JPH0245588A - Complex friction material - Google Patents

Abstract

PURPOSE:To obtain the title material having slight variability of coefficient of friction even at high temperature, preventing occurrence of contact sound comprising an organic material not containing asbestos fibers by adding hollow spherical non-glass ceramic to a base material consisting essentially of thermosetting resin and graphite. CONSTITUTION:A base material consisting essentially of (A) a thermosetting resin such as phenol resin and (B) 3-30(vol)% graphite is blended with (C) 5-60vol% hollow spherical non-glass ceramic which preferably comprises one or more selected from mullite, alumina, silica, magnesia, titania and zirconia and has 10-500mum particle diameter to give the aimed material.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is an organic friction material that does not contain asbestos fibers, which has little variation in friction coefficient even at high temperatures, and which is intended to prevent the generation of squealing noise. It is related to.

[Conventional technology]

Conventionally, friction materials used for friction brakes and flanch for automobiles, industrial machinery, etc. have been manufactured using asbestos fibers as a base material. As for the composition, asbestos fiber as a reinforcing material is 10
~70% by volume, thermosetting resin as binder 10-4
It consists of metal fibers or metal powder particles, inorganic powder, organic powder, etc. as a friction and wear adjusting material, and is manufactured by mixing, molding, and, in some cases, polishing and grinding these components.

However, as asbestos fibers are considered to be harmful, the manufacture and use of products containing asbestos fibers as a main component are subject to regulations, and there is an urgent need to develop materials to replace asbestos fibers as friction materials.

In response to this, a semi-metallic friction material containing still fiber as H and fibric acid components was developed, and has come to be widely used primarily as brake pads for automobiles.

This semi-metallic friction material has reinforcing properties, heat resistance, and crushability, and its main components are metal components such as steel fiber and iron powder, which are readily available and inexpensive, and graphite, mixed with organic or inorganic fillers, and phenolic resin. It is hardened with a binding material such as. However, this semi-metallic friction material also has the disadvantage that steel fibers and the like are easily rusted, so that when rust occurs, the material becomes more aggressive toward the friction material and generates squealing noise.

In addition, a friction material (Japanese Patent Application Laid-open No. 149786/1986) has been proposed in which lightweight carbonaceous hollow spheres are blended into raw materials consisting of a reinforcing base material, a friction adjustment material, and a thermosetting resin, but the carbonaceous material is slippery. Moreover, since the pores are secured by the lightweight carbonaceous hollow spheres, there are problems such as that it is difficult to increase the blending ratio from the viewpoint of strength.

[Problem to be solved by the invention]

Friction materials such as asbestos fiber-based, semi-metallic, and non-asbestos-based friction materials using inorganic fibers, organic fibers, etc. used in electromagnetic clutches and brakes of automobiles and industrial machinery may fade or fade depending on the conditions in which they are used. At high temperatures, braking force may decrease, and unpleasant vibrations and squealing noises may occur.

An object of the present invention is to provide a friction material that does not cause rust, stably obtains a desired coefficient of friction even at high temperatures, and suppresses noise generation.

[Means to solve the problem]

As a result of intensive research to achieve the above object, the inventor of the present invention has found that when hollow spherical non-vitreous ceramics are added, which hardly decreases in hardness even at high temperatures, As the decomposed gas escapes into the voids formed by the pores of the friction material, fading is prevented without increasing gas pressure.In addition, a stable friction coefficient at high temperatures is obtained, the wear rate is low, and the mating material is The present invention was completed by discovering that there was almost no wear on the parts.

That is, the gist of the present invention resides in a composite friction material characterized by being formed by adding hollow spherical non-vitreous ceramics to a base material whose main components are a thermosetting resin and graphite.

As the hollow spherical ceramic used in the present invention, a material other than glass is used. Glassy material is made by adding melting point lowering components such as Na and Ni to silica, and this material is not suitable because at high temperatures, the glass hollow spheres melt due to frictional heat, and the glassy material spreads over the friction surface, reducing friction performance. do not have. For this reason, ceramic hollow spheres are stable at high temperatures.
For example, it is preferably selected from mullite, alumina, silica, magnesia, titania, zirconia, and the like.

Graphite is necessary to improve lubricity and prevent wear, and thermosetting resin is used as a binder during molding. The composition ratio of graphite is preferably 3 to 30 volume %, more preferably 5 to 20 volume %, and the ceramic hollow spherical powder is preferably 5 to 80 volume %, more preferably 10 to 20 volume %.
It is 50%. If the graphite content is less than 3% by volume, the lubricity is insufficient, and if it exceeds 30% by volume, the strength will be reduced. If the ceramic hollow spherical powder is less than 5% by volume, the effect of preventing squealing noise will be insufficient. If it exceeds the volume %, the attack on the friction partner material will increase. When using two or more types of ceramic hollow spheres, it is preferable that the total falls within the above range.

In addition to the above three types of combinations, based on these combinations, solid ceramic powder,
Inorganic materials such as barium sulfate, molybdenum disulfide, and boron nitride, organic materials such as Camus dust and rubber, and metal powder can also be appropriately added in a total amount of 30% by volume or less.

If the ceramic hollow spherical powder used in the present invention is less than 10 gm, it will be difficult to form it, and if it exceeds 500 gm, it will be difficult to make uniform contact with the friction partner material, so a particle size of 10 to 500 gm is preferable. If the proportion of the hollow space in the spherical powder is less than 30%, the effect of the hollow space will be insufficient, and if it exceeds 80%, the strength of the ceramic will decrease, so it is preferably 30 to 90%, more preferably 50 to 8
It is 0%.

The friction material of the present invention may be manufactured using well-known techniques, such as mixing the above-mentioned materials in appropriate proportions, molding under heat and pressure, and cutting, polishing, etc. as necessary.

Comparing the friction material of the present invention with conventional resin-based friction materials, the conventional resin-based friction materials have poor friction properties at high temperatures;
The dynamic friction coefficient, static friction coefficient, and wear rate all show a tendency for deterioration. For example, the coefficient of static friction of conventional resin systems is 10 from room temperature.
Up to around 0°C, there is little change at approximately 03, but beyond that it shows a rapid decrease, and above 200°C, the static friction coefficient reaches 0.
, significantly below 1. Furthermore, the wear rate of conventional resin systems increases with increasing temperature, and at 250°C the wear rate increases by approximately 10%.
×107cm'/kgm, and a stable wear rate cannot be obtained. These causes have resulted in a reduction in braking force and the generation of unpleasant vibrations and squealing noises.

On the other hand, the friction material of the present invention has good friction properties even at high temperatures, and the static friction coefficient is stable between 0.2 and 0.4 in the friction material temperature range of 0 to 300'C. The wear rate is also 2X 1O-7c at a friction material temperature of 0 to 300°C.
m” can be maintained at a value of 7 kgm or less.

〔Example〕

The results of the present invention will be explained below using Examples and Comparative Examples.

The test method was as follows.

A friction material sample molded to have an outer diameter of 100mm, an inner diameter of 60I, and a thickness of 2mm was glued to an outer diameter of 100mm and a thickness of 5mm.
The friction material is adhered to a carbon steel base material, and the surface of the friction material is finished by polishing or the like in order to obtain flatness and smoothness with the carbon #4X material. This combination is hereinafter referred to as a ``friction material''. The friction partner material in contact with the friction material has an outer diameter of 10
Carbon steel with an inner diameter of 80 am and a thickness of 5 cm is used, and the parts that come into contact with the friction material are polished to a smooth finish. Hereinafter, this will be referred to as the "mate material."

The mating material rotates the motor at θ ~ 1000 rpm with a transmission.
Install it so that ffl rotation can be done. The non-rotating friction material is installed so that its entire surface is in contact with the mating material, and the surface pressure can be adjusted.

Using this test device, the temperature of the friction material, torque, rotational speed friction coefficient, generated noise, wear condition of the friction material, wear condition of the mating material, etc. are observed.

The measurement conditions were as shown in Table 1.

Table 3 shows examples of test results for friction materials having the compositions shown in Table 2.

(Margins below) Table 1: Composition shown in Table 2 for this test device (unit: volume %)
) were investigated. Here, the ceramic hollow spherical powder in Table 2 is mullite (2S+02/3A, 0
3) with an average particle size of 70 tiles.

Ceramics were used in which the percentage of hollow spaces was 70%.

The comparative examples are conventional products, and 1 is an asbestos-based product and 2 is a semi-metallic-based typical product.

Table 1 [Effects of the Invention] The composite friction material according to the present invention has excellent friction properties such as friction coefficient and wear rate even at high temperatures, and has the characteristics as a friction material with little noise generation.

teenager Reason Man

Claims (1)

[Claims] 1. A composite friction material characterized in that it is made by adding hollow spherical non-vitreous ceramics to a base material whose main components are a thermosetting resin and graphite. 2. The composite friction material according to claim 1, wherein the hollow spherical non-vitreous ceramic is made of at least one selected from mullite, alumina, silica, magnesia, titania, and zirconia. 3. The particle size of the hollow spherical non-vitreous ceramics is 10-5.
The composite friction material according to claim 1 or 2, which has a diameter of 00 μm. 4. The composite friction material according to any one of claims 1, 2 and 3, wherein the hollow spherical non-vitreous ceramic occupies 30 to 90% of the hollow space. 5. In the composite friction material, the proportion of graphite is 3 to 30% by volume, and the proportion of hollow spherical non-vitreous ceramics is 5.
The composite friction material according to any one of claims 1, 2, 3, and 4, wherein the content is 60% by volume.