JPS63135616A - Composition for sliding member - Google Patents

Abstract

PURPOSE:To obtain a composition for a sliding member avoiding generation of abnormal noise, by forming the composition from a solid lubricant such as graphite as a primary component, and mixing a reinforcing material, a calcium carbonate powder and a synthetic resin binder. CONSTITUTION:The composition is composed of a solid lubricant such as graphite and molybdenum disulfide as a primary component, and the solid lubricant is mixed with a reinforcing material selected from a metal chop of wire, fiber, wool, ribbon or foil, or a metal powder, 2-30wt% of calcium carbonate powder and/or boron oxide powder, and phenol resin. The composition is filled in a metal mold having a desired shape, and is pressed to obtain a sliding member having the desired shape. The sliding member is improved in friction and wear characteristics and avoids generations of abnormal noise.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a composition for sliding members suitable for use in locations where heat resistance is required.

In the present invention, "sliding members" refer to bearing bushings used in locations that receive loads and slips in various machines;
These include sliding plates, or seal rings used in spherical pipe joints of automobile exhaust pipes, which require a sealing function in addition to load and slip resistance.

[Conventional technology]

Conventionally, this type of sliding member has been made of metal materials, non-metal materials such as graphite and other ceramics, composite materials such as cermet, and even tetrafluoroethylene resin (
Heat-resistant plastic materials such as PTFE) and polyimide resin are known.

All of these materials have heat resistance, but under dry friction conditions, there are problems with friction and wear, mechanical strength, especially impact strength, and compatibility with the mating material. However, there are still problems such as poor performance.

Already, in order to solve these problems, expanded graphite obtained by special treatment of graphite is used as a reinforcing material ( Sliding members molded with metal fibers, etc.) have been developed, but while they are heat resistant and have excellent compatibility with mating materials, they often make abnormal noises when sliding under dry friction. It has the disadvantage of causing

In addition, sliding members made of heat-resistant materials such as mica or asbestos, together with reinforcing materials, are also known, but these also have similar problems.

Furthermore, Japanese Patent Application Laid-Open No. 57-33267 discloses a sliding member formed by press molding a mixture of graphite and metal fiber cotton, but this also often causes abnormalities during sliding due to dry friction. It has the disadvantage of generating sound.

[Problem that the invention seeks to solve]

As a result of conducting experiments from various angles, the inventors of the present invention discovered the following about the cause of this abnormal sound.

In other words, in this type of sliding member, the metal fibers that serve as reinforcing materials constituting the member are deposited on the sliding surface as fine abrasion powder, and this abrasion powder is oxidized at high temperatures to become oxides that prevent the sliding member from sliding. This means that it acts aggressively on the sliding surface, significantly impairing the friction and wear characteristics and causing abnormal noise. We have also discovered that under dry friction conditions, the quality of film formation of the solid lubricant film on the surface of the mating material has a great effect on the friction and wear characteristics.

The present invention is suitable for applications where it is difficult to apply lubricants such as oil or wax to sliding surfaces, for example, from room temperature to high temperature (300°C).
A composition for sliding members that is suitable for use under dry friction conditions over a wide temperature range (up to The purpose is to obtain.

[Means for solving problems]

The present invention employs the following technical means (configuration) to achieve the above-mentioned object.

That is, the main component is a solid lubricant such as graphite or molybdenum disulfide, and a reinforcing material selected from metal wire, fiber, wool, ribbon, chopped foil, or metal powder, and calcium carbonate and/or boron oxide powder. and a synthetic resin binder.

In the above configuration, graphite, molybdenum disulfide, tungsten disulfide, etc. are used as the main solid lubricant, and are mixed in the composition at a ratio of 10 to 35% by weight.

Metal wire, fiber, wool as reinforcement,
For ribbons, foil chops, and powders, iron or iron-based alloys such as steel and stainless steel are used, but copper or copper-based alloys such as bronze, phosphor bronze, It can also be used as a mixture of lead bronze, brass, aluminum bronze, etc.

Wire, fiber and wool chops as reinforcement have a diameter of 20-200μ and a length of 100μ-10m
m, ribbon and foil chops - side 100μ ~ 3m
The metal powder used is approximately rectangular in shape and has a mesh size of 40 to 400 mesh.

- These reinforcements are mixed in the composition in a proportion of 40 to 80% by weight, preferably 50 to 70% by weight. 40% by weight
If the weight is less than 80 kg, the effect as a reinforcing material is poor, and cracks or deformations are likely to occur during use, and if the weight exceeds 80 weight, a large proportion of the material will be exposed on the sliding surface, reducing the lubricating effect of the solid lubricant, which is the main component. let

Calcium carbonate (CaCo) and/or boron oxide (B203) powder in the composition does not exhibit any lubricity by itself, but when mixed with a solid lubricant and a reinforcing material, it forms a film on a mating material of the solid lubricant. It promotes the film-forming properties of the sliding member, improves the friction and wear characteristics of the sliding member, and prevents the oxidation of the metal wear powder of the reinforcing material caused by friction, and reduces the abrasive action of the oxidized wear powder caused by the oxidation of the wear powder. This has the extremely important effect of suppressing the This improvement in frictional wear characteristics and the suppression of the abrasive action of oxidized wear particles lead to the effect of preventing abnormal noise during friction. Each of these can be mixed alone or as a mixture in the composition, and the composition can contain 2 to 301%, preferably 5 to 30%.
They are mixed in a proportion of 20% by weight. If it is less than 2% by weight, the above-mentioned effects will not be exhibited, and if it is more than 30% by weight, the lubricating effect of the solid lubricant, which is the main component, will be reduced.

Phenol resin is used as the synthetic resin binder.
3-15% by weight in the composition, preferably 7-10% by weight
mixed in the proportion of

Next, a method of applying the above-mentioned composition for sliding members will be described below.

A first application method is to fill a mold having a desired shape with the composition for a sliding member and press-form it to obtain a sliding member having a desired shape. The method is to apply it as a sliding layer to the surface (sliding surface) of a sliding base material.

That is, a sliding base material obtained by molding a heat-resistant material such as expanded graphite, mica, or asbestos so as to be integrated with a reinforcing material consisting of metal fiber, metal wire, or a wire mesh obtained by weaving or knitting these materials. A sliding member is obtained by coating the above-mentioned composition for a sliding member on one side (sliding surface).

〔Example〕

Examples of the present invention will be described below.

(Example) Steel wool chop 6 with a diameter of 100μ and a length of 2mm
0-70% by weight, 5-20% by weight of calcium carbonate and/or boron oxide powder, 7% by weight of phenolic resin powder
The remaining graphite was placed in a mixer and mixed to prepare a composition for a sliding member.

This composition was loaded into a mold and press-molded so that one side was 2
A rectangular preform with a diameter of 0 mm and a thickness of 5 mm was prepared.

Next, this preformed body was placed in a furnace set at a temperature of 80°C for 30 minutes to preheat it, and then the phenol resin was cured by heating at a temperature of 180°C for 2 hours, and then taken out from the furnace and integrated. A sliding member was obtained.

Table 1 shows the composition of the sliding member thus obtained.

Table 1 No. 7 in the table indicates a comparative example.

Also, the friction coefficient and wear in the table! (ms) is the test result conducted under the following conditions, the friction coefficient is shown as the value 1 hour after the start of the test, and the amount of wear is shown as the value 20 hours after the start of the test.

(Test conditions) Load: 5 Kg/am" Sliding speed: 12 m/wi
n Atmosphere temperature: 400° C. Comparing material: 5115304 test Thrust test Table 2 shows the results of determining the presence or absence of abnormal noise for the above-mentioned test pieces.

The evaluation of abnormal sounds is as shown below.

Evaluation symbol ■: Only normal fricative sounds and no abnormal sounds.

Evaluation symbol ■: When the ear is brought close to the test piece, a faint abnormal sound can be heard in addition to the fricative sound.

Evaluation symbol ■: At the fixed position (1.5 m away from the test piece), it is drowned out by the sounds of the living environment, and is difficult to distinguish in general, but can be identified as an abnormal sound by the test person.

Evaluation symbol ■: A sound that anyone can identify as an abnormal sound (unpleasant sound) in a fixed position.

(Margins below) As can be seen from the test results in Table 2 and above, the sliding member made of the composition of the present invention has significantly reduced wear compared to the comparative example (No. 7), and has no abnormal noise. It has received extremely good evaluations throughout the testing period.

Regarding the generation of abnormal noises, there was not much difference between the samples of the present invention and those of the comparative example at the initial stage of friction (breaking-in period), but as the test time progressed, a noticeable difference appeared in the generation of abnormal noises.

This is due to the fact that over the course of the test, wear particles from the reinforcing steel accumulate on the friction surface and are oxidized to become oxidized wear particles.
The abrasive action of this oxidized wear powder on the friction surface significantly impeded the wear resistance and caused the generation of abnormal noise.After the test, the surface of the sliding member was observed. The comparative example was 61 Ll discolored to reddish brown due to oxidation of the steel.

In addition, the surface of the mating material of the present invention was uniformly coated with a thin film of solid lubricant (graphite), whereas the surface of the material of the comparative example had damage such as scratches caused by oxidized wear particles. was fully recognized.

Table 3 shows the results of tests on rocking torque and sealing function when the composition of the present invention was used in a seal ring for a spherical joint of an automobile exhaust pipe, with a radius of curvature of 3Q.
A seal ring having a convex spherical surface of mm was attached to one end of the tube, and was brought into sliding contact with a concave spherical surface of stainless steel provided at the other end of the tube under the following conditions.

Pushing force 60kgf Pipe gas pressure 0.3kg/cm” Swing angle
±4° Vibration frequency 20 Hz 100,000 cycles Atmosphere temperature Room temperature to 400°C (alternating) The product of the present invention
The effect has been seen in the swing torque, and the sealing function is also about the same level or slightly improved.

Also, in this test, the comparative products (No. 7) produced abnormal sounds from immediately after the start of the test throughout the test period, but the products of the present invention, Nos., 2, and No. 4, produced some abnormal sounds immediately after the start of the test. Although the generation of sound was observed, it was not observed at all after that, and for No. 6, no abnormal noise was observed at all.

〔effect〕

As described above, the composition for sliding members of the present invention is suitable for use under dry friction conditions over a wide temperature range from room temperature to high temperature, and calcium carbonate and/or boron oxide in the composition Frictional wear properties are improved by preventing the oxidation of metal wear particles generated by friction, suppressing the abrasive action of oxidized wear particles on the friction surface, and promoting the formation of a solid lubricant film on the surface of the mating material. It is possible to obtain a sliding member that has excellent properties and does not generate abnormal noise, which has been a problem in the past.

Furthermore, since the sliding member made of the composition has a sealing function in addition to the above-mentioned effects, it can be used particularly as a sealing member in exhaust pipe joints for automobiles.

Claims (2)

[Claims] (1) The main component is a solid lubricant such as graphite or molybdenum disulfide, and a reinforcing material selected from metal wire, fiber, wool, ribbon, chopped foil, or metal powder, and calcium carbonate and/or boron oxide. A composition for sliding members comprising a mixed powder obtained by mixing powder and a synthetic resin binder. (2) The composition for a sliding member according to claim 1, wherein calcium carbonate and/or boron oxide powder are mixed in the composition at a ratio of 2 to 30% by weight.