JPH04153291A - Friction material - Google Patents

Abstract

PURPOSE:To lower the abrasion loss in an operation at low speed and to reduce the increase in the coefficient of friction at high speed by incorporating a specified amount of SiC, Al2O3 or graphite into a carbon fiber reinforced carbon composite. CONSTITUTION:A friction material made of a carbon fiber reinforced carbon composite consisting of 30-80wt.% aggregate comprising carbon fibers and 70-20wt.% filler comprising a carbonaceous material, which contains at least one of SiC, Al2O3 and graphite in an amount of 2-20wt.% based on the total weight of the filler. In the friction material, for the purpose of bonding the carbon fibers to one another, hardly graphitizable raw material, such as phenolic resin or furan resin, is used for the carbonaceous material serving as filler. The hardly graphitizable or non-graphitized carbonaceous material is readily oxidized. Therefore, conventional brake material made of CFRC is readily oxidized when heated to a high temperature due to friction under high speed and high load conditions. SiC and Al2O3 are excellent in resistance to oxidation, while graphite has better resistance to oxidation than that of non-graphitized carbonaceous material; therefore, it is supposed that they will produce an effect on the frictional performance at high temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a friction material effective as a brake material for vehicles such as aircraft and automobiles.

BACKGROUND ART Conventionally, carbon fiber reinforced carbon composite materials (hereinafter referred to as CFRC), which were developed as materials for space use, have been used as brake materials for aircraft, racing cars, and the like. This is because this composite material has better mechanical properties at high temperatures than conventional materials.

CFRC for brakes is made by impregnating carbon fiber woven or non-woven fabric with thermosetting resin, such as phenol resin or furan resin, either singly or in layers.
100 kg/d to 200 kg at temperatures between ℃ and 200℃
/cffl and molded at 1000°C.
It is made by repeating the process of firing at the above temperature, impregnating with pitch or thermosetting resin for densification, and firing. Brake materials made in this way are generally used due to the friction between CFRCs, and are excellent as brake materials in severe conditions at high speeds and high loads, but they suffer from a large amount of wear at low speeds, and are This has the disadvantage that the coefficient of friction increases. In other words, in the case of aircraft, it has a great effect when landing, but when operating at low speeds inside an airport, there is a lot of wear and tear, and in the case of vehicles, when operating at high speeds, there are drawbacks such as excessive braking and accidents. Ta.

Problems to be Solved by the Invention The present invention solves these problems, and aims to reduce the amount of wear at low speeds and to reduce the increase in the coefficient of friction at high speeds.

Means for Solving the Problem In order to solve this problem, the present invention uses carbon fibers of 30 to 8
A friction material made of carbon fiber-reinforced carbon composite material consisting of aggregate consisting of 0% wt and filler consisting of 70 to 20% wt carbon, wherein 2% of the total weight of the filler is
It is characterized by containing ~20%wt of at least one of SiC, Ar103, or graphite.

That is, in the present invention, when impregnating carbon fiber woven fabrics, nonwoven fabrics, knitted fabrics, and short fibers with thermosetting resins such as epoxy resins, phenolic resins, furan resins, pitch, etc., S is added to 98 to 80% wt of these resins. I CSA
A' 203 and graphite are used alone, or two or three types, and stirred well so that the total amount is 2 to 20% wt to prepare a mixed resin. These Al103, Si
c. The graphite may be a powder with a diameter of 1 or less, preferably 100μ or less, or a fiber with a length of 3 or less, preferably 5Hμ or less. AI! The powder or short fiber of No. 203 may have a purity of 70% or more. S
The iC powder or short fibers may have a purity of 70% or more. Further, the Si powder or short fibers may also have a purity of 70% or more, and these become SiC by heating at 2000° C. or more. Therefore, SiC
5iO7 powder may also be used. This mixed resin is impregnated in a ratio of 2 to 0.2 to one part of carbon fiber fabric, needle-punched felt, or short fibers.

The Bripre rugs made in this way are stacked or stuffed into a mold for 100 to 300 sheets, in the case of woven fabrics, several dozen sheets, in the case of needle-punched felt, several sheets, and in the case of short fibers, they are stacked or stuffed into a mold as they are.
By applying pressure at 00 kg/cd and heating to 100 to 200°C to cause a curing reaction, a carbon fiber reinforced resin composite material using carbon fiber as an aggregate can be produced. When heated in an inert atmosphere at a temperature of 800°C or higher, the thermosetting resin decomposes and becomes porous as described above, so the resin is impregnated and fired repeatedly until the specific gravity shows almost no change. By densifying it to 20% wt content, SiC and graphite combined 2 to 20% wt, A/203 and graphite combined 2 to 20% wt, SiC, A/203 and graphite combined 2 A friction material made of a carbon fiber-reinforced carbon composite material containing carbon containing ~20% wt as a filler and 30 to 70% carbon fiber as an aggregate is obtained. The firing temperature ranges from 1000°C to 2200°C, but 200°C
A temperature of 0°C or higher is desirable. When the temperature exceeds 2200℃, SiC and A
12O3 may decompose. Carbonization is insufficient at temperatures below 1000°C. When the total of SiC, Al 203, and graphite alone, two types, and three types of mixture is less than 2%wt, there is no effect on the friction properties, and when it exceeds 20%wt, the strength of the carbon filler decreases. In addition, adhesion to carbon fibers is poor, resulting in a decrease in strength as a carbon fiber-reinforced carbon composite material. If the amount of carbon fiber used as aggregate is less than 30% wt, the strength will decrease, and if it is more than 80% wt, the carbon content will be small and the strength will decrease.

Effect As described above, the reason why the friction coefficient is stably high and the wear rate is reduced by mixing S i Cs A A' 203 and graphite is considered to be due to the following reasons. That is, in order to bond the carbon fibers together, the carbon filler uses a non-graphite material such as phenol resin or furan resin. These non-graphitic or non-graphitized carbons are oxidized quickly. Therefore, conventional CFRC brake materials oxidize quickly when they generate heat at high temperatures due to friction under high speed and high load conditions. On the other hand, Sl'C1Al2O3
has excellent oxidation resistance, and graphite also has better oxidation resistance than non-graphitized carbon. Therefore, it seems to have an effect on friction performance at high temperatures.

Example Hereinafter, one embodiment of the present invention will be described in detail.

A phenolic resin (UNIPEX S manufactured by Unitika ■) was dissolved in acetone at a ratio of 1=1, and S 1 , A 1 203 and graphite were mixed therein as shown in Table 1.

A fabric made of 6000 filament acrylic carbon fiber (manufactured by Toshi) with 420 warp threads, 420 weft threads, and a weight of 330 gr/af is added to the mixed resin liquid containing one to three types of S1, Al2O3, and graphite. Eight types of brippure rugs were made so that the weight of the fabric and the weight of each mixed resin after acetone evaporated was 1:1. Each is put into a mold and 150 kglo is produced using a 200 ton hot press machine.
A curing reaction was carried out at 200° C. under a pressure of f. This is placed in a vacuum furnace and fired at 2000°C under a vacuum of 1 G-'T or r. After cooling, the process of impregnating it with phenol resin and further firing is repeated until the specific gravity does not increase.
It has become more detailed. A CFRC made from Briprelag made of only phenolic resin without the mixture of Sample Toru 8 shown in Table 1 on the friction disk of a JISD4411 constant speed friction tester.
Attach a plate of 5 mm x 25 mm to the specimen support arm.
Sample N11L1~ shown in Table 1 with a size of mm x 25m
Tests were carried out on the resin mixture of Round 8 according to the method of J I 5D4411. As shown in Table 2, the results are superior in both the friction coefficient and the wear rate compared to the conventional brake material made of CFRC without a mixture of sample Nα8.

<Margin below> Effects of the Invention As described above, according to the present invention, 5iC1AI! 203,
By mixing at least one type of artificial graphite into the filler, the coefficient of friction can be stably increased and the wear rate can be lowered.

Agent Hiroshi Mori Moto

Claims (1)

[Claims] 1. Aggregate consisting of 30-80%wt carbon fiber and carbon 7
A friction material made of a carbon fiber-reinforced carbon composite material comprising a filler of 0 to 20% wt, and 2 to 20% wt of SiC or A based on the total weight of the filler.
A friction material characterized by containing at least one type of l_2O_3 or graphite.