JPH0441590A - Preparation of sliding member - Google Patents

Abstract

PURPOSE:To remarkably improve sliding characteristics by vacuum-depositing a graphite on a sliding face of a ceramic base material with a specified open void ratio. CONSTITUTION:A graphite is vacuum-deposited on a sliding face of a ceramic base material with an open void ratio of 3-35% by the chem. vapor deposition method. The thickness of the graphite film may be of such a order that the open voids on the surface of the ceramic base material are sufficiently filled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a sliding member whose sliding characteristics are improved by processing the sliding surface.

[Conventional technology]

Ceramic sliding members are usually manufactured by making a dense sintered body of ceramics molded into a predetermined shape and polishing the sliding surface to a mirror surface.

[Problem to be solved by the invention]

However, there is a strong desire for ceramic sliding members to have a low coefficient of friction and a low amount of wear.

[Means to solve the problem]

As a result of research into methods for improving these sliding properties, the present inventors discovered that graphite could be deposited on the sliding surface of a ceramic base material with a specific open porosity. The invention was completed.

That is, the gist of the present invention is a sliding member characterized in that graphite is deposited on the sliding surface of a ceramic base material having an open porosity of 3 to 35% by chemical vapor deposition method (hereinafter referred to as CVD method). It is in the manufacturing method.

The material of the ceramic base material used in the present invention is S
IC, Sl 3N41 SiAl ON+ A sintered body of mullite, corantum, partially stabilized zirconia, spinel, etc. Among them, SiC, which has a small coefficient of friction, is preferable.

The open porosity (ratio of open pore area per unit surface area) of these ceramic substrates is 3 to 35%, preferably 8 to 35%.
It is 20%. Outside this range, the friction coefficient will be large and the amount of wear will be large.

The crystal grains that make up the ceramic base material, due to sliding,
The detached crystal grains, which are easy to separate from the base material in grain units, are
The larger the particle size, the greater the wear on the substrate. Therefore, the average grain size of the crystal grains constituting the base material is 2.
The thickness is preferably 1 μm or less, preferably about 1 μm. In order to produce such a ceramic base material, the average particle size must be 2 μm.
This is achieved by using ceramic powder of m.

Graphite is deposited on the sliding surface of the ceramic base material by CVD. As a result, a dense and strong graphite film can be deposited regardless of the shape of the ceramic substrate.

The conditions for this CVD method are that the furnace temperature is 1.500°C.
The temperature is preferably about 1,600°C, a hydrocarbon gas such as methane or propane is used as a raw material gas, and hydrogen is added if necessary, the pressure in the furnace is set to 100 Torr or less, preferably about 20 Torr, and the hydrocarbon gas partial pressure is 1
It is set to 0 τ orr or less, preferably about 3 Torr.

The thickness of the graphite film may be such that the open pores on the surface of the ceramic base material are sufficiently filled.

[For production]

When graphite is deposited on the sliding surface of a ceramic base material by the CVD method, graphite is also deposited inside the open pores. Since this graphite is gradually consumed by sliding, it is thought that the sliding characteristics are improved. Therefore, it is necessary that open pores exist on the sliding surface of the ceramic substrate, but if there are too many open pores, the crystal grains constituting the base material will be likely to separate, resulting in poor sliding characteristics.

〔Example〕

Examples 1 to 7, Comparative Examples 1 to 4 Test pieces with an inner diameter of 10 mm, an outer diameter of 50 m, and a thickness of 9 m were prepared from SiC sintered bodies with different porosities using boron and carbon as sintering aids.

This test piece was placed in a furnace at a temperature of 1, 600°C, a pressure of 20 Torr, and a propane gas flow. 100cc7
'min (value at 25℃, fat-), hydrogen gas flow rate 900
Graphite was deposited to a thickness of 20 μm on the test piece under conditions of cc/min (value at 25° C. and 1 atlI+).

Next, the surfaces of these test pieces were polished with a paste containing fine diamond particles until the ceramic base material appeared on the surface, thereby producing a pinion disk friction coefficient measurement disk and a pinion disk wear test disk.

Using these disks, pinion disk friction coefficient measurements and pinion disk wear tests were conducted under the following test conditions.

Test conditions Bottle material: Carbon sintered body Load: 500
gf Speed: 540 m/min Test time: 30 minutes Friction coefficient and wear amount = average value of 5 measurements The results are shown in Table 1.

In addition, as a comparative example, using the test pieces used in Examples 1, 3, and 5.7, the surface of the test piece was polished with a paste containing diamond fine particles without vapor-depositing graphite, and a disk was prepared and tested. provided.

The results are shown in Table 1.

Table 1 [Effects of the Invention] The sliding member manufactured by the method of the present invention had an extremely small coefficient of friction, a small amount of wear, and significantly improved sliding characteristics.

Claims (1)

[Claims] 1. A method for manufacturing a sliding member, which comprises depositing graphite on the sliding surface of a ceramic base material having an open porosity of 3 to 35% by chemical vapor deposition.