JP2009143772A - Slide member and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carbon slide member superior in abrasion resistance and load bearing property. <P>SOLUTION: The slide member 4 contains a carbon base material 1 and a metal, also a carbide or an oxide, and is characterised in that, in the sliding surface, the metal is dispersed insularly and the metal is surrounded by the carbide or the oxide. Also, it is characterised in that the surface layer part containing the abrasion surface has a three-dimensional network structure, in which mutually connected metal skeletons are included, and the surfaces thereof are covered by the carbide or the oxide, and the other parts are formed of carbon. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sliding member, and relates to a sliding part of a bearing or a machine product using the sliding member.

  Sliding members used in bearings and sliding parts that operate without supplying lubricating oil, or sliding parts that use less lubricating oil during startup, etc., are seized under conditions where metal is in contact with each other or when the lubricating oil is depleted. In order to avoid this, carbon fired materials have been used in some cases. The carbon fired material is less likely to cause seizure even without oil supply due to the self-lubricating property of graphite by appropriately blending the graphite component.

  On the other hand, generally, since the open pores remain in the carbon fired material, there is a drawback that it is difficult to obtain fluid lubrication with a lubricating oil or a lubricating liquid. Moreover, the carbon fired material has a low strength due to weak bonding between carbons and the presence of pores, and the compressive strength is limited to about 280 MPa.

  In Patent Document 1, in order to prevent wear and seizure of a bearing portion of a compressor, a carbonaceous base material is used as a bearing, and a metal selected from Group VIII, Group VIII excluding Fe, and Sn is used for the pores. The use of impregnated members is disclosed.

  Patent Document 2 discloses a method for producing a graphite-silicon carbide composite material, in which a eutectic alloy in which silicon accounts for the majority of the composition ratio is pressure-infiltrated and reacted with a green compact made of graphite powder. Yes.

  Patent Document 3 discloses a sliding component in which a carbon compound pore is provided with a mixed compound containing layer containing silicon oxide and a metal phosphate compound.

  In Patent Document 4, any one or two or more of carbide, nitride, oxide, sulfide, hydroxide, carbonate and relatively low melting point metal are present in the pores present in the silicon carbide sintered body. A sliding member impregnated with a molten material is disclosed.

  Patent Document 5 discloses a carbon-silicon carbide-metal composite material in which a surface layer portion of a sliding portion of a carbon base material is silicified, and the entire carbon base material is impregnated with metal. Here, antimony, silver, tin, and copper are described as the metal to be impregnated.

  Patent Document 6 discloses a metal-containing carbon sliding material in which a carbon base material is impregnated with an alloy containing Sb and Cu.

  Patent Document 7 discloses a metal-containing carbon sliding material in which a carbon base material is impregnated with an alloy containing Al, Cu, Mg, Ti, Be and the balance Zn.

  Patent Document 8 includes a coating containing carbon and nitrogen on at least a part of a sliding surface, and this coating may be used as another compound as well as elements IVa, Va, VIa group elements, iron group metals, Al in the periodic table. And a sliding member containing Si and at least one selected from carbides, nitrides, and carbonitrides thereof, and other compounds being amorphous.

  Patent Document 9 discloses a metal-impregnated carbon bearing material in which a carbon base material containing a solid lubricant is impregnated with an alloy containing Zn, Cu, and the remaining Sn.

  Patent Document 10 discloses a compressor bearing in which pores of a carbonaceous substrate containing graphite are impregnated with one kind of metal selected from Group IB, Group VIII excluding Fe, and Sn, or an alloy mainly composed of these metals. It is disclosed.

JP 2002-213356 A JP-A-3-290367 JP 2002-323141 A Japanese Patent Application Laid-Open No. 60-141689 JP-A-8-109083 JP 2007-162111 A JP 2005-187288 A JP 2000-192183 A JP 2003-322153 A JP 2003-314448 A

  When a force that deforms the surface by friction acts on the carbon, the bond between the carbons breaks, causing the carbon particles to fall off, leading to wear. When a frictional force is applied to the metal, the metal part is deformed or affixed with the counterpart material and deforms and breaks, resulting in wear. In the conventional material, since the bond between the carbon part and the metal part is weak, the carbon and the metal often fall off alone and wear.

  The strength of the metal-impregnated carbon as the sliding member depends on the strength of the base material of the carbon fired material, and it is necessary to increase the strength of the carbon base material in order to obtain high strength. On the other hand, the wear resistance of the metal-impregnated material is improved as the compressive strength is increased. However, when the pressure is 300 MPa or more, the effect of improving the wear resistance due to the strength is reduced. In order to improve the wear resistance, it is necessary to improve the material structure in addition to the strength.

  When the load is high, the wear of the carbon particles on the surface of the friction surface of the carbon base material increases rapidly due to buckling and dropping. Although the strength of the whole part is improved by metal impregnation, it is considered that carbon particles are easy to drop off because the bond between carbon and impregnated metal is weak. In order to improve the wear resistance, it is necessary to improve at least the strength near the friction surface.

  Furthermore, the metal impregnation requires pressing the molten metal into the pores of the carbon base material in a high-pressure atmosphere of 10 MPa or more, and the manufacturing cost is high because a large apparatus such as a hot hot pressure press is used.

  An object of the present invention is to provide a sliding member having excellent wear resistance and load resistance.

  The sliding member of the present invention is a sliding member containing a carbon base material and a metal, and containing a carbide or an oxide, wherein the metal is dispersed in an island shape on the friction surface, and the periphery of the metal is the carbide or the metal. It is characterized by being surrounded by an oxide.

  According to the present invention, it is possible to provide a lightweight sliding member that is excellent in wear resistance and load resistance not only in a lubricating atmosphere but also in an oil-free and non-lubricating atmosphere.

  The structure of the friction surface of the carbon sliding member according to the present invention includes a carbon base material, a metal part, and a three-phase of carbide or oxide.

  In general, the carbon base material has low friction because the graphite contained therein causes slipping between thin crystal lattices due to friction with the counterpart material. The metal is filled in pores that are inevitably generated in the carbon base material to prevent the deformation and dropping of the carbon, and the metal itself is also prevented from excessive deformation by the carbon base material. However, the carbon substrate and the metal filled in the pores may be in contact with each other and not chemically bonded.

  Therefore, in the present invention, a carbide layer that is easily bonded to both the carbon base material and the metal is disposed between the carbon base material and the metal. Thereby, the strength of the friction surface can be improved.

  The carbide is harder than the carbon base material and the metal, and supports the pressing load of the counterpart material during friction and can reduce the load load of the carbon base material and the metal part, thereby improving the wear resistance. In addition, the carbide surrounds the metal part on the friction surface, and suppresses plastic flow of the metal part due to adhesion between the counterpart material and the metal part, so that wear of the metal part can be prevented.

  The oxide formed so as to surround the metal part is harder than the carbon base material and metal like the carbide, and reduces the load load of the carbon base material and the metal part and plastic deformation of the metal part due to adhesion with the counterpart material. Prevent and improve wear resistance.

  It is known that the stress applied to the sliding portion is the resultant force of the load and the frictional force and extends not only to the friction surface but also to the inside. The friction surface layer is peeled off by the stress applied to the inside due to friction, leading to wear and destruction. Therefore, it is important that the metal portions exposed on the friction surface are bonded to each other in a mesh form in the surface layer portion in order to resist the force to be peeled off.

  The carbon base materials are bonded to each other by firing in advance, and have open pores connected to each other. By filling the open pores with metal, a mesh-like metal can be formed. Furthermore, the boundary surface between the metal and the carbon base material is a carbide or oxide for increasing the bonding force between the carbon and the metal, so that even if the metal exposed on the surface adheres to the counterpart material, It is possible to prevent the falling off due to the anchor effect, and to prevent the friction surface from being largely broken or worn.

  The sliding member according to the present invention is a sliding member containing a carbon base material and a metal, and containing a carbide or an oxide. The metal is dispersed in an island shape on the friction surface, and the periphery of the metal is the carbide. Alternatively, it is characterized by being surrounded by the oxide. Further, in the sliding member according to the present invention, the surface layer portion including the friction surface has a three-dimensional network structure, and includes metal skeletons connected to each other, and the surface of the metal skeleton is covered with carbide or oxide. The portion is made of carbon. Further, in the sliding member according to the present invention, the carbon base material is composed of a carbon fired material, the surface layer portion including the friction surface is impregnated with metal in the pores of the carbon fired material, and the boundary between the carbon fired material and the metal A carbide layer or an oxide layer is formed in the part.

  Here, since the surface layer portion including the friction surface of the sliding member has a three-dimensional network structure and has a metal skeleton connected to each other, a cross section of the three-dimensional network structure is exposed on the friction surface, and is formed in an island shape. Looks scattered.

  As described above, the wear is maintained even when the wear progresses, and the wear resistance is continuously improved.

  The carbon substrate according to the present invention is a carbon material mainly composed of at least one selected from carbon and graphite. In particular, from the viewpoint of reducing the friction coefficient and improving the wear resistance, it is preferable to make the graphite 30 to 70% by weight. Further, as the graphite, two or more types of graphite having different crystallinity degrees of crystallinity may be used in combination, and it is preferable to adjust the hardness according to the strength of the sliding partner material, in which case the graphite range is 10 to 10 100%. If the hardness is low, the load resistance is impaired and the wear amount tends to increase. On the other hand, when the hardness is high, there is a tendency that the sliding partner material is damaged and the sliding property is deteriorated.

  As raw materials for producing the carbon base material of the carbon sliding member according to the present invention, graphite powder, coke powder or the like is used as an aggregate, and talc, molybdenum disulfide or the like is used as a solid lubricant as necessary. Further, tar pitch, coal tar and the like are used as binders.

  The carbon substrate used in the present invention can be obtained by using the above-mentioned raw materials, heating and kneading, pulverizing and molding, followed by firing. In the heat-kneading, each raw material is preferably kneaded at a temperature of 230 to 270 ° C. using a double-arm kneader or the like. If the kneading temperature is high, the mechanical strength tends to decrease, and if it is low, the kneading time tends to be long. The kneading time varies depending on the amount of the kneaded material, the blending ratio of the aggregate, and the binder, and is appropriately selected each time.

  The pulverization is performed by pulverizing the material obtained by heat-kneading using various pulverizers so that the average particle diameter becomes 20 to 30 μm. When the average particle size is large, the denseness tends to be impaired, and when the average particle size is small, the mechanical strength tends to decrease.

  The molding is performed by molding the powder obtained by pulverization into a block shape by a method such as a die press. When the molding pressure is low, the mechanical strength tends to decrease, and when the molding pressure is high, there is a tendency to crack during firing.

  Firing is preferably performed at a temperature of 800 to 1000 ° C. in an inert atmosphere. The firing time is preferably 300 to 500 hours. As a method for firing in an inert atmosphere, there is a method of filling a molded product with carbon powder or the like and firing.

The apparent density of the carbon fired material thus obtained is 1600 to 1850 kg / m ³ .

  The metal part is mainly composed of an element that is difficult to form carbides such as aluminum (Al), zinc (Zn), copper (Cu), silver (Ag), gold (Au), tin (Sn), and the like. In order to enhance the bond between the carbon substrate and the metal via the element, an element such as chromium (Cr) that easily forms a carbide is added, or an element such as titanium (Ti) that easily bonds to an oxide is added. Elements that easily form carbides can facilitate filling into the carbon substrate. When using an element that easily binds to an oxide, it is effective to previously form a thin metal oxide (50 nm or more) in the pores of the carbon substrate.

  The metal oxide is filled in the pores of the carbon substrate with a solution obtained by diluting a sol solution containing at least one selected from alumina, titania, calcia, yttria, zirconia, and magnesia with a solvent, and heated in the air to remove volatile components. It is obtained by removing.

  In the case of an alloy containing copper as a main component, the addition amount of chromium for the purpose of carbide formation and titanium for the purpose of bonding with an oxide is preferably 0.2% by weight or more. This is to utilize the diffusion of chromium and titanium contained in the molten alloy and the reaction on the surface of the carbon substrate.

  Further, if the amount of chromium added to the alloy containing copper as a main component exceeds 1.25% by weight, chromium precipitation in the molten metal occurs before the impregnation, so that it is preferably less than 1.25% by weight. Furthermore, the amount of titanium added to the alloy containing copper as a main component is that the titanium is partly dissolved in copper, and at the same time, the ductility of the copper alloy is reduced by the intermetallic compound of copper and titanium. In order to improve the properties, the content is preferably 10% by weight or less. Hereinafter, an alloy shall be contained in a metal.

  In the present invention, since the bonding between the carbon base material and the metal or between the carbon base material and the metal via the oxide phase is promoted, the molten metal is impregnated into the pores near the surface of the carbon base material under a vacuum. . When it is necessary to impregnate the inside of a component that requires a complicated shape and high strength, so-called pressure impregnation, in which a base material is immersed in a molten metal under a vacuum and reduced pressure, is effective.

  The pressure impregnation of the metal is performed by heating the carbon base material to a melting temperature of the metal in a state where vacuum degassing is performed to a vacuum degree of 1.4 kPa or less using a heating impregnation pot, and then immersing in the molten metal. In the immersed state, the carbon sliding member according to the present invention is obtained by holding under pressure at a pressure of 0.9 to 10.0 MPa for 1 to 2 hours under an inert atmosphere and then taking out and cooling the carbon base material. . As a method of pressurizing in an inert atmosphere, there is a method of pressurizing using an inert gas such as nitrogen. When the degree of vacuum does not reach 1.4 kPa or when the applied pressure is less than 0.9 MPa, the metal is not uniformly impregnated in the carbon base material, and pores remain partially.

  Since the sliding member of the present invention is not required to supply lubricating oil, particularly mineral oil, due to the crystalline graphite particles blended in the carbon base material, a liquid conveying pump that does not need to supply lubricating oil is desired. And suitable for sliding parts of gas compression pumps. Furthermore, when performing high-speed sliding in a gas atmosphere or liquid atmosphere, the pores of the carbon substrate are sealed with carbides or oxides and metals, so that the fluid lubrication state where the gas or liquid acts on the friction surface as a pressure fluid Can be obtained.

  In the positioning and conveying device, since the sliding member according to the present invention is used as a component, the strength and wear resistance are high, a lubricant is unnecessary, and an environmentally friendly component can be used. Therefore, high reliability and high accuracy can be achieved. Can be realized.

  The carbon base material was formed by mixing carbon powder particles with a binder, pressure forming, and then firing at a high temperature.

  After blending 76% by weight of the coke pulverized product with 20% by weight of tar pitch and 4% by weight of coal tar, the mixture is heated and kneaded at a temperature of 250 ° C. for 5 hours using a double-arm kneader. The pulverized product was placed in a mold having a size of 150 × 250 × 50 mm and molded at a molding surface pressure of 112 MPa. The obtained molded article was heated to 900 ° C. over 400 hours in an inert atmosphere over 400 hours. The carbonized block was heated up to 3000 ° C. over 96 hours under an inert atmosphere, then cooled. 23% by weight of homemade artificial graphite powder obtained by pulverization from 15%, commercially available oil smoke (trade name: SUNBLACK # 35, manufactured by Asahi Carbon Co., Ltd.), and commercially available artificial graphite powder (trade name: TIMREX KS44 Graphite, manufactured by TIMCAL) ) 3% by weight of each aggregate, 54% by weight of tar pitch and 5% by weight of coal tar were blended as binders, and kneaded by heating at a temperature of 280 ° C. for 8 hours using a double-arm kneader.

  The kneaded product was pulverized to an average particle size of 25 μm, and the pulverized product was placed in a mold having a size of 150 × 250 × 50 mm and molded at a molding surface pressure of 123 MPa. The obtained molded product was heated to 900 ° C. over 400 hours under an inert atmosphere and then cooled to obtain a carbon substrate. The amount of graphite in the obtained carbon base material was 45.9% in terms of the integrated intensity ratio when the diffraction peak profile of the graphite (200) plane was separated and analyzed into a graphite component and a carbon component by X-ray diffraction.

  Thereafter, the metal to be filled in the carbon base material was a copper alloy containing copper as a main component and 0.4% by weight of chromium.

  After the above carbon base material is vacuum degassed to a vacuum degree of 1.2 kPa with a heat impregnation kettle, heated to 1150 ° C., immersed in the molten copper alloy, and pressurized under a pressure of 9.5 MPa in the immersed state Then, it was taken out and cooled to obtain a carbon sliding member. The resulting carbon sliding member was measured for bulk density, bending strength, hardness, and open porosity. The measurement results are shown in Table 1.

  Here, the bulk density is in accordance with Japanese Industrial Standard JIS R 7212, the size of the test piece (approximately 10 × 10 × 50 mm) is measured with a micrometer to determine the volume, and the weight of the test piece is measured with a balance. Calculated by the formula.

d = (W / V) × 1000
(D: bulk density (kg / m ³ ), W: weight (g), V: volume (cm ³ ))
The bending strength is based on Japanese Industrial Standard JIS R 7212 and the thickness of the test piece (test piece approximate dimensions 10 × 10 × 50 mm) is measured with a micrometer. Next, the test piece is supported from below by a distance between fulcrums of 40 mm, a load is applied from above the center with a pressure wedge, and the load when the test piece is broken is measured. The bending strength is calculated by the following formula. In collecting the test piece, the thickness direction at the time of molding is taken as the thickness direction of the test piece.

Sa = (3PL / 2a ² b) × 0.098
(Sa: bending strength (MPa), P: load when the specimen is broken (kg), a: specimen thickness (cm), b: specimen width, (cm), L: between fulcrums Distance (cm)
The hardness is in accordance with Japanese Industrial Standard JIS Z 2246, and three or more molding pressure surfaces of a test piece having an approximate size of 10 × 10 × 50 mm are measured with a D-type shore hardness meter, and the average value is taken as the hardness. However, extremely high and low values are excluded.

  The open porosity is measured based on the mercury intrusion method using a mercury porosimeter. Examples of the measuring device include an AUTO SCAN-33 type mercury porosimeter manufactured by QUANTA CHRME. The cumulative pore volume is calculated from the pore distribution curve collected by this method, and the open porosity is obtained by “cumulative pore volume” × “specific gravity of the carbon sliding material” × 100 (%).

  The schematic diagram of the cross-sectional structure | tissue inside the sliding member obtained in FIG. 1 is shown. Inside the sliding member 4, the pores of the carbon base material 1 are filled with the copper alloy 21 and the carbide 31, and the carbide 31 is formed so as to surround the copper alloy 21 at the boundary between the base material 1 and the copper alloy 21. In this example, the thickness of the carbide 31 was about 3 μm on average. Since the outermost surface of the completed carbon base material 1 is covered with chromium carbide, the carbide layer on the surface of the sliding member is removed by machining, the sliding surface exposes the carbon base material 1, and the copper alloy 21 And it adjusted so that chromium carbide might appear. Table 1 also shows the results of an in-oil wear test which will be described later.

The amount of graphite in the carbon substrate 1 of this example was 45.9% in terms of the integrated intensity ratio by X-ray diffraction, but the amount of graphite should be at least 10% in terms of the integrated intensity ratio by X-ray diffraction. is required. A desirable graphite amount is 20% or more, and a more desirable graphite amount is 40% or more.
[Comparative Example 1]
After blending 76% by weight of the coke pulverized product with 20% by weight of tar pitch and 4% by weight of coal tar, the mixture is heated and kneaded at a temperature of 250 ° C. for 5 hours using a double-arm kneader. The powder is pulverized to an average particle size of 50 μm, and the pulverized product is put into a mold having a size of 150 × 250 × 50 mm and molded at a molding surface pressure of 112 MPa. The resulting molded product is heated to 900 ° C. in an inert atmosphere over 400 hours. The carbonized block obtained by raising the temperature was heated to 3000 ° C. in an inert atmosphere for 96 hours, cooled and then pulverized, and 23% by weight of homemade artificial graphite powder, commercially available oil smoke (trade name: 15% by weight of SUNBLACK # 35, manufactured by Asahi Carbon Co., Ltd. and 3% by weight of commercially available artificial graphite powder (trade name: TIMREX KS44 Graphite, manufactured by TIMCAL) are used as an aggregate, Then, 54% by weight of tar pitch and 5% by weight of coal tar were blended and heated and kneaded at a temperature of 280 ° C. for 8 hours using a double-arm kneader.

  The kneaded product was pulverized to an average particle size of 25 μm, and the pulverized product was placed in a mold having a size of 150 × 250 × 50 mm and molded at a molding surface pressure of 123 MPa. The obtained molded product was heated to 900 ° C. over 400 hours under an inert atmosphere and then cooled to obtain a carbon substrate.

  The schematic diagram of the cross-sectional structure | tissue of the carbon base material obtained in FIG. 4 is shown. The carbon substrate 1 has pores 7 dispersed therein.

The resulting carbon sliding member was measured for bulk density, bending strength, hardness, and open porosity. The measurement results are shown in Table 1. Table 1 also shows the results of the in-oil wear test described later.
[Comparative Example 2]
The bulk density, bending strength, hardness, and open porosity of the sliding member impregnated with a copper alloy (bronze CAC403 (BC3)) not added with chromium using the carbon base material of Comparative Example 1 were measured. The measurement results are shown in Table 1. Here, the conditions when the copper alloy was impregnated were the same as in the case of Example 1, and after the vacuum deaeration to a vacuum degree of 1.2 kPa with a heating impregnation pot, the copper alloy was heated to 1150 ° C. and melted. And was pressurized at a pressure of 9.5 MPa.

  In the case of this comparative example, copper has penetrated into the pores of the carbon substrate. FIG. 2 is a schematic diagram showing a cross-sectional structure of the sliding member 5 of Comparative Example 2. The copper alloy to which chromium is not added hardly forms carbides, and is a composite material composed of two phases of the carbon base material 1 and the copper alloy 22. Table 1 also shows the results of the in-oil wear test described below.

  A mixture of 76% by weight of the coke pulverized product, 20% by weight of tar pitch and 4% by weight of coal tar as a binder, and heat-kneaded at a temperature of 250 ° C. for 5 hours using a double-arm kneader. After cooling, the powder was pulverized to an average particle size of 50 μm, and the pulverized product was put into a mold having dimensions of 150 × 250 × 50 mm and molded at a molding surface pressure of 112 MPa. The obtained molded product was heated to 900 ° C. in an inert atmosphere over 400 hours, and the resulting carbonized block was heated to 3000 ° C. in an inert atmosphere in 96 hours, cooled, and then pulverized. . 23% by weight of homemade artificial graphite powder thus obtained, 15% by weight of commercially available oil smoke (trade name: SUNBLACK # 35, manufactured by Asahi Carbon Co., Ltd.) and commercially available artificial graphite powder (trade name: TIMREX KS44 Graphite, manufactured by TIMCAL) 3% by weight was aggregated, 54% by weight of tar pitch and 5% by weight of coal tar were blended as binders, and the mixture was heat-kneaded at a temperature of 280 ° C. for 8 hours using a double-arm kneader.

  The kneaded product was pulverized to an average particle size of 25 μm, and the pulverized product was placed in a mold having a size of 150 × 250 × 50 mm and molded at a molding surface pressure of 123 MPa. The obtained molded product was heated to 900 ° C. over 400 hours under an inert atmosphere and then cooled to obtain a carbon substrate.

  Thereafter, the metal to be filled in the carbon base material was a copper alloy containing copper as a main component and 0.4% by weight of chromium.

  The carbon base material is vacuum degassed to a vacuum degree of 1.2 kPa with a heat impregnation pot, then heated to 1150 ° C. and immersed in the molten copper alloy, then taken out, cooled, released to atmospheric pressure, and carbon slides. A moving member was obtained. FIG. 3 shows a schematic diagram of a cross-sectional structure in the vicinity of the surface layer of the obtained sliding member.

  In this embodiment, the outermost surface of the carbon base material 1 is covered with chromium carbide 31, and the inside is penetrated by the copper alloy 21 from the surface 6 side of the carbon base material 1 to the base pores having a depth of about 30 μm. A chromium carbide 31 is formed at the boundary between the copper alloy 21 and the carbon substrate 1. The chromium carbide 31 on the outermost surface of the carbon substrate 1 was removed by machining, and the sliding surface was adjusted so that the carbon substrate 1 was exposed and the copper alloy 21 and the chromium carbide 31 appeared. Table 1 shows the results of the in-oil wear test described below.

  20% by weight of tar pitch and 4% by weight of coal tar were combined with 76% by weight of the coke pulverized product, and the mixture was heated and kneaded at a temperature of 250 ° C. for 5 hours using a double-arm kneader, and the kneaded product was cooled. Then, it grind | pulverized to the average particle diameter of 50 micrometers. The obtained pulverized product was put into a mold having dimensions of 150 × 250 × 50 mm and molded at a molding surface pressure of 112 MPa. The obtained molded article was heated to 900 ° C. in an inert atmosphere over 400 hours, and the carbonized block was heated to 3000 ° C. in an inert atmosphere in 96 hours, cooled, and then pulverized. . 23% by weight of homemade artificial graphite powder obtained, 15% by weight of commercially available smoke (trade name: SUNBLACK # 35, manufactured by Asahi Carbon Co., Ltd.) and 3% by weight of commercially available artificial graphite powder (trade name: TIMREX KS44 Graphite, manufactured by TIMCAL) % Was aggregated, 54% by weight of tar pitch and 5% by weight of coal tar were blended as binders, and kneaded by heating at a temperature of 280 ° C. for 8 hours using a double-arm kneader.

  The kneaded product was pulverized to an average particle size of 25 μm, and the pulverized product was placed in a mold having a size of 150 × 250 × 50 mm and molded at a molding surface pressure of 123 MPa. The obtained molded product was heated to 900 ° C. over 400 hours under an inert atmosphere and then cooled to obtain a carbon substrate.

A film of yttria (oxide, Y ₂ O ₃ ) was formed on the inner wall surface of the pores of the obtained carbon substrate. The oxide film was formed by immersing a carbon base material in a solution obtained by diluting yttria sol to 3% with a solvent, and standing in the atmosphere at room temperature for 4 hours or more and pre-drying. Furthermore, after heating at 100 ° C. for 1 hour in atmospheric pressure, the temperature was raised to 150 ° C. and heat treatment was performed for 2 hours to form an oxide film having an average thickness of about 50 nm on the inner wall surface of the pores.

  FIG. 5 shows a cross-sectional structure of the oxide formed. An oxide 33 is formed on the inner wall surfaces of the pores 307 of the carbon substrate 1.

  Here, the production method of the yttria sol liquid is as follows.

Was dissolved yttrium chloride hexahydrate _{(YCl 3 · 6H 2 O)} 0.013 mol in 99.5% ethanol 1.268 mol. And after adding the liquid mixture of 0.263 mol of water and 0.079 mol of 60% nitric acid, it heated at 40 degreeC for 2 hours. The obtained solution was diluted with ethanol, and a 3% yttria sol solution suitable for permeating into the pores was prepared.

  Although not described here, as another method for producing the yttria sol solution, there is a method using yttrium acetate as a starting material.

  Although only yttria has been described here, a composite oxide film in which a plurality of oxides such as alumina, titania, calcia, zirconia, and magnesia are combined may be used.

  Thereafter, as the metal filled in the carbon base material, a copper alloy containing copper as a main component and adding 0.2% by weight of titanium was used.

  The above carbon base material is vacuum degassed to a vacuum degree of 1.2 kPa with a heat impregnation kettle, then heated to 1150 ° C., immersed in the molten copper alloy, pressurized with a pressure of 9.5 MPa in the immersed state, and taken out. And cooled to obtain a carbon sliding member. The resulting carbon sliding member was measured for bulk density, bending strength, hardness, and open porosity. The measurement results are shown in Table 1.

  The schematic diagram of the cross-sectional structure | tissue inside the sliding member obtained in FIG. 6 is shown. The inside of the sliding member 5 is filled with the copper alloy 23 and the oxide 33 in the pores of the carbon base material 1, and the oxide 33 is formed so as to surround the copper alloy 23 at the boundary between the carbon base material 1 and the copper alloy 23. Has been. The average thickness of the oxide 33 was about 40 nm. Since the outermost surface of the carbon substrate 1 is covered with an oxide, the oxide layer on the outermost surface of the carbon substrate 1 is removed by machining, the sliding surface exposes the carbon substrate 1, and Adjustment was performed so that copper and yttria (oxide) appeared. Table 1 also shows the results of the in-oil wear test described later.

  FIG. 7 shows an outline of the wear tester. The test piece 100 of the embodiment of the present invention or the test piece 100 of the comparative example is fixed to the upper test piece holder 102, and the test piece 100 is pressed against the mating member ring 101 by the spring 103 through the holder 102. Friction is caused by rotating the ring 101, and the friction torque is measured by the load cell 104.

  The in-oil wear test was performed by placing a 5 × 10 × 36 mm test piece on a 10 × 36 mm side down in a commercially available car engine oil (trade name: epro-extra 10w-30, Hino Motors genuine oil). The ring (material FH-15) with an inner diameter of 26 mm (Ф) and an outer diameter of 30 mm (Ф) is rotated at a peripheral speed of 2.1 m / s while the surface pressure is 16.5 MPa. The test was carried out for 1 hour by pressing in a more covered state, and the dimensional change of the test piece at the portion where the ring slid was measured as the amount of wear.

  The results of Comparative Examples 1 and 2 and Examples 1 to 3 are shown in Table 1. The amount of wear in Example 1 was improved to 1/15 of the non-impregnated material of Comparative Example 1 and further 1/7 of Comparative Example 2 without carbide, so that the impregnated metal and carbide coexisted. It is clear that the wear resistance can be dramatically improved.

  The amount of wear in Example 2 is 10 μm in a one-hour test, and wear resistance is ensured if only the friction surface is a metal, carbide and carbon substrate. However, when friction is made for 2 hours or more, the portion where the metal and carbide are present is worn away, and the friction surface becomes only the carbon base material, so that wear is accelerated. However, if the wear rate is reduced, such as by reducing the load, it can be put to practical use, wear is less than that of the comparative material, and the parts can be made lighter than the first embodiment. The thickness of the surface layer of the present invention required for the parts can be increased by increasing the impregnation pressure.

  FIG. 8 shows a schematic diagram of a cross-sectional structure of the sliding member according to the present invention. In the sliding member 4, the pores of the carbon substrate 1 are filled with the carbide or oxide 3 and the metal 2, and the carbide or oxide 3 is at the boundary between the metal 2 and the carbon substrate 1.

  An example in which the sliding member according to the present invention is applied to a bearing bush is shown in FIG. A hollow bearing bush 201 was formed with a carbon base material, and a layer in which a metal and carbide coexisted was formed from the surface to a depth of about 30 μm on the inner surface 202 using the same method as in Example 2 of the present invention. When the bearing bush 201 was used as a bearing for a submersible pump, the sealing performance and wear resistance were improved.

  FIG. 10 shows an example in which the sliding member according to the present invention is used for the positioning slide guide mechanism 203. The guide rail 204 in contact with the pin portion 205 that reciprocates linearly is formed of carbon steel, and the contact surface 206 with the pin 205 is a sliding member similar to that of the first embodiment of the present invention, thereby improving the durability of the guide rail. The improvement was about 10 times.

  By configuring these bearings, guide rails, or parts corresponding to the counterpart material with the sliding member of the present invention, it is possible to reduce the weight of the apparatus and improve the wear resistance reliability. Furthermore, the friction of the sliding portion can be reduced. The sliding member according to the present invention can be applied to other parts having the same frictional form. For example, in a cam mechanism part, a rolling bearing, a gear, a slider, etc., weight reduction, improved wear resistance, and low friction loss are achieved. Can be planned.

It is a schematic diagram of the cross-sectional structure | tissue of the metal impregnation sliding member which formed the carbide | carbonized_material which shows Example 1 by this invention. 6 is a schematic diagram showing a cross-sectional structure of a sliding member of Comparative Example 2. FIG. It is a schematic diagram of the cross-sectional structure | tissue in the surface vicinity of the metal impregnation sliding member which formed the carbide | carbonized_material which shows Example 2 by this invention. It is a schematic diagram which shows the cross-sectional structure | tissue of a carbon base material. It is a schematic diagram which shows the cross-sectional structure | tissue of the carbon base material which formed the oxide film in the inner wall surface of a pore. It is a schematic diagram of the cross-sectional structure | tissue in the surface vicinity of the metal impregnation sliding member which formed the oxide which shows Example 3 by this invention. It is the schematic of the abrasion testing machine used by the comparative test. It is a schematic diagram of the cross-sectional structure | tissue of the sliding member by this invention. It is a perspective view which shows the example which applied the sliding member by this invention to the bearing bush. It is a perspective view which shows the example which used the sliding member by this invention for the sliding guide mechanism for positioning.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Carbon base material, 2 ... Metal, 3 ... Carbide or oxide, 4 ... Sliding member, 6 ... Base material surface, 7 ... Pore, 31 ... Chromium carbide, 33 ... Yttria.

Claims (16)

  A sliding member including a carbon base material and a metal, and including a carbide or an oxide, wherein the metal is dispersed in an island shape on the friction surface, and the periphery of the metal is surrounded by the carbide or the oxide A sliding member characterized by comprising:   The surface layer portion including the friction surface has a three-dimensional network structure, includes a metal skeleton connected to each other, the surface of the metal skeleton is covered with carbide or oxide, and other portions are formed of carbon. The sliding member according to claim 1.   The carbon base material is composed of a carbon fired material, a surface layer portion including a friction surface is impregnated with the metal in pores of the carbon fired material, and a carbide layer or a boundary portion between the carbon fired material and the metal. The sliding member according to claim 1, wherein an oxide layer is formed.   The sliding member according to claim 1, wherein the amount of crystalline graphite of the carbon base material is 10 to 100% in terms of an integrated intensity ratio by X-ray diffraction. The sliding member according to claim 4, wherein an apparent density of the carbon fired material is 1600 to 1850 kg / m ³ .   The sliding member according to claim 1, wherein the metal includes at least one of Al, Zn, Cu, Ag, Au, and Sn.   The sliding member according to claim 6, wherein the carbide layer is a compound of a component of the metal impregnated in pores of the carbon base material and carbon of the carbon base material.   The sliding member according to claim 6, wherein the metal includes Cr or Ti.   The sliding member according to claim 8, wherein the metal contains Cu as a main component and Cr or Ti in an amount of 0.2 wt% or more.   A bearing using the sliding member according to claim 1.   A sliding part for a pump, wherein the sliding member according to claim 1 is used.   A sliding part for a compressor, wherein the sliding member according to claim 1 is used.   A sliding part for a conveying device, wherein the sliding member according to claim 1 is used.   A sliding component for a positioning device, wherein the sliding member according to claim 1 is used.   A method of manufacturing a sliding member containing a carbon base material and a metal, and containing carbide or oxide, wherein the oxide is formed on the inner wall surface of the pores of the carbon base material, and then the pores of the carbon base material And a step of impregnating the metal.   The step of impregnating the pores of the carbon base material with the metal is performed by evacuating the carbon base material and then immersing the carbon base material in a molten metal and pressurizing the carbon base material. Manufacturing method of sliding member.

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