JPH1053871A - Diamond-coated carbon member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a diamond-coated carbon member excellent in adhesion between a base metal and diamond film by forming a coating layer inverted into silicon carbide on the surface of a carbonaceous substrate and forming diamong film on the layer. SOLUTION: A coating layer 22 inverted into SiC by a chemical vapor phase reaction is formed on the surface of a carbonaceous substrate 21. As the carbonaceous substrate 21, a high strength isotropic graphite material small in impurities and in which the coefficient of thermal expansion is close that of SiC is preferably used. Furthermore, the chemical vapor phase reaction can be executed in such a manner that Si and SiO2 are brought into reaction in an atmosphere of an inert gas, and the generated SiO is brought into reaction with the substrate 21 at about 2,000K. Scratches are preferably formed on the inverted layer 22, and after that, diamond film 23 is formed on the surface of the layer. This film 23 is formed, e.g. in such a manner that, while the substrate 21 is subjected to induction heating to about <=1,000K in an evacuated Ar atmosphere, gaseous CH4 is fed thereto together with gaseous H2 as a carrier, and microwave plasma is applied thereto. As for the inverted layer 22 and the diamond-coating layer 23, preferably, their thicknesses and regulated to >=1μm and 1 to 100μm, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon member having a surface coated with diamond. More specifically, the present invention relates to tools, various elements used for various sensors, constituent materials of various semiconductor devices, and the like. Magnetic recording media, various electric and electronic members, optical elements and optical devices of various optical instruments,
The present invention relates to a diamond-coated carbon member used for a material for a nuclear fusion device, a component of an acoustic device or the like.

[0002]

2. Description of the Related Art Diamond is the hardest material currently known, has excellent thermal conductivity, is extremely stable scientifically, has a large elastic modulus, has good electrical insulation, and has many other advantages. Therefore, it is attracting attention as a new material applicable to a wide range of industrial fields such as the electronics, machinery, and aerospace industries.
As a method for synthesizing diamond, a low-pressure synthesis method capable of forming a large-area diamond thin film on the surface of a base material such as a ceramic or a metal is widely known, in addition to a high-pressure synthesis method that synthesizes under high temperature and high pressure. I have.

Further, the low-pressure synthesis method is a physical vapor deposition method (Ph).
Hereafter, it is abbreviated as PVD method and chemical vapor deposition method (Chemica).
Hereafter, it can be roughly classified into a CVD method and a CVD method.
In recent years, the synthesis method by the CVD method has been the main force because diamond has higher crystallinity than the D method over a large area and can be formed at a high speed.

[0004] Usually, as a base for forming a diamond film (hereinafter simply referred to as a base material), diamond,
Tungsten sintered body, silicon carbide sintered body, silicon single crystal, molybdenum, niobium, tantalum, vanadium, chromium, hafnium, germanium, nickel, copper, gold and other metals, cubic boron nitride sintered body, silicon nitride sintered Ceramics such as cement, aluminum oxide, silicon dioxide, stellite, and cermet are used.

When a diamond coating is formed on the above-mentioned base material, about 500 Kelvin (hereinafter abbreviated as K) to 1
Heat to 500K, dilute gaseous gases such as methane, ethylene, propane, acetylene, carbon monoxide, carbon dioxide and gaseous liquids such as methyl alcohol, ethyl alcohol, benzene and acetone with hydrogen gas, The atmosphere is set to an argon gas atmosphere or a hydrogen gas atmosphere, the source gas is excited, and an appropriate method is performed among various CVD methods such as a chemical transport method, a thermal CVD method, a plasma CVD method, a combustion method, and a photo CVD method. The goal is achieved by doing.

However, in forming a diamond coating on the base material, there are various considerations. Specifically, it is necessary to select a base material having good heat resistance. Is difficult to process because it is very hard, the adhesion between the base material and the diamond coating is not very good, etc.
Consideration must be given to reduce these disadvantages depending on the application of the diamond-coated product, and even if processing is performed with such considerations, it is not always satisfactory under the requirement that economical efficiency is also secured. The product was not always available.

Therefore, while studies for improving the diamond coated member are being advanced, attention has been paid to the excellent properties of the carbon material, such as good heat resistance, easy processing, and economical cost. Attempts have been made to form a diamond coating directly on the surface of a carbon material as a base material. However, the thermal expansion coefficient is so different that the adhesion to the diamond coating is not good, and when the CVD method is performed, the carbon material is directly exposed to a reducing atmosphere containing a large amount of hydrogen. There is a disadvantage that the carbon material is consumed by reacting with the hydrogen gas, and the superior characteristics of the carbon material itself cannot be utilized.

Further, for the purpose of solving such a drawback, a diamond coating obtained by forming a silicon carbide coating layer on the surface of a carbon material molded body by a CVD method as a base material and forming a diamond coating on the base material. A carbon member has been proposed (Japanese Patent Application Laid-Open No. Hei 1-2201478).

[0009]

However, when the present inventors actually use the above-mentioned diamond-coated carbon member, cracks and peeling are liable to occur in the base material, and it is applied to the cutting edge of a cutting tool. When applied, it has been found that there is a problem that the service life is short, and the number of replacements of the cutting edge increases, which in turn increases the manufacturing cost.

The present invention has been made in view of the above circumstances, and improves the adhesion between a base material and a diamond coating to eliminate the occurrence of cracks and peeling which are likely to occur at the interface between the two and to reduce the carbon material itself. It is an object of the present invention to provide a diamond-coated carbon member capable of maximally and effectively exhibiting the excellent characteristics of a diamond coating while ensuring the superiority of the properties possessed.

[0011]

Means for Solving the Problems In the present invention which has achieved the above object, the diamond-coated carbon member according to the first aspect of the present invention is characterized in that the surface of a carbonaceous substrate is subjected to a chemical vapor reaction (hereinafter, referred to as a "chemical vapor reaction").
It is called "CVR (Chemical Vapor Reaction) method". ), A coating layer converted to silicon carbide is formed, and a diamond coating is further formed on the surface of the coating layer. This eliminates cracks and delaminations at the interface between the base metal and the diamond coating, which have been a problem in the past, and ensures the superior properties of the carbon material itself while maximizing the effective properties of the diamond coating. A diamond-coated carbon member that can be formed.

The diamond-coated carbon member according to the second aspect of the present invention is the diamond-coated carbon member according to the first aspect, wherein the thickness of the coating layer converted into silicon carbide is 1 μm or more,
The diamond coating has a thickness of 1 μm to 100 μm. Thereby, the effect of the invention described in claim 1 (improving the adhesion between the base material and the diamond film) can be further remarkable.

Hereinafter, the present invention will be described in detail. The present inventors have been conducting intensive research to develop a high quality diamond-coated carbon member, and the SiC layer near the interface (carbon member surface layer) of the conventional diamond-coated carbon member has a crystal structure. Paying attention to the fact that they are formed in a dense and layered form, it is considered that the low adhesion between the base material and the diamond coating is caused by the existence of this form. That is, a laminated form in which a boundary surface between a lower surface of a layer converted into silicon carbide (hereinafter, simply referred to as a conversion layer) and an upper surface of a carbonaceous molded body (hereinafter, referred to as a carbonaceous substrate) is not laminar but wavy. In this case, the two are brought into a state of being engaged with each other, so that the adhesion can be improved. Therefore, the method developed earlier by the present inventors, that is, silicon monoxide (SiO) gas is applied. As a result of applying the method of forming a silicon carbide molded body (SiC film) on a graphite base material by a chemical reaction, it was confirmed that a diamond coated member satisfying in terms of adhesion was obtained. This shows the completion of the invention.

Further, by proceeding with experiments and optimizing the film thickness of the conversion layer and the film thickness of the diamond film formed thereon, the diamond film and the base material (hereinafter, the base material in the present invention are referred to as the conversion material). (Referred to as a carbonaceous substrate having a layer), the improvement of the adhesion to the surface layer portion becomes more remarkable, and furthermore, the occurrence of cracks and peeling at the interface between the carbonaceous substrate and the conversion layer can be completely avoided. Thus, the present invention has been achieved (the invention of claim 2).

In the structure of the present invention, the carbonaceous substrate will be described first. As the carbonaceous substrate used in the present invention,
What consists essentially of only carbon and may be manufactured by a conventional method, for example, a graphitized carbon material, a carbon fiber reinforced carbon composite material (so-called C / C material), a vitreous carbon molded product, and an expanded graphite molded product can be used. .

It is desirable to minimize the impurities contained in the carbonaceous substrate as much as possible.
It is more desirable to use a high-purity graphite material shown in R722-1979. Above all, the carbonaceous substrate is heated to 2,000 K to 3,000 K with chlorine gas, fluorine gas, or a gas containing these chlorine gas and fluorine gas, for example, monochlorotrifluoromethane, dichlorodifluoromethane, trichloromonofluoromethane, etc. It is particularly desirable to select and use a carbonaceous substrate that has been purified and has an ash content of 50 ppm or less. Among them, cobalt, which lowers the adhesion strength between the diamond coating and the base material and suppresses the growth rate of diamond, is 1%.
It is most desirable to use a carbonaceous substrate of 0 ppm or less.

As a method for measuring the cobalt content, for example, “Analytical Chemistry” Vo
l. 42 (1993) reprinted on page 486.
A method shown in “Inductively coupled plasma mass spectrometry (also referred to as ICP-MS method)” can be exemplified.

Further, it is desirable to select a carbonaceous substrate having high strength in consideration of prevention of breakage, for example, a carbonaceous substrate having a bending strength of 40 MPa or more measured by a three-point strength test. In addition, among the above carbonaceous substrates, a carbonaceous substrate having a thermal expansion coefficient close to that of silicon carbide in order to prevent peeling and cracking of the carbonaceous substrate and silicon carbide, for example, is referred to in Japan Carbon Standard (hereinafter referred to as JCAS). The average coefficient of thermal expansion from room temperature to 1273 K measured by the “method of measuring average coefficient of thermal expansion with quartz dilatometer” is 4.0 × (1
0 ^-6 /K)~5.0×(10 ^-6 / K) It is further desirable to select the carbonaceous substrate is anisotropically ratio among them is to use an isotropic graphite material 1.2 In order to convert the surface layer of the carbonaceous substrate to silicon carbide, it is particularly desirable to use an average pore radius of 0.5 μm to 1.8 μm by a mercury intrusion method.
It is desirable to select an isotropic graphite material. The cumulative pore volume and the average pore radius can be measured by, for example, a mercury intrusion method. The pore volume when pressurized to a maximum pressure of 98 MPa is defined as a cumulative pore volume (× 10 ^-2 Mg / m ³ ).
A value (μm) corresponding to の of the cumulative pore volume can be determined as the average pore radius. The term “isotropic graphite material” as used herein refers to a graphite material having an anisotropy in thermal expansion coefficient of 1.2 or less in a direction perpendicular to an arbitrary direction.

Next, the silicon carbide conversion layer will be described. As a method of converting the surface layer portion of the carbonaceous substrate into silicon carbide, basically, the method disclosed in Japanese Patent Application Laid-Open No.
Although the CVR method described in JP-A-264969 may be followed,
Specifically, the carbonaceous substrate processed into a predetermined shape is placed in an electric furnace and an inert gas atmosphere is formed. Then, for example, SiO ₂ is generated by reacting metallic silicon with SiO _2, and about 2 μm is generated.
The carbonaceous substrate may be reacted with the SiO gas at 000 K to form a conversion layer on the surface of the carbonaceous substrate. It is also possible to convert the conversion layer only partially or entirely in the surface layer of the carbonaceous substrate.

It is desirable that the thickness of the conversion layer be 1 μm or more over the depth direction from the surface of the carbonaceous substrate. The reason is that if the depth of the conversion layer is less than 1 μm, it is not possible to sufficiently prevent the carbonaceous substrate from being etched by hydrogen gas when forming a diamond film. Although there is no upper limit to the thickness of the conversion layer,
When the thickness is larger than μm, gas trapped in pores existing in the conversion layer, for example, water vapor, silicon monoxide, carbon monoxide,
Oxygen and carbon powder are released from the pores of the inversion layer by thermal diffusion when forming the diamond film, not only affecting the growth rate of the diamond film, but also carbon monoxide and carbon powder are not excited by thermal excitation. It may precipitate as a shaped hard carbon film and affect the purity of the diamond film. Therefore, it is safe and desirable to set the thickness of the conversion layer to 10 μm to 500 μm in order to obtain a more certain effect.

A conversion layer is formed to reduce the average pore radius to 0.5 μm or less, and the cumulative pore volume is 5 (× 10 ^−2).
The present inventors have also found that the above effect, that is, the enhancement of the crystallization speed of the diamond coating and the purity of the diamond coating can be further improved by making the content of Mg / m ³ ) or less.

Further, the pores present in the conversion layer may be formed of glassy carbon having a thermal expansion coefficient between that of diamond and the conversion layer and having high airtightness and high hardness, or silicon having excellent adhesion to the diamond coating. The present inventors have also found that impregnation with (or may be used in combination with) is effective in sealing the pores of the conversion layer and improving the strength of the base material.

The base material prepared by the above operation is subjected to ultrasonic cleaning in a liquid containing diamond powder (also called diamond compound) having a particle size of 0.1 μm to 1 μm, or using diamond sand paper. The maximum surface roughness (R _max ) shown in JIS B0601-1982 is 0.5 μm to 1.0 μm.
By forming a scratch (hereinafter referred to as a scratch) on the surface so as to obtain m, the growth rate of the diamond film and the adhesion to the base material can be further improved. The scratching operation in this case is simpler than in the case where the surface of the CVD-SiC layer in the conventional diamond-coated carbon member is scratched. That is, since the conventional CVD-SiC layer is very dense and its surface is flat, a stronger scratching operation is required, whereas the CVR-SiC layer of the present invention is relatively porous. Since the surface is also very uneven, a lighter scratch is sufficient, which is advantageous for reducing the working cost.

The diamond coating formed on the surface of the base material will be described. It is desirable that the thickness of the diamond film formed on the surface of the base material be 1 μm or more and 100 μm or less. The reason is that the thickness of the diamond coating is 1
If the thickness is smaller than μm, the diamond coating formed on the base material surface will be worn away immediately.If the thickness is larger than 100 μm, the diamond has a coefficient of thermal expansion much smaller than that of the conversion layer. Stress occurs,
Not only is it easy for peeling and cracking to occur between the base material and the diamond coating, but also the time for forming the diamond coating is lengthened. Therefore, the thickness of the diamond film to be formed on the base material surface is 10 μm to 5 μm.
It is safe and desirable to set it to 0 μm.

The conditions for forming the diamond coating will be described below. Means for forming the diamond film include microwave plasma CVD, hot filament, high frequency plasma CVD, and electron impact CVD.
Method, a photo-CVD method, a direct-current CVD method and the like can be exemplified, and it is possible to arbitrarily select from them.

An example in which a diamond film is formed by a microwave plasma CVD method will be described below as an example. First, the base material on which the scratch is formed is put into the device. The apparatus is evacuated to an argon gas atmosphere of about 1 Torr to 100 Torr, and the base material is heated by induction heating. The temperature at which the base material is heated is preferably as low as possible so as not to cause peeling, cracking, etc. of the base material, and is desirably 1000 K or less.

Subsequently, a microwave of 2.45 GHz is launched from the waveguide. Methane gas is used as a source gas as a source of diamond, and hydrogen gas is used as a carrier gas.
Is supplied at a volume ratio of In this case, it is possible to initially decrease the concentration of methane gas and gradually increase the concentration of methane gas. If the deposition rate of the diamond film is less than 1 μm per hour, it takes a long time to obtain a predetermined film thickness, and the heating time becomes long, which affects the base material, that is, causes peeling and cracks. When the deposition rate is 10
If it is faster than μm, an amorphous hardened carbon film is deposited in addition to a high-purity polycrystalline diamond film, which not only reduces the purity of diamond but also is undesirable in improving the adhesion to the base material.

Although the diamond-coated carbon product of the present invention can be produced in this manner, the characteristics of diamond can be further utilized depending on the application. When used in the most commonly used cutting tools, such as cutting tools, dressers, cutters, drills, and glass cutters, not only high hardness is required, but it is also necessary to impart high machining accuracy to the workpiece. is there. A problem when used as the cutting tool is that the sharpness of the cutting edge is lost due to wear. Therefore, when formed for use in the cutting tool, it is necessary to secure a sufficient film thickness to sufficiently withstand abrasion while utilizing the sharpness of the cutting edge, and the diamond film thickness is 10 μm to It is desirable that the thickness be about 30 μm.

When used in applications requiring high thermal conductivity, it is desirable that the base material has a high thermal conductivity in addition to the high thermal conductivity of diamond. In such a case, the thickness of the conversion layer having a low thermal conductivity is made as thin as possible, for example, about 1 μm. As the carbonaceous substrate, a high carbonaceous substrate having a thermal conductivity of 100 W / (mk) or more is selected. ,
It is desirable to increase the thermal conductivity of the entire base material.

As described above, in the present invention, a carbonaceous substrate having specific physical properties is selected, and CV is applied to the surface layer of the carbonaceous substrate.
Since the coating layer converted to silicon carbide by the R (Chemical Vaper Riaction) method is formed with a thickness of 1 μm to 1000 μm, no separation or crack occurs at the interface between the conversion layer and the carbonaceous substrate. If necessary, the average pore radius and the cumulative pore volume of the conversion layer are adjusted, and in some cases, the airtightness of the base material can be improved by impregnating the pores of the conversion layer with glassy carbon or silicon. Therefore, when forming a diamond coating, there is almost no formation of an amorphous hard carbonized film and the like, and a high-purity diamond coating can be obtained, the adhesion between the diamond coating and the base material is good, and no peeling or cracking occurs. .

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. Example 1 (Preparation of carbonaceous substrate) The average pore radius by the mercury intrusion method was 1.1 μm, and the bending strength by the three-point bending test method was 60 MP.
a, An isotropic graphite material having an average thermal expansion coefficient of 4.7 (× 10 ⁻⁶ / K) from room temperature to 1273 K measured by a quartz thermal dilatometer was prepared. After processing this isotropic graphite material to dimensions of 50 mm square and 10 mm thick, it was highly purified and used as a test piece. The ash content in the test piece was 10 ppm. (Preparation of base material) On the other hand, the inner diameter is 100 mm and the thickness is 10 m
m, graphite crucible having a height of 100 mm, metallic silicon 0.3
kg, and metallic silicon was melted at 1800 K by high frequency induction heating. The test piece was put in the molten silicon to form a 200 μm conversion layer of β-silicon carbide on the entire surface of the test piece, and this was used as a base material. When the cumulative pore volume and average pore radius of the pores of the converted layer in the base material were measured by a mercury intrusion method, they were 4.0 (× 10 ^-2 Mg / m ³ ) and 0.4 μm, respectively.
m. To this base material, at 2000K in vacuum for 2 hours,
Silicon was impregnated with 95% of the pores of the conversion layer. The content of cobalt contained in the converted layer of the base material impregnated with silicon was measured by ICP-MS, and was 1.8 ppm. A diamond compound having an average particle size of 0.1 μm is placed in a commercially available 0.5 liter beaker, pure water is added thereto to disperse the diamond compound, and the base material subjected to the above-described ultrasonic treatment is put therein and taken out. After that, the surface roughness of the base material was measured by the method described in JIS B0601-1982, and as a result, the maximum surface roughness (R _max ) was 0.5 μm. (Formation of diamond film on base material) A base material is put into an apparatus, methane gas is used as a source gas, hydrogen gas is used as a carrier gas, and a methane gas concentration in the hydrogen gas is set to 0.5% by volume. 1. The pressure in the apparatus is set to 50 Torr, the temperature of the substrate (base material) is set to 1200 K, and
A microwave of 45 GHz is introduced into the center of the reaction tube through a waveguide to form a diamond coating at 1 μm / hour.
The diamond film was deposited and allowed to react continuously for 20 hours to form a diamond film having a thickness of 20 μm by a microwave plasma CVD method.

Example 2 (Preparation of Carbonaceous Substrate) The average pore radius by the mercury intrusion method was 1.8 μm, and the bending strength by the three-point bending test method was 40 MP.
a, An isotropic graphite material having an average thermal expansion coefficient of 4.7 (× 10 ⁻⁶ / K) from room temperature to 1273 K measured by a quartz thermal dilatometer was prepared. This isotropic graphite material was processed into a size of 50 mm square and 10 mm in thickness to obtain a test piece. The ash content in the test piece was 12 ppm. (Preparation of Base Material) On the other hand, a partition was provided in an electric furnace, a graphite crucible was placed in a part of the partition, and 0.1 kg of metal silicon and 0.1 kg of silicon dioxide were put in the graphite crucible. A test piece was placed in another room, and the entire inside of the electric furnace was filled with argon gas.
After flowing at an inert gas atmosphere at a rate of 1 liter per minute, heating to 2300 K to generate silicon monoxide gas, and then reacting the carbonaceous substrate with the silicon monoxide gas to cause the surface layer of the carbonaceous substrate A conversion material formed on the entire surface to a thickness of 500 μm was used as a base material. When the cumulative pore volume and average pore radius of the pores of the conversion layer in the base material were measured by the mercury intrusion method,
They were 2.0 (× 10 ^-2 Mg / m ³ ) and 0.2 μm, respectively. The content of cobalt contained in the converted layer of the base material impregnated with silicon was measured by the ICP-MS method.
It was 5 ppm. A diamond compound having an average particle diameter of 0.1 μm is placed in a commercially available 0.5-liter beaker, pure water is added thereto to disperse the diamond compound, the base material is placed therein, and ultrasonic vibration is applied for 10 minutes. To form a scratch. After taking out the base material subjected to the ultrasonic treatment, the surface roughness of the base material was measured according to JIS B06.
As a result of measurement by the method shown in 01-1982, the maximum surface roughness (R _max ) was 0.7 μm. (Formation of diamond film on base material) A base material is put into an apparatus, methane gas is used as a source gas, hydrogen gas is used as a carrier gas, and a methane gas concentration in the hydrogen gas is set to 0.5% by volume. Was flowed into the apparatus, the internal pressure of the apparatus was set to 50 Torr, the substrate temperature was set to 1200 K, microwaves of 2.45 GHz were introduced into the center of the reaction tube through a waveguide, and the diamond film was made to have a volume of 1 μm per hour. The reaction was continued for a period of time to form a 20 μm diamond coating by microwave plasma CVD.

Example 3 (Preparation of Carbonaceous Substrate) The average pore radius was 0.5 μm by the mercury intrusion method, the three-point bending strength was 90 MPa, and the average thermal expansion coefficient from room temperature to 1273 K was 4.
9 (× 10 ⁻⁶ / K) isotropic graphite material was prepared. This isotropic graphite material was processed into a size of 50 mm square and 10 mm in thickness to obtain a test piece. The ash content in the test piece is 12
ppm. (Preparation of Base Material) The same operation as in Example 1 was performed to form a base material having a converted layer formed on the entire surface layer portion of the carbonaceous substrate in a thickness of 250 μm. When the cumulative pore area and the average pore radius of the pores of the converted layer in the base material were measured by a mercury intrusion method, they were 1.8 (× 10 ⁻² Mg / m ³ ) and 0.1 μm, respectively. When the content of cobalt contained in the converted layer of the base material impregnated with silicon was measured by the ICP-MS method, it was found to be 0.9%.
ppm. Put a diamond compound having an average particle size of 0.1 μm into a commercially available 0.5 liter beaker,
Pure water was added thereto to disperse the diamond compound, and the above-mentioned base material was put therein, and ultrasonic vibration was applied for 10 minutes to form a scratch. After taking out the base material subjected to the ultrasonic treatment, the surface roughness of the base material was measured according to JIS B060.
As a result of measurement by the method described in 1-182, the maximum surface roughness (R _max ) was 0.9 μm. (Formation of Diamond Coating on Base Material) The base material was placed in an apparatus, methane gas was used as a raw material gas, hydrogen gas was used as a carrier gas, and the methane gas concentration in the hydrogen gas was 0.1%.
A gas having a volume of 5% by volume was flowed into the apparatus, and the internal pressure of the apparatus was set to 50
At a temperature of 1200 K, the thickness of the diamond film was deposited at 1 μm per hour, and the reaction was continued for 20 hours to form a 20 μm diamond film by the hot filament CVD method.

Example 4 (Preparation of Carbonaceous Substrate) The average pore radius by the mercury intrusion method was 1.1 μm, and the bending strength by the three-point bending test method was 60 MP.
a, An isotropic graphite material having an average coefficient of thermal expansion from room temperature to 1273 K measured by a quartz thermal dilatometer of 5.0 (× 10 ⁻⁶ / K) was prepared. This isotropic graphite material was processed into a size of 50 mm square and 10 mm in thickness to obtain a test piece. The ash content in the test piece was 14 ppm. (Preparation of Base Material) The same operation as in Example 1 was performed to form a base material having a converted layer formed on the entire surface layer portion of the carbonaceous substrate in a thickness of 250 μm. The cumulative pore volume and average pore radius of the pores of the converted layer in the base material were measured by mercury porosimetry to be 3.4 (× 10 ⁻² Mg / m ³ ) and 0.6 μm, respectively. When the content of cobalt contained in the converted layer of the base material impregnated with silicon was measured by the ICP-MS method, it was 3.8.
ppm. A diamond compound having an average particle diameter of 0.1 μm was dispersed in a commercially available 0.5 liter beaker, and the above-described base material was put therein, and ultrasonic vibration was applied for 10 minutes to form a scratch. After taking out the base material subjected to the ultrasonic treatment, the surface roughness of the base material was measured according to JIS B0601.
As a result of measurement according to the method described in -1982, the maximum surface roughness (R _max ) was 1.0 μm. (Formation of diamond film on base material) A base material is put into an apparatus, methane gas is used as a source gas, hydrogen gas is used as a carrier gas, and a methane gas concentration in the hydrogen gas is set to 0.5% by volume. Was flowed into the apparatus, the pressure in the apparatus was set to 50 Torr, the substrate temperature was set to 1200 K, a diamond film was deposited at 2 μm per hour, and the reaction was continued for 10 hours to form a 20 μm diamond film by hot filament CVD.

Example 5 (Preparation of Carbonaceous Substrate) The average pore radius by the mercury intrusion method was 1.1 μm, and the bending strength by the three-point bending test method was 60 MP.
a, An isotropic graphite material having an average thermal expansion coefficient of 4.0 (× 10 ⁻⁶ / K) from room temperature to 1273 K measured with a quartz thermal dilatometer was prepared. This isotropic graphite material was processed into a size of 50 mm square and 10 mm in thickness to obtain a test piece. The ash content in the test piece was 2.1 ppm. (Preparation of Base Material) The same operation as in Example 1 was performed to form a base material having a converted layer formed on the entire surface layer portion of the carbonaceous substrate in a thickness of 250 μm. The cumulative pore volume and average pore radius of the pores of the converted layer in the base material were measured by a mercury intrusion method, and were 2.8 (× 10 ⁻² Mg / m ³ ) and 0.4 μm, respectively. The content of cobalt contained in the converted layer of the base material impregnated with silicon was measured by the ICP-MS method.
ppm. Diamond having an average particle diameter of 0.1 μm was dispersed in a commercially available 0.5 liter beaker, the above-described base material was put therein, and ultrasonic vibration was applied for 10 minutes to form a scratch. After taking out the base material subjected to the ultrasonic treatment, the surface roughness of the base material was measured according to JIS B0601-1982.
As a result, the maximum surface roughness (R _max ) was 0.9 μm. (Formation of diamond film on base material) A base material is put into an apparatus, methane gas is used as a source gas, hydrogen gas is used as a carrier gas, and a methane gas concentration in the hydrogen gas is set to 0.5% by volume. Was flowed into the apparatus, the pressure in the apparatus was set to 50 Torr, the substrate temperature was set to 1200 K, a diamond film was deposited at 2 μm per hour, and the reaction was continued for 10 hours to form a 20 μm diamond film by hot filament CVD.

Example 6 (Preparation of carbonaceous substrate) The test piece prepared in Example 1 was used. (Preparation of Base Material Example 1) The same operation as in Example 1 was performed to form a 950 μm inversion layer on the entire surface of the carbonaceous substrate. The cumulative pore volume and average pore radius of the pores of the converted layer in the base material were measured by a mercury intrusion method, and were 2.8 (× 10 ⁻² Mg / m ³ ) and 0.4 μm, respectively. The content of cobalt contained in the converted layer of the base material impregnated with silicon was measured by the ICP-MS method.
ppm. A diamond compound having an average particle size of 0.1 μm is put into a commercially available 0.5 liter beaker, pure water is added to the diamond compound to disperse the diamond compound, and the base material is put into this, and ultrasonic vibration is applied for 10 minutes. A scratch was formed. After taking out the base material subjected to the ultrasonic treatment, the surface roughness of the base material was measured according to JIS B0601.
As a result of measurement by the method described in -1982, the maximum surface roughness (R _max ) was 0.5 μm. (Formation of Diamond Film on Base Material) A 20 μm diamond film was formed in the same manner as in Example 1.

Example 7 (Preparation of carbonaceous substrate) The test piece prepared in Example 1 was used. (Preparation of Base Material) The same operation as in Example 1 was carried out to form a base material having a conversion layer of 1.1 μm formed on the entire surface of the carbonaceous substrate. The cumulative pore volume and average pore radius of the pores in the converted layer in the base material were measured by mercury porosimetry to be 3.3 (× 10 ⁻² Mg / m ³ ) and 0.8 μm, respectively. When the content of cobalt contained in the converted layer of the base material impregnated with silicon was measured by an ICP-MS method, it was 2.2.
ppm. Diamond having an average particle diameter of 0.1 μm was dispersed in a commercially available 0.5 liter beaker, the above-described base material was put therein, and ultrasonic vibration was applied for 10 minutes to form a scratch. After taking out the base material subjected to the ultrasonic treatment, the surface roughness of the base material was measured according to JIS B0601-1982.
As a result, the maximum surface roughness (R _max ) was 0.5 μm. (Formation of Diamond Film on Base Material) A 20 μm diamond film was formed in the same manner as in Example 1.

Example 8 (Preparation of Carbonaceous Substrate) The average pore radius by the mercury intrusion method was 1.2 μm, and the bending strength by the three-point bending test method was 60 MP.
a, An isotropic graphite material having an average thermal expansion coefficient of 4.7 (× 10 ⁻⁶ / K) from room temperature to 1273 K measured by a quartz thermal dilatometer was prepared. This isotropic graphite material was processed into a size of 50 mm square and 10 mm in thickness to obtain a test piece. The ash content in the test piece was 50 ppm. (Preparation of Base Material) The same operation as in Example 1 was carried out to form a base material having a converted layer of 200 μm formed on the entire surface of the carbonaceous substrate. When the cumulative pore volume and average pore radius of the pores of the converted layer in the base material were measured by a mercury porosimetry, they were 4.9 (× 10 ^-2 Mg / m ³ ) and 0.8 μm, respectively. When the content of cobalt contained in the converted layer of the base material impregnated with silicon was measured by an ICP-MS method, 9.8 was obtained.
ppm. A diamond compound having an average particle diameter of 0.1 μm is put into a commercially available 0.5 liter beaker, pure water is added thereto to disperse the diamond compound, and the above-mentioned base material is put therein, and ultrasonic vibration is applied for 10 minutes. A scratch was formed. After taking out the base material subjected to the ultrasonic treatment, the surface roughness of the base material was measured according to JIS B060.
As a result of measurement by the method described in 1-182, the maximum surface roughness (R _max ) was 0.5 μm. (Formation of Diamond Film on Base Material) A 20 μm diamond film was formed in the same manner as in Example 1.

Example 9 (Preparation of Base Material) Using the base material prepared in Example 1, a diamond compound having an average particle diameter of 0.1 μm was put into a commercially available 0.5 liter beaker, and pure water was added thereto. In addition, the diamond compound was dispersed, the base material was put therein, and ultrasonic vibration was applied for 10 minutes to form a scratch. After taking out the base material subjected to the ultrasonic treatment, the surface roughness of the base material was measured by the method described in JIS B0601-1982, and as a result, the maximum surface roughness (R _max ) was 0.8.
μm. (Formation of diamond film on base material) A base material is put into an apparatus, methane gas is used as a source gas, hydrogen gas is used as a carrier gas, and a methane gas concentration in the hydrogen gas is set to 0.5% by volume. 1. The pressure in the apparatus is set to 50 Torr, the temperature of the substrate (base material) is set to 1200 K, and
A microwave of 45 GHz is introduced into the center of the reaction tube through a waveguide to form a diamond coating at 1 μm / hour.
The diamond film was deposited and allowed to react for 1.5 hours to form a diamond film having a thickness of 1.5 μm by microwave plasma CVD.

Example 10 (Preparation of base material) The same base material as in Example 1 was used.
A diamond compound having an average particle diameter of 0.1 μm is put in a 5 liter beaker, pure water is added thereto to disperse the diamond compound, and the above-mentioned base material is put therein, and ultrasonic vibration is applied for 10 minutes to scratch the diamond compound. Formed. After taking out the base material subjected to the ultrasonic treatment, the surface roughness of the base material was measured by the method described in JIS B0601-1982, and as a result, the maximum surface roughness (R _max ) was 0.8.
μm. (Formation of diamond film on base material) A base material is put into an apparatus, methane gas is used as a source gas, hydrogen gas is used as a carrier gas, and a methane gas concentration in the hydrogen gas is set to 0.5% by volume. And the substrate (base material) temperature was set to 1200 K, and the pressure was set to 2.4 Torr.
A microwave of 5 GHz was introduced into the center of the reaction tube through a waveguide to deposit a diamond film at a thickness of 1 μm per hour, followed by a continuous reaction for 100 hours to form a diamond film of 100 μm by a microwave plasma CVD method.

Comparative Example 1 (Preparation of Base Material) The test piece prepared in Example 1 was placed in a CVD apparatus, and silicon tetrachloride was used as a raw material gas, and propane gas was used as a carrier gas, at 1800 K and a gas was supplied at a flow rate of 0.1 kg / min. 3 liters of dense silicon carbide layer on the surface of the test piece
A thickness of 00 μm was formed. When the cumulative pore area and the average pore radius of the pores of the converted layer in the base material were measured by a mercury intrusion method, they were 2.0 (× 10 ^-2 Mg / m ³ ) and 0.1 μm, respectively.
Met. (Formation of Diamond Coating on Base Material) In the same manner as in Example 1, a diamond coating was deposited at 1 μm per hour, and allowed to react continuously for 20 hours to obtain microwave plasma C.
A 20 μm diamond film was formed by the VD method. Comparative Example 2 (Preparation of carbonaceous substrate) Average pore radius by mercury intrusion method was 2.0 μm and bending strength by three-point bending test method was 30 MP.
a, An isotropic graphite material having an average thermal expansion coefficient of 4.7 (× 10 ⁻⁶ / K) from room temperature to 1273 K measured by a quartz thermal dilatometer was prepared. This isotropic graphite material was processed into a size of 50 mm square and 10 mm thick, and then highly purified to obtain a test piece. The ash content in the test piece was 10 ppm. (Preparation of Base Material) In the same manner as in Example 1, a 200 μm conversion layer of β-silicon carbide was formed on the entire surface of the test piece, and this was used as a base material. When the cumulative pore volume and average pore radius of the pores of the conversion layer in the base material were measured by the mercury intrusion method,
They were 4.0 (× 10 ^-2 Mg / m ³ ) and 0.4 μm, respectively. The content of cobalt contained in the converted layer of the base material impregnated with silicon was measured by the ICP-MS method.
It was 8 ppm. A diamond compound having an average particle diameter of 0.1 μm is put into a commercially available 0.5 liter beaker, pure water is added to disperse the diamond compound, the above-described base material is put therein, and ultrasonic vibration is applied for 10 minutes. A scratch was formed. After taking out the base material subjected to the ultrasonic treatment, the surface roughness of the base material was measured according to JIS B06.
The maximum surface roughness (R _max ) was 0.5 μm as a result of measurement by the method described in 01-1982. (Formation of diamond coating on base material) A base material is put into an apparatus, methane gas is used as a source gas, hydrogen gas is used as a carrier gas, and a gas having a methane gas concentration of 0.5% by volume in hydrogen gas is used. 1. Flow into the apparatus, set the pressure in the apparatus to 50 Torr, and set the substrate (base material) temperature to 1200 K.
A microwave of 45 GHz is introduced into the center of the reaction tube through a waveguide to form a diamond coating at 1 μm / hour.
The diamond film was deposited and allowed to react continuously for 20 hours to form a diamond film having a thickness of 20 μm by a microwave plasma CVD method.

Comparative Example 3 (Preparation of Carbonaceous Substrate) The average pore radius by the mercury intrusion method was 0.15 μm, and the bending strength by the three-point bending test method was 80 M.
An isotropic graphite material having an average thermal expansion coefficient of 4.7 (× 10 ⁻⁶ / K) from room temperature to 1273 K measured by a Pa and quartz thermal dilatometer was prepared. After processing this isotropic graphite material to a size of 50 mm square and a thickness of 10 mm, it was highly purified and used as a test piece. The ash content in the test piece was 10 ppm. (Preparation of Base Material) In the same manner as in Example 1, a 0.8 μm conversion layer was formed of β-silicon carbide over the entire surface portion of the test piece, and this was used as a base material. When the cumulative pore volume and average pore radius of the pores of the conversion layer in the base material were measured by the mercury intrusion method,
They were 1.0 (× 10 ^-2 Mg / m ³ ) and 0.1 μm, respectively. When the content of cobalt contained in the converted layer of the base material impregnated with silicon was measured by the IP-MS method, it was 1.8.
ppm. A diamond compound having an average particle diameter of 0.1 μm is placed in a commercially available 0.5-liter beaker, pure water is added thereto to disperse the diamond compound, the base material is placed therein, and ultrasonic vibration is applied for 10 minutes. To form a scratch. After taking out the base material subjected to the ultrasonic treatment, the surface roughness of the base material was measured according to JIS B06.
The maximum surface roughness (R _max ) was 0.5 μm as a result of measurement by the method described in 01-1982. (Formation of Diamond Coating on Base Material) A base material was put into an apparatus, methane gas was used as a source gas, hydrogen gas was used as a carrier gas, and a gas having a methane gas concentration of 0.5% by volume in hydrogen gas was used. 1. Flow into the apparatus, set the pressure in the apparatus to 50 Torr, and set the substrate (base material) temperature to 1200 K.
A microwave of 45 GHz is introduced into the center of the reaction tube through a waveguide to form a diamond coating at 1 μm / hour.
The diamond film was deposited and allowed to react continuously for 20 hours to form a diamond film having a thickness of 20 μm by a microwave plasma CVD method.

Comparative Example 4 (Preparation of Carbonaceous Substrate) The average pore radius by the mercury intrusion method was 1.1 μm, and the bending strength by the three-point bending test method was 60 MP.
a, An isotropic graphite material having an average thermal expansion coefficient of 5.2 (× 10 ⁻⁶ / K) from room temperature to 1273 K by a quartz thermal dilatometer was prepared. After processing this isotropic graphite material to a size of 50 mm square and a thickness of 10 mm, it was highly purified and used as a test piece. The ash content in the test piece was 10 ppm. (Preparation of Base Material) In the same manner as in Example 1, a 200 μm conversion layer of β-silicon carbide was formed on the entire surface of the test piece,
This was used as a base material. When the cumulative pore volume and average pore radius of the pores of the converted layer in the base material were measured by a mercury intrusion method, they were 4.0 (× 10 ^-2 Mg / m ³ ) and 0.4 μm, respectively.
Met. The content of cobalt contained in the converted layer of the base material impregnated with silicon was measured by ICP-MS method to be 1.8 ppm. A diamond compound having an average particle diameter of 0.1 μm is placed in a commercially available 0.5-liter beaker, pure water is added thereto to disperse the diamond compound, the base material is placed therein, and ultrasonic vibration is applied for 10 minutes. To form a scratch. After taking out the base material subjected to the ultrasonic treatment, the surface roughness of the base material was measured according to JIS.
As a result of measurement by the method described in B0601-1982, the maximum surface roughness (R _max ) was 0.5 μm. (Formation of Diamond Coating on Base Material) A diamond coating having a thickness of 20 μm was formed in the same manner as in Example 1.

Comparative Example 5 (Preparation of Carbonaceous Substrate) The average pore radius by the mercury intrusion method was 1.1 μm, and the bending strength by the three-point bending test method was 60 MP.
a, An isotropic graphite material having an average thermal expansion coefficient of 3.7 (× 10 ⁻⁶ / K) from room temperature to 1273 K by a quartz thermal dilatometer was prepared. After processing this isotropic graphite material to a size of 50 mm square and a thickness of 10 mm, it was highly purified and used as a test piece. The ash content in the test piece is 10 ppm. (Preparation of Base Material) In the same manner as in Example 1, a 200 μm conversion layer of β-silicon carbide was formed on the entire surface of the test piece,
This was used as the base material. When the cumulative pore volume and average pore radius of the pores of the conversion layer in the base material were measured by the mercury intrusion method,
They were 4.0 (× 10 ^-2 Mg / m ³ ) and 0.4 μm, respectively. When the content of cobalt contained in the conversion layer of the base material impregnated with silicon was measured by the ICP-MS method,
1.8 ppm. A diamond compound having an average particle diameter of 0.1 μm is placed in a commercially available 0.5 liter beaker,
Pure water was added thereto to disperse the diamond compound, and the above-mentioned base material was put therein, and ultrasonic vibration was applied for 10 minutes to form a scratch. After taking out the base material subjected to the ultrasonic treatment, the surface roughness of the base material was measured according to JIS B060.
As a result of measurement by the method described in 1-182, the maximum surface roughness (R _max ) was 0.5 μm. (Formation of Diamond Coating on Base Material) In the same manner as in Example 1, a diamond coating was deposited at 1 μm per hour, and allowed to react continuously for 20 hours to obtain microwave plasma C.
A 20 μm diamond film was formed by the VD method.

Comparative Example 6 (Preparation of Carbonaceous Substrate) The average pore radius was 1.1 μm by a mercury intrusion method, and the bending radius was 60 M by a three-point bending test method.
An isotropic graphite material having an average thermal expansion coefficient of 4.7 (× 10 ⁻⁶ / K) from room temperature to 1273 K measured by a Pa and quartz thermal dilatometer was prepared. After processing this isotropic graphite material to a size of 50 mm square and a thickness of 10 mm, it was highly purified and used as a test piece. The ash content in the test piece was 100 ppm. (Preparation of Base Material) In the same manner as in Example 1, a 200 μm conversion layer of β-silicon carbide was formed on the entire surface of the test piece,
This was used as a base material. When the cumulative pore volume and average pore radius of the pores of the converted layer in the base material were measured by a mercury intrusion method, they were 4.0 (× 10 ^-2 Mg / m ³ ) and 0.4 μm, respectively.
Met. When the content of cobalt contained in the conversion layer of the base material impregnated with silicon was measured by an ICP-MS method,
It was 11.8 ppm. A diamond compound having an average particle diameter of 0.1 μm is placed in a commercially available 0.5 liter beaker, pure water is added thereto to disperse the diamond compound, and the above-described base material is placed therein, and ultrasonic vibration is performed for 1 minute.
Give for 0 minutes to form a scratch. After taking out the base material subjected to the ultrasonic treatment, the surface roughness of the base material was measured according to JIS.
As a result of measurement by the method shown in B0601-1982,
The maximum surface roughness (R _max ) was 0.5 μm. (Formation of Diamond Coating on Base Material) In the same manner as in Example 1, a diamond coating was deposited at 1 μm per hour, and allowed to react continuously for 20 hours to obtain microwave plasma C.
A 20 μm diamond film was formed by the VD method.

Comparative Example 7 (Preparation of Carbonaceous Substrate) The test piece prepared in Example 1 was used. (Preparation of base material) On the other hand, the inner diameter is 100 mm and the thickness is 10 m
m, graphite crucible having a height of 100 mm, metallic silicon 0.3
kg, and metallic silicon was melted at 1800 K by high frequency induction heating. A test piece was put in molten silicon to form a 1100 μm conversion layer of β-silicon carbide over the entire surface of the test piece, and this was used as a base material. When the cumulative pore volume and average pore radius of the pores of the converted layer in the base material were measured by the mercury intrusion method, they were 10.0 (× 10 ^-2 Mg / m ³ ) and 0.7, respectively.
μm. The content of cobalt contained in the converted layer of the base material impregnated with silicon was measured by ICP-MS to be 1.8 ppm. A diamond compound having an average particle size of 0.1 μm is put in a commercially available 0.5 liter beaker, pure water is added thereto to disperse the diamond compound, and the ultrasonically treated base material is taken out. , The surface roughness of the base material is JIS B0601-
As a result of measurement by the method shown in 1982, the maximum surface roughness (R _max ) was 0.5 μm. (Formation of Diamond Film on Base Material) In the same manner as in Example 1, a diamond film was deposited at a thickness of 1 μm per hour, and allowed to react continuously for 20 hours.
A 20 μm diamond film was formed by Method D.

Comparative Example 8 (Preparation of Carbonaceous Substrate) The test piece prepared in Example 1 was used. (Preparation of base material) On the other hand, the inner diameter is 100 mm and the thickness is 10 m
m, graphite crucible having a height of 100 mm, metallic silicon 0.3
kg, and metallic silicon was melted at 1800 K by high frequency induction heating. The test piece was put in the molten silicon to form a 200 μm conversion layer of β-silicon carbide on the entire surface of the test piece, and this was used as a base material. When the cumulative pore volume and average pore radius of the pores of the converted layer in the base material were measured by a mercury intrusion method, they were 4.0 (× 10 ^-2 Mg / m ³ ) and 0.4 μm, respectively.
m. The content of cobalt contained in the converted layer of the base material impregnated with silicon was measured by ICP-MS to be 1.8 ppm. A diamond compound having an average particle diameter of 0.1 μm is placed in a commercially available 0.5 liter beaker, pure water is added thereto to disperse the diamond compound, and the above-described base material is placed therein and subjected to ultrasonic vibration for 5 minutes. To form a scratch. After taking out the base material subjected to the ultrasonic treatment, the surface roughness of the base material was measured according to JIS.
As a result of measurement by the method shown in B0601-1982,
The maximum surface roughness (R _max ) was 1.3 μm. (Formation of Diamond Film on Base Material) In the same manner as in Example 1, a diamond film was deposited at a thickness of 1 μm per hour, and allowed to react continuously for 20 hours.
A 20 μm diamond film was formed by Method D.

Comparative Example 9 (Base Material) The base material having a conversion layer of 200 μm prepared in Example 1 was used. (Formation of Diamond Coating on Base Material) In the same manner as in Example 1, a diamond coating was formed at 0.8 μm / hour.
The diamond film was deposited and allowed to react for 1 hour to form a 0.8 μm diamond film by microwave plasma CVD.

Comparative Example 10 (Base Material) A base material having a conversion layer of 200 μm prepared in Example 1 was used. (Formation of Diamond Coating on Base Material) In the same manner as in Example 1, a diamond coating was deposited at 1 μm per hour, and a continuous reaction was performed for 110 hours to form a microwave plasma coating at 110 μm.

The above Examples 1 to 10 and Comparative Example 10 are summarized in Table 1.

[0051]

[Table 1]

EXPERIMENTAL EXAMPLE 1 The samples obtained in Examples 1 to 10 were subjected to a drawing method (shown in the figure) to test the adhesion between the carbonaceous substrate and the silicon carbide and diamond coatings, and to determine the presence or absence of peeling and cracking. confirmed.

(Drawing method) Diameter 7.96 mm, length 9
After sufficiently washing a 5.0 mm S45C stainless steel rod 11, a contact agent (polyvinyl acetate) 12 is applied,
The sample was adhered to the surface of each of the samples obtained in Examples 1 to 10 and Comparative Example 10. The bonding condition at this time is 443K
For 1 hour, and then allowed to cool to room temperature. The pulling bar 11 and the load cell 14 were brought into contact with each other with a wire, and were pulled in the horizontal direction as shown in FIG. The measurement was performed twice for one sample. The state of the sample at that time was visually observed. Table 2 shows the results.

[0054]

[Table 2]

Experimental Example 2 Further , the samples obtained in Examples 1 to 10 and Comparative Example 10 were rapidly heated to 1273 K, and then thrown in water to repeat the thermal shock test. -It was checked whether cracks occurred. Table 2 also shows the results.

Example 11 The carbonaceous substrate produced in Example 1 was processed into a chip shape having a regular triangle of 18.7 mm on a side and a thickness of 4.7 mm. The corners of the chip were chamfered. The surface layer of this chip was converted into 200 μm silicon carbide over the entire surface of the chip by the method of Example 1, and a diamond coating was further formed by the method of Example 1.
0 μm was formed.

COMPARATIVE EXAMPLE 11 A dense silicon carbide film was formed to a thickness of 100 μm on the chip material prepared in Example 11 by the CVD method (the conditions were the same as in Comparative Example 10). Formed.

Experimental Example 3 A cutting test was performed using the chips prepared in Example 11 and Comparative Example 11. Aluminum was used as the material to be cut.
As a result, the chip prepared in Example 11 did not peel between the carbonaceous substrate and the silicon carbide even after the test for 1 hour, but the chip prepared in Comparative Example 11 was not used for 10 hours after the start of use.
Within minutes, peeling occurred at the interface between the carbonaceous substrate and the dense silicon carbide, making it unusable.

Example 12 The carbonaceous substrate prepared in Example 1 was processed into a sukiyaki pan having an outer diameter of 240 mm, an inner diameter of 200 mm, and a depth of 40 mm.
In the same manner as in Example 1, the outer bottom surface of the pot was converted to 200 μm silicon carbide, and a diamond coating was formed thereon to 20 μm.

Comparative Example 12 The carbonaceous substrate prepared in Example 1 was processed into a sukiyaki pan having an outer diameter of 240 mm, an inner diameter of 200 mm and a depth of 40 mm.

Experimental Example 4 The sukiyaki pans prepared in Experimental Example 12 and Comparative Example 12 were filled with water and heated with a gas stove, and the time until the amount of water in the pan became half was measured. As a result, while the pot prepared in Example 12 took 30 minutes, the sukiyaki pot prepared in Comparative Example 12 required 50 minutes.

[0062]

As described above, in the diamond-coated carbon member according to the first aspect of the present invention, the surface layer of the carbonaceous substrate is chemically converted into silicon carbide by a CVR (Chemical Vaper Reaction) method. Coating layer, ie CVD
A silicon carbide coating layer formed by a chemical method and a crystal structure are completely different from a silicon carbide coating layer, and a diamond coating is further formed on the surface thereof. First, it is possible to prevent cracks and peeling occurring between the silicon carbide layer and the silicon carbide layer. As a result, a diamond-coated carbon member capable of improving the adhesion between the base material and the diamond coating and ensuring the superior properties of the carbon material itself and maximally effectively exhibiting the excellent properties of the diamond coating. It can be provided.

Further, the conversion layer made of CVR-SiC is
Compared to the CVD-SiC layer, the surface is considerably porous, and the surface is considerably uneven, so that the scratching operation as a pretreatment of the diamond film is very easy, and the production cost is reduced, so that the diamond-coated carbon is inexpensive. A member can be provided.

The diamond-coated carbon member according to the second aspect of the present invention is the same as the first aspect of the invention, except that
The thickness of the VR-SiC layer (conversion layer) is 1 μm or more, and the thickness of the diamond coating is 1 μm to 100 μm. Therefore, the effect of the invention described in claim 1 can be more reliably and remarkably realized, and an economical diamond-coated carbon member can be provided.

[Brief description of the drawings]

FIG. 1 is an outline of a test apparatus for adhesion by a drawing method.

FIG. 2 is a longitudinal sectional view of the diamond-coated carbon product of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 drawer rod 12 adhesive 13 sample 14 load cell 21 carbonaceous substrate 22 conversion layer converted to silicon carbide by CVR method 23 diamond coating

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Katsunori Goda 2791 Matsuzaki, Takuma-cho, Mitoyo-gun, Kagawa Pref.

Claims (2)

[Claims] 1. A diamond-coated carbon member comprising a carbonaceous substrate having a coating layer converted to silicon carbide by a chemical vapor reaction formed on a surface thereof, and further having a diamond coating formed on the surface thereof. 2. The coating layer converted to silicon carbide has a thickness of 1
μm or more, and the thickness of the diamond coating is 1 μm
The diamond-coated carbon member according to claim 1, which has a thickness of from 1 to 100 µm.