JPH06300907A - Parts for optical purpose and x-ray formed by using silicon carbide sintered compact and their production - Google Patents

Abstract

PURPOSE:To provide an optical parts or parts for X-rays having a high thermal conductivity, high rigidity and high corrosion resistance and having a high reflectivity at need by using a silicon carbide sintered body which is sintered with boron or a compd. of the boron and carbon or a compd. of the carbon as a sintering assistant, is substantially the single phase of the silicon carbide after sintering and has a high density. CONSTITUTION:The optical parts formed to a required shape by polishing by using the silicon carbide sintered body which is sintered with 0.15 to 1.0wt.% boron or the compd. of the boron in terms of boron and 0.3 to 5wt.% carbon as the sintering assistant, is substantially the single phase of the silicon carbide and has >=2.9g/cm<3> density. The surface of at least a part of this sintered compact 2 is smoothly worked, by which the optical parts and the parts for X-rays having the high thermal conductivity, the high rigidity and the high corrosion resistance are obtd. The smooth surface is coated with a reflection film 1 at need, by which the high reflectivity is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical and X-ray component of a silicon carbide sintered body. INDUSTRIAL APPLICABILITY The silicon carbide sintered body of the present invention is useful as a reflection mirror for visible light, laser light, X-rays, etc., and its base material.

[0002]

2. Description of the Related Art Conventionally, glass or metal has been often used as a reflecting mirror as an optical or X-ray component or its base material.

However, with the industrialization of high technology, high precision is required, and there is a growing demand for a material that has high rigidity and high thermal conductivity without change over time and can maintain shape precision.

That is, in the conventional glass member, glass having a relatively large coefficient of thermal expansion is inexpensive, but its shape is largely changed with respect to temperature fluctuation, which makes it unsuitable as an optical component, while the coefficient of thermal expansion is small. Glass is difficult to manufacture and expensive.

Further, the metal member generally has a large coefficient of thermal expansion and is further deteriorated with time, so that it is inferior in shape stability.

As a result of studying application of ceramics to these requirements, the present inventors have found that silicon nitride ceramics, sialon ceramics, alumina ceramics and silicon carbide ceramics are useful.

Among these ceramics, silicon carbide ceramics are considered to be useful from the viewpoints of ease of manufacturing a sintered body, good workability, and thermal conductivity.

On the other hand, it has been conventionally practiced to coat the surface of graphite with a silicon carbide film as a laser reflecting mirror. However, in this method, the silicon carbide film may be peeled off from the graphite substrate due to repeated thermal shock due to laser irradiation.

It has also been proposed to use a silicon carbide sintered body for this purpose. Japanese Patent Application No. 4-6151 is a reflecting mirror for a laser which uses a silicon carbide sintered body obtained by sintering silicon carbide without adding a sintering aid. However, the manufacturing cost is high and the sintering aid is used in the manufacturing method. It is industrially extremely difficult and not useful to fire without addition.

Further, in general, a silicon carbide sintered body containing no sintering aid has many defects such as a large number of pores and a low reflectance.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to use a dense silicon carbide sintered body, which allows the silicon carbide sintered body to have high thermal conductivity, high rigidity, high corrosion resistance, and good workability. It is possible to obtain an optical component and an X-ray component that are easy to obtain, and at the same time, a reflective film is coated on the reflective surface, if necessary, to obtain a high reflectance and suppress the diffusion of impurities. It will be possible.

[0012]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that boron or a compound of boron is 0.15 to 1.0 wt% in terms of boron and carbon is 0.3%. ˜5 wt% Sintered as a sintering aid and after sintering is essentially a silicon carbide single phase with a density of 2.9 g / c
Using a silicon carbide sintered body of m ³ or more, an optical component was obtained by polishing into a required shape.

At least a part of the surface of this sintered body was processed to be smooth to obtain an optical and X-ray component having high thermal conductivity, high rigidity and high corrosion resistance.

Further, it has become possible to obtain a high reflectance by coating a reflecting film on a smooth surface, if necessary.

The optical and X-ray components of the present invention will be described in detail below based on the manufacturing method thereof.

Silicon carbide powder having an average particle diameter of 0.1 to 10 μm, boron or a compound of boron in an amount of 0.15 to 1.0 wt% in terms of boron, and carbon in an amount of 0.3 to 5 wt%.
Mix as a sintering aid to obtain a raw material mixture. The raw material powder is desirably 1 μm or less.

Boron or a boron compound is preferably added in an amount of 0.3 to 0.6 wt% in terms of boron, and if it is out of this range, densification may be difficult depending on manufacturing conditions.

Although the optimum value of carbon varies depending on the amount of oxygen contained in the silicon carbide raw material, carbon is sufficiently densified by adding about 0.3 to 5 wt%.

Then, the above-mentioned raw material mixture is formed into a desired shape, and the obtained green body is fired at 1900 ° C. to 2800 ° C. to obtain a sintered body, or the above raw material mixture is obtained by hot pressing to obtain a sintered body.

For molding, conventionally known methods such as press molding, extrusion molding and injection molding can be employed.

In this case, a known substance such as an organic polymer may be used as a molding binder or a dispersant.

As for sintering, atmospheric pressure sintering, hot press sintering, atmospheric pressure sintering, hot isostatic pressing (HIP), or a combination thereof can be used, but silicon carbide sintering is possible. The body has a density of 2.9 g / cm ³ or more, preferably a density of 3.
1g / cm ³ or more, otherwise there are many pores in the sintered body, and when used as a mirror substrate for reflection, etc., the reflectance decreases, so hot pressing for higher density It is better to use sintering or HIP.

Regarding the sintering temperature, if the temperature is lower than 1900 ° C., the sintered density is insufficient, and if it is higher than 2300 ° C., decomposition of silicon carbide is likely to occur.

To minimize the pores in the sintered body, 21
It is desirable to bake at 00 ° C to 2250 ° C.

The thus-obtained sintered body is processed into a predetermined shape and surface roughness by a known method such as grinding or lapping to obtain optical and X-ray parts.

It is difficult to obtain a sufficient reflectance as a reflecting mirror unless the surface roughness of the reflecting surface is Ra 50 nm or less, preferably Ra 10 nm or less.

In the case of being used as a mirror for a laser or the like, if a predetermined reflectance cannot be obtained even if the reflecting surface is smoothed by polishing, the reflecting surface is coated with a reflecting film. The reflectance can be obtained.

As the reflective film, a film containing at least one of aluminum, gold, copper, and platinum as a main component is used, but vapor deposition of silicon carbide or the like may be used depending on the application.

[0029]

【Example】

[0030]

Example 1 B _FourC 0.45 wt% (Boron conversion 0.3
4 wt%) and carbon 2.0 wt% β-type silicon carbide powder
Powder and silicon carbide ball mill in normal hexane
After mixing for 24 hours, drying and granulating, 400 kg / cm
²Hot press firing at 2200 ℃ under the load pressure of
It was.

The density of the sample was 3.15 g / cm ³ . This sample was cut out, subjected to surface grinding with a diamond grindstone, and then lapping was performed using free abrasive grains.

The surface roughness of the lap surface after lapping is Ra2n.
It was m. The reflectance of the lap surface was about 30% in the wavelength range of 1 μm to 5 μm.

Further, when aluminum was vapor-deposited on the lap surface of this sample and the reflectance was measured in the same manner, the reflectance was about 95%.

[0034]

[Example 2] B ₄ C 0.45 wt% (boron conversion 0.3
4 wt%) and carbon 2.0 wt% are mixed with β-type silicon carbide powder in normal hexane for 24 hours using a ball mill made of silicon carbide, dried and granulated to form a square of about 60 mm and 5.0 ton / Cold isostatic pressing was performed at cm ² to obtain a molded body.

This compact was fired at 2200 ° C. under atmospheric pressure, and further hot isostatic pressing (HIP) was performed at 2000 ° C. in an atmosphere of Ar gas at 1800 atm.

The density of the sample was 3.1 g / cm ³ . This sample was cut out, subjected to surface grinding with a diamond grindstone, and then lapping was performed using free abrasive grains.

The surface roughness of the lap surface after lapping is Ra3n.
m (FIG. 3). The reflectance of the lap surface is from 1 μm wavelength
The reflectance was about 30% in the range of 5 μm.

The reflectance of the mirror-polished surface of silicon carbide after aluminum deposition is shown in FIG.

Since silicon carbide is vapor-deposited on the surface, aluminum absorbs light having a wavelength of about 800 nm, so that the reflectance is lowered at this portion. In the other portions, the surface roughness of silicon carbide is good and the reflectance is 85% or more.

When the wavelength used is close to 800 nm, the reflectance can be improved by using a vapor deposition film other than aluminum.

When used as a mirror for laser reflection, a reflectance of about 85% is the minimum necessary, and the above reflectance satisfies this.

That is, a member having high thermal conductivity, high rigidity, high corrosion resistance, which are the original characteristics of silicon carbide, and a high reflectance can be manufactured as required.

[0043]

According to the manufacturing method of the present invention, an optical component or an X-ray component having high thermal conductivity, high rigidity, high corrosion resistance and, if necessary, high reflectance can be obtained.

[Brief description of drawings]

FIG. 1 shows a cross-sectional view of the present invention.

FIG. 2 shows a cross-sectional view of a conventional product

FIG. 3 is a diagram showing the surface roughness of a mirror-polished surface of silicon carbide.

FIG. 4 is a diagram showing the relationship between the reflectance and the wavelength of light after vapor deposition of aluminum on the mirror-polished surface of silicon carbide.

[Explanation of Codes] 1 Aluminum vapor deposition 2 Silicon carbide sintered body 3 Glass

Claims (5)

[Claims] 1. Boron or a compound of boron and carbon or a compound of carbon is sintered as a sintering aid, and after sintering, it is substantially a silicon carbide single phase and has a density of 2.9 g / cm ^3. An optical component and an X-ray component using the above silicon carbide sintered body. 2. The optical component according to claim 1, wherein the density is 3.1 g / cm ³ or more, and at least one location is better than surface roughness Ra50 nm, preferably surface roughness Ra1.
An optical and X-ray component having a surface roughness of better than 0 nm and having a reflective film coated on the location. 3. An optical component and an X-ray component according to claim 2, wherein the reflective film contains at least one of aluminum, gold, copper and platinum. 4. An optical component and an X-ray component according to claim 2, wherein the reflective film is a silicon carbide film. 5. A silicon carbide powder having an average particle size of 0.1 to 10 μm, preferably 0.3 to 1.0 μm is used, and boron or a compound of boron is converted into boron in an amount of 0.15 to 1.0.
wt%, preferably 0.3 to 0.6 wt%, and carbon to 0.3 to 5 wt% are added as a sintering aid, and after molding, a silicon carbide sintered body is obtained by firing at 1900 ° C to 2250 ° C. And a sintered body is used as an optical component and an X-ray component, and a method for manufacturing an optical component and an X-ray component.