JPS627668A - Carbon fiber reinforced carbon composite material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a nine-carbon fiber-reinforced carbon composite material with excellent frictional properties.

[Prior art]

Carbon fiber-reinforced carbon composites (hereinafter referred to as rC/C composites) are generally made by adding heat to long or short carbon fibers such as polyacrylonitrile, pitch, or rayon with phenolic resin or furan resin. It is particularly manufactured by impregnating or mixing a matrix material such as a curable resin or a thermoplastic resin such as pitch, heating and molding the product, and firing the product at COO to t000c in a non-oxidizing atmosphere such as an inert gas.

However, in the C/C composite obtained by this method, the carbonization yield of the matrix carbon is 4Io~SO%, so the density of the C/C composite obtained only reaches the theoretical density of 6 sides, and its The strength is also low. Additionally, in general, when the coefficient of dynamic friction of a friction member, especially a sliding member, exceeds o, 17, the amount of friction increases and the frequency of replacement of the sliding member, etc. increases; Since there is a problem with the surface, a range of 0.7 to O,a is appropriate for the dynamic R1 friction coefficient, and the wear fireflies are Q, Q / after 7 uses.
Although it is desired that the wear resistance is below fl, conventional C/C composite materials do not have sufficient wear resistance, and there are problems in using them as sliding members.

Therefore, in order to improve its strength, the C/C composite material obtained by the above method is further impregnated with resin or pitch, etc., and then the process of re-firing is repeated to perform a densification treatment. C/C composite material is filled with pyrolytic carbon, etc., using a method of increasing the density of C/C, or chemical vapor deposition method (hereinafter referred to as "rCVD method") to fill the voids existing in the C/C composite material and perform a numerical conversion process. A method of increasing the density of the /C composite material has been proposed.

[Problems to be Solved by the Invention] However, although it is possible to make the density of the C/C composite material approximately S side rootness of the theoretical density by this densification method, the obtained C/C composite material is Further improvements in wear resistance and sliding properties were still desired.

[Failure to solve the problem]

Therefore, the inventors of the present invention focused on densification treatment using the CVD method, and as a result, they found that instead of simply filling the voids in the matrix carbon with pyrolytic carbon, etc., as in the past,
The present invention was completed based on the finding that abrasion resistance and sliding properties can be significantly improved by providing a carbon coating layer on the surface of a C/C composite material.

That is, an object of the present invention is to provide a carbon fiber-reinforced carbon composite material with excellent friction properties, and the purpose is to provide a carbon coating layer formed by chemical vapor deposition on the surface of the carbon fiber-reinforced carbon composite material. This is achieved by a carbon fiber-reinforced carbon composite material having the following characteristics.

Hereinafter, one aspect of the present invention will be explained in detail.

The carbon fiber used in the present invention may be any known carbon fiber such as pitch-based, polyacrylonitrile-based, rayon-based, etc.
fibers can also be used. Furthermore, if necessary, silicon carbide 1,
l1lt alumina 05. Inorganic fibers such as carbon black, or inorganic substances may be added. Their shape may be any of woven fabrics, nonwoven fabrics, short fibers, etc.

The carbon fibers are mixed with or impregnated with a matrix material such as a phenol resin, a furan resin, or petroleum-based or coal-based pitch, and then dried to obtain a composition comprising the carbon fibers and the matrix material. In this case, the matrix material used is one that has been dissolved in a solvent such as alcohol, acetone, anthracene oil, etc. and adjusted to an appropriate viscosity.

Next, the composition is prepared such that the volume content of carbon fibers is 1O to 7θ.
filling the mold, preferably as
Too-! Pressure molding is performed at a temperature of 00C. After that, in an inert gas atmosphere such as nitrogen gas, the temperature is raised to goo~/,000℃ at a heating rate of 1-100℃/hour and fired.
/C composite material is obtained.

In the case of unexploded gA, this C/C composite material may be left as it is, or
Alternatively, it is important to perform reheat treatment at a temperature higher than the previous firing temperature and then deposit pyrolytic carbon on the surface of the C/C composite material by CVD to form a complete coating layer of pyrolytic carbon.

As the CVD method, a normal method, that is, thermal Cv'
Examples include D method and plasma CVD method. In the case of the thermal CVD method, methane, propane, propylene, benzene, acetylene, halogenated hydrocarbons, etc. are used as raw materials for pyrolytic carbon, and s ~
Examples include a method of thermally decomposing the raw material under a reduced pressure of approximately A OtpmHf or under normal pressure.

In the present invention, in particular, a halogenated hydrocarbon is used as a raw material, and the temperature is preferably 100 to 100°C.
The method of thermal decomposition at a temperature of /100° C. is preferable because a pyrolytic carbon coating layer with better wear resistance is formed.

There are various types of halogenated hydrocarbons.
□ can be used, but specifically, l, /,! −
trichloroethane, /, /-monotrichloroethane, /
, cordichloroethylene, /,/-di-chloroethylene, and the like. These halogenated hydrocarbons may be used alone or in combination of two or more.

The above-mentioned halogenated hydrocarbon may be vaporized as it is, or may be diluted with an inert gas such as nitrogen, helium, or argon. Preferably, a method in which the carbon is diluted to a concentration of 1% to 1% and thermally decomposed in the above temperature range to coat the pyrolytic carbon is preferred because it is low temperature and has a high precipitation rate.

In the present invention, the carbon coating J- is usually 20 μm or more, preferably! 00 μm or more, particularly preferably Q, j; -1
Pyrolytic carbon by chemical vapor deposition method to make it 0m? deposit

After forming the carbon coating layer as described above, the C of the present invention
/C composite material further has l, θθ0~. Reheat treatment may be performed at 7,000C as appropriate.

Further, in the present invention, a conventional densification treatment may be performed before forming the carbon coating layer.

In other words, C/
After impregnating pitch etc. into C composite material, 600~lθθθ℃
In the process of firing at a temperature of .

Alternatively, the voids in the matrix carbon are filled by the chemical vapor deposition method, and pyrolyzed carbon is then deposited to form a carbon coating layer.
After reheating at a temperature of 00° C. to 3θ0θC, a carbon coating layer may be formed.

(Effects) According to the present invention, by providing a carbon coating layer on the entire surface of a C/C composite material, it is possible to easily obtain a sliding member etc. whose frictional characteristics are significantly improved.

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention does not go beyond its gist.

The present invention is not limited to the following examples.

Example 1 31 parts by weight of pitch-based carbon fibers of length and length were
After mixing with 77 parts by weight resin and 52 parts by weight ethanol, about 211. After drying for a long time, this was filled into a mold and pressurized at a temperature of 21θ°C to obtain a molded body with a carbon fiber volume content (Vf) of Sθ. This molded body is fired at 1000°C in a nitrogen gas atmosphere in a heating furnace to produce a C/C composite material with a complete absence of C/C composite material.
After being impregnated with liquid pip at a temperature of °C, it was fired again in a heating furnace in a nitrogen gas atmosphere. After repeating the impregnation-firing operation 1+ times under the same treatment conditions, further heat treatment 1- in a nitrogen gas atmosphere (100° C.).

Bulk density halo? /Taka densified C/C composite material was obtained.

After processing the obtained C/C composite into a full disk shape, it was placed in a CvD processing device, heated at 700°C using a high-frequency induction coil, and processed into an IJ body using υ argon gas as a carrier gas from the bottom of the device. CVD treatment was performed by supplying 6111-/2-dichloroethylene vapor for IQ hours to produce a homogeneous carbon coating layer of about 0θμ on the surface of the c7c composite. This C/C composite material having a carbon coating layer was heat-treated again in an argon gas atmosphere/AOOC to obtain a C/C composite material of the present invention.

All friction tests were carried out by rubbing the disk-shaped C/C composite materials having the carbon coating layer against each other. The results are shown in Table 1.

Comparative Example 1 Bulk density before CVD treatment obtained in Example/Ay
-/c111 C/C composite material processed into a disk shape was subjected to a friction test in the same manner as in Example 1. The results are shown in Table 1.

Example 2 - The CVD treatment time was 50 hours, respectively, and the carbon coating layer of Sμ, Sθ071, and 2000μ was C/C.
The same method as in Example 1 was carried out except that the particles were formed on the surface of the composite material, and then the same friction test was carried out by heat treatment at i&00C in an argon gas atmosphere in the same manner as in Example. The results are shown in Table 1.

As is clear from Table 1, as long as the carbon coating layer remains on the surface of the C/C composite material, it can be seen that it has excellent frictional properties similar to Example 1.

Examples j, 6 The thickness of the carbon coating layer was approximately 200μ in the same manner as in Example 1 except that the volume content (Vf) of the carbon fiber was 20 and 0.
A C/C composite material was obtained. A friction test was conducted on this in the same manner as in Example 1, and the results are shown in Table 1.

Example 1, g C in which the carbon coating layer obtained in Example 1 has a thickness of about -〇θμ
/C composite material in argon gas atmosphere
or:, to obtain a disk-shaped C/C composite material having a carbon coating layer. A friction test was conducted in the same manner as in Example 1.

The results are shown in the gt table.

Comparative Example The molded body obtained in Example 1 with a carbon fiber volume content (vf) of 0 was fired at 7000°C in a nitrogen gas atmosphere to obtain a composite material of C70, and then Example 1 and C under similar conditions
C7C is densified by VD treatment and densification treatment is performed to fill the voids existing in the C7C composite with pyrolytic carbon.
A C composite material was obtained. After heat-treating this C/C composite material at A00C in an argon gas atmosphere, it is processed into a disk shape, and the friction surface is made of carbon fiber and ma) A bulky material made of IJ Lux decomposed carbon! /, jg-/cfA C/C composite material was obtained. This was subjected to a friction test by applying pressure in the same manner as in Example/, and the results were
It is shown in Table J1.

(Simple theory of reference photo F!4) (375 times), and Figure 2 shows c/
c Scanning electron micrograph showing the surface part of the composite material (3
5 times).

Procedure Ne City Official Book (Method) January 1985/Ta day

Claims (4)

[Claims] (1) A carbon fiber-reinforced carbon composite material characterized by having a carbon coating layer formed by chemical vapor deposition on the surface of the carbon fiber-reinforced carbon composite material. (2) The carbon coating layer is formed by thermally decomposing a gas containing a halogenated hydrocarbon at a temperature of 400°C or higher. Carbon fiber reinforced carbon composite material. (3) The carbon fiber-reinforced carbon composite material according to claim 1, wherein the carbon coating layer has a thickness of 20 μm or more. (4) A patent characterized in that the carbon fiber-reinforced carbon composite material is obtained by carbonizing and firing a molded body made of carbon fibers and a matrix material in which the volume content of carbon fibers is 10 to 70%. The carbon fiber reinforced carbon composite material according to claim 1.