JPH0368091B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a dry sintered friction material having a high coefficient of friction, and more particularly, to two-wheeled and four-wheeled vehicles,
This invention relates to friction alloy materials useful as brake lining materials, disc brake pad materials, clutch facing materials, etc. for industrial vehicles, railway vehicles, etc. Conventional technology and its problems Conventionally, resin molds containing asbestos have been used as friction materials for vehicles, especially two- and four-wheeled vehicles, but in order to meet the current demands for pollution prevention, metal fiber molds have been used. Semi-metallic type materials containing . However, this semi-metallic type friction material also has drawbacks, such as a decrease in the coefficient of friction during rain, and a decrease in the coefficient of friction due to carbonization of the resin under severe conditions such as high loads. Therefore, recently, sintered alloy friction materials have been increasingly used, but there is also a demand for further improvement in performance. That is, automobiles are rapidly becoming smaller and more compact in order to save energy, and disc brake mechanisms and the like are also required to be smaller. In order to realize the miniaturization of disc brake mechanisms and the like, new sintered alloy friction materials with a high coefficient of friction and low wear are required. Means for Solving the Problems The present invention was made in response to the above-mentioned demands, and includes (1) 30 to 70% by weight of copper, (2) 4 to 20% by weight of tin or tin and zinc in total. %, (3) graphite 5-15% by weight, (4) at least one sulfide solid lubricant 0.3-15%
7% by weight, (5) at least one metal oxide 0.5~
10% by weight and (6) at least one hard nitride21~
It pertains to a sintered alloy friction material characterized in that it consists of 50% by weight. According to the present invention, it is possible to obtain a sintered alloy friction material that has excellent wear resistance, a high coefficient of friction, excellent operability, and whose coefficient of friction does not substantially decrease even when it rains. Each component of the sintered alloy friction material of the present invention will be explained below. Since each of these components is mutually related and affects the physical properties of the friction material, it is not necessarily appropriate to discuss the reasons for each limitation individually, but the reasons for the limitations will be shown together. (1) Copper and (2) Tin or tin and zinc These make up the base of alloy friction materials, and are alloyed by sintering to form what is called a bronze base and increase the strength of the base. Particularly from the viewpoint of strength, the content of tin or tin and zinc is 4 to 20% by weight relative to 30 to 70% by weight of copper. If tin or tin and zinc is less than 4% by weight, it will not have sufficient strength to hold graphite and other non-metals, while if it exceeds 20% by weight, it will embrittle the friction material.
Reduce strength. (3) Graphite The addition of graphite mainly stabilizes the coefficient of friction. That is, in general, the frictional force generated between two surfaces of friction materials that slide against each other is (a) the force required to shear the adhesion that occurs in a part of the two surfaces, and (b) the force required to shear the adhesion that occurs on a part of the two surfaces, and (b) the force caused by the hard particles of the opposing material. It is said that this is due to the power of digging. By existing between these two surfaces, graphite controls adhesion that occurs between the two surfaces.
Therefore, the presence of an appropriate amount of graphite improves and stabilizes the friction coefficient of the friction material, and also improves the wear resistance. If the amount of graphite is less than 5% by weight, the above effects will not be sufficiently exhibited, whereas if it exceeds 15% by weight, the material strength will decrease and the coefficient of friction will decrease. (4) At least one type of sulfide solid lubricant such as molybdenum disulfide, tungsten disulfide, manganese sulfide, etc. Molybdenum disulfide not only has the same effect as graphite, but also prevents so-called "squeal" and under high loads. It also has the remarkable effect of imparting lubricity when used. The amount of molybdenum disulfide, etc. used is
The content should be 0.3 to 7% by weight. The usage of these is 0.3
If the amount is less than 7% by weight, the effect of addition will not be sufficiently exhibited, while if it exceeds 7% by weight, the material strength and coefficient of friction will decrease. (5) At least one metal oxide such as alumina, silica, mullite, etc. Alumina, etc., has the above-mentioned excavation effect when used in the range of 0.5 to 10% by weight, and also forms on the mating sliding surface due to frictional heat. By removing the oxide film, adhesion between friction materials is stably generated and stable frictional force is exerted. If the amount used is less than 0.5% by weight, the above effects will not be fully exhibited, while if it exceeds 10% by weight, there is a tendency for the mating sliding surface to become rough. (6) At least one hard nitride such as Si ₃ N ₄ , AlN, BN, TiN, etc. These particularly contribute to improving the coefficient of friction. If the amount is less than 21% by weight, the coefficient of friction cannot be sufficiently improved, while if it exceeds 50% by weight, the strength of the base material decreases and the amount of wear increases. In order to manufacture a desired product, such as parts for disc brakes, using the material of the present invention, each raw material powder is blended according to a conventional method, and after press-molding it into a predetermined shape, a neutral or reducing It may be fired at a temperature of about 730 to 880° C. under pressure of about 3 to 7 kg/cm ² in an atmosphere. Effects of the invention The friction coefficient of the sintered alloy friction material according to the invention is as follows:
Higher than conventional products (about 0.3 to 0.5), 0.5 to 0.8
reach a certain extent. Therefore, when the present invention material is used, for example, as a disc brake pad for two-wheeled and four-wheeled vehicles, (a) improved braking performance, (b) improved wear resistance of pads and discs, and (c)
Effects such as miniaturization of the brake mechanism and simplification of the (d)pad insulator are produced. Examples Hereinafter, the features of the present invention will be further clarified by Examples and Comparative Examples. Examples 1 to 6 and Comparative Examples 1 to 2 After molding 100 parts by weight of a blend consisting of each raw material and residual copper in the proportions shown in Table 1 at a pressure of 4 ton/cm ² ,
The molded product was placed on a Cu-plated steel plate and fired at 780° C. for 60 minutes under a load of 5 kg/mm ² in an N ₂ atmosphere.

[Table] Using the thus obtained fired product as a pad material, the inertia force
1.25Kg・m・sec ² , initial braking speed 50Km/hr, contact area 20cm ² , surface pressure 20Kg/cm ^{2 , and} the brake was brought into repeated contact with the mating disc material (13 chrome steel) 300 times at 60 second intervals. Ta. Table 2 shows the average coefficient of friction and the amount of wear of the pad material and disk material.

【table】

[Table] As is clear from the results shown in Table 2, the sintered alloy friction material according to the present invention has a high coefficient of friction, excellent wear resistance, and a small amount of wear on the mating material.

Claims (1)

[Claims] 1 (1) 30 to 70% by weight of copper, (2) 4 to 20% by weight of tin or a total amount of tin and zinc, (3) 5 to 15% by weight of graphite, (4) Sulfide solids At least one lubricant 0.3-7
(5) 0.5 to 10% by weight of at least one metal oxide;
and (6) 21 to 50% by weight of at least one hard nitride. A sintered alloy friction material.