JP2012046369A - Carbon fiber-reinforced carbon composite material and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a C/C composite whose coefficient of friction at a low temperature is high compared with a C/C composite and temperature dependence of coefficient of friction is controlled, and a method for manufacturing the same.SOLUTION: By using a thermal CVD method such as an alcoholic CVD method to form carbon nanotubes (CNT) on the surface of a C/C composite, the C/C composite whose coefficient of friction at a low temperature is raised and temperature dependence of a coefficient of friction is improved and which has friction characteristics excellent in a broad temperature range and is suitable as a constituent material for application with intense temperature change like brake materials of vehicles of automobile, motorcycles, etc. and aircrafts etc. can be provided.

Description

  The present invention relates to a carbon fiber reinforced carbon composite material (hereinafter also referred to as “C / C composite”) and a method for producing the same. More specifically, the friction coefficient is improved in a low temperature region such as room temperature. The present invention relates to a C / C composite obtained by improving the temperature dependency of and a manufacturing method thereof.

  C / C composite is a composite material using carbon fiber as a reinforcing material and carbon as a matrix. Generally, it has higher mechanical properties than carbon materials and is lighter than metal materials. There are many advantages over. Further, the C / C composite has advantages such as high heat resistance and good friction and wear characteristics. For this reason, C / C composites are widely used for nozzle cones for spacecrafts, leading edges, aircraft, automobiles, motorcycle brake disks, artificial tooth roots, and the like.

  As described above, the C / C composite has excellent mechanical properties, heat resistance, etc., but has a low coefficient of friction at low temperatures, and a coefficient of friction coefficient such that the coefficient of friction is about three times higher at high temperatures than at low temperatures. There is a problem of high dependency. Brake discs for aircraft, automobiles, and motorcycles are required to stably exhibit friction characteristics in a wide temperature range from room temperature to high temperature. Therefore, it has been desired to develop a C / C composite capable of suppressing temperature dependency and stably exhibiting excellent friction characteristics in a wide temperature range.

  2. Description of the Related Art Conventionally, a composite member in which carbon fibers such as carbon nanotubes (hereinafter sometimes abbreviated as “CNT”) are dispersed in a matrix in order to improve the friction characteristics of a C / C composite. Has proposed a carbon fiber-containing composite member in which the tip of the carbon fiber protrudes (see, for example, Patent Document 1). However, in the carbon fiber-containing composite member in which the CNT is dispersed in the matrix, the surface of the composite member is reduced in friction by causing the tip of the CNT dispersed in the matrix to protrude from the surface of the composite member. Thus, the object of the present invention is to completely increase the coefficient of friction of the C / C composite at a low temperature and suppress the temperature dependence of the coefficient of friction.

JP 2004-107534 A

  In view of the problem related to the friction coefficient in the conventional carbon fiber reinforced carbon composite material (C / C composite) as described above, the present invention has a higher friction coefficient at a lower temperature than that of a normal C / C composite. An object of the present invention is to provide a C / C composite in which the temperature dependency is suppressed and a method for producing the same.

  As a result of intensive studies to achieve the above object, the present inventors have generated carbon nanotubes (CNT) in the carbonized C / C composite, thereby increasing the coefficient of friction at low temperatures and increasing the coefficient of friction. The present inventors have found that a C / C composite with suppressed temperature dependence can be obtained and completed the present invention.

  That is, the carbon fiber reinforced carbon composite material (C / C composite) according to the present invention is characterized in that carbon nanotubes are formed on at least the surface of a carbon fiber reinforced carbon composite member as a base material.

In one embodiment of the C / C composite according to the present invention, the carbon nanotube has a diameter of 10 to 500 nm and a length of 0.5 to 10 μm. In another embodiment, the carbon nanotubes have a diameter of 50 to 350 nm and a length of 2.5 to 5.0 μm.
In one embodiment of the C / C composite according to the present invention, the production density of carbon nanotubes on the surface of the carbon fiber reinforced carbon composite member is 0.0030 mg / mm ² or more.
In one embodiment of the C / C composite according to the present invention, the friction coefficient at room temperature is 0.20 or more.
In one embodiment of the C / C composite according to the present invention, the fluctuation range of the friction coefficient from room temperature to 300 ° C. is 0.1 or less.

  Further, the method for producing a carbon fiber reinforced carbon composite material (C / C composite) according to the present invention comprises contacting the carbon fiber reinforced carbon composite member as a base material with a catalyst metal dispersion, and After the catalyst metal is supported on the carbon nanotube, carbon nanotubes are generated on at least the surface of the carbon fiber reinforced carbon composite member as a base material by supplying a hydrocarbon compound in a heating furnace and thermally decomposing it. And

In one embodiment of the method for producing a C / C composite according to the present invention, Co (II) acetate tetrahydrate and / or Mo (II) acetate is used as the catalyst metal.
In one embodiment of the method for producing a C / C composite according to the present invention, ethanol is used as a dispersion solvent for the catalyst metal dispersion.
In one embodiment of the method for producing a C / C composite according to the present invention, ethanol is used as the hydrocarbon compound.
In one Embodiment of the manufacturing method of the C / C composite based on this invention, what was produced by the resin impregnation method is used as a carbon fiber reinforced carbon composite member as said base material.

  The carbon fiber reinforced carbon composite material (C / C composite) according to the present invention as described above can be suitably used as a brake material.

  The C / C composite according to the present invention as described above has a carbon nanotube (CNT) generated at least on its surface, so that the friction coefficient at a low temperature is increased as compared with that before CNT generation, and the temperature dependence of the friction coefficient. And improved friction characteristics in a wide temperature range. Therefore, the C / C composite according to the present invention can be suitably used as a constituent material for applications where the temperature change is severe, such as brake materials for vehicles and aircraft.

  In the conventional C / C composite, the friction coefficient at room temperature was a low value of 0.15 or less. However, according to the present invention, by generating CNT, the friction coefficient of the C / C composite at room temperature can be reduced. It can be raised to 0.2 or more.

  According to the present invention, by generating CNTs, it is possible to provide a C / C composite in which the variation range of the friction coefficient at room temperature to 300 ° C. is 0.1 or less and the temperature dependence of the friction coefficient is suppressed. .

  In addition, as a method for supporting the catalyst metal, contact with a catalyst metal dispersion (catalyst in a liquid phase state), in particular, a dip coating method in which the catalyst metal is supported on the C / C composite by being immersed in the catalyst metal dispersion. Thus, it is expected that the catalyst is also supported inside the pores of the C / C composite serving as the base material, and the generation of CNT in the inside is expected. Thereby, the change of the friction characteristic by the surface abrasion of the carbon fiber reinforced carbon composite material obtained is suppressed, and the possibility of permanent use as a brake material or the like can be expected.

Schematic of the thermal CVD apparatus used for the production | generation of a carbon nanotube. Schematic of a friction tester. The SEM photograph of the carbon nanotube produced | generated on the C / C composite surface. The SEM photograph of the carbon nanotube of the C / C composite surface from which CNT production | generation time (CVD time) differs. The graph which shows the relationship between CVD time and a carbon nanotube production density. The graph which shows the relationship between a carbon nanotube production density and the friction coefficient in room temperature. The graph which shows the change of the friction coefficient by the temperature change of a C / C composite. Graph showing the ionic strength of the O ₂ and CO ₂ in the friction test at room temperature of C / C composite. It is a SEM photograph of the friction surface of the C / C composite after a friction test, the left side is an untreated material, and the right side is a CNT production | generation material.

  In the present invention, carbon nanotubes (CNT) are formed on at least the surface of a carbonized C / C composite member as a substrate, and the C / C composite itself used as the substrate is obtained by a known method. What is manufactured can be used.

  As a general method for producing a C / C composite, there are a resin impregnation method and a chemical vapor deposition method (CVD method). The resin impregnation method is a simple method that does not require large-scale equipment as compared with the CVD method. In the resin impregnation method, a carbon fiber preform impregnated with a thermosetting resin as a carbon precursor such as furan resin or phenol resin is molded and cured, and then carbonized in an inert atmosphere to obtain a C / C composite.

  The carbon fiber as the reinforcing material may be any of carbon fibers such as pitch, PAN, and rayon. Further, the diameter and elastic modulus of the carbon fiber may be in a range generally used as a composite material and are not particularly limited. Further, the form of the carbon fiber preform is not particularly limited, and a one-dimensional oriented preform formed by a filament wiping method, a two-dimensional oriented preform such as a plain weave, satin weave, a woven fabric, and a non-woven fabric, and a three-dimensional oriented preform. Either of these may be used. In the present invention, the “carbon fiber preform” refers to a sheet-like carbon fiber impregnated with a precursor resin (matrix resin) serving as a matrix, and the resin-impregnated carbon fiber. Can be formed by a filament wiping method, including both those formed into a sheet shape, and those obtained by impregnating a carbon fiber aggregate formed into a predetermined shape such as a sheet shape with a resin.

  There is also no particular limitation on the precursor resin (matrix resin) that becomes a C / C composite matrix that is impregnated into the carbon fiber, and there are known matrix resins such as phenol resins, furan resins, and petroleum-based and coal-based pitches. Either is acceptable. Among these resins, a phenol resin is preferable because it is inexpensive and has a high carbonization yield.

  Furthermore, when producing a C / C composite by a resin impregnation method, carbon powder may be added to a precursor resin (matrix resin) as a matrix to be impregnated into the carbon fiber preform. As the carbon powder, carbonized microfibrillated cellulose (hereinafter also referred to as “carbonized MFC”) can be used. As the carbonized MFC, carbonized MFC powder obtained by carbonizing MFC in an inert atmosphere is preferably used. The use of carbonized MFC powder is expected to improve the carbonization yield and the interfacial properties of the C / C composite due to the three-dimensional microstructure of the carbonized MFC powder. Mechanical strength such as bending strength and shear strength between layers Is thought to improve. In particular, by carbonizing lyophilized MFC in an inert atmosphere, carbon powder that maintains the three-dimensional structure of MFC can be obtained. Normally, MFC can maintain a three-dimensional network structure only when it contains moisture. If carbonized as it is, the moisture contained in MFC will dry and evaporate, and entanglement will occur due to self-condensation and network structure. End up. Therefore, as a pretreatment for carbonization, by removing the water adsorbed on the MFC by lyophilization and then carbonizing, the water harmful to the resin contained in the MFC is removed, and the microfibrillated cellulose Carbonization can be performed while maintaining the three-dimensional microstructure, dispersibility with respect to the precursor resin is improved, and an increase in resin viscosity can be suppressed. When carbonized without being lyophilized, the three-dimensional structure is not maintained, and there are cases where the intended effect of improving the bending strength or the like is not sufficiently exhibited.

  As an MFC carbonization method, MFC containing water is freeze-dried by using a freeze dryer, and the MFC after freeze-drying is calcined in an inert atmosphere at a high temperature, for example, 800 ° C. for about 3 to 5 hours. Thus, carbonized MFC powder is obtained.

  There is no particular limitation on the amount of carbonized MFC powder added to the precursor resin, but if the added amount is small, the effect may not be exhibited, but the addition of 1% by weight has the effect of improving the desired bending strength. Has been obtained.

  The impregnation method of the precursor resin into the carbon fiber as the reinforcing material, the resin adhesion amount, and the like may be known. The carbon fiber preform is prepared by forming a carbon fiber pre-impregnated one-dimensionally oriented preform, plain weave, satin weave, woven fabric, non-woven fabric, etc. Alternatively, resin impregnation may be performed after carbon fibers are formed into a carbon fiber composite having a predetermined shape as described above.

  A carbon fiber preform as a base material is obtained by impregnating the carbon fiber with the precursor resin. The carbon fiber preform is heat-pressed and then carbonized in an inert atmosphere. An improvement in the carbonization yield of the carbon precursor resin can be expected by molding the carbon fiber preform as a base material under high temperature and high pressure conditions of about 150 ° C. and about 15 MPa, for example.

  The carbon fiber preform formed as described above is heated to a maximum temperature, for example, 1000 ° C. in about 10 hours from room temperature in an inert atmosphere, and held for about 1 hour, whereby the precursor resin is carbonized. The intended C / C composite is obtained.

  In the present invention, by generating carbon nanotubes on at least the surface of the carbonized C / C composite produced by a known method as described above, the friction coefficient at low temperature of the resulting C / C composite is increased, Reduces temperature dependence of friction coefficient.

  The method for producing CNTs in the C / C composite as the base material is not particularly limited, and a normal chemical vapor deposition (CVD) method or a super-growth (SG) -CVD in which a small amount of water is added to the synthesis atmosphere of the conventional CVD method. For example, a general CVD method, particularly an alcohol CVD method is preferably used. The general CVD method is a method of thermally decomposing a catalyst metal and a hydrocarbon serving as a carbon source of CNT at 500 to 1,000 ° C. to obtain CNT. The alcohol CVD method is an alcohol as a hydrocarbon as a carbon source. CVD method using

  In the present invention, a C / C composite serving as a substrate is brought into contact with a liquid phase catalyst (catalyst metal dispersion). The method for bringing the C / C composite into contact with the catalyst metal dispersion is not particularly limited. Various methods such as immersing the C / C composite in the catalyst metal dispersion, spraying the catalyst metal dispersion onto the C / C composite, etc. There is. Among these, it is preferable to use a dip coating method in which the catalyst metal is supported on the C / C composite by being immersed in a catalyst metal dispersion. As a result, the catalyst metal is supported inside the pores of the C / C composite serving as the base material, and generation of carbon nanotubes inside the pores can be expected. The CNT-generated C / C composite material thus obtained maintains the high surface wear characteristics by exposing the CNTs generated inside the pores to the new surface after the wear even if the surface is worn. A decrease in the coefficient of friction due to wear can be suppressed.

  There is no particular limitation on the dispersion solvent of the catalyst metal dispersion used when the catalyst metal is supported on the C / C composite as the base material by dip coating or spraying, but it is a hydrocarbon that serves as a carbon source during CNT production. It is preferable to use hydrocarbons that are liquid at room temperature, such as lower alcohols such as ethanol, methanol, and propanol.

  Further, there is no particular limitation on the catalyst metal for CNT generation, and examples thereof include cobalt (Co), molybdenum (Mo), nickel (Ni), iron (Fe), palladium (Pd), and the like. It is not limited.

  An example of a method for supporting the catalytic metal by the dip coating method on the C / C composite as the base material is shown below.

(1) Catalyst supporting step A catalyst metal is dispersed in ethanol at a concentration of 0.01% by weight, for example, to prepare a catalyst metal dispersion. A C / C composite serving as a base material is immersed in this catalyst metal dispersion to coat the catalyst metal on the C / C composite, and then dried and oxidized in a heating apparatus such as an electric furnace. By repeating this dip coating step as necessary, a desired amount of catalyst metal can be supported on the C / C composite serving as the base material. When a plurality of different types of catalyst metals are used in combination, each catalyst metal is immersed in the catalyst metal dispersion, dried, and oxidized with the catalyst metal in the same manner as described above.

(2) CNT production process (thermal CVD method)
An outline of a thermal CVD apparatus used for producing CNTs is shown in FIG. This thermal CVD furnace includes a heater, a temperature controller, a sample holder (not shown), a transparent quartz tube, and a gas controller.
The C / C composite carrying the catalyst metal is placed in a thermal CVD furnace, degassed inside the furnace, filled with inert gas, and the exhaust valve is adjusted to reduce the pressure in the furnace, for example, 40 kPa (absolute pressure) The temperature is raised to the reaction temperature (for example, 900 ° C.) while maintaining the degree. Next, the inert gas in the furnace is discharged, and a carbon source gas such as ethanol gas is supplied. At this time, the furnace temperature is maintained at the reaction temperature (for example, 900 ° C.), and the furnace pressure is also maintained at a reduced pressure of, for example, about 5 kPa.
After a predetermined reaction time (CVD time) has elapsed, the supply of the carbon source gas is stopped and the gas in the furnace is discharged. Thereafter, the inert gas is again supplied into the furnace, and the furnace is cooled to room temperature. Even during this cooling, the pressure in the furnace maintains the reduced pressure during the reaction. In the present specification, the “room temperature” means a temperature of about 25 ° C.

  In the C / C composite material according to the present invention produced as described above, CNT is generated at least on the surface, the friction coefficient at low temperature is increased, and the temperature dependence of the friction coefficient is suppressed, Since the coefficient of friction is stabilized, it can be suitably used as a brake material for brake disks for aircraft, automobiles, motorcycles and the like.

  In addition, when producing CNTs on a C / C composite as a base material, a catalyst metal is supported on the C / C composite as a base material by a dip coating method using a catalyst in a liquid phase state, so that the pores of the base material If the catalyst metal is supported inside and CNTs can be generated to the inside of the pores, a decrease in coefficient of friction due to surface wear of the obtained CNT-generated C / C composite material is suppressed, and a permanent friction effect is also expected. it can.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

  According to the following procedure, a catalytic metal was supported on a C / C composite as a base material by a dip coating method using a liquid phase catalyst, and CNTs were generated by a thermal CVD method (hereinafter simply referred to as “thermal CVD treatment”). Say.).

<1. Catalyst support>
A C / C composite (AC250 manufactured by Across, 20 mm × 20 mm × 3 mm) was used as the substrate. Two types of catalytic metals (Co (II) acetate tetrahydrate, Mo (II) acetate) were used for the production of CNTs. The catalyst was supported on the surface of the C / C composite by using a dip coating method. The procedure for supporting the catalyst is shown below.
(1) A catalytic metal was dispersed in ethanol at a concentration of 0.01% by weight to prepare a Co (II) acetate solution and a Mo (II) acetate solution.
(2) In order to remove impurities on the surface of the C / C composite as a substrate, the C / C composite was heated in an atmosphere of 500 ° C. for 5 minutes using an electric furnace.
(3) After immersing the C / C composite as the base material in the Mo (II) acetate solution for 5 minutes, it was lifted from the Mo (II) acetate solution at a lifting speed of 3 cm / min, and acetic acid was applied to the surface of the C / C composite. Coated with Mo (II).
(4) The coated C / C composite was held in an electric furnace at 400 ° C. for 5 minutes to dry and oxidize the catalytic metal.
(5) The steps (3) and (4) were repeated three times.
(6) Using the Co (II) acetate solution, the same operation as the Mo (II) acetate was performed.

<2. Production of CNT>
Using the thermal CVD apparatus shown in FIG. 1 on the catalyst-supported C / C composite, CNTs were produced by the following procedure.
(1) A catalyst-supported C / C composite was placed on a quartz board, placed in a thermal CVD furnace, and the gas in the furnace was discharged using a vacuum pump.
(2) The furnace was filled with inert gas (Ar, H ₂ -3%), the exhaust valve was adjusted, and the temperature was raised to 900 ° C. while maintaining the furnace pressure at 40 kPa (absolute pressure).
(3) The inert gas in the furnace was discharged and ethanol gas was supplied. At this time, the temperature and pressure in the furnace were maintained at 900 ° C. and 5.0 kPa, respectively.
(4) After a predetermined time (CVD time) had elapsed, the supply of ethanol gas was stopped, and the reactor was discharged from the furnace using a vacuum pump.
(5) The inert gas was again supplied into the furnace, and the furnace was cooled to room temperature. At this time, the pressure in the furnace was maintained at 5.0 kPa.

<3. Evaluation Test Method>
(1) Friction test An outline of the friction tester is shown in FIG. The friction tester includes an AC motor, a torque meter, an atmosphere chamber, and a load cell. The sample temperature was controlled by a heater installed in the sample mounting part. Table 1 shows the conditions of the friction test.

  The friction coefficient (μ) was calculated from the rotational torque, effective radius, and pressing force by the following general friction coefficient calculation formula.

μ = (Tr / R) / N
(However, Tr: Torque, R: Effective radius, N: Pushing force, R = 8mm.)

(2) CNT production density The CNT production density was quantified by dividing the weight difference from the C / C composite not subjected to thermal CVD treatment by the surface area of the C / C composite member as the substrate (see the following formula 1). ).

(3) Gas analysis The change of the atmospheric gas during the friction test was evaluated by a quadrupole mass spectrometer (manufactured by ULVAC, product number: REGA RG201). The ionic strength of the molecules contained in the atmospheric gas was obtained by averaging the values for 10 seconds.

(4) Observation with a scanning electron microscope (SEM) CNT generated on the surface of a C / C composite as a substrate is subjected to electron beam acceleration voltage using a scanning electron microscope (SEM, manufacturer: JEOL Ltd., product number: JSM7001FD). Observation was performed at 15.0 kV.

<4. Evaluation results>
(1) Confirmation of CNT produced | generated on C / C composite surface The SEM photograph of CNT produced | generated on the C / C composite surface when CVD time is 30 minutes is shown in FIG. It was confirmed that CNTs were generated on the surface of the C / C composite (indicated by white arrows in the figure).

(2) Relationship between CVD time and CNT formation density FIG. 4 shows a SEM photograph of CNT on the surface of the C / C composite when the CVD time is 15 minutes, 30 minutes, and 45 minutes, and FIG. 5 shows the generation density. As shown in FIGS. 4 and 5, it was found that the CNT generation density increases in proportion to the CVD time.

(3) Relationship Between CNT Generation Density and Friction Coefficient FIG. 6 shows the relationship between the CNT generation density and the friction coefficient between C / C composite materials having CNTs generated on the surface. The rotational speed of the friction tester was 100 rpm, the applied pressure was 1.0 MPa, and the measurement temperature was room temperature. As is clear from FIG. 6, the friction coefficient of the C / C composite material in which CNTs were generated on the surface increased with an increase in the generation density of the CNTs generated on the surface.

  Table 2 shows the CVD time, CNT generation density, and friction coefficient at room temperature of the obtained C / C composite.

(4) Temperature dependence of friction coefficient In Table 3 and FIG. 7, the change in the friction coefficient due to the temperature change of the C / C composite with a CVD time of 30 minutes and a CNT generation density of ρ = 0.039 mg / mm ² is shown. (Indicated by “Modified” in FIG. 7). FIG. 7 also shows a change in the friction coefficient due to a temperature change of a normal C / C composite not subjected to the CVD process (indicated by “Unmodified” in FIG. 7). As is apparent from FIG. 7, the C / C composite not subjected to CVD treatment has a low friction coefficient at low temperature (room temperature) and the temperature dependence of the friction coefficient is high. In the C composite, the friction coefficient at low temperature (room temperature) increased, the fluctuation range of the friction coefficient from room temperature to 300 ° C. was 0.1 or less, and the temperature dependence of the friction coefficient decreased. Thus, it was found that the generation of CNTs on the surface of the C / C composite is effective not only for increasing the friction coefficient of the C / C composite but also for suppressing the temperature dependence of the friction coefficient.

(5) Gas analysis FIG. 8 shows a normal C / C composite not subjected to CVD treatment (Unmodified) and a C / C composite in which CNTs are generated on the surface by the CVD treatment (Modified, ρ = 0.444 mg / mm ^2). And the ionic strength of O ₂ and CO ₂ during the friction test at room temperature. However, the ionic strength was normalized by the O ₂ ionic strength before the test. As shown in FIG. 8, in the C / C composite not subjected to the CVD treatment, there is no significant change in the ionic strength changes of O ₂ and CO ₂ before and after the friction test. On the other hand, in the C / C composite in which CNTs were generated by the CVD process, the O ₂ ionic strength decreased and the CO ₂ ionic strength increased after the friction test. From this result, it is considered that in the C / C composite in which CNTs were generated on the surface, an oxidation phenomenon occurred due to wear even at room temperature. This phenomenon is similar to a phenomenon in which the coefficient of friction of the C / C composite increases due to oxidation of graphite under high friction conditions. From this, it is considered that in the C / C composite of the present invention, by generating carbon nanotubes on the surface, graphite is oxidized even under low friction conditions, and the friction coefficient is increased.

(6) SEM observation of friction surface after friction test After friction test in C / C composite not subjected to CVD treatment and C / C composite (ρ = 0.039 mg / mm ² ) produced CNT by CVD treatment (See FIG. 9. In FIG. 9, the photo on the left is a C / C composite not subjected to CVD treatment, and the photo on the right is a C / C composite in which CNT is generated by CVD treatment) . From the two photographs of untreated material (left) and CNT generating material (right) shown in FIG. 9, in the C / C composite in which CNT is generated by CVD processing, the friction surface roughness is increased by the friction test. I understand that. This suggests the occurrence of abrasive friction due to CNT formation on the surface.

Compared to conventional C / C composites, the C / C composite according to the present invention has an increased friction coefficient at a low temperature, and the temperature dependence of the friction coefficient is suppressed. Can be suitably used.

Claims (11)

  A carbon fiber reinforced carbon composite material comprising carbon nanotubes formed on at least the surface of a carbon fiber reinforced carbon composite member as a base material.   The carbon fiber reinforced carbon composite material according to claim 1, wherein the carbon nanotube has a diameter of 10 to 500 nm and a length of 0.1 to 10 µm. The carbon fiber reinforced carbon composite material according to claim 1 or 2, wherein the generation density of carbon nanotubes on the surface of the carbon fiber reinforced carbon composite member is 0.0030 mg / mm ² or more.   The carbon fiber reinforced carbon composite material according to any one of claims 1 to 3, which has a friction coefficient at room temperature of 0.20 or more.   The carbon fiber reinforced carbon composite material according to any one of claims 1 to 4, wherein a fluctuation range of a friction coefficient at room temperature to 300 ° C is 0.1 or less.   The brake material which consists of a carbon fiber reinforced carbon composite material in any one of Claims 1-5.   A carbon fiber reinforced carbon composite member as a base material is brought into contact with a catalyst metal dispersion and the catalyst metal is supported on the carbon fiber reinforced carbon composite material, and then a hydrocarbon compound is supplied in a heating furnace and thermally decomposed. Thus, a method for producing a carbon fiber reinforced carbon composite material, wherein carbon nanotubes are generated on at least the surface of a carbon fiber reinforced carbon composite member as a base material.   The method for producing a carbon fiber-reinforced carbon composite material according to claim 7, wherein Co (II) acetate tetrahydrate and / or Mo (II) acetate is used as the catalyst metal.   The method for producing a carbon fiber-reinforced carbon composite material according to claim 7 or 8, wherein ethanol is used as a dispersion solvent for the catalyst metal dispersion.   The method for producing a carbon fiber-reinforced carbon composite material according to any one of claims 7 to 9, wherein ethanol is used as the hydrocarbon compound.   The method for producing a carbon fiber reinforced carbon composite material according to any one of claims 7 to 10, wherein the carbon fiber reinforced carbon composite member as the base material is produced by a resin impregnation method.