JPH05345670A - Carbon fiber-reinforced carbon composite material and sliding material produced therewith - Google Patents

Abstract

PURPOSE:To provide a carbon fiber-reinforced carbon composite material having excellent abrasion resistance. CONSTITUTION:A short carbon fiber bundle composed of plural single fibers and free from collecting agent is opened to obtain a sheet containing fibers randomly oriented in two dimensions. The sheet is impregnated with a resin and the impregnated sheets are laminated, formed, baked and finally densified with an impregnating pitch having a softening point of 70-120 deg.C, a toluene insoluble content of 10-30%, a quinoline insoluble content of <=1% and a fixed carbon content of >=40% to obtain the carbon fiber-reinforced carbon composite material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon fiber reinforced carbon composite material (hereinafter referred to as C / C composite material) having excellent friction and sliding characteristics, and a sliding material using the same.

[0002]

2. Description of the Related Art Carbon fiber-carbon composite materials have excellent mechanical properties, heat resistance properties, and friction braking properties, and are being put to practical use as disks and pads for brake sliding parts of aircraft, racing four-wheeled vehicles, two-wheeled vehicles, etc. I'm out. Generally C / C composites are PA
N-type, pitch-type, or rayon-type long and short carbon fibers are impregnated with a thermosetting resin to form a prepreg, which are laminated and cured to form a molded body, which is fired at 600 to 2500 ° C. in an inert atmosphere. Are manufactured by.

At this stage, the bulk density is low and the strength is very insufficient. Therefore, it is highly densified by impregnating thermosetting resin such as phenol resin or furan resin or thermoplastic resin such as pitches or by repeating the densification process by the CVD method using organic gas such as methane, propane, dichloroethylene as a raw material. (Lower porosity) and higher strength.

[0004]

However, when a thermosetting resin such as a phenol resin or a furan resin is used, it is easy to close the pores while repeating the steps of impregnation, curing and firing, and the pores remain inside. It is difficult to reduce porosity.
Further, when the CVD method using an organic gas such as methane, propane, or dichloroethylene as a raw material is used, the adhesiveness with the carbon fiber is poor and the wear due to abrasion becomes large when applied to the brake sliding portion.

When a thermoplastic resin such as pitch is used, it is common to use one having a high softening point in order to obtain a high carbonization yield. However, pitch having a high softening point is inferior in impregnation property and requires high temperature treatment, so that equipment for producing a C / C composite material becomes excessive and handling becomes complicated. In other words, each method has advantages and disadvantages and is not satisfactory.

[0006]

[Means for Solving the Problem] Therefore, the present inventors
In order to solve such a problem, as a result of extensive studies on a densification method of a C / C composite material, it was found that the above problems can be solved by performing a densification treatment using a pitch having a specific property as an impregnated pitch. After knowing it, the present invention was completed. That is, an object of the present invention is to propose a C / C composite material exhibiting a low wear rate, the object of which is a softening point of 70 to 120 ° C, preferably 80 to 90 ° C, and a toluene insoluble content of 10 to 30 and preferably 13 ~ 20%, quinoline insoluble content 1% or less, fixed carbon 40% or more, preferably 50
It is achieved by performing a densification treatment using an impregnated pitch that is at least%.

The present invention will be described in detail below. As the carbon fiber used in the present invention, any known carbon fiber such as pitch-based, PAN-based or rayon-based carbon fiber can be used, and if necessary, SiC, Al ₂ O ₃ , an inorganic fiber such as carbon black, or an inorganic substance. Etc. may be added. The form of these carbon fibers is usually 2000 to 800
A tow, a strand, a roving, a yarn, or the like, which is a bundle of 0 single fibers, and a short fiber-like one obtained by cutting these is used. For the present invention, usually 0.3 to 100 mm, preferably 5 to 50 mm
Use only short fibers. The diameter and elastic modulus of the carbon fiber itself are not particularly limited within the range generally used as a composite material.

In forming a C / C composite material, for example, JP-A-62-62
-96364, JP-A-1-176273, and other methods to defibrate and disperse a sheet. As an example of a concrete defibration and a method for producing a two-dimensional random sheet, for example, a carbon fiber is mechanically made into a monofilament commonly used in spinning, and a sheet is produced using a random webber, or air is used. Disentangled by
There is a method of manufacturing a sheet.

As a method for wet-defibration to produce a two-dimensional randomly oriented sheet, for example, a beater usually used for beating of pulp or the like or a pulper used for defibration is used in a solvent. After defibrating the short fibrous carbon fibers with, for example, supply them little by little to a mold having a screen at the bottom, or evenly disperse them by means such as stirring after defibration, make paper with a wire mesh, etc., and then make by drying There is a way to do it.
As a solvent for uniformly dispersing short fiber carbon fibers,
Preferably, water, acetone, alcohol having 1 to 5 carbon atoms, anthracene oil, or the like is used, but other organic solvent may be used. Further, it is preferable to disperse or dissolve a phenol resin, a furan resin, pitch or the like in the solvent, because the carbon fibers are adhered to each other and the handling in the next step becomes easier. Furthermore, if a thickening agent such as sodium fibrin glycolate, polyvinyl alcohol, or hydroxycellulose is added to the solvent,
This is preferable because the effect is further increased.

Although various weights (weight per 1 m ² ) of the sheet can be taken, 10-500 g / m ² is optimal in view of handleability, impregnation property and uniformity. The two-dimensional randomly oriented sheet thus obtained is impregnated with a phenol resin, furan resin, or a matrix such as petroleum-based or coal-based pitch and then dried. At this time, the matrix used is one that is dissolved in a solvent such as alcohol, acetone, or anthracene oil and adjusted to have an appropriate viscosity.

Then, the dried sheets are laminated, filled in a mold, and pressure-molded at a temperature of 100 to 500 ° C. to obtain V.
f (fiber volume content) is 5 to 65%, preferably 10
A 55% compact is obtained, and then 800 at a temperature rising rate of 1 to 200 ° C./hr in an inert gas atmosphere such as N ₂ gas.
Up to 2500 ° C and after firing, softening point 70-1
20 ° C., preferably 80 to 90 ° C., toluene insoluble content 10 to
30%, preferably 13 to 20%, quinoline insoluble matter 1% or less, fixed carbon is 40% or more, preferably 50% or more, is used for densification treatment, or further densification effect is exhibited. A C / C composite material is obtained by performing a densification treatment for impregnating and carbonizing by a method described in JP-A-1-298013 or the like. The specific dense processing will be described below.

The above C / C composite material is placed in a bath heated to a predetermined temperature, the interior of the bath is evacuated, and then resin or molten pitch is supplied, and the voids formed by firing are impregnated with a matrix. After that, it is fired again at a temperature of 800 to 2500 ° C. By repeating the above steps, the target C / C composite material is densified.

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Production Example 1 A pitch-based carbon fiber bundle having a length of 30 mm and 4000 filaments is defibrated by a random webber to obtain a sheet having a basis weight of 200 g / m ^{2 which} is two-dimensionally randomly oriented. This sheet was impregnated with a phenol resin diluted with ethanol and then dried to obtain 200 g / m ² of carbon fiber,
A sheet impregnated with 0 g / m ² of phenol resin was prepared. This sheet was laminated in a mold and pressure-molded at 250 ° C. to obtain a molded body having Vf of 50%. After the molded body was fired to 2000 ° C. in a heating furnace, the softening point was 85 ° C., the toluene insoluble content was 15%, the quinoline insoluble content was not substantially contained, and the pitch in which fixed carbon was 55% was impregnated at 500 ° C.
Then, after heat treatment under a pressure of 6 kg / cm ² for 5 hours, it was fired at 1000 ° C. in a heating furnace. Further, the same operation of impregnation-solidification-firing is repeated 4 times, and thereafter 2000 °
Was performed to obtain a C / C composite material of the present invention having a porosity of 6%. Using this C / C, the rotation speed is 7,000 rpm and the surface pressure is 12
When the wear rate was examined under the condition of kg / cm ² , it was 0.5 ×
It was 10 ⁻⁴ mm / stop · surf.

[0015]

As described above, the present invention has a softening point of 70-12.
0 ° C, toluene insoluble matter 10 to 30%, quinoline insoluble matter 1
%, The densification treatment is performed using an impregnated pitch having a fixed carbon content of 40% or more, whereby a brake sliding portion with a small amount of wear can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeo Matsui No. 1 state in Sakaide city, Kagawa Prefecture Mitsubishi Kasei Corporation Sakaide factory

Claims (2)

[Claims] 1. A short fiber-like carbon fiber bundle composed of a plurality of single fibers is defibrated to prepare a sheet in which the fibers are two-dimensionally randomly oriented, impregnated with a resin, laminated and molded, and fired, Softening point 70-120 ° C, toluene non-solution 10-30
%, A quinoline insoluble content of 1% or less, and a fixed carbon of 40% or more obtained by a densification treatment with a carbon fiber-reinforced carbon composite material. 2. A short fibrous carbon fiber bundle composed of a plurality of single fibers is defibrated to prepare a sheet in which the fibers are two-dimensionally randomly oriented, impregnated with a resin, laminated and molded, and fired, Softening point 70-120 ° C, toluene non-solution 10-30
%, Quinoline insoluble content of 1% or less, and fixed carbon of 40% or more, a sliding material composed of a carbon fiber reinforced carbon composite material obtained by a densification treatment with an impregnated pitch.