JPS5925867A - Friction braking material - Google Patents

Abstract

PURPOSE:A friction braking material, prepared by bonding a base material consisting of an inorganic material to silicon carbide whiskers, a filler or modifying material and a friction improving material with a thermosetting resin, and molding the resultant bonded materials and having a high abrasion resistance without using asbestos. CONSTITUTION:A friction braking material prepared by incorporating preferably 30-70% base material consisting of fibers, e.g. glass fibers, or powder, e.g. zinc oxide, of an inorganic material with preferably 1-10% silicon carbide whiskers, preferably 5-20% organic or inorganic filler or modifying material, e.g. copper powder or rubber compound, and preferably 5-10% friction improving material, hot pressure molding the resultant mixture with a thermosetting resin, e.g. a phenolic resin, as a binder, and if necessary polishing the surface of the resultant molded material. EFFECT:No reduction in the coefficient of friction at high temperatures.

Description

[Detailed description of the invention] The present invention relates to improvements in friction brake materials.

Friction brakes are used in the braking mechanisms of automobiles, motorcycles, railway vehicles, aircraft, and various machines.
Conventionally, brake materials have been used that are made of asbestos as a base material, to which various additives have been added, and then molded into a desired shape using a thermosetting resin binder such as phenolic resin.

However, it has become clear that asbestos that scatters as brake materials wear out has an adverse effect on the human body, and efforts are being made to develop brake materials that do not contain asbestos. Friction brake materials that use thermosetting resin as a binder generally have a tendency for the friction coefficient to drop rapidly and the amount of wear to increase at temperatures exceeding 300°C. increase

On the other hand, the conditions under which brake materials are used are becoming increasingly severe, and even in brakes for relatively light loads, it is inevitable that the temperature of the friction surface will rise considerably.
This often leads to dangerous consequences such as fading phenomena and abnormal wear.

The present inventors have solved a public health problem by eliminating the use of asbestos in friction brake materials (particularly woven or molded brake materials), and have demonstrated excellent performance while withstanding harsh usage conditions. We have conducted extensive research with the goal of providing brake materials. As a result, the present inventors have discovered that this goal can be achieved by using silicon carbide whiskers in combination with shingled fibers and aramid fibers or carbon fibers, leading to the present invention.

In particular, the combined use of silicon carbide whiskers and aramid fibers yields excellent results.

The basic structure of the friction brake material of the present invention is to heat various materials consisting of a base material made of inorganic fiber or powder, silicon carbide whiskers, an organic or inorganic filler or modification material, and a friction improving material. It is obtained by bonding with a curable resin binder and molding.

A modification of the invention provides that a portion of the silicon carbide whiskers is
It was replaced with carbon fiber.

Another modification of the present invention is to replace a portion of the silicon carbide whiskers with aramid fibers.

Conventional woven or molded brake materials contain as much as 40 to 70% (by weight) asbestos as a base material, but the present invention does not use asbestos at all, and as mentioned above, other materials are used. The base material is fiber sludge or powder of inorganic material.

Glass fiber is a typical example of inorganic fibers other than asbestos, but rock wool and others can also be used. Of course, it is not necessary to use long fibers; short fibers are better from the standpoint of ease of mixing. Examples of inorganic material powders include zinc oxide.

Examples include calcium carbonate and calcium sulfate, and powders of other similar inorganic compounds can also be used. They may be used alone or in combination of two or more. Either the fiber or the powder of the inorganic material as the base material is sufficient, but both may be used, and even better results can be obtained. The amount of substrate is 30-70% based on the weight of the product. Usually around 50 inches is appropriate.

Silicon carbide whiskers have a diameter of 0.1 to 1μ and a length of 50
Short fibers of about 100 microns are readily available on the market, and it has been confirmed that they are useful as a material for the brake system of the present invention.

As the carbon fiber, short fibers available on the market may be used.

Aramid fiber is a synthetic fiber commercially available under trade names such as "Kevlar" and has high abrasion resistance in addition to tensile strength. The heat resistance is also about 200°at, which is lower than silicon carbide or carbon fiber, but is higher among synthetic fibers.

The maximum amount of silicon carbide whiskers that can be replaced with carbon fibers or aramid fibers is about half to -, depending on the amount of silicon carbide used. If the amount of silicon carbide is suitable, based on the weight of the product brake material.
The scar content should be selected from a range of 1 to 10%, preferably 2 to 5%, and the carbon fiber or aramid fiber should be selected from a range of 1 to 15%, preferably 2 to 7%.

The benefits of using aramid fibers lie partly in weight and partly in price. That is, aramid fibers have a lower density than silicon carbide whiskers (approximately 1.4
), and much cheaper. Moreover, as shown in the examples described later, a brake material using this material exhibits performance comparable to that when a relatively large amount of silicon carbide whiskers are used. The fact that aramid fibers, which have a heat resistance temperature of about 200° C., is useful for brake materials that are exposed to high temperatures due to friction was something that the present inventors had not anticipated.

Organic heavy or inorganic fillers or modifiers are blended materials that have the purpose of increasing their weight and adding something to their performance as brake materials. One group of them includes copper powder and zinc powder. There are some metal powders. These act to increase the thermal conductivity of the product brake material and moderate the local temperature rise on its surface. The appropriate amount is in the range of 5 to 20%. Examples belonging to the other group include fillers such as rubber compounds, pallite, cashew grains, and clay, whose addition can be expected to improve wear resistance and mechanical properties. It is also preferable to mix one type or two or more types, and in the case of two or more types, the total amount is about 5 to 20%.

Friction improving materials refer to conventionally used lubricants at high temperatures, such as carbon black and molybdenum disulfide. The appropriate amount is 5 to 10%.

The friction brake material of the present invention may be manufactured according to known techniques. In short, each of the above-mentioned materials is mixed in appropriate proportions, a thermosetting resin such as phenolic resin, which is also commonly used in the manufacture of brake materials, is used as a binder, and the material is heated and pressed. , polish the surface if necessary.

According to the present invention, it is possible to obtain a brake material that eliminates asbestos from a friction brake material, has high wear resistance, and does not have a decrease in friction coefficient even at high temperatures.

Brake materials with these characteristics are ideal for braking mechanisms that require durability and use under high loads.
It has a wide range of uses including automobile brakes.

Example Using a Littleford mixer, which has an excellent ability to mix tangled short fibers, fibrous materials including silicon carbide whiskers as shown in the table were loosened, and the remaining ingredients were added to the mixer. They were blended in the proportions listed in the table and stirred to form a homogeneous mixture.

The mixture was applied to a compression molding machine and preformed by applying a pressure of 100 to 9/c4 at room temperature.

Then, using a mold shaped to give a test piece, the temperature was 150°C.
Pressure and heat molding was carried out for 7 minutes at ~155°C and a pressure of 250 H/crl. After that, 180~200℃
A brake material test piece was obtained by heat-treating at a temperature of 5 hours, cooling, and polishing the surface.

``For comparison, a conventional brake material test piece using an asbestos base material was manufactured under similar conditions.

These test pieces were run on a full-size dynamometer.
A test was conducted under the conditions of an initial brake speed of 507 cm/hr and a number of braking cycles of 1000 times, and the wear thickness at various temperatures was measured.

The results are shown in FIG. Examples according to the invention include:
There is less wear compared to conventional technology, and the difference is particularly noticeable on the high temperature side.

Separately, a brake material test piece was prepared in accordance with JASO-6914 passenger car brake system dynamometer test method, and the friction coefficient was measured.

The results are shown in Figure 2. Also in this test, it is clear that the brake performance according to the present invention does not suffer from a decrease in braking performance at high temperatures.

(weight%)

[Brief explanation of drawings]

The drawings are all graphs showing the influence of temperature on the performance of the friction brake material of the present invention in comparison with conventional products, with Fig. 1 showing the wear thickness and Fig. 2 showing the coefficient of friction. . Patent Applicant Daido Steel Co., Ltd. Representative Patent Attorney Souo Suga 1 Figure 100 300 500 1 Ant (0C) Fang 2 Figure 100 300 500 Mitsuyu (°C) Procedural Amendment (Method) % Formula % 2, Name of the invention: Friction brake material 3. Relationship with the case of the person making the amendment. Patent applicant address: 66 Kade, Hoshizaki-cho, Minami-ku, Nagoya, Aichi Prefecture (371) Daido Steel Co., Ltd. 4, Agent: 104 Address: Tokyo, Japan Chuo-ku Tsukiji 2-15-14 Shipping date
On October 26, 1981, 6, the detailed description of the invention in the specification to be amended 7 and the table on page 11 of the specification of the contents of the amendment are submitted.

Claims (6)

[Claims] (1) A base material made of inorganic fiber or powder, silicon carbide whiskers, an organic or inorganic filler or modifier, and a friction improving material are bonded together with a thermosetting resin binder and molded. A friction brake material that is characterized by its advantages. (2) The friction brake material according to claim 1, in which a part of the silicon carbide whiskers is replaced with aramid fiber or carbon fiber. (3) Based on the weight of the product, silicon carbide whiskers are
10%, preferably 2-5%, 1-1 aramid fiber
Claim 2 containing 5%, preferably 2 to 7%
Friction brake material. (4) The friction brake material according to any one of claims 1 to 3, which contains glass fiber as the inorganic material fiber in an amount of 30 to 60% of the product weight. (5) As an inorganic material powder, use one or more of zinc oxide, calcium carbonate, and barium sulfate. If two or more are used, the total amount is 20 to 50% of the product weight.
% of the friction brake material according to any one of claims 1 to 3. (6) As an inorganic modifying material, use one or both of copper powder and zinc powder, in the case of both, the total amount is 5.
The friction brake material according to any one of claims 1 to 3, containing ~20%.