JPS5984991A - Oil-less sliding material - Google Patents

Abstract

PURPOSE:To provide an oil-less sliding material exhibiting high resistance to pressure and excellent low frictional property over a wide temperature range from room temperature to high temperature, by mixing carbon fiber, graphite, TiO2 and a phenolic resin at a specific ratio, and baking the mixture at a high temperature. CONSTITUTION:The objective oil-less sliding material is prepared by baking a composition composed of (A) 2-30wt% of carbon fiber, (B) 15-50wt% of graphite, (C) 3-30wt% of TiO2 and (D) a phenolic resin e.g. in an nonoxidative atmosphere at 1,000 deg.C for 24hr. EFFECT:Excellent formability and heat resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sliding material used without lubrication, and provides a sliding material that exhibits excellent low friction in a wide temperature range from room temperature to high temperature. , is.

For materials such as engine cylinder liners and compressor cylinder liners, materials that can slide at high temperatures and without lubrication and have a low coefficient of friction are desired. Problems in selecting materials for parts where such characteristics are required and problems with conventionally used materials will be explained below, focusing on a study of engine cylinder liners for high-temperature, non-lubricated applications as an example.

Improving the energy efficiency of engines is a major technical challenge now and in the future), and vigorous research is being conducted both domestically and internationally with the aim of improving energy efficiency (improving fuel efficiency). To achieve improved energy efficiency,
It is essential to convert the thermal energy that is currently being taken away as cooling heat into effective energy for the engine, and for this purpose, the most effective way is to insulate the combustion part of the engine. considered a means. However, when performing this insulation, the cylinder liner and piston ring portion are exposed to high temperatures, making it impossible to use lubricating oil. That is, the operating temperature limit of engine oil currently used as a lubricating oil between cylinder liners and piston rings is up to 300° C. even for the oil with the highest heat resistance. On the other hand, when insulation is applied, the temperature of the grain cylinder between the cylinder liner and piston ring reaches around 600℃, so 41'J
The use of lubricating oil is not possible. Therefore, there is a need to develop materials that can slide at high temperatures and without lubrication. Further, in this case, an increase in the frictional force between the cylinder liner and the piston ring must be avoided since this increases the friction loss of the engine.

Therefore, there is a need for the development of a material that not only can slide as described above at high temperatures and without lubrication, but also exhibits a low coefficient of friction.

Common materials that can be used under such conditions include SiC, ceramic materials such as 8i3N4,
Inorganic materials such as graphite and BH and CaF2. Mo5a
Composite materials with solid lubricants such as polytetrafluoroethylene (FTFB), and polyimide-based organic materials can be considered. However, none of these materials could satisfy either or both of low friction properties and heat resistance.

Among the materials generally considered, carbon-carbon fiber composite materials (hereinafter referred to as C-C composite materials) are most suitable for sliding at high temperatures and without lubrication.

One of them is low load capacity. When used as a sliding material, it operates while receiving some kind of load, and especially as a material for engine cylinders and piston rings, it is necessary to slide while receiving cylinder internal pressure. . This internal pressure is I to Ry
/ crl ~ 140 Kr / ca, and this much load capacity is required. On the other hand, the friction coefficient of C-C composite material starts to increase from 65 kg/art.
At l 10 Kf/ca, there is a sudden rise, and the surface appears to be broken (see curve B in Figure 3).

Another problem is the high coefficient of friction on the high surface pressure side. In fact, in an engine, the greatest internal pressure is generated near the top dead center, resulting in high surface pressure, so seizure at this point often becomes a problem. This seizure (scuffing) does not occur in areas where the friction coefficient is low, but as shown in curve B in Figure 3, the friction coefficient exceeds 0.1 on the high surface pressure side, and in this case, scuffing occurs. Possible danger.

Therefore, an object of the present invention is to provide a low-friction material that is suitable for sliding without lubrication in a wide temperature range from room temperature to high temperature, especially in high temperature range, and has excellent heat resistance, load carrying capacity, etc. It's about doing.

According to the research of the present inventors, a high-temperature fired product of a composition consisting of carbon fiber, graphite, TiO2, and phenol resin in a specific composition range, even when sliding at high temperature and without lubrication,
It was discovered that the friction coefficient did not increase on the high surface pressure side, the material surface did not break even under high surface pressure, and it exhibited high surface pressure resistance and a stable low friction coefficient, leading to the completion of the present invention. It is.

That is, the non-lubricated sliding material according to the present invention contains 2 to 30 fi of carbon fiber, 15 to 50 wt% of graphite, and TiO2.
It is a high-temperature fired product of a composition having a weight ratio of 3 to 30% by weight and the balance being a phenol resin.

Here, the high-temperature fired product is one obtained by molding the above composition into a desired material shape, subjecting it to heat treatment if necessary, and then firing it at a high temperature.

Among the above materials, if carbon fiber is less than 2% by weight, it will have little effect contributing to wear resistance, while if it exceeds 30% by weight, the friction coefficient of the core material will increase, so the content should be within the range of 2 to 30% by weight. Add with

Graphite is added as an inorganic filler, but it also promotes low friction properties, and if the number of rows is less than 15, this effect is small, while if it exceeds 50, it impairs formability, so it is not preferable. .

TlO2 is thought to be effective in improving low-friction properties and increasing strength, but when triple t is less than 1, the effect of improving both properties is small; on the other hand, when it exceeds 30 Ml:t' %, it has the same effect as graphite. Similarly, molding is difficult t11. Because I'm yelling, 3~3
Add in a range of 0% by weight.

Phenolic resin is the remainder of the above composition range and is carbonized in high temperature firing.

As described above, the non-lubricated sliding material according to the present invention is a live-fired product of a composition consisting of carbon fiber, graphite, T i 02, and phenol resin in a specific composition range, and therefore has excellent moldability and heat resistance. It also exhibits high surface pressure resistance and a stable low coefficient of friction even when sliding at high temperatures and without lubrication. Furthermore, unlike graphite materials, as shown by curve A in Figure 3, no increase in the coefficient of friction is observed on the high surface pressure side, and no damage to the material surface is observed. The material of the present invention, which has such properties, exhibits particularly excellent properties in areas where sliding under high temperature and without lubrication is desired, such as engine cylinder liners and compressor cylinder liners.

Next, the characteristics and effects of the sliding material of the present invention will be specifically explained with reference to Examples.

Examples Carbon fiber: 3% by weight Graphite: 47% by weight TiO: 25% by weight Phenol resin: 45% by weight The above composition was molded and heat-treated, and then fired in a non-oxidizing atmosphere at a temperature of 1000°C for 24 hours to form phenol. The resin material was carbonized to produce the material of the present invention.

Photographs of the structure of the obtained material are shown in FIGS. 1 and 2. Figure 1 is an electron micrograph of the structure X (SE image), Figure 2
The figure shows a TIKα image (X
α) to the line wavelength (both times 1000) 6 From Figures 1 and 2, it can be seen that 'J''i (which appears white) is finely and uniformly dispersed around the granular carbon fibers.

Sliding test For the material obtained in the above example, initial speed; 0.
A sliding test was conducted under the following conditions: 48 m/sec, ambient temperature: 300°C, mating ring: 81VF thermal sprayed material, and no lubricating oil. The results are shown in song MA in FIG. For comparison, curve B also shows the results for graphite material (CC composite with forsterite) under the same conditions (300° C., no lubrication).

As is clear from FIG. 3, in the case of the material of the present invention, medium
The coefficient of friction on the high surface pressure side did not exceed 0.05, and the material surface maintained a clear sliding surface without damage even under surface pressure l 33 K9 / aJ. On the other hand, graphite material exhibits a very high coefficient of friction, and the coefficient of friction increases especially on the high surface pressure side. Therefore, it is clear that the above properties of the material of the present invention are not simply due to the lubricity of graphite.

[Brief explanation of the drawing]

FIG. 1 is an electron micrograph of the structure (SE image) of the sliding material of the present invention obtained in the example, (magnification
100O), Fig. 2 is a TiKα image obtained by analyzing Ti in the same area as Fig. 1 (magnification: It is a graph showing the results of a sliding test. Applicant Komatsu Ltd. Representative Patent Attorney Masaaki Yonehara Patent Attorney Tadashi Hamamoto - -64: Figure 1 Figure 2

Claims (1)

[Claims] Carbon fiber 2-30% by weight, aged lead 15-50% by weight, Ti
A non-lubricated sliding material which is a high-temperature fired product of a composition having a weight ratio of 023 to 30 and a balance of phenol resin.