JPH06159411A - Brake sliding section - Google Patents

Abstract

PURPOSE:To provide a brake sliding section comprising carbon fiber reinforced composite having stable braking effect. CONSTITUTION:In a brake sliding section comprising a disk and pad, both disk material and pad material are constituted by carbon fiber reinforced carbon composite wherein short carbon fibers comprising a plurality of bundles of monofilament frayed are used as reinforcements. A material of a hardness of 40 to 110 HRP in Rockwell hardness is used for the disk, and a material of 80 to 120 HRP in Rockwell hardness is used for the pad, and for the pad, a material higher than that for the disk in Rockwell hardness is used.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, in a vehicle disc brake, a C / C composite material has been used for a brake sliding portion of a disc or a pad from the viewpoint of weight reduction and performance improvement.

[0003]

However, the friction coefficient of the disk or pad using the C / C composite material is apt to change with temperature, and for example, the friction coefficient is low in a low temperature region such as the initial stage of braking, and then the friction progresses. The friction coefficient gradually or rapidly rises as the temperature rises, or
The phenomenon that the coefficient of friction remained low remained, and it was difficult to obtain a stable braking effect.

Therefore, the inventors of the present invention have conducted extensive studies on the brake sliding portion made of a C / C composite material, and as a result, by making the hardness of the disk material and the pad material specific, respectively, particularly at high temperature. Has a large coefficient of friction and is stable, has excellent response at high temperature (that is, biting property in braking), and has excellent pad wear resistance, and is known to have a stable braking effect. did.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a brake sliding portion composed of a disc and a pad, wherein the disc material and the pad material are both short fiber-shaped fibers each consisting of a bundle of a plurality of single fibers. Composed of carbon fiber reinforced carbon composite material, which is made by defibrating the carbon fiber of
The disk material has a Rockwell hardness of 40 to 110 HRP, the pad material has a Rockwell hardness of 80 to 120 HRP, and the Rockwell hardness of the pad material is higher than the Rockwell hardness of the disk material.

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, A
Inorganic fibers such as l ₂ O ₃ and carbon black, and inorganic substances may be added.

The form of these carbon fibers is a tow, a strand, a roving, a yarn or the like which is composed of a bundle of a plurality of single fibers, and a short fiber form obtained by cutting these is used. In the present invention, usually 0.3 to
Short fibers of about 100 mm, preferably about 5 to 50 mm are used. The diameter and elastic modulus of the carbon fiber itself are not particularly limited within the range generally used as a composite material.

When making a C / C composite material, for example, JP-A-62-62
-96364, JP-A-1-176273, and the like to defibrate and disperse to obtain a preform or sheet. These are impregnated with a matrix material, filled in a mold, and pressure-molded at a temperature of 100 to 500 ° C. to obtain a molded product having V _f (fiber content) of 5 to 65%, preferably 10 to 55%. . Then, in an inert gas atmosphere such as N ₂ gas at a temperature rising rate of 1 to 200 ° C./hr and 800 to 2500 ° C.
The temperature is raised up to the temperature and is fired to obtain a C / C composite material.

The C / C composite material obtained by the above-mentioned firing is subjected to a densification treatment and a final treatment, for example, by the following methods for disc material and pad material, respectively.
/ C composite material is obtained.

(1) Densification treatment with thermosetting resin or pitch: The above-mentioned C / C composite material is loaded in a tank heated to a predetermined temperature, and the inside of the tank is evacuated, then the thermosetting resin, preferably phenol. A matrix is impregnated into the voids formed by firing by supplying resin or pitch. After this, 800 ~ 25 again
Bake at a temperature of 00 ° C. By repeating the above steps, the target C / C composite material is densified.

(2) Densification treatment by CVD The above C / C placed in the reactor by an induction heating coil or the like.
The composite material is heated, steams of hydrocarbons or halogenated hydrocarbons are supplied into the reactor together with H ₂ gas, Ar gas or N ₂ gas, and voids are impregnated with the generated pyrolytic carbon to densify. To do. Further, if necessary, graphitization treatment can be performed.

In the present invention, as described above, the firing temperature, the densification method and the degree of densification are selected so as to be within the desired hardness when the disk material and the pad material are obtained. Although it cannot be generally stated depending on the combination of the reinforcing material and the matrix, generally, the higher the firing temperature and the lower the degree of densification, the lower the hardness.

Thus, in the present invention, the pad material has a Rockwell hardness of 80 to 120 HR.
P, more preferably C / C in the range of 90 to 115 HRP
The composite material is used, and the disk material is 40 to 110 HRP,
More preferably, a C / C composite material in the range of 55 to 95 HRP is used, and a pad material having a hardness higher than that of the disc material is used. It is more preferable that the hardness of the pad material is higher than the hardness of the disc material by 5 HRP or more.

[0015]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Production Example 1 A pitch-based carbon fiber having 4000 filaments cut into a length of 30 mm was defibrated to obtain a two-dimensionally randomly oriented sheet. This sheet was impregnated with phenol resin and then dried to prepare a sheet in which 65 parts of phenol resin was impregnated with respect to 100 parts of carbon fiber. This sheet was laminated in a mold and pressure-molded at 250 ° C. to obtain a molded body having V _{f of} about 50%. The compact was fired to 2000 ° C. in a heating furnace.

Then, after impregnating the pitch, 1 in a heating furnace
It was baked at 000 ° C. Further, the same impregnation-firing operation was repeated again, and then heat treatment at 2000 ° C. was performed to obtain a C / C composite material for a disk material having a porosity of 8%. The Rockwell hardness of this product was 73 HRP.

Manufacture Example 2 Pitch-based carbon fiber having a length of 10 mm and a number of filaments of 4000 was wet defibrated, and then an outer cylinder 300 mm and an inner cylinder 120
mm donut-shaped bottom with a screen having a mesh of 150 mesh and a bottom plate on the outside, together with water, put into a molding die and stirred evenly. A donut-shaped preform in which the fibers were uniformly dispersed was obtained.

After drying the preform, it is impregnated with a phenol resin, dried to form a prepreg, and then placed in a mold having the same inner and outer diameters as above, molded and cured at a temperature of 250 ° C., and V _f 50%. A molded body of was obtained. After densifying this molded body in a heating furnace to 2000 ° C., it is heated by a high frequency induction heating device, and hydrocarbon vapor is introduced into the reactor as a carrier gas of nitrogen gas, and densification is performed by filling pores with pyrolytic carbon. Processed.

Then, after impregnating with the phenol resin, it was baked at 1000 ° C. in a heating furnace. Further, the same impregnation-firing operation was repeated again, and then heat treatment at 2000 ° C. was performed to obtain a C / C composite material for a pad material having a porosity of 14%.
The Rockwell hardness of this product was 99 HRP.

The bench test results according to JIS D4411 using the disk material and the pad material thus obtained show that the temperature is 100 to 450 ° C. from a low temperature range of 100 ° C. or less.
Friction coefficient up to the high temperature range of μ = 0.4
.About.0.5 and .mu. = 0.45 to 0.5, the variation of the friction coefficient in the low temperature region is .mu. = 0.1 to 0.15, and the variation of the friction coefficient in the high temperature region is .mu. =
It was 0.05 or less. Furthermore, the pad wear amount is 0.1
It was less than mm. Moreover, the response at high temperature was very good.

Comparative Example 1 A conventional C / C composite material having a Rockwell hardness of 78 HRP was used as a disk material and a pad material, and the same test as above was carried out. As a result, the friction coefficient in the low temperature range of 100 ° C. or lower was ,
The friction coefficient in the high temperature region of μ = 0.33 to 0.35 and 100 to 450 ° C. was μ = 0.35 to 0.4. Also,
The variation of the friction coefficient in the low temperature range is μ = 0.10-
The coefficient of friction was 0.15, and the variation in the friction coefficient in the high temperature range was μ = 0.05 to 0.1. Further, the amount of wear was 0.2 to 0.3 mm. The response at high temperature was good.

[0023]

As described above, the present invention uses a C / C composite material having a Rockwell hardness of 40 to 110 HRP as a disc material and a C / C composite material having a Rockwell hardness of 80 to 120 HRP as a pad material, and By making the Rockwell hardness of the pad material higher than the Rockwell hardness of the disc material, the friction coefficient is large and stable especially in the high temperature range, the response at high temperature is excellent, the wear amount is small, and the braking effect is A stable brake sliding portion can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahiro Yanagisawa Inventor Masahiro Ueda City, Nagano Prefecture 840 Kokubu, Nissin Industry Co., Ltd. (72) Inventor Kohei Okuyama 1000 Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Sanryo Kasei Co., Ltd. Inside the Research Institute (72) Inventor Kazuo Niwa, No. 1 state town in Sakaide City, Kagawa Prefecture, Sakaide Factory, Mitsubishi Chemical Co., Ltd. (72) Toshihiro Fukagawa, No. 1 state town, Sakaide City, Kagawa Prefecture, Sakaide Factory, Mitsubishi Chemical Corporation

Claims (1)

[Claims] 1. In a brake sliding portion composed of a disc and a pad, the disc material and the pad material are both made of a carbon fiber obtained by defibrating short fiber carbon fibers each consisting of a bundle of a plurality of single fibers as a reinforcing material. Composed of fiber-reinforced carbon composite material, the disk material has Rockwell hardness of 40 to 110 HRP
And the pad material has Rockwell hardness of 80 to 120 HRP
The brake sliding part is characterized in that the Rockwell hardness of the pad material is higher than the Rockwell hardness of the disc material.