JPS61219759A - Manufacture of diamond massed body - 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 (1) Industrial Application Field The present invention relates to a diamond sintered body used for grinding, cutting tools, etc., and particularly to a dense arm body containing almost no substance other than diamond.

←) Conventional technology Diamond sintered bodies do not sinter diamond alone, so Fe e Nf + C is added to the diamond powder.

A known method is to add a metal or alloy powder that melts diamond, such as diamond, and process and sinter it at a high temperature and high pressure in the thermodynamically stable diamond range. Furthermore, a method has also been proposed in which one part of graphite powder is further added to the above method. The added graphite converts into diamond under high temperature and pressure, and at the same time, the diamond powder is sintered.

There is also a method in which a thin plate made of the above-mentioned metal or alloy and a diamond powder compact are stacked and treated under high temperature and high pressure conditions, and the thin plate melts and penetrates into the diamond sintered body, thereby sintering the diamond. be.

However, in these methods, part of the diamond or graphite dissolves in the metal, etc., and when it precipitates as diamond, the particles become coarse, resulting in a non-uniform sintered body, which has poor properties such as strength. In addition, if metals with lower hardness than diamond remain, if graphite is added, a portion of the graphite may remain in the sintered body. Similarly, the hardness of the sintered body
The strength etc. will be inferior.

f→ Problems to be Solved by the Invention The present invention avoids deterioration of properties due to the inclusion of substances such as graphite and metals in the diamond dense lump, and provides a sintered body consisting essentially only of diamond. The purpose is to prevent the generation of coarse diamond particles and obtain a uniform diamond sintered body.

(2) Means for Solving the Problems The present invention involves adding a small amount of so-called i-carpine or diamond-like carbon powder to diamond powder, and treating it at a high temperature and high pressure in the thermodynamic constant stability range of diamond, to form diamond powder particles. This is a method in which the i-carbon is directly converted into diamond at the surface and sintered into a single body.

It has long been known that carbon includes graphite and diamond. However, recently carbon has been discovered with a structure different from that of diamond and graphite. Figure 1 in Ramansuictor
As shown in the figure, there is a broad peak 1 near 1550 an.

This is what is called i-carbon or diamond-like carbon. On the other hand, in the graphite structure, 159
0fi-', diamond has a peak 2 at 1332cIrL. References regarding i-carbon or diamond-like carbon include J, VAC, SC1, TE.
CH, Vol 20, No. 3, 338-34
0 * 1981 r 1. J, Morave
c, J, Mat, Sci +vol 17 r
3106 + 1982 r S, Mats
Examples include umoto + et *a1.

The present invention is based on the results of various studies on i-carpine or diamond-like carbon (hereinafter referred to as i-carpine) and the discovery that it is effective as a sintering aid for diamond.

It is said that diamond is usually obtained from graphite by dissolving graphite in a metal or the like to form atomic carbon, which forms a diamond structure when it precipitates in the diamond stability region.

It is also said that it is possible to directly convert graphite into a diamond structure, especially in areas of high pressure. However, this is difficult in practice.

If i-carpine does not use metal or the like, it is difficult to convert it into diamond with a certain degree of yield within a practical range, except at particularly high pressures. However, it has been found that when this i-carn is mixed with diamond powder and treated under practically possible high temperature and high pressure, most of the i-carn is converted into diamond. This is because i-carpine has an unstable structure compared to graphite, and therefore it is considered that it converts to diamond on the surface of diamond particles under conditions of high temperature and high pressure.

The method for producing i-carbon is to convert hydrocarbons such as CH4 into H
There is a method (plasma CVD method) in which i-carpine is diluted with 2 or H2 and an inert gas, excited with microwaves or high frequency waves, and then deposited as i-carpine on a substrate such as silicon that has been heated to a predetermined temperature. . This process generally results in a mixture of diamond and i-carpine, often containing small amounts of graphite. To reduce graphite, the pressure is 0.5-10%. In the case of microwave, the CH4 concentration is 0.1-0.59g, and the substrate temperature is 7.
00 to 1000℃, the microwave power is such that the temperature of the substrate at the center of the plasma is 700 to 1000℃,
In addition, in order to increase the amount of i-carbon while reducing the amount of diamond, the conditions are CH4 concentration of 2 to 4 cm and pressure of 1 to 5 KP.
a. Microwave Power sets the substrate temperature to 850-950
The size should be such that it can be maintained at ℃.

The diamond powder used in the present invention preferably has a particle size in the range of 1 to 10 μm and has uniform particle size in order to increase the lump density and strength. The carbon to be added to this is used by peeling off the film deposited on the substrate by, for example, the plasma CVD method described above, and pulverizing it into about 1 to 5 pieces. This pulverization may be performed by stirring after mixing with diamond. A suitable mixing ratio of both is 2,710 to 50 parts by weight of i-car to 100 parts by weight of diamond. If the amount of i-carpin is too small, the bonding strength of the arm will not increase; on the other hand, if it is too large, the i-carpin will become diamond-like and the number of i-carpins will increase, making it undesirable for the arm. In the present invention, the i-cargan should not remain in the arm body as much as possible, and preferably the weight of the mass should be 5 cm or less. For this purpose, the amount of i-carbon is determined in relation to the processing conditions.

Generally, if the treatment is carried out at a sufficiently high temperature, high pressure, and time, the amount of i-carbon in the raw material can be increased.

The diamond powder and the i-carbine powder are thoroughly mixed, and the molded product is loaded into an ultra-high pressure device and processed.

Basically, the processing conditions may be within the thermodynamic stability range of diamond, but there may be problems such as conversion rate and equipment.#) 1300
~1800°C, 5~5GPa, and 10~30 minutes are preferred.

(E) Example Using a mixed gas of 3 volumes of methane and 97 volumes of hydrogen, this was excited with a 2.45 GHz microwave in a reaction tank, and the mixture was placed in the reaction tank and heated to 850°C. An i-carbon was deposited on a silicon substrate.

The pressure inside the reaction tank at this time was 2 KPa. The substrate precipitate was peeled off and the Raman spectrum was examined, and the results were as shown in FIG. As shown in this Raman spectrum, this i-carn contained less than 10 diamonds. This i-carbon is crushed in a mortar, and most of it is
~3RIL was used.

Most of the diamond powder used is 2 to 8 μm,
To this 100 parts by weight, 20 parts by weight of the above i-carbon powder was added, mixed well, and compression molded to a diameter of 20 cm and a height of 5 cm. This was loaded into a belt-type ultra-high pressure device and heated to 1500℃.
After holding at 6 GPa for 20 minutes, the temperature was returned to normal temperature and pressure. The molded body is tightly bonded, and its apparent density is 3.371-/c.
m3 (Knoop hardness 6600 kg/1 m"). The Raman spectrum of this material is shown in FIG.

(f) Effects of the Invention According to the present invention, a diamond arm containing a small amount of graphite or no graphite can be obtained, and since it does not contain metal or ceramics, it becomes an ideal diamond arm with high hardness.

[Brief explanation of drawings]

FIG. 1 shows the Raman spectrum of i-carbon used in Examples of the present invention, and FIG. 2 shows the Raman spectrum of the diamond arm of the present invention. 1...i-carbon, 2...diamond. Figure 2 rrt-t

Claims (1)

[Claims] A method for producing a dense diamond mass, which comprises adding i-carbon or diamond-like carbon to diamond powder and subjecting it to high temperature and high pressure treatment in the thermodynamic stability range of diamond.