JPH08134489A - Self-lubricating composite material - Google Patents

Abstract

PURPOSE: To provide a self-lubricating composite material having heat resistance and strength. CONSTITUTION: A self-lubricating composite material comprising: 5 to 90vol% at least one compd., as a solid lubricant, selected from the group consisting of copper oxide, nickel oxide, calcium oxide, boron nitride, graphite, talc, mica, molybdenum disulfide, tungsten disulfide, and tungsten selenide; and 10 to 95vol% in total of substance A and substance B as a binder, the substance A being water glass or a suspension of colloidal silica, the substance B being at least one frit selected from the group consisting of mica, talc, aluminum silicate, and alumina cement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-lubricating composite material excellent in heat resistance and strength.

[0002]

2. Description of the Related Art In order to make the operation of a sliding part of a machine that operates at a high temperature such that a liquid lubricant (lubricating oil) deteriorates in the atmosphere, it is conventionally necessary to use a solid material such as molybdenum disulfide. The method of use is such that a lubricant is directly used as a film, or a solid lubricant is mixed with grease and used, and a film is formed with the solid lubricant remaining after evaporation of oil.

However, in any of these cases, it is not possible to endure long-term use, and the higher the operating temperature, the more frequent maintenance is required, and it is not easy to refuel at any interval when working at high temperatures. .

Therefore, recently, sliding parts are being developed which maintain their self-lubricating properties even when they are used for a long period of time under high temperature in the atmosphere. For example, as materials for sliding parts, which are self-lubricating and do not require external supply of lubricant, plastic-based, metal-based, and ceramic-based composite materials containing graphite and molybdenum disulfide are known. [For example, see the data book "Tribology and the Environment" for designers, published by Shinjusha in 1990].

[0005]

However, even in the case of such a self-lubricating composite material, there are many cases where a plastic composite material does not satisfy the heat resistance requirement. Also,
Since the metal-based composite material is likely to have many gaps at the crystal grain boundaries, the grain boundaries are likely to be oxidized and the strength is likely to be deteriorated during long-term use. Further, even a ceramic-based composite material produced by the powder sintering method has a technical problem that it is difficult to obtain high strength because the solid lubricant enters the crystal grain boundaries to prevent the sintering.

The present invention has been made in view of such a conventional technique, and provides a self-lubricating composite material excellent in heat resistance and strength.

[0007]

The self-lubricating composite material of the present invention comprises a solid lubricant, a binder and a reinforcing material. However, the reinforcing material may not be used for a light load.

As solid lubricants, metal oxides such as copper oxide, nickel oxide and calcium oxide, boron nitride,
One or more metal oxides selected from the group of layered inorganic compounds such as graphite, talc, mica, molybdenum disulfide, tungsten disulfide, tungsten selenide are suitable. The content is preferably 5 to 90 vol%. 5 vol
If it is less than%, the lubricity is insufficient, and if it is more than 90 vol%, the life is short.

The type of solid lubricant is selected according to the sliding conditions of the machine part using the material of the present invention. Generally, it is preferable to select disulfide in a dry atmosphere, graphite in a high humidity atmosphere, and boron nitride in a high temperature atmosphere. However, since it may be complicatedly affected by the mating material, load, speed, operating cycle, etc., in such a case, it is necessary to consider all of them and select the optimum mixture of solid lubricants. good.

The ratio of the solid lubricant to the binder is 5 to 98 vol%, and when sliding with a partner having a small area, a small amount of about 5 to 25 vol% is preferable, and when sliding with a partner having a large area, When the solid lubricant is used in a temperature or environmental substance where it is likely to be lost, an appropriate amount between 25 and 98 vol% may be selected according to each condition.

As the binder, a substance A which is a suspension of water glass or colloidal silica and a substance B which is one or more frits selected from the group of mica, talc, aluminum silicate and alumina cement are mixed. Those reacted are preferable. The total content is preferably 10 to 95 vol%. If it is less than 10 vol%, the strength is insufficient, and 9
If it is more than 5 vol%, the lubrication is insufficient. The binder of the present invention is characterized in that it does not form a gap with the solid lubricant and does not oxidize at a high temperature, so that it can withstand stable use for a long period of time.

Mica, talc, as the B substance of the binder,
Aluminum silicate has different hardness when cured by reaction with water glass as the substance A or a colloidal silica suspension. Mica and talc are soft and have the function of solid lubrication, but their strength as a binder is weak. With aluminum silicate or the like, the bonding strength is strong, but in some cases it is too hard and may impair the sliding characteristics. Therefore, it is necessary to empirically select them according to the requirements of the parts used. Generally, the ratio of substances A and B is 0.5: 1 to 3:
A value between 1 is suitable.

As the reinforcing material, at least one selected from the group consisting of carbon fiber, glass-alumina composite fiber and stainless steel fiber is suitable. The total content is 10
50 vol% is preferred. If it is less than 10 vol%, the breaking strength is insufficient, and if it is more than 50 vol%, lubrication becomes poor. Further, regarding the fiber content, when the friction coefficient required for the sliding parts using the material of the present invention is 0.2 or less, it is less than 25 vol%, and when the required mechanical strength is high, it is 25%. It is better to select it up to 50 vol%. In addition, stainless steel fibers are usually used,
Especially when low friction is required, it is better to use carbon fiber. For very light load applications that do not require breaking strength, the reinforcing material may be 0%.

As a fiber as a reinforcing material, a metal material such as stainless steel may be usually used since the binding material suppresses oxidation, but carbon fiber or carbon fiber may be used especially when strength at high temperature is required. It is better to use ceramic fibers such as alumina fibers.

Next, the manufacturing method will be described. First, a solid lubricant and a binder (A substance + B substance) are mixed in a mortar or a ball mill while adding a small amount of water to prepare a mud-like substance (C). Next, the fiber material is mixed with the above-mentioned mud-like (C) by an appropriate method so that (D) is prepared. And this (D) is dried in a 200 degreeC or less furnace. The atmosphere of the furnace may be atmospheric air. Sufficiently dried (D) is molded by a press and heat-treated in a vacuum furnace or an inert atmosphere furnace to solidify the binders A and B by a chemical reaction. About 700 to 1000 ° C. is suitable for the heat treatment.
The higher the heat treatment temperature is, the more the materials with less gas release and dimensional change at high temperature can be formed. However, when a high temperature furnace or an atmosphere adjusting furnace cannot be used, it can be cured and used even by heating at about 400 ° C. The heat-treated material is finally cut into fine parts by cutting and grinding.

[0016]

【Example】

[0017]

[Table 1]

Mixing ratio (vol%) shown in Table 1 above for substances A and B adjusted in a weight ratio of 1: 1.2.
Then, the predetermined solid lubricant and the fiber are mixed. Then 20
Dry in air at 0 ° C and dry to 5 ton / c
Press molding is performed at m ² to prepare a sample of 10 × 10 × 10 mm ³ . Finally, heat treatment was performed under the conditions shown in Table 1.

In the comparative example, the substance B was not used as the binder, the lubricant and the fiber were mixed at a predetermined compounding ratio, molded at 5 ton / cm ² , and then heat-treated under the conditions shown in Table 1.

This example was compared with the comparative example. Regarding the moldability, the comparative example was inferior, and a large amount of cracks were generated. Comprehensive evaluation of the friction coefficient and the compressive strength revealed that at least one of the friction coefficient and the compressive strength of this example was superior to that of the comparative example. In addition, even if the heat resistance is compared, in the present embodiment, it is 5
While no discoloration was observed even at 00 ° C. for 24 hours, yellowing was remarkable in each of the comparative examples. Further, in this example, even when the friction surface temperature reached 500 ° C., the frictional wear was small, but in the comparative example, a marked increase in friction and wear was observed at 430 ° C. or higher.

Also, when the metal oxide such as copper oxide, nickel oxide or calcium oxide is mixed as the solid lubricant or carbon fiber is used as the reinforcing material, the same result as in Table 1 can be obtained. confirmed.

The coefficient of friction shown in Table 1 is measured by a two-wire tribometer at a speed of 0.4 m / sec and a load of 20 k.
g, Counterpart material: S45C, values after 90 seconds in the atmosphere.

Next, the results of various experiments are shown in FIGS. The friction coefficient in this test was measured by a two-wire tribometer under the conditions of 2500 rpm and a load of 10 kg. The test material was sintered at 600 ° C. in vacuum.

FIGS. 1 to 7 show the results of measuring the friction coefficient by changing the type and proportion of the solid lubricant and the type of the binder. Incidentally, FIG. 7 shows a comparative example corresponding to FIG. 6 in which the binder is only water glass or colloidal silica. Then, as can be seen from FIGS. 1 to 6, it is understood that the friction coefficient decreases as the addition amount of the solid lubricant of the present invention increases. However, the combination of different types of solid lubricants varies in how the friction coefficient is reduced. It has also been found that similar materials can be formed from stainless steel fibers and glass-alumina composite fibers, colloidal silica as substance A can be replaced with water glass, and alumina cement can be replaced with mica. Then, as shown in FIG. 7, good lubricity cannot be obtained unless the binder contains both the substance A and the substance B as in the present invention.

FIG. 8 is a diagram showing the relationship between the amount of binder and the number of friction cases. It is recognized that the friction coefficient tends to increase as the amount of binder increases. In addition, in the case of a combination of solid lubricants, which are expected to have lubricity at high temperatures in the atmosphere, the coefficient of friction measured at room temperature is high, but the relationship with the amount of binder changes almost in parallel. I also understand that.

FIG. 9 is a diagram showing the relationship between the amount of reinforcing material and the number of friction cases. The coefficient of friction tends to increase as the number of reinforcing materials increases. In addition, solid lubricant for high temperature lubrication (BN
- Graphite -CuO-CaO) than the low-temperature lubricating solid lubricants (BN-WS ₂ - also seen that the direction of the graphite) exhibit a low coefficient of friction.

[0027]

The self-lubricating composite material according to the present invention has the contents as described above, and since the solid lubricant and the reinforcing material react with the binder to form a connective structure, Sufficient strength can be obtained without forming a gap with the binder. Further, since it also has excellent heat resistance that does not oxidize to a high temperature, sufficient self-lubricating property is maintained even if it is used for a long time under severe temperature conditions in the atmosphere.

[Brief description of drawings]

FIG. 1 is a graph showing the coefficient of friction when the proportion of mica, boron nitride, graphite, and tungsten disulfide is changed as a solid lubricant.

FIG. 2 is a graph showing a friction coefficient when talc, boron nitride, a graphite ratio, and tungsten disulfide are changed as solid lubricants.

FIG. 3 is a graph showing the coefficient of friction when the proportions of calcium oxide, boron nitride, graphite, and tungsten disulfide are changed as solid lubricants.

FIG. 4 is nickel oxide, boron nitride as a solid lubricant,
It is a graph which shows a friction coefficient when changing the ratio of graphite and tungsten disulfide.

[FIG. 5] Copper oxide, boron nitride, graphite as a solid lubricant,
It is a graph which shows a friction coefficient when changing the ratio of tungsten disulfide.

FIG. 6 is a graph showing the coefficient of friction when the proportions of tungsten disulfide, boron nitride, and graphite are changed as the solid lubricant.

FIG. 7 is a graph showing a comparative example corresponding to FIG. 6 in which the binder is only water glass or colloidal silica.

FIG. 8 is a graph showing the relationship between the amount of binder and the coefficient of friction.

FIG. 9 is a graph showing the relationship between the amount of reinforcing material and the coefficient of friction.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C10M 103: 06 CF 125: 26 125: 28 125: 02 125: 04 125: 10) C10N 10: 02 10:04 10:06 10:12 10:16 20:06 B 30:08 40:02 50:08

Claims (4)

[Claims] 1. As the solid lubricant, 5 or more selected from the group consisting of copper oxide, nickel oxide, calcium oxide, boron nitride, graphite, talc, mica, molybdenum disulfide, tungsten disulfide, and tungsten selenide. 90vo
1% content of B as a binder, which is water glass or colloidal silica suspension, and at least one frit selected from the group consisting of mica, talc, aluminum silicate and alumina cement.
A self-lubricating composite material comprising a total of 10 to 95 vol% of the substance. 2. The reinforcing material contains at least one selected from the group consisting of carbon fiber, glass-alumina composite fiber, and stainless steel fiber in a proportion of 50 vol% or less.
The self-lubricating composite material described. 3. The ratio of solid lubricant to binder is 5 to 5.
The self-lubricating composite material according to claim 1 or 2, which is in a range of 98 vol%. 4. The self-lubricating composite material according to claim 1, wherein the weight ratio of the substances A and B in the binder is in the range of 0.5: 1 to 3: 1. .