JPS591236B2 - Manufacturing method of carbon-SiC composite member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a carbon-SiC composite member.

Carbon-SiC composite members, which have a SiC layer formed on the surface layer of a carbon base material, can withstand high temperatures, are chemically stable, have high hardness and excellent wear resistance, and do not contaminate other parts with which they come into contact. Due to these excellent properties, its application has been expanding in recent years, particularly as sealing jigs for various electronic components, seal rings for mechanical seals, and mechanical sliding parts such as bearings.

However, there is a drawback that the dimensional accuracy of the base material cannot be maintained as it is after forming SiC due to the volumetric expansion when forming SiC on the surface layer portion of the carbon base material.

Further, the surface roughness of the surface on which the SiC layer is formed is rougher than the surface roughness resulting from mechanical finishing of the carbon base material, and it is difficult to control the surface roughness to a desired surface roughness.

Therefore, in the case of a member that requires highly accurate dimensions and a high degree of surface finish, it is necessary to form a SiC layer in advance, taking into account the polishing allowance, and then perform processing polishing to achieve the desired dimensional accuracy and surface roughness.

As a result, the number of work steps has increased, leading to a significant increase in costs and lengthening of production time.

The purpose of the present invention is to improve the above-mentioned drawbacks and to apply S to only the necessary parts.
By forming the iC layer and leaving other parts as the carbon base material, dimensional accuracy and surface roughness can be maintained, and post-processing is not required, or the parts that require processing can be left as carbon. An object of the present invention is to provide a method for easily manufacturing a carbon-SiC composite member.

As a result of various studies on the above-mentioned drawbacks, the present inventors found that the SiC layer on the surface layer of the carbon base material does not allow reactive gases such as SiC to pass through unnecessary areas, and the porosity is 90% or less and the temperature is 1500°C or higher. Carbon-Si, which is coated with fine powder that is thermally stable at various temperatures, and then subjected to a prescribed SiC treatment to form a SiC layer only in the necessary areas.
We have discovered a method to obtain C composite members.

The present invention is a carbon-SiC composite member in which a SiC layer is formed on the surface layer of a carbon base material. carbon fiber, which is then covered with a carbon material and then subjected to SiC treatment to form a partial SiC layer.
The present invention relates to a method for manufacturing a SiC composite member.

In the present invention, the SiC processing method is performed by a conventionally known method and is not particularly limited.

Further, the porosity in the present invention is expressed by the following formula.

Furthermore, the fine powder used in the present invention has a porosity of 90%.
It is necessary to be thermally stable at temperatures below and above 1500°C.

When the porosity exceeds 90%, the reaction gas for forming the SiC layer passes through the fine powder, and the S
An iC layer is formed and the intended purpose cannot be achieved.

Further, if the fine powder is thermally unstable at temperatures of 1500° C. or higher, it will react with the carbon base material and the fine powder itself will undergo thermal deformation such as melting and evaporation.

Natural graphite, artificial graphite, soot, alumina, etc. can be used as fine powders that meet these conditions.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a cross-sectional view showing a method for manufacturing a carbon-SiC composite member according to an embodiment of the present invention, in which a cylindrical carbon base material 2 processed to a predetermined size is placed in a graphite container 1, Next, the inner and outer circumferential surfaces of the cylindrical carbon base material 2 have a porosity of 9.
Covered with 0% natural graphite powder 3 S in a nitrogen flow of 21 min/min
SiC processing was performed at 2000°C using SiO vapor generated at 1600°C from a powder mixture of i02 and carbon.

After reacting for a predetermined period of time, the cylindrical carbon substrate 2 was cooled to room temperature and taken out. As shown in FIG. Areas not covered with Si are covered with Si to a depth of approximately 1 mm.
A carbon-SiC composite member on which a C layer 9 was formed was obtained.

Next, we measured the dimensions and surface roughness of this carbon-SiC composite member, and found that the outer surface was 4.0. It was confirmed that the surface accuracy was almost maintained, and the dimensional accuracy was also maintained at a predetermined level.

In FIG. 2, 8 is a sliding end surface, and 10 is a 01J ring.

According to the present invention, it is possible to form the SiC layer only in the necessary places, so when applied to a seal ring of a mechanical seal, the SiC layer is formed only on the sliding end face, and the state of the carbon base material is almost maintained in other parts. It is possible to obtain a product in a maintained state.

Further, in areas where the SiC layer is unnecessary, the dimensional and surface accuracy of the carbon base material is maintained, so no post-processing is required.

Furthermore, the contact surface of the 01J song and other parts that require precision machining can be easily processed by normal cutting after performing a predetermined SiC process.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a method of manufacturing a carbon-SiC composite member according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the carbon-SiC composite member obtained by the present invention. Explanation of symbols, 1... Graphite container, 2...
・Cylindrical carbon base material, 3...Natural graphite, 4.
...Outer circumferential surface, 5...0 ring 1 contact surface, 6
...Dorsal end surface, 1...Inner peripheral surface, 8...
...Sliding end face, 9...SiC layer, 10...
...0 ring.

Claims (1)

[Claims] 1. In a carbon-SiC composite member in which a SiC layer is formed on the surface layer of a carbon base material, areas where the SiC layer is unnecessary are covered with fine powder that has a porosity of 90% or less and is thermally stable at temperatures of 1500°C or higher. 1. A method for producing a carbon-SiC composite member, which comprises covering the carbon-SiC composite member with a carbon material, and then performing a SiC treatment to partially form a SiC layer.