JPH0699188B2 - Method for manufacturing diamond sintered body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a diamond sintered body which is useful as a wear-resistant component such as a cutting edge of a cutting tool, a dresser, and a die.

[Prior Art] Since a diamond sintered body has a high hardness and abundant wear resistance, it has been conventionally used as a material for a cutting edge of a cutting tool, a wire drawing die, or the like.

As a method for producing such a diamond sintered body,
It is common to sinter diamond powder under high temperature and high pressure. However, with such a conventional technique, since powdery raw materials are used, there is a problem that gas is easily adsorbed on the surface of the powdery raw materials, and thus sintering is hindered and unsintered parts remain. It was In addition, since the raw material is powder or a powder compact, gas remains between the raw materials, and this residual gas cannot be completely degassed. Therefore, the pressure generation efficiency in the high-pressure container is poor and a strong diamond firing is performed. There was also the problem that a union could not be obtained.

[Problems to be Solved by the Invention] The present invention has been made under such a technical background, and an object of the present invention is to obtain a diamond sintered body having high hardness and excellent wear resistance. The point is to provide the optimum method for

[Means for Solving the Problems] The production method of the present invention which has achieved the above-mentioned object means that a diamond sintered body is produced by a high temperature / high pressure method.
Phenol resin, acetone-furfural copolymer resin,
Resin-derived amorphous carbon obtained by carbonizing one or more selected from the group consisting of furfuryl alcohol / phenol copolymer resin, urea resin, melamine resin, xylene resin and guanamine resin, and diamond A metal or alloy containing 5 wt% or more of an iron group metal is brought into contact with the resin-derived amorphous carbon in a state where powder is dispersed in 40 to 95 wt%, and a thermodynamic diamond at a temperature of 1250 ° C. or higher It has the gist of performing pressure sintering at a pressure in the stable region.

[Function] As a result of intensive studies conducted by the present inventors to achieve the above object, the resin-derived amorphous carbon containing a predetermined amount of diamond powder is used as a raw material, and the raw material is sintered at high temperature and high pressure. It was found that the desired diamond sintered body can be realized by doing so, and completed the present invention.

Since the resin-derived amorphous carbon can be produced from a liquid monomer as described below, the resin-derived amorphous carbon serves as a matrix to appropriately disperse the diamond powder, and the disadvantages such as the gas adsorption described in the prior art occur. The optimum diamond sintered body can be realized without doing so.

Resin-derived amorphous carbon is also called glassy carbon, and a typical example thereof is phenol resin-derived amorphous carbon, which is obtained by heat treatment and carbonization treatment of a liquid resole type resin. Therefore, when the phenol resin-derived amorphous carbon is used as the resin-derived amorphous carbon in the present invention, a predetermined amount of diamond powder is obtained by mixing and dispersing diamond powder in liquid phenol and then performing the above treatment. The solid phenolic resin-derived amorphous carbon contained is obtained. After degassing the obtained diamond powder-containing resin-derived amorphous carbon under high temperature vacuum (this is a problem in the prior art), the metal catalyst is laminated or concentrically arranged and brought into contact with the metal catalyst at high temperature. -By sintering under high pressure, the resin-derived amorphous carbon itself is also converted into diamond, and a diamond sintered body having a high hardness as a whole is obtained.

Resin-derived amorphous carbon in which diamond powder is dispersedly contained is a dense solid substance, and once degassed, adsorption of gas components is small, and a raw material powder is uniformly coated with carbon to form a compact.

The above-mentioned resin-derived amorphous carbon is an integral form due to an amorphous carbon bond, but the resin-derived amorphous carbon used in the present invention has disadvantages even if it contains a graphitized portion. Absent. That is, an attempt to utilize the conversion reaction from graphite to diamond by adding graphite to the raw material has been conventionally made, and there was a problem that the powders were unevenly distributed to each other, but the present invention has such a disadvantage. Does not happen.

In the above description, a phenol resin-derived amorphous carbon obtained by carbonizing a phenol resin is shown as a typical example of the resin-derived amorphous carbon, but the resin-derived amorphous carbon used in the present invention is derived from the phenol resin. Not limited to acetone, furfural copolymer resin, furfuryl alcohol
The same treatment can be performed even if it is derived from a thermosetting resin such as a phenol copolymer resin, a urea resin, a melamine resin, a xylene resin, or a guanamine resin. These resins may be used as a mixture of two or more kinds.

On the other hand, the sintering temperature for obtaining the desired diamond sintered body is
It is necessary to set the temperature to 1250 ° C or higher, and if it is lower than 1250 ° C, the sinterability is poor. As a matter of course, the pressure at the time of sintering needs to be a thermodynamic diamond stable region pressure, and a pressure of about 40 kb or more is required. Furthermore, the catalyst used in the sintering process must be an iron group metal such as iron, cobalt, nickel, etc., and an alloy containing at least 5% by weight of any iron group metal will exhibit sufficient catalytic action. To be done. However, when the iron group metal is less than 5% by weight, the catalytic action is not exhibited and the sinterability is deteriorated.

In the present invention, the content of diamond powder is 40-95.
It is necessary to set it to the weight percent. This is because when the content of diamond powder is less than 40% by weight (that is, when the resin-derived amorphous carbon is more than 60% by weight), the more amorphous carbon is converted into diamond, the more amorphous carbon is. Since a large amount of the catalytic metal is required, the amount of the catalytic metal that remains in the sintered body is inevitably large and the metal has a non-uniform structure, so that a good diamond sintered body cannot be obtained. Is. If the content exceeds 95% by weight, it becomes difficult to uniformly disperse the diamond powder, and unsintered parts remain in the sintered body. The preferred content of diamond powder is 60-85%
It is a degree.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are not of a nature limiting the present invention.
Any design changes made within the spirit of the later description are included in the technical scope of the present invention.

[Example] A liquid resol type phenol resin synthesized from phenol and formaldehyde using ammonia as a catalyst was mixed with diamond powder having a particle diameter of 2 to 4 µm at various ratios, and the mixture was kept at 70 ° C for 2 days and then heated to 140 ° C. And cured. These are heated to 900 ° C under a nitrogen atmosphere to carbonize,
A dense solid diamond-dispersed phenolic resin-derived amorphous carbon was obtained. The obtained phenolic resin-derived amorphous carbon was processed into a disk shape with a diameter of 11 mm and a thickness of 1 mm, and 1 × 10 ⁻⁵ Torr, 1
Degassed at 450 ° C.

Amorphous carbon derived from phenol resin containing diamond powder was laminated with various metal catalysts with a diameter of 11 mm and sintered under the conditions of 60 kbar and 1500 ° C to obtain various sintered bodies No. 1 to 10
Got The hardness and structure of each of the obtained sintered bodies No. 1 to 10 were investigated. The results are shown in Table 1. The hardness of sintered bodies Nos. 8 to 10 is not measured because they do not have a homogeneous structure.

As is clear from the results shown in Table 1, all of the diamond sintered bodies (Nos. 1 to 7) obtained by the method of the present invention had a homogeneous structure and sufficient hardness.

[Effects of the Invention] As described above, according to the present invention, by adopting the above-described structure, it is possible to provide a high-hardness diamond sintered body that can eliminate the drawbacks of the conventional manufacturing method and exhibit excellent performance. Was obtained.

Claims (1)

[Claims] 1. When manufacturing a diamond sintered body by a high temperature / high pressure method, phenol resin, acetone / furfural copolymer resin, furfuryl alcohol / phenol copolymer resin, urea resin, melamine resin, xylene resin and guanamine resin are used. A resin-derived amorphous carbon obtained by carbonizing one or more selected from the group consisting of 40 to 95% by weight of diamond powder is added to the resin-derived amorphous carbon. A metal sintered body containing 5% by weight or more of an iron group metal, and pressure-sintered at a temperature of 1250 ° C. or higher and at a thermodynamic diamond stable region pressure, to produce a diamond sintered body. Method.