material by high-pressure casting method, and Figure 3 is Figure 4 shows the amount of mullite crystals in alumina-silica fibers and the amount of alumina crystals in the alumina-silica fibers.
A graph showing the relationship between the hardness of silica fibers and mullite. Figure 6, a graph showing the amount of crystals on the horizontal axis, shows the results of wear tests conducted on composite materials made of copper alloys reinforced with alumina-silica fibers of various volume fractions, using bearing steel as the mating material. Figure 7 is a graph showing the results of an abrasion test conducted on a composite material made of an aluminum alloy reinforced with alumina-silica fibers containing mullite crystals, using parameters such as the hardness of steel as a mating material. FIG. 8 is a graph showing the results of an abrasion test conducted on a composite material made of a magnesium alloy reinforced with alumina-silica fibers containing mullite crystals and a magnesium alloy using stainless steel as a mating material. DESCRIPTION OF SYMBOLS 1... Fiber molded object, 1'... Composite material, 2... Alumina-silica fiber, 3... Mold, 4... Mold cavity, 5... Molten metal, 6... Plunger, 7... Solidified body.

Claims (1)

[Scope of Claims] 1. A combination of a first member and a second member that are in contact with each other and slide relative to each other, and at least a sliding surface portion of the first member with respect to the second member is
35~65wt% _{Al2O3 ,} 65~35wt% _SiO2 , balance 10wt
% or less of other metal oxides, and the amount of mullite crystals is 15 wt% or more, and the particle size contained in the aggregate is 150μ
Alumina-silica fibers having a content of 5 wt% or less of the above non-fibrous particles are used as reinforcing materials selected from the group consisting of aluminum, magnesium, tin, copper, lead, zinc, and alloys containing these as main components. It is made of a composite material having a metal matrix and a volume percentage of alumina-silica fibers of 0.5% or more, and at least the sliding surface of the second member relative to the first member has a hardness of Hv (10 kg). but
A combination of members characterized by being composed of 200 or more steels. 2. The combination of members according to claim 1, wherein the alumina-silica fiber has a mullite crystal content of 19 wt% or more. 3. In the combination of members set forth in claim 1 or 2, the content of non-fibrous particles with a particle size of 150μ or more contained in the alumina-silica fiber aggregate is 1wt% or less. A combination of parts characterized by: