JPS6121972A - Hard polycrystal diamond and manufacture - 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) Field of Industrial Application This invention relates to hard polycrystalline diamond used in tools such as cutting tools, drilling tools, and wire drawing dies, and to a method for producing the same.

(a) Conventional technology A sintered body made by sintering fine diamond powder under ultra-high pressure is
It is already widely used as cutting tools for non-ferrous metals, zeril bits, wire drawing dies, etc.

As such a sintered body, for example, Japanese Patent Publication No. 52-121
According to the method described in Publication No. 26, diamond powder is placed in contact with a compact or sintered body of WC-Co cemented carbide, and is heated at an ultra-high pressure above the temperature at which the liquid phase of the cemented carbide occurs. Sintered underneath.

At this time, some of the particles in the cemented carbide penetrate into the diamond powder layer and act as a bonding metal. The sintered body made by this method contains about 10-15% by volume of 6 in the sintered body.

(3) Problems to be Solved by the Invention Although this sintered body has sufficient practical performance as a cutting tool for non-ferrous metals, it has the disadvantage of poor heat resistance. For example, if this sintered body is heated to 750°C or higher, the wear resistance and strength will decrease, and if it is heated to 900°C or higher, the sintered body will break. The reason for this is thought to be that graphitization of the diamond occurs at the interface between the diamond particles and the bond @C, and thermal stress due to the difference in coefficient of thermal expansion when the two are heated.

Furthermore, it is known that when a sintered body using these materials as a binder is treated with an acid to remove most of the binding metal phase, the heat resistance of the sintered body is improved.

For example, JP-A-53-114589 discloses a method for manufacturing a diamond sintered body with improved heat resistance. However, in this case, the removed portions of the bonded metal phase become pores, which inevitably leads to a decrease in strength.

Attempts have been made to sinter only some diamond powder under ultra-high pressure, but because the diamond particles are deformed and thin, pressure is not transmitted to the gaps between the particles, resulting in graphitization. Only diamond-graphite composites have been obtained.

(4) Means for solving the problems This invention relates to a hard polycrystalline diamond that has improved heat resistance, which is a drawback of conventional sintered diamond, and a method for producing the same.

That is, in this invention, the weight of diamond is 60.0 to 99.
．． 9%, and the remainder is metals from group 8 of the periodic table or M
At least one or more of n and Ti, Zr, 1-ff, ■,
The object of the present invention is to provide a hard polycrystalline diamond characterized by being an intermetallic compound consisting of at least one of Ta, Cr, and W, and a method for producing the same.

In this invention, the carbon-containing material is used as a raw material with a carbon content of 59.9 to 99%.
．． 8% by weight, the remainder being at least one metal of group 8 of the periodic table or Mn and "l, zr, lj.

A mixture of at least one of V, Nb, Ta, Cr, I'&, and W is used.

The present inventors exposed this raw material to ultra-high pressure and high temperature where diamond is thermodynamically stable, promoting the formation and sintering of diamond, and at the same time forming an intermetallic compound consisting of the metal or an alloy thereof. They discovered that a hard diamond sintered body could be obtained by sintering.

It also contains 59.9 to 99.8% by weight of a carbon-containing substance,
A mixture in which the remainder is at least one metal of group 8 of the periodic table or Mn, including Ti, Zr, K, V,
F&l, 1, Cr, t'b, and W into a reaction vessel, or containing 59.9 to 99.8% by weight of a carbon-containing substance, with the remainder being Ti, Zr5.
A mixture of at least one of lj, v1, Ta, Cr, h, and W is charged into a reaction vessel containing at least one metal of group 8 of the periodic table or Mn, and the mixture is thermodynamically A similar process can be achieved by exposing the diamond to ultra-high pressure and high temperature under which it is stable, generating and sintering the diamond, and at the same time, forming intermetallic compounds by avoiding the diffusion of the metal or alloy constituting the reaction vessel into the raw material mixture. A strong sintered body can be obtained.

(5) Effect The hard polycrystalline diamond according to the present invention has greatly improved heat resistance compared to conventional sintered diamond, and was found to be able to withstand heating of 1000°C. The reason for the remarkable improvement in heat resistance is that firstly, the binder phase contains at least 1% of metals from group 8 of the periodic table or Mn.
More than species and Ti, Zr, Hf.

Since it is an intermetallic compound consisting of at least one of V, Nb, Ta, and Cr in a ratio of 1 to 1, it can perform the reverse conversion from diamond to graphite even in high-temperature conditions where conventional sintered bodies using L as a binder deteriorate due to heat. It is conceivable that this will not occur.

The second reason is that these intermetallic compounds have a smaller difference in thermal expansion coefficient with diamond than metals such as G that act as diamond formation catalysts or their alloys, so the heat generated in the sintered body when heated is It is presumed that stress is reduced.

From the above, the present invention has made it possible to produce a diamond sintered body with significantly improved heat resistance.

In carrying out this invention, the carbon-containing materials used as starting materials include diamond, graphite, pyrolytic graphite, glassy carbon, and diamond, which are exposed to high temperatures under thermodynamically unstable conditions. Alternatively, those in which the entire graphite is converted, and mixtures thereof are used.

Diamonds can be either natural or synthetic.

Among these, diamond powder is most preferably heated to 1400° C. or higher in vacuum or in a non-oxidizing atmosphere to convert part or all of it into graphite.

These carbon-containing substances are prepared so as to account for 59.9 to 99.8% by weight of the raw materials.

If the content of this carbon-containing substance is less than 59.9% by weight, the wear resistance of the sintered body will decrease, and if it exceeds 99.8% by weight, sintering will become difficult and graphite will remain partially. Therefore, only a sintered body with low strength can be obtained.

The above carbon-containing substance is a metal of No. 88 in the periodic table or M
At least one or more of n and Ti, Zr, Hf, ■, Takashi,
-1 After mixing with at least one of Cr, A, and W, the diamond is placed in a high pressure chamber of an ultra-high pressure generator such as a belt type device, and the diamond is stabilized to 50 kb.

Sintering is performed by exposing to ultra-high pressure and high temperature of 1300°C or higher.

Under these conditions, the carbon-containing material as a raw material undergoes diamond formation and sintering due to the action of at least one metal of group 8 of the periodic table or Mn.

At the same time, these diamond-forming catalyst metals are mixed Ti, Zr', W, V, Nb, Ta.
, Cr.

- forms an intermetallic compound with at least one or more of 1W;

In forming the intermetallic compound of this binder, a mixture containing 5.9.9 to 99.8% by weight of a carbon-containing substance and the balance being at least one metal of Group 8 of the periodic table or Mn is used. Ti, Zr, ) (f, ■, positive, 1, Cr
, Mo, and W, or fill a carbon-containing material with a carbon content of 59.9 to 99.8
Contains % by weight, with the remainder being T&, Zr, Bo, ■, Yang,
By filling a mixture of at least one of Ta, Cr, & W into a reaction vessel made of at least one metal of group 8 of the periodic table or Mn, the mixture can be heated under the ultra-high pressure and high temperature conditions described above. It is also possible to diffuse the metal or alloy forming the reaction vessel into the raw material mixture.

All of the sintered bodies obtained according to the above method have high hardness and can withstand heating at 1000°C.

(6) Example of implementation Hereinafter, this invention will be explained in detail with reference to Examples.

Example 1 Synthetic diamond having an average particle size of 10 μm was mixed with metal powder in the proportions shown in Table 1 and filled into a metal reaction vessel.

Table 1: 70kb1160 using a belt-type ultra-high pressure generator
Sintering was performed for 10 minutes at 0°C. All recovered sintered bodies were strong.

These sintered bodies and a sintered body using commercially available 6 as a binder were subjected to a heating test at 1000° C. in vacuum.

As a result, no change was observed in the appearance or specific gravity of any of the sintered bodies A to F, but cracks appeared in the sintered body G and the commercially available sintered body in which N was used as a reaction vessel. In this heated-cracked sintered body, it was confirmed by X-ray diffraction that graphite was generated.

Example 2 A cutting tip was prepared by processing a commercially available sintered diamond in which sintered bodies A-D shown in Table 2 and 80% by weight of diamond were combined with WC-Co, and an alumina sintered body with a hardness of 2000 was prepared. The performance was evaluated by cutting.

Table 2 The cutting test was performed at cutting speed: 50 m/min, depth of cut: 0.5 mm, feed rate: 0.05 mm/ rD
IIl Cutting time: Cutting was carried out under dry conditions for 15 minutes.

The results are shown in Table 3. Although the sintered bodies had a high content of binder phase and had poor wear resistance, samples A to C all showed high wear resistance.

Table 3 (7) Effects by the method of this invention. Hard polycrystalline diamond has excellent heat resistance and wear resistance as a material for tools such as cutting tools, drilling tools, wire drawing dies, and dressers. As the hard scratches have been significantly improved without reducing the strength, the range of application and performance as a tool material has been dramatically improved.

Claims (7)

[Claims] (1) Diamond accounts for 60.0 to 99.9% by weight, the remainder being metals from group 8 of the periodic table or Mn and Ti,
A hard polycrystalline diamond characterized by being an intermetallic compound consisting of at least one of Zr, Hf, V, Nb, Ta, Cr, Mo, W, or an alloy thereof. (2) Contains 59.9 to 99.8% by weight of carbon-containing substances, with the remainder being at least one member of Group 8 of the periodic table or Mn, and Ti, Zr, Hf, V, Nb, Ta, Cr, and Mo.
, W is exposed to ultra-high pressure and high temperature at which diamond is thermodynamically stable, thereby promoting the formation and sintering of diamond and at the same time forming an intermetallic compound made of the metal. 60.0 to 99.9% by weight of diamond, which is characterized by
A method for producing hard polycrystalline diamond, which is an intermetallic compound consisting of at least one of V, Nb, Ta, Cr, Mo, and W. (3) As the carbon-containing material, a raw material obtained by exposing diamond to high temperature under thermodynamically stable conditions and converting part or all of it into graphite is used as the carbon-containing material. A method for producing hard polycrystalline diamond. (4) A mixture containing 59.9 to 99.8% by weight of a carbon-containing substance, with the remainder being at least one metal of Group 8 of the periodic table or Mn, such as Ti, Zr, Hf, V, or Nb.
, Ta, Cr, Mo, and W, and exposed to ultra-high pressure and high temperature under which diamond is thermodynamically stable, to promote diamond formation and sintering, and at the same time, the reaction vessel is heated. 60.0 to 99.9% by weight of the diamond, characterized in that the metal or alloy thereof used as
%, and the remainder is at least one metal of group 8 of the periodic table or Mn, and Ti, Zr, Hf, V, Nb, and T.
A method for producing hard polycrystalline diamond, which is an intermetallic compound consisting of at least one of a, Cr, Mo, and W. (5) As the carbon-containing material, a raw material obtained by exposing diamond to high temperature under thermodynamically stable conditions and converting part or all of it into graphite is used as the carbon-containing material. A method for producing hard polycrystalline diamond. (6) Contains 59.9 to 99.8% by weight of carbon-containing substances, with the remainder being Ti, Zr, Hf, V, Nb, Ta, Cr, M
A mixture of at least one of O and W is filled in a reaction vessel made of at least one metal of group 8 of the periodic table or Mn, and exposed to ultra-high pressure and high temperature at which diamond is thermodynamically stable. , is characterized by promoting the formation and sintering of diamond, and at the same time, diffusing the metal or alloy thereof used in the reaction vessel into the mixture to form an intermetallic compound with the metal or alloy thereof in the mixture. 60.0-99.9% of the diamond by weight
and the remainder is at least one metal of group 8 of the periodic table or Mn, and Ti, Zr, Hf, V, Nb, and Ta.
, Cr, Mo, and W. (7) The carbon-containing material used is a raw material obtained by exposing diamond to high temperature under thermodynamically stable conditions and converting part or all of it into graphite. A method for producing hard polycrystalline diamond.