JPH04310568A - Carbon fiber reinforced carbon composite material having high coefficient of friction - Google Patents

Abstract

PURPOSE:To provide a carbon fiber reinforced carbon composite material having a high coefficient of friction. CONSTITUTION:This carbon fiber reinforced carbon composite material consists of a base composed of carbon fiber reinforced carbon and 3-20wt.% oxide-based ceramics powder and/or fiber having >=1,600 deg.C melting point, hardly being reacted with carbon of the base and embedded in the base. This carbon composite material has a high coefficient of friction of about 0.29-0.47 in a dry state. MgO, TiO2, Bad, Cab, Al2O3, ZrO2, BeO or SiO2 may be used as oxide-based ceramics. When an average thermal expansion coefficient alpha1 of a base constituting the carbon composite material at 20-1,000 deg.C and an average thermal expansion coefficient alpha2 of oxide-based ceramics at 20-1,000 deg.C have a correlation shown by the formula -2X10<-6>/ deg.C<=alpha1-alpha2<=3.5X10<-6>/ deg.C, this carbon composite material has a high coefficient of friction and excellent wear resistance.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention has a high coefficient of friction, excellent heat resistance and oxidation resistance, and is suitable for use in brake shoes, brake linings, brake pads, bushes, and washers for aircraft and race vehicles. The present invention relates to a carbon fiber-reinforced carbon composite material suitable for use in friction drive rotors, sleeves, etc.

The carbon composite material of the present invention can be applied as a sliding member to both dry friction members and wet friction members. Specifically, it can be used for brake materials and mechanical structures for friction drives, which require a high friction coefficient under sliding conditions and excellent seizure resistance.

0003

2. Description of the Related Art Carbon composite materials used as brake materials for aircraft, race vehicles, etc. are particularly required to have heat resistance and wear resistance. On the other hand, since the sliding parts of mechanical structures have low seizure resistance, they are usually used under oil lubrication. As sliding members used under dry conditions, oil-impregnated sintered materials, copper-based sintered alloys, and carbon materials are known. The carbon material used is one obtained by baking carbonaceous powder and pitch powder, or one obtained by graphitizing by sintering at high temperature.

[0004] In recent years, carbon fiber-reinforced carbon materials have been provided as materials with improved strength of carbon materials used for such purposes. This carbon fiber-reinforced carbon material is made of, for example, carbon fibers as a reinforcing material that have been carbonized or graphitized and subjected to surface treatment such as oxidation treatment.
It is produced by impregnating a liquid carbonaceous material as a binder such as silica, pitch, or thermosetting resin, firing it in an inert atmosphere, and graphitizing it if necessary.
206351).

Furthermore, for the purpose of increasing the friction coefficient of carbon fiber-reinforced carbon materials, carbon fiber-reinforced carbon composite materials have been reported in which carbon fiber-reinforced carbon materials are blended with metal or carbide ceramic powder (Japanese Unexamined Patent Application Publication No. 63 -13926, Japanese Unexamined Patent Publication No. 63-60173).

[0006]

Conventional carbon fiber-reinforced carbon materials have the disadvantage of having a low coefficient of friction μ, especially under low loads. Also, JP-A-63-13926
The carbon fiber-reinforced carbon composite material containing metal and carbide ceramic described in Japanese Unexamined Patent Publication No. 63-60173 has a higher coefficient of friction than the carbon fiber-reinforced carbon material. However, depending on the application, carbon fiber-reinforced carbon composite materials with even higher coefficients of friction are required.

The present invention has been made in view of these problems, and an object thereof is to provide a carbon fiber-reinforced carbon composite material having a high coefficient of friction. Furthermore, it is an object of the present invention to provide a carbon fiber-reinforced carbon composite material that has a high coefficient of friction and excellent wear resistance.

[0008]

[Means for Solving the Problems] The carbon fiber-reinforced carbon composite material of the present invention has a base material made of carbon fiber-reinforced carbon, and has a melting point of 1600° C. or more in the base material. It is characterized by embedding 3 to 20% by weight of oxide-based ceramic powder and/or fibers that are difficult to react.

[0009] The present inventor prepared various carbon fiber-reinforced carbon composite materials by blending various ceramics with carbon fiber-reinforced carbon materials, and determined the density, strength, and friction coefficient under dry and wet conditions of the resulting composite materials. and the amount of wear have been investigated in detail. When oxides are used as ceramics, only extremely brittle composite materials are obtained in most cases, but oxide-based ceramics with specific physical properties have a high coefficient of friction and excellent mechanical properties as structural materials. It turned out to be true.

[0010] Therefore, the inventors of the present invention filed patent applications for some of their findings in Japanese Patent Application No. 1-341883 and Japanese Patent Application No. 2-163388. These patented inventions are mainly characterized by a base material made of carbon fiber-reinforced carbon material, in which carbonaceous powder with self-sintering properties and uncarbonized carbon fibers that have not yet been completely carbonized are integrally sintered. It is a solid sintered body and has particularly excellent wear resistance. A carbon fiber-reinforced carbon composite material made of this sintered body as a base material and mixed with various ceramics has excellent wear resistance and, by selecting the ceramic, can obtain a desired coefficient of friction.

[0011] The present inventor further expanded the range of carbon fiber-reinforced carbon materials that serve as base materials, and as a result of research on combining a wide range of oxide ceramics, the inventor found that the material has a high coefficient of friction and can be used as a structural material. The present invention was completed by discovering a new carbon fiber-reinforced carbon composite material with mechanical strength. The carbon fiber-reinforced carbon composite material of the present invention comprises a base material made of carbon fiber-reinforced carbon, and oxide ceramic powder and/or fibers that have a melting point of 1600° C. or more and are difficult to react with the carbon of the base material. 20% by weight.

[0012] The base material is composed of carbon fibers and matrix carbon. As the carbon fiber, carbon fiber spun using PAN (polyacrylonitrile), coal, or petroleum pitch as a raw material and carbonized can be used. A preferred carbon fiber is a pitch-based optically isotropic carbon fiber. This optically isotropic carbon fiber has no anisotropy in thermal expansion coefficient depending on the fiber direction, and has an average thermal expansion coefficient of 2 to 4 x 10-6/°C in the range of 20 to 1000°C. Further, PAN-based and pitch-based carbon fibers having high strength, high rigidity, and optical anisotropy are known. This carbon fiber has a negative thermal expansion coefficient in the fiber direction from room temperature to about 400°C, and a thermal expansion coefficient of 0 to 2 x 10-6 from 400 to 1000°C.
/°C, and the coefficient of thermal expansion in the longitudinal direction of the fiber is different from that in the direction perpendicular thereto. This fiber can also be fully utilized depending on the purpose.

[0013] The fiber length of these carbon fibers is not limited to short fibers or long fibers. However, in the case of short fibers, 0.01~
A 50mm one can be used. In particular, 0.0
A diameter of 3 to 10 mm is preferred from the viewpoint of ease of mixing and aspect ratio. If the length is too long, the fibers will become entangled with each other and the dispersibility will decrease, resulting in poor anisotropy of the product properties.
．． If it is shorter than 0.1 mm, the strength of the product will drop rapidly, which is not preferable. Further, the fiber diameter is preferably about 5 to 25 μm. Furthermore, these fibers can also be used as nonwoven fabrics or coated fabrics.

[0014] It is preferable that the carbon fiber is further surface-treated with a material containing a caking component such as tar, pitch, or organic polymer to improve its compatibility with the binder. This surface treatment can be carried out by adding about 100 to 1000 parts by weight of a material containing a viscous component to 100 parts by weight of carbon fibers, stirring the mixture, washing with an organic solvent, and drying. The carbon fibers are subjected to a dispersion treatment if necessary. That is, since the dried fibers may be lumped or aggregated, in such a case, dispersion is carried out by any means such as a conventional powder mill, an atomizer, or a pulverizer.

Matrix carbon includes carbonized resins such as phenol resins, coal or petroleum pitch heated and further carbonized, crushed coke, self-sintering powders such as mesocarbon microbeads, CV
Carbon etc. obtained by a vapor phase method using D can be used. The oxide ceramic needs to have a high melting point of 1600° C. or higher and be difficult to react with carbon during composite material production. As such oxide ceramic, MgO
, TiO2, BaO, CaO, Al2O3, Zr
There are O2, BeO, SiO2, etc. As will be explained later, in addition to the above-mentioned high melting point and difficulty in reacting with carbon, oxide ceramics also have a low coefficient of thermal expansion (α
) is preferable. Mullite (3Al2O3 ・2SiO2, α2
;4.5~5.7×10-6/℃), alumina (Al
2 O3, α2; 7.2-9.0×10-6/℃)
, rutile (TiO2, α2; 6.8-8.3×10
-6/℃), zirconia (ZrO2, α2; 10.
4×10-6/℃), beryllia (BeO, α; 7.5~
9.0×10-6/°C) is recommended. In addition, magnesia (MgO, α; 13.0 to 13.5×
10-6/°C) has the effect of increasing the coefficient of friction, but since the coefficient of thermal expansion is large, the strength of the material decreases when it is made into a composite material. For this reason, it is not preferable to mix a large amount.

From many test results, the present inventor found that the closer the thermal expansion coefficient of the base material constituting the carbon fiber-reinforced carbon composite material and the thermal expansion coefficient of the oxide ceramic, the better the material of the carbon fiber-reinforced carbon composite material. It is known that mechanical properties such as strength are improved. In the temperature range of 20 to 1000°C in which the carbon fiber-reinforced carbon composite material of the present invention is expected to be used, the average coefficient of thermal expansion of the carbon fiber-reinforced carbon material constituting the base material is relatively low; Ceramics have a high average coefficient of thermal expansion.

[0017] Therefore, it is preferable that the base material has a coefficient of thermal expansion as high as possible within a range where a decrease in strength is acceptable. Note that the thermal expansion coefficient of the carbon fiber-reinforced carbon material constituting the base material can be arbitrarily adjusted to some extent by selecting the matrix carbon raw material and the type of carbon fiber to be used, or by changing the manufacturing method. It is preferable to select an oxide ceramic having a small coefficient of thermal expansion. When it is necessary to select a ceramic with a high coefficient of thermal expansion depending on the application, methods such as reducing the blending amount or mixing it with other ceramics with a low coefficient of thermal expansion can be adopted.

It is preferable that the average thermal expansion coefficient α1 of the base material of the carbon fiber-reinforced carbon composite material of the present invention at 20 to 1000°C and the average thermal expansion coefficient α2 of the ceramic at 20 to 1000°C have the following relationship. −2×10−6/℃≦α1 −α2 ≦3.5×10−
6/°C (α1 - α2) is smaller than -2, that is, when the average coefficient of thermal expansion α1 of the base material is 2 × 10-6/°C smaller than the average coefficient of thermal expansion α2 of the ceramics, the boundary between the base material and the ceramics A gap that cannot be ignored occurs in the part,
Wear resistance decreases. Also, the same thing is (α1 − α
2) is larger than +3.5, that is, the average coefficient of thermal expansion α1 of the base material is the average coefficient of thermal expansion α2 of the ceramics.
If the temperature is 3.5×10 −6 /° C., non-negligible distortion will occur at the boundary between the base material and the ceramic, resulting in lower wear resistance. The reason why (α1 - α2) differs between the plus side and the minus side is that the relationship between the boundary between the base material of the carbon fiber reinforced carbon composite material and the ceramics is determined by the firing temperature.
We believe that this is because when the temperature drops from the firing temperature to room temperature, the relationship between the boundary between the base material and the ceramic changes due to thermal contraction due to the temperature change. (α1 −α2
) is negative, that is, if the coefficient of thermal expansion of the ceramic is large, the ceramic will shrink significantly when the temperature drops to room temperature, creating a gap at the boundary between the base material and the ceramic. On the other hand, if (α1 - α2) is positive, that is, the coefficient of thermal expansion of the ceramic is small, the base material will shrink significantly when the temperature drops to room temperature, and the base material will strongly trap the ceramic and create a gap based on the same principle as shrink fitting. do not. Note that if (α1 − α2 ) is too large, the base material will not be able to absorb the strain caused by the difference in thermal expansion, and the base material will be destroyed, resulting in a significant decrease in wear resistance.

For reference, the difference in thermal expansion coefficient (α1 - α
2) Several types of carbon fiber-reinforced carbon composite materials were made with different values, and a diagram showing the relationship between the difference in thermal expansion coefficient (α1 - α2) and specific wear amount is shown in FIG. In addition, in FIG. 1, the difference in thermal expansion coefficients (α1 − α2) is shown as an absolute value. From FIG. 1, it can be seen that the closer (α1-α2) is to zero (0), the lower the specific wear amount is.

[0020] The carbon fiber reinforced carbon composite material of the present invention
The proportion of the oxide ceramic powder and/or fiber is preferably 3 to 20%, when 0% by weight (hereinafter, % indicates weight% unless otherwise specified). 3
If it is less than 20%, it is not sufficient to improve the friction coefficient;
If it exceeds this value, the strength of the material will decrease significantly. Further, the content of carbon fiber is preferably 40% or less. If it exceeds 40%, the material strength will drop significantly.

[0021] The carbon fiber reinforced carbon composite material of the present invention preferably has an apparent density of 1.7 g/cm3 or more. The higher the apparent density, the better the mechanical properties such as material strength and wear resistance. The shape of the carbon fiber reinforced carbon composite material of the present invention is not particularly limited.
Kill lining, brake pad, bush, washer,
It can be made into a predetermined shape such as a rotor or a sleeve.

The carbon fiber-reinforced carbon composite material of the present invention can be produced by a known method. When using self-sintering carbon powder as the matrix carbon, it can be manufactured by a simple process of dry mixing, dry molding, and firing, as shown in FIG. 2, for example. In order to make the carbon powder, ceramic powder, and fiber isotropic in strength and wear resistance, it is preferable to uniformly mix the above-mentioned raw materials.

[0023] Molding can be carried out by a conventional method, and the molding may be carried out into a predetermined shape under pressure of about 1 to 10 ton/cm2. Alternatively, the molding may be performed by a CIP method, a HIP method, a hot press method, or the like. The molding is
This can be carried out at room temperature or under heating up to about 500° C. in an inert atmosphere. In the firing, carbon fibers and self-sintering carbonaceous powder are carbonized and solidified by heating to about 700 to 1500°C. Note that, if necessary, this carbonized composite may be heated to a temperature higher than the sintering temperature in a graphitization furnace to graphitize it.

[0024] When a liquid or a raw material that can be liquefied by heating is used as the matrix carbon, the oxide ceramic is mixed with the matrix carbon raw material. The carbon fibers may be mixed with the matrix carbon raw material as in the conventional method, or the matrix carbon raw material may be attached to a preformed body made of carbon fibers. To obtain a composite, the obtained molded body is heated to promote carbonization of the matrix carbon raw material, and the whole is integrated. The carbonization conditions are not particularly limited, but usually the temperature is raised from room temperature to about 1500°C at a rate of about 0.1 to 300°C/hour in a non-oxidizing atmosphere, and held for about 0.5 to 10 hours. Just go. Note that during sintering, if the composite is sintered at a higher temperature, a portion of the composite will be carbonized and then graphitized.

[0025] Furthermore, the conditions for graphitization are not particularly limited;
0.1 to 500℃ from the temperature during sintering in a non-oxidizing atmosphere
The temperature may be raised to a temperature of about 1500 to 3000° C. at a rate of about 100° C./hour and maintained for about 0.5 to 10 hours. When graphitization is performed, graphite crystals grow sufficiently and are oriented in an orderly manner, thereby further improving the density, strength, wear resistance, etc. of the product.

[0026]

[Examples] Examples of the present invention will be described below. (Example 1) As the carbon fiber, a pitch-based carbon fiber (optically isotropic fiber, Donna Carbo S210 manufactured by Donac) with a length of 20 mm was used. A phenol resin was used as a matrix carbon raw material and was dispersed in alcohol. Mullite (3Al2O3.2SiO2, α2;4.
8×10-6/℃), alumina with an average particle size of 0.5 μm (
Al2O3, α2; 7.2×10-6/℃) and magnesia (MgO, α2; with an average particle size of 0.6 μm).
Three types of formulations were obtained, each containing 50 g of one of the following: These were individually and uniformly stirred, and then 300 g of the carbon fibers were added to each mixture and further stirred for 30 minutes. These mixtures were individually put into molds, alcohol was dripped from the bottom, and the molds were dried at 80° C. for 10 hours. Thereafter, it was cured at 180°C.

[0027] Each solidified molded body was taken out from the mold and heated to a maximum of 1700°C in an argon atmosphere to carbonize and graphitize the phenol. Thereafter, densification was further performed by CVD to obtain a carbon fiber-reinforced carbon composite material of the present invention. Note that in CVD, the graphitized material obtained in a high-frequency induction heating furnace is heated to 600°C, dichloroethylene is introduced into the furnace,
It is densified by thermal decomposition.

The proportions of mullite, alumina and magnesia in these carbon fiber-reinforced carbon composite materials are each 5.
1%, 5.6% and 5.3%, and their apparent densities were all 1.7 g/cm3. Also, mullite,
The average thermal expansion coefficients of carbon fiber-reinforced carbon composite materials containing alumina and magnesia at 20 to 1000°C are 5.4 x 10-6/°C and 5.7 x 10-6/°C, respectively.
℃ and 6.2 x 10-6/℃.

The base material constituting the carbon fiber-reinforced carbon composite material of this example can be considered to be the same as the carbon fiber-reinforced carbon material of Comparative Example 1, which will be explained later. Therefore,
As can be seen from Comparative Example 1, the average coefficient of thermal expansion α1 of this base material from 20 to 1000°C is 5.5×10 −6 /°C. Calculating (α1 - α2) from the average coefficient of thermal expansion α1 of this base material and the average coefficient of thermal expansion α2 of the ceramics, we get:
(α1 −α2) of the carbon fiber reinforced carbon composite material of this example containing mullite, alumina, and magnesia
) are +0.7×10-6/℃ and −1.7×1, respectively.
0-6/℃ and -7.5×10-6/℃. (Example 2) As the carbon fiber, pitch-based carbon fiber with the same length of 20 mm as used in Example 1 was used, and this was ground into milled powder (fiber length: 0.5 mm). . Coal tar-based mesocarbon microbeads (manufactured by Osaka Gas) with an average particle size of 7 μm were used as the matrix carbon raw material. Furthermore, the same three types of oxide powders as used in Example 1 were used as oxide ceramics. Then, carbon fibers, mesocarbon microbeads, and oxide powder were blended in a weight ratio of 25:75:5 to obtain three types of blends. These three types of formulations were mixed individually in a Raikai machine, and then mixed in a universal press at room temperature.
Molding was carried out at a molding pressure of ton/cm2. Thereafter, these molded bodies were heated to 1000°C at a heating rate of 150°C/hour in a non-oxidizing atmosphere at normal pressure, held at the same temperature for 1 hour, and then heated at a heating rate of 500°C/hour in a non-oxidizing atmosphere. de1
It was heated to 700°C and sintered. As a result, three types of carbon fiber-reinforced carbon composite materials of the present invention were obtained.

The proportions and apparent densities of mullite, alumina, and magnesia in these carbon fiber-reinforced carbon composite materials are 6.1%, 1.75 g/cm3, and 6.2, respectively.
% and 1.86g/cm3 and 6.1% and 1.71g
/cm3. Furthermore, the average coefficient of thermal expansion between 20 and 1000°C of carbon fiber-reinforced carbon composite materials containing mullite, alumina, and magnesia is 7.
2×10-6/℃, 7.0×10-6/℃ and 8.3
×10-6/°C.

A carbon fiber-reinforced carbon material containing no oxide powder was prepared using the same method as in this example except that it did not contain any oxide powder. It was used as a base material for forming a carbon fiber-reinforced carbon composite material. Then, the average coefficient of thermal expansion α1 of this base material at 20 to 1000°C was determined. The average coefficient of thermal expansion α1 of the base material from 20 to 1000°C was 7.3×10 −6 /°C. Calculating (α1 − α2 ) from the average coefficient of thermal expansion α1 of this base material and the average coefficient of thermal expansion α2 of ceramics, it is found that (α1 − α2 ) of the carbon fiber-reinforced carbon composite material of this example containing mullite, alumina, and magnesia, respectively. ) are +2.5×10-6/℃ and +0.1×10-6/℃, respectively.
℃ and -5.7 x 10-6/℃. (Example 3) Pitch-based carbon fiber consisting of 3000 filaments was used as the carbon fiber. As the matrix carbon raw material, an equal weight mixture of pulverized pitch and pulverized coke with a softening point of 280° C. was used. The same three types of oxide ceramics used in Example 1, mullite, alumina, and magnesia, were used.

First, a pitch-pulverized product, a coke-pulverized product, and one type of oxide ceramic were each weighed at 1;
They were blended at a ratio of 1:0.5 and thoroughly mixed to obtain three types of mixed powders. Next, one type of the mixed powder was attached to the surface of each filament of the carbon fiber using a particle attachment device. The surface of each fiber to which these mixed powders are attached is coated with a film thickness of 1
Cover with 0 μm polyethylene and wind up on a bobbin.
We made various intermediates. Each of these three types of intermediates is arranged in one direction in a mold to form a plate-shaped aggregate, and the molding pressure is 5
00 kg/cm2 and sintered by hot pressing at 600°C for 30 minutes, and further heated to 1700°C to graphitize to obtain three types of carbon fiber-reinforced carbon composite materials of this example.

The proportions and apparent densities of mullite, alumina, and magnesia in these carbon fiber-reinforced carbon composite materials are 1.0% and 1.75 g/cm3, 8% and 1.75 g/cm3, and 10% and 1.76 g, respectively. /cm
It was 3. In addition, two types of carbon fiber-reinforced carbon composite materials containing mullite, alumina, and magnesia are also available.
The average coefficient of thermal expansion from 0 to 1000℃ is 5.6 x 1, respectively.
0-6/℃, 5.9×10-6/℃ and 6.1×10
-6/℃.

[0034] A carbon fiber-reinforced carbon material containing no oxide powder was prepared using the same method as in this example except that it did not contain any oxide powder. It was used as a base material for forming a carbon fiber-reinforced carbon composite material. Then, the average coefficient of thermal expansion α1 of this base material at 20 to 1000°C was determined. The average coefficient of thermal expansion α1 of the base material from 20 to 1000°C was 5.6 x 10-6/°C. Calculating (α1 − α2 ) from the average coefficient of thermal expansion α1 of this base material and the average coefficient of thermal expansion α2 of ceramics, it is found that (α1 − α2 ) of the carbon fiber-reinforced carbon composite material of this example containing mullite, alumina, and magnesia, respectively. ) are +0.8×10-6/℃ and −1.6×10-6/, respectively.
℃ and -7.4 x 10-6/℃. (Example 4) A plain-woven cloth made of 1000 filaments of PAN-based carbon fibers was used as the carbon fiber. The self-sintering carbon powder used in Example 2 was used as the matrix carbon raw material. The same three types of oxide ceramics used in Example 1, mullite, alumina, and magnesia, were used.

First, carbon powder and one type of oxide ceramic were mixed at a ratio of 4:1 in terms of weight, and thoroughly mixed to obtain three types of mixed powder. Next, one type of the mixed powder was kneaded and adhered to the surface of each of the carbon fiber cloths to obtain prepregs, thereby producing three types of intermediates. Each of these three types of intermediates was put into a mold and sintered by hot pressing at 200°C for 10 minutes at a molding pressure of 200 kg/cm2, and then heated to 1700°C at a pressure of 500 kg/cm2 to form graphite. The amounts of three types of carbon fiber-reinforced carbon composite materials of this example were obtained.

The proportions and apparent densities of mullite, alumina and magnesia in these carbon fiber reinforced carbon composite materials are 8% and 1.70g/cm3, and 7% and 1.70g/cm3, respectively.
They were 72g/cm3 and 8% and 1.72g/cm3. In addition, carbon fiber-reinforced carbon composites containing mullite, alumina, and magnesia have a
The average coefficient of thermal expansion at 00℃ is 4.2×10-6/
℃, 4.3 x 10-6/℃ and 4.5 x 10-6/℃
Met.

A carbon fiber-reinforced carbon material containing no oxide powder was prepared using the same method as in this example except that it did not contain any oxide powder. It was used as a base material for forming a carbon fiber-reinforced carbon composite material. Then, the average coefficient of thermal expansion α1 of this base material at 20 to 1000°C was determined. The average coefficient of thermal expansion α1 of the base material from 20 to 1000°C was 4.0×10 −6 /°C. Calculating (α1 − α2 ) from the average coefficient of thermal expansion α1 of this base material and the average coefficient of thermal expansion α2 of ceramics, it is found that (α1 − α2 ) of the carbon fiber-reinforced carbon composite material of this example containing mullite, alumina, and magnesia, respectively. ) are -0.8 x 10-6/℃ and -3.2 x 10-6/℃, respectively.
℃ and -9.0×10-6/℃. (Comparative Example 1) A carbon fiber-reinforced carbon material containing no ceramics was produced in the same manner as in Example 1 except that the oxide ceramics were not used. The apparent density of this comparative example 1 is 1.69 g/cm3
Met. Further, the average coefficient of thermal expansion from 20 to 1000°C was 5.5 x 10-6/°C. (Comparative Example 2) In Example 1, silicon carbide (SiC) with an average particle size of 3 μm was used instead of the oxide ceramics,
A carbon fiber-reinforced carbon composite material containing silicon carbide was produced in the same manner as in Example 1 in other respects. The proportion and apparent density of silicon carbide in Comparative Example 2 are 5.3% and 1.7%.
It was 0g/cm3. Further, the average coefficient of thermal expansion from 20 to 1000°C was 5.3 x 10-6/°C. (Comparative Example 3) In Example 2, silicon carbide (SiC) with an average particle size of 3 μm was used instead of the oxide ceramics,
A carbon fiber-reinforced carbon composite material containing silicon carbide was produced in the same manner as in Example 2 in all other respects. The proportion and apparent density of silicon carbide in Comparative Example 3 are 6.3% and 1.7%.
It was 3g/cm3. Further, the average coefficient of thermal expansion from 20 to 1000°C was 7.2 x 10-6/°C. (Comparative Example 4) In Example 3, silicon carbide (SiC) with an average particle size of 3 μm was used instead of the oxide ceramics,
A carbon fiber-reinforced carbon composite material containing silicon carbide was produced in the same manner as in Example 3 in all other respects. The proportion and apparent density of silicon carbide in Comparative Example 4 are 11% and 1.75.
g/cm3. Further, the average coefficient of thermal expansion from 20 to 1000°C was 5.2 x 10-6/°C. (Evaluation 1) Measure the friction coefficient without lubrication for the amount of carbon fiber-reinforced carbon composite material and carbon fiber-reinforced carbon material of Examples 1 to 4, each consisting of three types, and Comparative Examples 1 to 4, each consisting of one type. did. This measurement was carried out using a mechanical testing laboratory type friction and wear tester at a rotational speed of 160 rpm (sliding speed: 2 cm/sec), increasing the load from a load of 50 kgf by 10 kgf every 2 minutes, and measuring the friction coefficient μ up to 50 kgf. . Note that high carbon chromium bearing steel (JIS SUJ2, hereinafter referred to as SUJ2) was used as the mating material. The results are shown in FIG.

As is clear from FIG. 3, the carbon fiber-reinforced carbon composite materials blended with the oxide ceramics of Examples 1 to 4 of the present invention all have high friction coefficients of about 0.28 to 0.47. have On the other hand, the friction coefficients of the carbon fiber-reinforced carbon composite materials blended with silicon carbide (SiC) as ceramics in Comparative Examples 1 to 3 were relatively low at about 0.2 to 0.29. However, as seen in Comparative Example 4, the friction coefficient of the amount of carbon fiber-reinforced carbon material that does not contain ceramics is 0.14 to 0.
．． It was even lower at 19.

From these results, it can be seen that the carbon fiber-reinforced carbon composite material of the present invention containing oxide ceramics has a high coefficient of friction. Note that among oxide ceramics, magnesia has a slightly higher coefficient of friction than other mullite and alumina. (Evaluation 2) Regarding the carbon fiber-reinforced carbon composite materials and carbon fiber-reinforced carbon materials of Examples 1 to 4 each consisting of three types and Comparative Examples 1 to 4 each of one type, the friction coefficient under wet conditions (oil lubrication) and the amount of wear was measured. This measurement was performed using an LFW friction and wear tester at a load of 15 kgf.
The test was conducted for 15 minutes at a rotation speed of 160 rpm. A SUJ2 ring was used as the mating material, and a 10.0 mm x 15.7 mm flat plate was used as the test piece. The friction coefficients of some of the results are shown in FIG. 4, and the amount of wear is shown in Table 1. For reference, the difference (α1 - α2) in average coefficient of thermal expansion between 20 and 1000°C between the base material and the oxide ceramic of each example is also shown.

As is clear from FIG. 4, among the carbon fiber-reinforced carbon composite materials blended with the oxide ceramics of Examples 1 to 4 of the present invention, those containing mullite and alumina have a friction coefficient of 0. It was relatively high at 16-0.18. However, in contrast to the dry process, those containing magnesia have a lower 0.1 than those containing mullite and alumina.
The coefficient of friction was between 3 and 0.16.

[0041] The comparative example containing silicon carbide has a slightly higher resistance value of 0.12 to 0.12 than that containing no ceramics.
The friction coefficient was 0.14. On the other hand, the friction coefficient of carbon fiber-reinforced carbon material without ceramics is 0.11.
It was ~0.14. These results show that the carbon fiber-reinforced carbon composite material of the present invention containing oxide ceramics has a relatively high coefficient of friction even under oil lubrication. Note that among oxide ceramics, magnesia has a slightly lower coefficient of friction than other mullite and alumina.

[0042]

[Table 1] Difference between wear amount and average coefficient of thermal expansion shown in Table 1 (α1 −
As is clear from the comparison with
．． It can be seen that the wear amount of the carbon fiber-reinforced carbon composite material in the range smaller than 5 is equivalent to or better than that of the carbon fiber-reinforced carbon material shown in the comparative example that does not contain oxide ceramics. In contrast, the carbon fiber-reinforced carbon composite materials blended with alumina of Examples 1 and 4 and the carbon fiber-reinforced carbon composite blended with magnesia have a difference in average coefficient of thermal expansion (α1 −α2) far smaller than −2. The material has a very high wear rate.

[0043]

[Effect] A carbon fiber-reinforced carbon composite material containing the oxide ceramics of the present invention has a higher coefficient of friction than a carbon fiber-reinforced carbon material containing no ceramics and a carbon fiber-reinforced carbon composite material containing silicon carbide. In addition, a material with a small difference between the coefficient of thermal expansion of the base material serving as a matrix and the coefficient of thermal expansion of the oxide ceramic has a small amount of wear. Therefore, the carbon fiber-reinforced carbon composite material of the present invention can be used in brake shoes, brake linings, brake pads, bushes, washers, friction drive rotors, sleeves, etc. for aircraft and race vehicles. Available for

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the difference in average coefficient of thermal expansion between a base material and ceramics constituting a carbon fiber-reinforced carbon composite material and specific wear amount.

FIG. 2 is a block diagram showing one method for manufacturing the carbon fiber-reinforced carbon composite material of the present invention.

FIG. 3 is a diagram showing the friction coefficient under dry friction of carbon fiber-reinforced carbon composite materials obtained in Examples and Comparative Examples.

FIG. 4 is a diagram showing the friction coefficient under wet friction of carbon fiber-reinforced carbon composite materials obtained in Examples and Comparative Examples.

Claims (4)

[Claims] [Claim 1] The base material is composed of carbon fiber reinforced carbon,
A high friction coefficient characterized by having 3 to 20% by weight of oxide-based ceramic powder and/or fibers having a melting point of 1600°C or higher and not easily reacting with the carbon of the base material embedded in the base material. Carbon fiber reinforced carbon composite material. 2. The carbon fiber reinforced carbon composite material according to claim 1, wherein the carbon fiber content is 40% by weight or less. 3. The carbon fiber reinforced carbon composite material according to claim 1, which has an apparent density of 1.7 g/cm 3 or more. 4. Between the average coefficient of thermal expansion α1 of the base material at 20 to 1000°C and the average coefficient of thermal expansion α2 of the oxide ceramic at 20 to 1000°C, -2×10-6/°C≦α1-α2. ≦3.5×10−
The carbon fiber reinforced carbon composite material according to claim 1, which has a relationship of 6/°C.