JPH01267A - Components with SiC coating - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a member having a β-3iC coating formed by CVD, and particularly to a member having a SiC coating suitable as a mirror.

[Conventional technology] In recent years, so-called new ceramics such as non-oxide ceramics such as silicon nitride, silicon carbide, and sialon, as well as aluminum oxide and zirconium oxide, have been attracting attention as high-temperature, high-strength materials, and much research and development has been carried out. is being done.

Among these ceramics, silicon carbide (rS i
Abbreviated as "C". ) is ■ a light material.

■ High mechanical strength and stability from room temperature to high temperature.

■ Excellent spalling resistance due to low thermal expansion and good thermal conductivity.

■ Extremely high corrosion resistance.

■ High hardness and excellent wear resistance.

■ It is conductive and can be used as an electric element.

It has these characteristics and is attracting attention as an extremely important industrial material.

In particular, Si produced by a vapor phase method such as a CVD method
Since C is dense and has high purity, these properties are extremely high. Therefore, methods have been conventionally proposed for improving the properties of various members by coating them with vapor phase S t C@.

[Problems to be Solved by the Invention] When using a member having a SiC film formed by CVD as a mirror, the SIC film formed on the surface of the base material must be polished, but since SiC has extremely high hardness, It has been extremely difficult to obtain good reflectance and scattering ratio with conventional members having SiC coatings.

In other words, in conventional products, the crystal grains of the SiC coating are generally interfolded, and the grain boundaries are sharp, so during polishing, micro-fractures in which the particles themselves are destroyed, and digging-up phenomena due to particles falling off easily occur. Therefore, a good smooth surface could not be obtained by polishing, and it was difficult to obtain a surface with excellent optical properties.

[Means for Solving the Problems] The present invention provides a member having a CVD-5LC coating with excellent polishing properties, the member having an SiC coating formed by CVD on a base material. , the surface of the SiC film is flat, and the strength of the SiC film is 60K g/m rr when measured by three-point bending. The object of the present invention is to provide a member having a SiC coating characterized by the above characteristics.

[Function] The SiC coating of the member of the present invention has a flat surface and a high strength of 60 kg/mm2 or more, so there is almost no microfracture or digging phenomenon caused by polishing.
A good smooth surface can be obtained. Therefore, the theoretical reflectance is high,
A member with excellent optical properties is provided.

[Examples] Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a partial sectional view of a member having a SiC coating according to an embodiment of the present invention. As shown in the figure, the member having a SiC film of the present invention is a member in which a SiC film 2 is formed on a base material 1, the surface of the SiC is flat, and the film has a three-point bending strength of 60 K g/m. rr? That's all.

When the surface is flat and the film has a high strength of 60 kg/mrn' or more, polishing is extremely easy, the final finish is good, and good reflectance and scattering ratio can be obtained.

In particular, if the SIC coating has crystal grains with uniform grain sizes as shown in Examples below, the polishing properties will be further improved.

In the present invention, various materials such as metal, ceramic, and synthetic resin can be used as the base material 1.

Moreover, the high-strength SiC coating on this base material 1 is formed by a CVD method.

The basic reaction of this CVD method is well known, for example, silicon halide such as Si Cf14 and Cs
Flowing hydrocarbons such as Hs with H2 as a carrier gas,
This is to precipitate StC.

In addition, in the present invention, various gases other than those described above may be used as the silicon source gas and the carbon source gas.

The method of polishing this SIC film is not particularly limited, and includes honing, superfinishing, polishing cloth processing, lapping, boring, barrel processing, ultrasonic processing, EEM (elastic emission machining), mechanochemical boring, and float polishing. Various methods such as polishing can be adopted.

A specific example will be explained below.

As an example of the present invention, S was applied to a graphite substrate under the following conditions: temperature: 1500°C, raw material gas: S i C1t4 and C3Hδ, carrier gas: H2, and gas flow rate 0.7 u/min.
An iC coating (0.25 mm thick) was formed.

Microscopic photographs of the surface structure and cross-sectional structure of this coating are shown in FIGS. 2(a) and 2(b) (100x magnification). Figure 2 (a), (
b) As is clearer, the crystal grain size of the SiC film of this example is relatively uniform, and the surface is extremely flat. FIG. 3(a) (400 times magnification) is a schematic diagram of a cross-sectional photograph showing the unevenness of the film surface. Flatness value of unevenness on the film surface (
The average depth of the membrane surface (based on the tip of the convex part) is 5
It was μm. Further, the three-point bending strength was measured and found to be 80 Kg/mrf.

When this coating was polished by a rotary polishing method, no microfractures or digging phenomena were observed, the reflectance was 95% or more, and the intensity ratio of scattering signal to noise was 10,000 or more.

The relationship between the film strength and the reflectance when a similar SiC film with a flat surface was formed on a graphite base material under various CVD conditions and then polished was shown below.

Film strength (Kg/mrn') Reflectance (%) As shown above, it can be seen that extremely excellent reflectance can be obtained when the film strength exceeds 60 kg/mm2.

As another comparative example, a SiC coating as shown in FIG. 3(b) (schematic diagram of a 400x cross-sectional photograph) was formed on a graphite base material. As is clear from Figure 3(b), the surface of these films is extremely uneven, the flatness of the unevenness is 15 μm, the SiC crystal grains are interfolded, and the surface strength is approximately 10K.
It was found to be as low as g/mm'.

When a film with a film strength of less than 80 kg/m was similarly polished, a good polished surface could not be obtained due to microfractures and digging phenomena, and the reflectance was less than 90%, resulting in a loss of scattering signals and noise. The intensity ratio was 1000 or less.

Thus, the member of the present invention was found to have a coating that is extremely easy to polish.

[Effects of the Invention] As detailed above, the member having the SiC coating of the present invention has a flat surface and high strength, so it is extremely easy to polish.
Good reflectance and scattering ratio can be obtained. In addition, the surface is SiC
Since it is a layer, it has excellent corrosion resistance and wear resistance of SiC.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of a member having a SiC coating according to the present invention, and FIG. 2 is a micrograph of the SiC coating, where (a) shows the surface structure and (b) shows the cross-sectional structure. be. Figures 3(a) and 3(b) are cross-sectional photographs showing the unevenness of the membrane surface (
400 times) Schematic % formula % Engraving of the drawing Figure 3 (a) (b) = r = Continued Neichi Original book (method) Display of 1119 1985 Patent Application No. 43958 2 Name of the invention SIC coating Part 3 Relationship with the person making the amendment Name of patent applicant (590) Mitsui Engineering & Shipbuilding Co., Ltd. 4 Address of agent 1-15-7 Toranomon, Minato-ku, Tokyo 1
05 7G115 Building 8th floor 6 Target of amendment Column for brief explanation of drawings in specification and drawing 7 Contents of amendment (1) In lines 12 to 14 of page 8 of the specification, “Figure 2 is... 3(a) and (b) is corrected to ``R'' in FIG. 2(a) and (b) as J. (2) Delete Figure 2 of the drawings. (3) "Figure 3" in the drawings has been changed to Figure 2, Figure 1. that's all

Claims (1)

[Claims] (1) A member having a SiC coating formed by CVD on a base material, the SiC coating having a flat surface and a three-point bending strength of 60 kg/mm^2 or more. A member having