JPS6357931A - High heat resistive frictional material - Google Patents

Abstract

PURPOSE:To obtain the frictional material having the stability in friction resis tance and frictional coefficient by mixing and molding the organic binder, fric tion adjusting material, and the ceramic fiber consisting of SiO2 in 35-65wt% and Al2O3 as the rest in the chemical component. CONSTITUTION:After ceramic fiber, resin, and friction adjusting material are mixed in a prescribed ratio, said materials are preparatory-molded under a pressure of 200-400kg/cm<2>. Then, the preparatory molded article is set into a heated metal mold and press-molded, and then after-cure is performed. Since the high heat-resistive frictional material thus obtained contains the ceramic fibers having an exceedingly high heat resistance, the superior stability in abrasion resistance and frictional coefficient can be obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a friction material with excellent heat resistance.

[Conventional technology]

Conventionally, organic friction materials whose main components are fibers such as asbestos, glass fibers, aramid fibers, and steel fibers have been known as friction materials used in the brakes of automobiles, railway vehicles, and various industrial machines.

[Problem that the invention seeks to solve]

However, there is a problem with the use of asbestos, as its dust has been shown to be a cause of lung cancer. Further, since asbestos becomes extremely brittle after releasing crystallization water at 700 to 800° C., conventional friction materials containing asbestos as a main component have problems such as a decrease in the coefficient of friction at high temperatures and low wear resistance.

Glass fiber has low heat resistance and begins to soften at around 300°C, after which the viscosity decreases as the temperature rises and it becomes molten. Therefore, friction materials that have glass fiber as its main component have low friction coefficients and wear resistance at high temperatures. There is a problem.

Various organic fibers including aramid fibers also range from 200 to 30%.
Because it thermally decomposes or melts at 0°C, friction materials based on it have the same problems as those using glass fibers, such as low friction coefficient and wear resistance at high temperatures. On the other hand, steel fibers are superior in terms of heat resistance compared to the above-mentioned various types of fibers, but friction materials containing steel fibers as a main component have high thermal conductivity and are susceptible to friction and corrosion due to the formation of rust.
This has the problem of adversely affecting the wear characteristics.

Further, those whose main component is carbon fiber have the problem of not only being expensive but also having a low coefficient of friction.

[Means for solving problems]

An object of the present invention is to provide a highly heat-resistant friction material that improves the drawbacks of the prior art, and achieves the above object by providing a highly heat-resistant friction material as described in the claims.

Ceramic fiber is made by electrically melting high-purity silica and alumina in -C and blowing out the trickle with high-pressure air.
Unlike glass fibers that soften at 0℃ or organic fibers that decompose and melt, and even asbestos that releases crystal water and becomes brittle at around 800℃, it starts to soften at around 900℃, but at the same time it begins to crystallize, so it softens. It is an extremely thin glassy fiber with an average fiber diameter of about 2 μm, which has a heat resistance of 1000° C. or higher. Furthermore, the non-fibrous glass grains called ceramic fiber G-shot are usually 50w.
This includes approximately t%. Shot has a particle size of 44-200
Most of the particles are coarse and coarse, so if they are included, there is a high possibility that they will damage the friction surface. Therefore, if this becomes a problem, remove this shot and reduce its content to 20wt.
% or less. A method for obtaining ceramic fibers having a shot content of 20 vat % or less used in the present invention will be described.

A predetermined amount of SiO□ and A1. A slurry of ceramic fibers is created by electrolytically melting O, and blowing off the resulting stream with a high-speed air stream or the centrifugal force of a high-speed rotating rotor. Next, this slurry is gradually introduced into a cylindrical container, and at the same time pressurized water is pumped through the side wall of the container to generate a swirling flow, which loosens the ceramic fibers and separates the shots. A slurry of disentangled ceramic fibers is sequentially flowed out from the center of the thin stream and guided onto a moving endless screen to collect the fibers. The ceramic fiber thus obtained has a grain size of 44μ or more and a shot content of 0.1 w.
t% or 18ut%.

As for the chemical components, if Sing is less than 35 wt%, the shot content will be extremely high, and if Sing is more than 65 wt%, the heat resistance will decrease, so 5i (h) must be within the range of 35 to 65 wt%.

The blending ratio of ceramic fibers in the highly heat-resistant friction material of the present invention can be 20 to 10 wt%.

The organic binder used in the present invention includes ceramic fiber,
It is preferably a thermosetting resin such as phenol resin, which binds together friction modifiers and the like. The mixing ratio is 1
It can be 0 to 30 wL%.

As the friction modifier, powders such as cashew dust, rubber powder barium sulfate, calcium carbonate, graphite, molybdenum disulfide, copper, brass, and aluminum are preferable. Their blending ratio can be 5 to 30 wt%.

Next, a typical manufacturing method of the highly heat-resistant friction material of the present invention will be described. After mixing ceramic fiber, resin, and friction modifier in a predetermined ratio, the mixture is preformed at a pressure of 200 to 400 kg/cd. Thereafter, this preformed body was
Place in a mold heated to 0-180℃ for 150-350k
After pressure molding at a pressure of g/crA for 5 to 10 minutes, it is after-cured at a temperature of 170 to 250°C for 5 hours or more.

The highly heat-resistant friction material of the present invention obtained in this manner has a patent that it has excellent wear resistance, stability of friction coefficient, etc. because it contains ceramic fibers with extremely high heat resistance. Hereinafter, the present invention will be explained with reference to examples.

〔Example〕

The chemical component on the plaque is SiO□52wt%, AZ20348wj
%, and the shot content is O, 1 wt% ceramic fiber, phenolic resin, brass powder, carbon powder, and cashew dust are mixed at the volume ratio shown in Table 1, and pressed at a pressure of 400 kg/cn. After preforming at 150°C and a pressure of 200 kg/ctA for 10 minutes. Next, the material was after-cured at 170° C. for 7 hours to obtain a highly heat-resistant friction material of the present invention. This was cut to a predetermined size and polished to provide a test piece for friction and wear testing.

Comparison ■± Asbestos and phenolic resin, brass powder, carbon powder,
Cassiny dust was mixed to the volume ratio shown in Table 1 and molded in the same manner as in the example to prepare a test piece.

Glass fiber and phenolic resin, brass powder,
Carbon powder and cashew dust were mixed in a volume ratio shown in Table 1, and molded in the same manner as in the example to prepare a test piece.

The test piece thus obtained was polished according to the method specified in JIS D4411. ! ! The coefficient and wear amount were measured and the results are shown in Table 2.

Table 1 Table 2 [Effects of the Invention] As described above, since the highly heat-resistant friction material of the present invention has a highly heat-resistant fiber called ceramic fiber as its main component, the coefficient of friction does not decrease even at high temperatures, and it resists wear. It is a friction material with excellent heat resistance and has the effect of being small in amount. Therefore, it is extremely excellent as a friction material used under harsh thermal conditions and is industrially useful.

Patent applicant: Ibiden Co., Ltd. Representative: Jun Taga

Claims (1)

[Scope of Claims] 1) A highly heat-resistant friction material comprising ceramic fibers whose chemical components are SiO_235 to 65 wt% and the remainder substantially Al_2O_3, an organic binder, and a friction modifier. 2) The highly heat-resistant friction material according to claim 1, wherein the ceramic fiber has a shot content of 20% or less.