JPS63103037A - Sliding member - Google Patents

Abstract

PURPOSE:To minimize wear loss by setting up respective Moh's hardnesses, diameters, and volume percentages of a grain reinforcement and a solid lubricant in a composite material in the primary member to suitable ranges and also by constituting the sliding surface, of a secondary member, of a steel having specific hardness so as to provide excellent wear resistance to both of the sliding surfaces. CONSTITUTION:The sliding surface part of a primary member is constituted of a composite material in which a mixture of a grain reinforcement of >=6 Moh's hardness, <=30mum diameter, and 3-40% volume percentage and a solid lubricant of 3-50% volume percentage selected from short fibers, grains, etc., of <=4.5 Moh's hardness and <=100mum diameter is used as reinforcement and an alloy composed principally of Al, Mg, Cu, Zn, Pb and Sn is used as matrix. On the other hand, at least the sliding surface part, of the secondary member, which slides on the above primary member is constituted of a steel of >=180 hardness Hv(10kg). Moreover, it is desirable that any one of oxides, nitrides, and mixtures thereof is used as the solid lubricant.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a sliding member consisting of two members that are in contact with each other and slide relative to each other, and more particularly, one member is made of reinforcing particles and a solid lubricant. The present invention relates to a sliding member made of two members, one made of a composite material reinforced with a mixture with a compound and the other made of steel.

Conventional technology In order to improve the specific strength and wear resistance of metal materials, fiber-reinforced metal back metal materials and particle-dispersed metal composite materials are reinforced with reinforcing materials such as reinforcing fibers and dispersed particles (reinforced particles). In general, since the reinforcing material is hard, the amount of wear of the mating material that comes into contact with it and slides relative to it is likely to be greater than that of a material made only of matrix metal that is not compositely reinforced with the reinforcing material. There's a problem.

In order to solve this problem, for example, Japanese Patent Application Laid-Open No. 53-1028
No. 24, No. 54-64263, No. 58-93844, No. 58-93845, No. 58-93847, No. 5
No. 8-113335, No. 59-59855, No. 59-
As described in Japanese Patent No. 59856, it is already known to add anti-friction substances having excellent self-lubricating properties to composite materials. According to such a composite material, it is possible to obtain a metal material that has superior friction and wear characteristics, that is, both its own wear resistance and its attack resistance against other materials, as compared to a composite material that does not contain an anti-friction substance.

As one of such composite materials, the inventors of the present application have obtained Japanese Patent Application No. 61-334 filed by the same applicant as the applicant of the present application.
No. 26, with a Mohs hardness of 6 or more and a diameter of 30μ
reinforcing material with a volume fraction of 1 to 40% selected from the group consisting of short fibers, particles, and mixtures thereof, having a Mohs hardness of 4.5 or less and a diameter of 100 μm or less, We have proposed a metal matrix composite material in which a matrix metal is composited with a solid lubricant selected from the group consisting of particles and mixtures thereof with a volume ratio of 3 to 50%.

Problems to be Solved by the Invention However, in two sliding members that are in contact with each other and slide relative to each other, when one of the members is made of the above-mentioned composite material, the other member is Depending on the material of the member, the wear of the other member increases significantly, and therefore, they cannot be used as sliding members that abut each other and slide relative to each other.

The inventors of the present application have proposed a sliding member consisting of two members that come into contact with each other and slide relative to each other, one of which is made of a composite material as described above, and the other member is made of steel. In order to minimize the amount of wear on both of these sliding members, various experimental studies have been conducted to find out what combination of materials and properties is appropriate. As a result, it was found that the composite material and the steel must each have specific characteristics.

The present invention is based on the findings 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 a mixture of reinforcing particles and a solid lubricant, and a metal such as an aluminum alloy is used as a matrix. Constructed of composite materials,
A sliding member consisting of two members, the other member of which is made of steel, which abut each other and slide relative to each other,
It is an object of the present invention to provide a sliding member in which the wear resistance of the sliding surfaces of both members relative to each other is improved.

Means for Solving the Problems According to the present invention, the above-mentioned object is achieved by providing a sliding member consisting of a first member and a second member that abut each other and slide relative to each other; At least the sliding surface portion of the first member relative to the second member has reinforcing particles having a Mohs hardness of 6 or more and a diameter of 30 μm or less and having a volume ratio of 3 to 40%;
A mixture with a solid lubricant with a volume ratio of 3 to 50% selected from the group consisting of short fibers, particles, and mixtures thereof having a Mohs hardness of 4.5 or less and a diameter of 100 μm or less is used as a reinforcing material, and aluminum , magnesium, copper, zinc,
It is made of a composite material whose matrix metal is a metal selected from the group consisting of lead, tin, and alloys containing any of these as a main component, and the sliding of the second member with respect to at least the first member is The hardness of the moving surface part is Hv (10kg
) is achieved by a sliding member characterized in that it is made of steel of 180 or more.

Effects of the Invention According to the results of experimental research conducted by the present inventors, the friction and wear characteristics of composite materials can be sufficiently improved depending on the type and amount of the solid lubricant (anti-friction substance) added. It has been found that not only cannot the improvement be achieved, but the friction and wear characteristics, strength, etc. of the composite material may actually deteriorate. In other words, some solid lubricants are suitable for composite materials with metal as a matrix, while others are not. Therefore, a solid lubricant suitable for composite materials must be selected, and solid lubricants The amount of solid lubricant and the like are not related to design matters that may be set at will by a person skilled in the art when manufacturing a composite material such as the one described above. It has been found that the hardness, size, and volume fraction of the reinforcing particles must be set optimally in relation to each other.

For example, the above-mentioned Japanese Patent Application Publication Nos. 58-93844 and 58-93
Publications No. 845 and No. 58-93847 indicate that particles of graphite, etc., and particles of lead, zinc, tin, etc. may be used as solid lubricants, but particles of graphite, etc. Even in the case of , if the diameter is large, the composite material itself becomes brittle and wear particles increase, resulting in an increase in the amount of wear on the composite material and the mating material, and the strength of the composite material also decreases. Furthermore, in the case of particles such as lead, zinc, tin, etc., these particles tend to melt and segregate in the composite material during the manufacture of the composite material, making it difficult to obtain sufficient lubrication effects and impairing the friction and wear characteristics of the composite material. It is difficult to sufficiently improve the strength of the composite material, and the strength of the composite material also tends to decrease due to segregation. Furthermore, since such problems are conspicuous in the melt impregnation method and sintering method that have been conventionally commonly used for manufacturing lubricant materials, it is difficult to successfully manufacture composite materials containing these solid lubricants using these methods. It is difficult to do so.

Also, the above-mentioned Japanese Patent Application Laid-open Nos. 53-103824 and 54-64
No. 263, No. 58-113335, No. 59-5985
Even when solid lubricants suitable for composite materials are used, such as the solid lubricants described in Publications No. 5 and No. 59-59856, the hardness of the solid lubricant must be below a specific value. In this case, the amount of wear of the composite material itself becomes large (the amount of wear is larger than when no solid lubricant is included), and the amount of wear of the mating material also increases due to the generation of wear particles. On the other hand, if the hardness of the reinforcing material exceeds a certain value, and the diameter exceeds a certain value, the aggressiveness of the composite material is large, and the composite material is damaged due to the generation of wear particles. The amount of wear on the material itself also increases. Moreover, if the amount of reinforcing material is too small, the hardness of the solid lubricant will be low, and the amount of wear of the composite material will be greater than in the case of a normal composite material without a solid lubricant.

Conversely, if the amount of reinforcing material is too large, the aggressiveness of the composite material will not decrease even if the amount of solid lubricant is increased.

Furthermore, if the hardness of the solid lubricant exceeds a certain value,
Naturally, the aggressiveness of the composite material increases. Even if the hardness of the solid lubricant is an appropriate value, if the amount is too small, it will not be possible to sufficiently reduce the aggressiveness of the composite material, and conversely, if the solid lubricant is too large, The composite material becomes brittle, the amount of wear of the composite material itself increases, and the amount of wear of the mating material also increases due to the generation of abrasion powder.

According to the present invention, the Mohs hardness, diameter, and volume fraction of the reinforcing particles and the solid lubricant of the composite material constituting the first member are set within the above-mentioned preferred range in relation to each other; As is clear from the results of experimental research conducted by the inventors, which will be explained in detail later, it has superior friction and wear characteristics compared to conventional composite materials, and the second member has a hardness of H.
Constructed of steel with v (IOkg) of 180 or more. Therefore, according to the present invention, there is provided a sliding member consisting of two members that abut each other and slide relative to each other, and the sliding surfaces of both members 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 it is also possible to obtain a sliding member in which one of the members has excellent specific strength and rigidity. .

According to another detailed feature of the invention, the solid lubricant is any of oxides, nitrides, and mixtures thereof.

In the present invention, suitable oxide solid lubricants include tungsten oxide (WO3), zinc oxide (ZnO), -
Lead oxide (PbO), potassium titanate (K2O・6
T102), etc., and boron nitride (BN) is a nitride solid lubricant.

According to yet another detailed feature of the present invention, the Mohs hardness and diameter of the reinforcing particles are set at 7 or more and 20 μm or less, respectively, and the Mohs hardness, diameter, and volume fraction of the solid lubricant are set at 4 or less and 5ouI11, respectively. Hereafter, it is set to 5 to 45%.

According to yet another detailed feature of the present invention, the Mohs hardness and volume fraction of the solid lubricant are 3 or less and 10 to 4, respectively.
Set to 0%.

In the sliding member of the present invention, the fiber length of the short fibers of the solid lubricant of the composite material is preferably about 10 μII to 5 cm. Furthermore, according to the results of experimental studies conducted by the inventors of the present application, when solid lubricants are short fibers, if they satisfy the requirements of the present invention, regardless of the orientation of the short fibers, The amount of wear on the composite material and mating material can be reduced,
Therefore, the orientation of the short fibers may be unidirectional, two-dimensional random orientation, or three-dimensional random orientation.

Further, in this specification, "particles" means particles having an aspect ratio of 3 or less, and percentages in this specification are weight percentages except in the case of volume percentages.

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 First, silicon nitride particles (manufactured by Kojundo Kagaku Co., Ltd., average particle size 10 μa+) with a Mohs hardness of 9 were prepared as reinforcing particles, and BN particles (electrochemical (manufactured by Kogyo Co., Ltd., average particle size 8 μrA) was prepared. The reinforcing particles and BN particles were then mixed at a volume ratio of 1:1, and the mixture was stirred in colloidal silica. Next, by compression molding the colloidal silica in which the particles thus obtained are uniformly dispersed, the first
As shown in the figure, reinforcing particles 2a and BNN Miko 2
b They were uniformly mixed with each other to form a molded body 1 having dimensions of 80x80x20Iffl.

Next, after preheating the molded body to 500°C, it is placed in the mold cavity 4 of the mold 3 as shown in FIG.
A molten metal 5 of aluminum alloy (JIS standard AC8A) at 720°C is poured into the mold cavity, and a plunger 6 that fits the molten metal into the mold 3 is used to transfer the molten metal to 1200 kg/
The pressure was increased to m+a: and the pressurized state was maintained until the molten metal completely solidified. Thus, as shown in FIG. 3, a cylindrical solidified body 7 with an outer diameter of 1101111% and a height of 50 mm was cast, and the solidified body was subjected to heat treatment T? A composite material 1' made of an aluminum alloy composited with reinforcing particles with a volume ratio of 10% and BN particles with a volume ratio of 10% substantially uniformly mixed from each solidified body is cut out. Block specimens A1 to A7 for wear testing were prepared by machining.

A block test piece A8 was prepared in the same manner and under the same conditions as the above-mentioned block test piece Al-A7, except that BN particles were not included in l. (1, C.

! A block test piece A9 was prepared in the same manner and under the same conditions as the above-mentioned block test piece A8, except that the particles were replaced with "particles selected from Saphir RGJ, average particle size 15 μm" manufactured by Sapphire Co., Ltd.

Next, each block test piece was sequentially set in a friction and wear tester, and brought into contact with the outer circumferential surface of the mating member, a steel cylindrical test piece of various hardness.
℃) while supplying lubricating oil (castle motor oil 5W-30), the contact surface pressure is 20 kg/IIIQ! ! , sliding speed 0. A wear test was conducted in which the cylindrical specimen was rotated for 1 hour at 3 mm/see.

The combinations of block test pieces and cylindrical test pieces in these wear tests were as shown in Table 1 below.

The results of these wear tests are shown in FIG. In Figure 4 (and the diagram showing the results of other wear tests described later), the upper half represents the wear amount (wear scar depth μm) of the block test piece, and the lower half represents the counterpart material. It represents the amount of wear (wear area mmg) of the cylindrical test piece.

From FIG. 4, the wear amount of the block test pieces of the combinations AT and A and the cylindrical test pieces of the combinations AI and A9 of the comparative examples is higher than that of the combination AI-A6, and the wear amount of the combination A
No. 1 to A6 have excellent wear characteristics in both block test pieces and cylindrical test pieces. Therefore, the hardness of the steel combined with the composite material whose reinforcement is a mixture of reinforcing particles and solid lubricant is Hv. (lokg) is preferably 180 or more.

Example 2 A study was conducted to find out what hardness is suitable for reinforcing particles.

First, as shown in Table 2 below, grains B, -B5, and WO3 grains having various Mohs' hardnesses were prepared. Next, each particle and W 03 particles were mixed at a volume ratio of 1:1, and using the mixture, the volume ratio of the reinforcing particles and W 03 particles was adjusted in the same manner and under the same conditions as in Example 1. Chromium m ( J I SMl Raku5Cr2
0, Hv-720) was used as the mating material.

The results of these wear tests are shown in FIG.

From FIG. 5, it can be seen that when the Mohs hardness of the reinforcing particles is 6 or more, preferably 7 or more, the wear amount of both the composite material and the mating material becomes a small value.

Example 3 A study was conducted to determine what hardness would be suitable as a solid lubricant.

First, solid lubricants c, -C as shown in Table 3 below
, , and alumina particles were prepared. Next, each solid lubricant c, -Ca and alumina particles are mixed at a volume ratio of 1=1, the matrix metal is replaced with JIs standard ACIA aluminum alloy (hot water temperature 720°C), and heat treatment is performed at T.
Composite materials in which the volume percentages of the solid lubricant and alumina particles were both 15% were manufactured in the same manner and under the same conditions as in Example 1, except that 6 was changed, and block test pieces were prepared from each composite material. c, -Ca were prepared, and each block test piece was subjected to an abrasion test using chromium steel (JIS standard 5Cr20, Hv-720) as a mating material in the same manner and under the same conditions as in Example 1. The results of these wear tests are shown in FIG.

From FIG. 6, it can be seen that when the Mohs hardness of the solid lubricant is 4.5 or less, preferably 4 or less, and more preferably 3 or less, the amount of wear on the composite material and the mating material is reduced.

Example 4 We investigated what diameter is suitable for reinforcing particles.

First, reinforcing particles D1 to D9 as shown in Table 4 below
and PbO particles were prepared. Next, the reinforcing particles and PbO particles were mixed in the same manner and under the same conditions as in Example 1, except that the reinforcing particles and PbO particles were mixed at a volume ratio of 1:2.
Composite materials with particle volume percentages of 10% and 20%, respectively, were manufactured, and block test pieces, -Dg, were created from each composite material, and each block test piece was subjected to the same procedures and conditions as in Example 1. Stainless steel j14 (J I 5
A wear test was conducted using ffl rating 5US420J2)Hv-500) as a mating material. The results of these wear tests were
As shown in the figure.

From FIG. 7, it can be seen that when the diameter of the reinforcing particles is 30 μm or less, preferably 20 μm or less, the amount of wear on the composite material and the mating material is reduced.

Example 5 A study was conducted to determine what diameter is suitable for a solid lubricant.

First, solid lubricants E1 to E as shown in Table 5 below.
T and alumina-silica particles were prepared.

Next, solid lubricant and alumina-silica particles were mixed at a volume ratio of 423, JIS standard AC7B aluminum alloy (hot water temperature 690°C) was used as the matrix metal, and heat treatment was replaced with T4. Example 1 except
Composite materials with volume percentages of solid lubricant and alumina-silica particles of 20% and 15%, respectively, were manufactured using the same procedure and conditions as in the case of
, ~E7 were prepared and Example 1 was prepared for each block test piece.
Stainless steel (JI
A wear test was conducted using S standard 5US420J2)Hv-500) as a mating material. The results of these wear tests are shown in FIG.

From Figure 8, regardless of whether the solid lubricant is particles or fibers, when the diameter of the solid lubricant is 100 μm or less, preferably 50 μm or less, the amount of wear on the composite material and the mating material is reduced. I understand.

Example 6 An appropriate value for the volume fraction of reinforcing particles was investigated.

First, the tungsten carbide particles and P shown in Table 6 below
bO particles were prepared. Next, the tungsten carbide particles and PbO particles were mixed at various volume ratios, and block test pieces F1 to F9 were created using the mixture thus obtained in the same manner and under the same conditions as in Example 1. In addition, a block test piece Fo was prepared consisting only of matrix metal without reinforcing particles and solid lubricant. Next, these block test pieces were subjected to bearing m (JIS standard SUJ 2) Hv-8 in the same manner and under the same conditions as in Example 1.
A wear test was conducted using 50) as a mating material.

The results of these wear tests are shown in FIG.

From Figure 9, the volume fraction of reinforcing particles is 3 to 40%, especially 5 to 40%.
It can be seen that when the amount of wear is about 35%, the amount of wear of the composite material and the mating material becomes a small value.

Example 7 An appropriate value for the volume fraction of the solid lubricant was investigated.

First, BN particles and alumina particles as shown in Table 7 below were prepared. Next, the BN particles and alumina particles were mixed at various volume ratios, and block test pieces 01 to G9 were created using the mixture in the same manner and under the same conditions as in Example 1. In addition, a block specimen made of a matrix metal composited only with reinforcing particles cyo
It was created. Next, these block test pieces were treated with chrome steel (JI) in the same manner and under the same conditions as in Example 1.
A wear test was conducted using S standard 5Cr20, Hv-720) as the mating material. The results of these wear tests are shown in FIG.

From FIG. 10, it can be seen that when the volume fraction of the solid lubricant is 3 to 50%, particularly 5 to 45%, and even 10 to 40%, the wear amount of the composite material and the mating material becomes a small value.

Example 8 Wear tests were conducted on combinations of steel and composite materials whose matrix metals were magnesium alloys, zinc alloys, lead alloys, tin alloys, and copper alloys.

First, alumina particles with a volume ratio of 25% ( A block test piece H1 was prepared from a magnesium alloy (JIS standard MDC1-A) which was interlaced with Table 7) and BN particles (C2 in Table 3) with a volume fraction of 25%.

Also, the hot water temperature and pressure are 500°C and 11,000k each.
Alumina particles with a volume ratio of 40% (Table 7) and BN particles with a volume ratio of 20% (C2 in Table 3) were prepared in the same manner and under the same conditions as in Example 1, except that g/ca + H was set. A block test piece 11 made of a composite zinc alloy (JIS standard ZDC1) was prepared.

Also, the hot water temperature and pressure are 410℃ and 1000k, respectively.
With silicon nitride particles (same as the particles used in Example 1) with a volume fraction of 20% in the same manner and under the same conditions as in Example 1 above, except that the particle size was set at A block test piece J1 was prepared from a lead alloy (JIS standard WJ8) composited with W 03 particles (C3 in Table 3) with a volume fraction of 50%.

Also, the hot water temperature and pressure are 330°C and 11000k each.
Silicon nitride particles with a volume fraction of 596 (same as the particles used in Example 1) and a volume fraction of 5
A block test piece was made of a tin alloy (JIS standard WJ 2) composited with % of potassium titanate whiskers (C4 in Table 3).

Furthermore, one silicon carbide particle (D2 in Table 4), BN sieve (c2 in Table 3), and copper alloy (Cu-10igt%Sn) powder were added, each with a volume fraction of silicon carbide particles and BN particles of 3. %, 5%, and mixed, a small amount of ethanol was added to the mixture, and the mixture was mixed for about 30 minutes in a Starsea. After drying the mixture thus obtained at 80°C for 5 hours, a predetermined amount of the mixture was filled into a mold, and the mixture was compressed with a punch at a pressure of 4000 kg/am'' to form a plate. The plate was then sintered by heating it at 770°C for 30 minutes in a batch-type sintering furnace set in an atmosphere of decomposed ammonia gas (dew point -30°C), and then placed in a cooling zone in the sintering furnace. A composite material is manufactured by slowly cooling the composite material, and a block test piece L is obtained from the composite material.
1 was created.

In addition, for the purpose of comparison, block test pieces H and -Lo were created from a material consisting only of the matrix metal of the composite material of the above-mentioned block test pieces H1 to L, respectively.

These block specimens were then tested with chrome steel (JI
A wear test using a cylindrical test piece made of Sfflr6SCr20, Hv-720) as a mating member was conducted in the same manner and under the same conditions as in Example 1. The results of these wear tests are shown in Table 8 below.

In Table 8, the wear amount ratio of the block test piece is the wear amount ratio of the block test piece H to the wear amount of test pieces H and -Lo, respectively.
, -L, means the percentage of the wear amount (wear scar depth μl11), and the upper and lower numbers of the wear amount of the cylindrical test piece are for the cylindrical test rubbed with the block test pieces H1 to L1 and HO-Lo, respectively. This is the wear amount of the piece (wear loss a+g).

From Table 8, even when the matrix metal is magnesium alloy, zinc alloy, lead alloy, tin alloy, and copper alloy,
When the Mohs hardness, volume fraction, etc. of the reinforcing particles and the solid lubricant are within the range of the present invention, the composite material can be manufactured without substantially increasing the wear amount of the mating material compared to the material made only of matrix metal. It can be seen that the amount of wear can be significantly reduced.

Although the present invention has been explained in detail above in connection with the experimental research conducted by the inventors of the present invention, the present invention is not limited to these examples, and any invention within the scope of the present invention. It will be apparent to those skilled in the art that various other embodiments are possible.

Table 1 (Part 1) Table 1 (Part 2) Note: 1) JIS standard 5UJ2 2) JIS standard SCr 20 3) JIS standard SUS420J2

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a molded body made of silicon nitride particles as reinforcing particles and BN particles as a solid lubricant uniformly mixed with each other, and FIG. Fig. 3 is a perspective view showing the solidified body formed by the high-pressure casting of Fig. 2, and Fig. 4 is a diagram showing the casting process of manufacturing composite materials by high-pressure casting. Graphs showing the results of wear tests conducted on composite materials made of aluminum alloys made of elementary particles and BN particles, and composite materials of comparative examples, using steels of various hardness as mating materials. reinforcement particles and W
Figure 6 is a graph showing the results of a wear test conducted on a composite material made of an aluminum alloy composited with 03 particles, using chromium steel as a partner material. A graph showing the results of wear tests conducted on composite materials made of aluminum alloys using chromium steel as a partner material. Figure 7 shows composite materials made of aluminum alloys composited with reinforcing particles of various diameters and PbO particles. Graph showing the results of a wear test conducted using stainless steel as a mating material, No. 8
Figure 9 is a graph showing the results of wear tests conducted on composite materials made of aluminum alloys made of solid lubricants of various diameters and alumina-silica particles, using stainless steel as the mating material. Figure 10 is a graph showing the results of a wear test conducted on a composite material made of an aluminum alloy made up of WC particles and PbO particles with various volume fractions, using bearing steel as the mating material. It is a graph showing the results of a wear test conducted on a composite material made of an aluminum alloy composited with alumina particles using chromium steel as a mating material. DESCRIPTION OF SYMBOLS 1... Molded object, 11... Composite material, 2a... Reinforcement particle. 2b... BN particles, 3... Mold, 4... Mold cavity, 5... Molten metal, 6... Plunger, 7...
...Coagulation Chief Priest Applicant Toyota Motor Corporation Representative Patent Attorney Masatake Akashi No. 11
Figure 3 Figure 2 "Figure 4 Figure 5 Day 5 Figure 6 Figure 7 Figure 8

Claims (4)

[Claims] (1) A sliding member consisting of a first member and a second member that are in contact with each other and slide relative to each other, and at least the sliding surface portion of the first member relative to the second member has a Mohs hardness. is 6 or more and the diameter is 30 μm or less
~40% of reinforcing particles, and a solid lubricant with a volume fraction of 3 to 50% selected from the group consisting of short fibers, particles, and mixtures thereof having a Mohs hardness of 4.5 or less and a diameter of 100 μm or less. It is composed of a composite material in which the reinforcing material is a mixture of the following, and the matrix metal is a metal selected from the group consisting of aluminum, magnesium, copper, zinc, lead, tin, and alloys containing any of these as main components. A sliding member, wherein at least the sliding surface of the second member relative to the first member is made of steel having a hardness Hv (10 kg) of 180 or more. (2) The sliding member according to claim 1, wherein the solid lubricant is any one of an oxide, a nitride, and a mixture thereof. (3) In the sliding member according to claim 1 or 2, the Mohs hardness and diameter of the reinforcing particles are respectively 7.
The Mohs hardness, diameter, and volume fraction of the solid lubricant are 4 or less, 50 μm or less, and 5, respectively.
45%. (4) In the sliding member according to claim 3, the solid lubricant has a Mohs hardness and a volume fraction of 3 or less, respectively;
A sliding member characterized in that the ratio is 10 to 40%.