JPS59184792A - Vapor phase synthesis of diamond - Google Patents

Abstract

PURPOSE:To synthesize artifical diamond having complete crystalline property on a coated layer of a member coated with W, or Nb by charging said coated member into a reaction furnace, specifying the distance between the coated layer and a filament and temp. condition, and flowing a regulated gaseous reaction mixture. CONSTITUTION:A coated layer comprising W of Nb is formed on the surface of a base material such as Fe group metal, cermet, or ceramics. Said coated material is charged into a reaction furnace, and a filament comprising W, Ta, Mo, or graphite is set at a position 0.5-3cm apart from the surface of the coated material. In this state, a gaseous reaction mixture having a proportion of CH4 to H2 regulated to 0.001-0.05 is flowed through said filament to collide with the surface of the coated material. The reaction is carried out by maintaining the temp. of the surface of the coated material at 500-1,200 deg.C, and the temp. of the filament at 1,800-2,500 deg.C. By this method, particles or film of artificial diamond having complete crystalline property are formed on the surface of the coated material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of depositing diamond in the form of grains or films using a vapor phase synthesis method.

Diamond is the hardest of all existing substances and is in the 'vJ phase with excellent thermal conductivity and electrical insulation, so it is used in a wide range of fields as an industrially useful material.

In addition to naturally occurring diamonds, we also use ultra-high pressure synthesis equipment to produce diamonds. Graphite powder is placed together with a catalyst in an ultra-high pressure generating container, and diamonds are produced at a temperature of 21,600°C or higher and a pressure of 60°C.
There is an artificial diamond produced by causing graphite to undergo phase transformation into diamond by reacting at high temperatures and pressures of kB or higher. This artificial diamond can be obtained in various particle sizes by controlling the particle size of the raw material powder and the reaction time, but not only does the equipment itself become large, but there is also a limit to the amount of production at one time. In terms of performance, there is no way to avoid high costs. Another method for synthesizing diamonds is to convert graphite into diamond by using the impact force from the explosion of gunpowder, but the artificial diamonds produced by this method are not produced by the ultra-high pressure synthesis method mentioned above. ! Although it is somewhat cheaper than those manufactured by Il, it is difficult to obtain one with perfect crystallinity, and therefore there are problems in terms of characteristics.

Therefore, from the above-mentioned viewpoint, the present inventors conducted research in order to manufacture perfectly crystalline artificial diamonds with high productivity and at low cost without using large press equipment, etc. As a result, Using a surface coating member formed by forming a coating layer made of W or Nl on the surface of a base member made of iron group metal, cermet, or ceramic as a substrate on which diamond is deposited, using a vapor phase synthesis method, With a filament made of W, Ta, Mo, or graphite positioned at a distance of 05 to 3 Cnl from the surface of the surface coating member, the capacitance ratio of CH4 and H2, that is, CH4/H2, was set to 0. While the mixed reaction gas adjusted to 001 to 005 passes through the filament and flows automatically onto the surface of the surface coating member, the surface temperature of the surface coating member is 500 to 1200°C, and the temperature of the filament is 1800 to 2500°C. They found that when the reaction was carried out under these conditions, perfectly crystalline diamond was present on the surface of the surface coating member in the form of grains or films.

In addition, in the method of the present invention, when the distance between the surface of the surface coating member and the filament is relatively small within the range of 0.5 to 30 mm, the density of diamond precipitation nuclei becomes high, and the precipitation nuclei are spread horizontally. Because they are arranged densely, they become film-like, and on the other hand, when the distance between the meats 11 increases, they become granular. The above-mentioned coating layer is essential for precipitating a large number of diamond nuclei. Therefore, if there is no coating layer, the precipitation of diamond will be extremely small and the desired diamond nuclei will not be formed. It is impossible to measure the precipitation and growth of .

Next, in the method of the present invention, the reason why the manufacturing conditions are limited to the following will be explained.

The temperature of the +a+ filament causes the filament to decompose methane (CH4) and at the same time the resulting C,! - H2 is thought to be harmful to diamond formation, but if the temperature is less than 1800°C, the activation of the reaction gas will not be sufficient, while if the temperature exceeds 250°C, thermal radiation will be harmful. If the filament temperature is too high, diamond formation will be insufficient in either case.
It was set at 2500C.

(1)) Surface temperature of the surface-coated member This surface temperature is determined by the radiant heat from the filament and the heating temperature of the member itself, but if the surface temperature is less than 500°C, the precipitation rate of diamond will be slow;
Since diamond does not precipitate at a surface temperature exceeding Ci, the surface temperature is set at 500 to 120 (l
It was set as C.

(C) Ratio of CH4/H2 in the mixed reaction gas If this ratio is less than o or oo1, the rate of diamond formation is extremely slow, while if this ratio exceeds 0.05, graphite will be mixed in the diamond. Therefore, C
The H4/H2 ratio k was set at 0.001-0.05.

(d) Distance between the surface of the surface-coated member and the filament If this distance is less than 0.5 on, the surface temperature of the member will exceed 1200'Ct due to the radiant heat of the filament9, and diamond precipitation will not occur. 9. On the other hand, if this distance becomes larger than 3 an f, the density of diamond nucleus formation decreases rapidly, so the distance f was determined to be 0.5 to 3 cm.

Further, when carrying out the method of the present invention, the reaction atmosphere is preferably a vacuum atmosphere with a pressure within the range of 5 to IQ Otorr, which is less than 5 torr/111
This is because at a pressure of 11 Torr, the precipitation rate of diamond is extremely high, while at a pressure exceeding 100 Torr, graphite becomes mixed.

Furthermore, the above-mentioned coating layer can be formed using a conventional method such as a chemical vapor deposition method, a physical vapor deposition method, or a thermal spraying method depending on the base member.

In addition, the diamond synthesized by the method of the invention contains W, which is a filament constituent, as an unavoidable impurity.
, Ivlo, Ta, etc. may be contained in the range of 1 to 10 atoms, but this level of impurity content does not have any adverse effect on the properties of diamond.

At the same time, the method of the present invention will be specifically explained with reference to Examples.

Each of the examples had the component composition shown in Table 1, and 10 m
A base member having dimensions of m' x thickness 2 ram is prepared, and a coating layer forming method shown in Table 1 is applied to the surface of this base member, that is, a chemical vapor deposition method (indicated by CVD), a physical vapor deposition method. Magnetron sputtering method (
Using either pVD-MS (indicated by pVD-MS) or plasma spraying method (indicated by ps), a coating layer of the material and average layer thickness shown in Table 1 is formed under normal conditions, and then the coating layer is formed in this manner. Methods 1 to 7 of the present invention and comparative methods 1 to 7 were carried out by subjecting the surface of the surface-coated member prepared in the same manner to a gas phase synthesis reaction for diamond formation under the conditions shown in Table 1. After the experiment, the average layer thickness of the synthetic diamond formed on the surface was measured and its condition was observed. These results are also shown in Table 1.

In addition, Comparative Methods 1 to 7 all involve conditions in which the vapor phase synthesis conditions for diamond formation are outside the scope of this invention (the conditions marked with * in Table 1 are conditions outside the scope of this invention). ).

From the results shown in Table 1, diamonds were synthesized in good condition in all methods 1 to 7 of the present invention, whereas diamonds were synthesized satisfactorily in all cases in comparative methods 1 to 7. It is clear that this will not be done.

All of the diamonds synthesized by Methods 1 to 7 of the present invention exhibited hardness and electrical resistance equivalent to those of natural diamond.

As described above, according to the method of the present invention, completely crystalline artificial diamond can be coated with grains or films on the surface of the surface coating part without using large-scale equipment and with high productivity. Therefore, when diamond is synthesized in the form of granules, it can be mechanically scraped off from the surface of the material to form a powder and used as a grindstone, abrasive, or raw material powder for powder metallurgy. In addition, when forming a film, the base member can be used for various tool parts that require wear resistance and weather resistance, or for engineering C or LSI that require thermal conductivity and electrical insulation. It may also be used as an insulating film or B.

In combination with doping with components such as P and M, it brings about industrially useful effects such as being able to be applied to applications such as semiconductor films.

Applicant Mitsubishi Metals Co., Ltd. Agent Tomi 1) Kazuo Kazuo and 1 other person amended proceedings (Jiri Kazuo Wakasugi, Commissioner of the Japan Patent Office, September 2, 1980 1, Patent Application No. 57044, 1982, Patent Application No. 2) Name of the invention: Diamond vapor phase synthesis method 3; Relationship with the case of the person making the amendment Patent applicant address: No. 5-2, Otemachi-cho, Chiyoda-ku, Higashihara City Name
(Name H626J Mitsubishi Metals Co., Ltd. Representative Water
Ken No 4 Agent 5 Date of notice of reasons for refusal Voluntary statement (1) Description, page 6, detailed description of the invention, line 15, "pressure within the range of 5 to 100 torr""Pressure within the range of 5 to 100 torr with a Pirani vacuum gauge (this pressure is the O when measured with a diaphragm vacuum gauge)
Corresponds to 1 to 10 torr (hereinafter the pressure is shown as the pressure measured with a Pirani vacuum gauge)" (corrected).

that's all

Claims (1)

[Claims] A surface coating member in which a coated layer of w'l or Nl) is formed on the surface of the base portion 4';A made of iron group metal, cermet, or ceramic is charged into a reactor, and the surface While maintaining the distance between the surface of the coating member and the filament made of W, Ta, Mo, or graphite at 0.5 to 30, the ratio of OH4/H2 is -tO,001 to
While flowing the mixed reaction gas adjusted within the range of 0.005 into the reactor, the surface temperature of the surface coating member: 500 to 1200.
℃, and a filament temperature of -1800 to 2500℃, thereby depositing diamond in the form of granules or film on the surface of the surface wrinkle covering member. .