JPH0960673A - Sintered metal friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide sintered metal friction material which has good abrasion resistance and moderate attack performance on an opposite surface. SOLUTION: Sintered metal friction material used as braking pad or braking lining of an automobile contains 70 to 80 volume % of copper or copper alloy as binding material, 0.2 to 5.0 volume % of titanium and 5 to 15 volume % of graphite powder as filling material and the surface of part or all of graphite powder are covered by titanium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material used for a brake pad or a brake lining of a vehicle such as an automobile, the friction material having good wear resistance and having a moderate attacking property against a facing surface. It relates to a sintered metal friction material.

[0002]

2. Description of the Related Art Conventionally, a sintered metal material is used as a brake material for decelerating or stopping a large vehicle or a heavy vehicle. This is because the sintered metal material is superior in wear resistance to the friction material using asbestos or thermosetting resin and can withstand severe use. Conventional copper-based sintered metal friction materials generally use a copper alloy such as copper or bronze as a binder and a filler such as graphite or molybdenum disulfide as a lubricant.

[0003]

Among these, graphite is useful for stabilizing the friction coefficient and reducing wear of the friction material itself and the facing material. However, graphite used as a lubricant has poor wettability with copper and copper alloys as binders,
Graphite easily comes off from the friction material body during brake braking. Therefore, graphite does not exert a sufficient effect as a lubricant, its contribution to the wear resistance of the friction material is small, and its aggressiveness to the facing rotor or the like is not good. Therefore,
The problem to be solved by the present invention is to use a copper alloy such as copper or bronze as a binder, in a sintered metal friction material using graphite as a lubricant, in which the binding force between copper or a copper alloy and graphite is a binder. It is an object of the present invention to provide a sintered metal friction material which is reinforced and in which graphite is less likely to drop from the friction material main body during braking.

[0004]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of solving the above-mentioned problems, and its constitution is a copper-based sintered metal friction material comprising 70 to 70% copper or copper alloy as a binder. 80 wt%, 0.2 titanium as a filler
.About.5.0% by weight and 5 to 15% by weight of graphite powder, and part or all of the surface of the graphite powder is coated with titanium. That is, the inventor of the present invention has found that if titanium, which has good wettability with both graphite and copper, is attached to the surface of the graphite powder, the graphite will not easily fall off from the friction material body, and the present invention has been accomplished. Of.

The graphite powder used in the present invention may be natural graphite such as scaly graphite, scaly graphite or earth graphite, or artificial graphite, but powdery graphite having an average particle diameter of 100 to 2000 μm is preferable. The thickness of titanium coating is 5μ
It is desirable that the diameter of m to 200 μm is about 1/10 to 1/30 of the graphite powder diameter. Therefore, the first titanium to be prepared is a powder having an average particle diameter of about 5 to 200 μm, which is a convenient size for adhering the titanium powder to the surface of graphite.

As a method of coating the surface of graphite powder with titanium, a method of granulating or compounding is required. Titanium powder is useful for strengthening the binding force between graphite and copper, but it is expensive, and therefore it is preferable that the amount is small, and granulation or compounding is a preferable method because the amount of titanium powder can be suppressed to a small amount.
Examples of the granulation method include rolling granulation, fluidized bed granulation, mixed granulation such as stirring granulation, forced granulation such as extrusion granulation, disintegration granulation, and heat utilization granulation such as melt granulation. It can be illustrated. Further, examples of the method of compounding include mechanofusion treatment, kryptron treatment, and hybridization treatment.

The content of titanium is preferably 0.2 to 5.0% by weight. If the content is 0.2% or less, the surface of graphite cannot be sufficiently covered, and if it is 5.0% or more, the friction performance of the friction material is high. May damage the Further, the graphite powder is preferably 5 to 15% by weight, and when the amount is 5 or less, the stability of the friction coefficient is poor,
In the above case, the coefficient of friction is lowered and a sufficient effect of the brake cannot be obtained. Further, 70 to 80% by weight of copper or copper alloy is desirable, and the strength of the friction material is low at 70% or less.
In the above case, the stability of the friction coefficient may be deteriorated. As for materials other than the above, it is possible to use an appropriate amount of materials conventionally used for sintered metal friction materials. Further, the sintered metal friction material can be manufactured by a method that has been conventionally performed except for the above-mentioned granulation or compounding operation.

[0008]

The sintered metal friction material of the present invention uses copper or copper alloy as the binder and graphite as the lubricant. Since the surface of the graphite is coated with the titanium film, the wettability is originally poor. The binding force between graphite and copper or copper alloy increases. As a result, graphite is less likely to fall off from the friction material body during brake braking, and the effect of graphite as a lubricant is fully exerted, and the wear resistance and face-to-face aggression of the friction material are improved.

[0009]

Next, an embodiment of the present invention will be described. Examples A to G First, the graphite surface was coated with titanium by mechanofusion treatment in vacuum. Graphite has an average particle size of 8
00 μm and titanium having an average particle size of 45 μm were used. The titanium coverage on the surface of the graphite powder was about 5% in Examples A to C, about 10% in Examples D and E, and about 30% in Examples F and G. Next, copper and bronze are used as the binder, graphite is coated with titanium as the filler, silicon dioxide and molybdenum disulfide are used to uniformly mix them in a ball mill, and the mixture is placed under an inert gas atmosphere. Temperature 820
Sintered metal friction materials of Examples A to G having the compositions shown in Table 1 were obtained by sintering at a temperature of 10 ° C / cm ² for 1 hour. still,
The numerical values in Table 1 show% by weight.

Comparative Examples a and b Without using titanium as a friction material, a sintered metal friction material of Comparative Example a having the composition shown in Table 1 was obtained in the same manner as in the Examples. Further, a sintered metal friction material of Comparative Example b having the composition shown in Table 1 was obtained in the same manner as in the example by using titanium carbide powder instead of titanium. Example A produced by the above method
To G and the sintered metal friction materials of Comparative Examples a and b,
Le Dynamo tester (1/1 of full size dynamo tester
Table 2 shows the results of the frictional wear test (JASO C406) and the tensile strength test according to 0). The friction coefficient in Table 2 is measured under the conditions of an initial speed of 50 km / h and a deceleration of 0.3 G.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

As described above, the sintered metal friction material of the present invention is
Consists of binder such as copper or bronze, filler such as silicon dioxide, molybdenum disulfide, etc. As a result of including graphite powder coated with titanium, wear resistance and face-to-face attack of friction material are improved Therefore, it is suitable as a friction pad used for a brake pad or a brake lining of a vehicle such as an automobile.

Claims (2)

[Claims] 1. Copper or copper alloy 70 to 8 as a binder
0% by weight, 0.2 to 5.0% by weight of titanium as a filler, 5 to 15% by weight of graphite powder, and part or all of the surface of the graphite powder is coated with titanium. Sintered metal friction material. 2. The titanium coating has a thickness of 5 μm to 200 μm.
The sintered metal friction material according to claim 1, wherein