JPS6121971A - Hard diamond sintered body 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 a hard diamond sintered body used in tools such as cutting tools, drilling tools, and wire drawing dies, and to a method for manufacturing the same.

(2) 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, drill 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, a part of 6 in the cemented carbide penetrates into the diamond powder layer and acts as a bonding metal. The sintered body made by this method contains about 10 to 15% by volume of algae.

(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 binder, 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, Japanese Unexamined Patent Publication No. 53-11asa9 discloses a method for producing 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 diamond particles are difficult to deform, pressure is not transmitted to the gaps between particles, resulting in graphite and oxidation. , only diamond-graphite composites have been obtained.

(4) Means for Solving the Problems The present invention relates to a hard diamond sintered body that has improved heat resistance, which is a drawback of conventional sintered diamond, and a method for manufacturing the same.

That is, the present invention uses a diamond synthesis catalyst made of a metal of group 8 of the periodic table, Cr, lln, Ta, or an alloy containing these used in diamond synthesis.
Synthetic diamond powder containing 0.01 to 10% by weight is exposed to high temperature under conditions where diamond is unstable, and part or all of it is graphitized to obtain a raw material, and the raw material is used as a raw material.
Hr, v, ti, Ta, Cr.

ultra-high pressure at which diamond is stable by filling a reaction vessel made of at least one metal selected from
A diamond sintered body sintered at high temperature, containing 0.02 to 12% by weight of an intermetallic compound consisting of the metal or alloy thereof contained in the raw diamond and the metal constituting the reaction vessel. It is an object of the present invention to provide a hard diamond sintered body and a method for manufacturing the same.

In this invention, the raw material powder is synthetic diamond powder, and metals from group 8 of the periodic table used as catalysts during synthesis, or Cr, I'+, Ta, or alloys of these metals are included in the crystal as impurities. Use what you do.

Depending on the growth conditions, synthetic diamond powder may grow with the catalyst metal used during synthesis incorporated into a specific plane or orientation within the crystal.

The present inventors selected a synthetic diamond powder containing a specific amount of such inclusions, and further heated it before sintering to graphitize some or all of the diamond.

This graphitized powder is Zy 1, ■, positive, 1
The diamond was filled in a reaction vessel made of at least one metal selected from among , Cr, Cr, W, etc., and sintered under ultra-high pressure and high temperature where diamond is stable.

As a result, when synthetic diamond powder containing 0.01 to 10% by weight of metal impurities is used as a starting material, graphitized diamond is converted back to diamond during sintering, and a dense sintered body can be obtained. I found out.

For comparison, 0.01 to 10% by weight of catalytic metal powder was mixed with synthetic diamond powder containing less than 0.01% by weight of metal impurities, which was heated to graphitize some or all of the diamond. However, in this case, a sufficiently dense sintered body could not be obtained, and it was found that graphite remained. In this mixing method, similar results were obtained even when natural diamond was used as the raw material.

The reason for this is that it is extremely difficult to uniformly mix trace amounts of catalytic metals with diamond powder, and the bonds between diamond particles are strong in areas where catalytic metals are unevenly distributed, but in areas where catalytic metals are not present, graphite particles form. This is thought to be because the diamond remains without being converted to diamond.

(5) The hard diamond sintered body according to the present invention has greatly improved heat resistance compared to conventional sintered diamond, and was found to be able to withstand heating up to 1000°C. The reason for this remarkable improvement is thought to be, firstly, that the metal content is lower than that of the sintered body produced by the conventional infiltration method, and secondly, the distribution state of the metal and the shape of the bamboo are different.

In other words, it is thought that the catalytic metal incorporated into the diamond during synthesis and the catalytic metal mixed in later have different effects during sintering.

In the hard diamond sintered body of this invention, the crystal grains are bonded extremely closely to each other, and most of the catalyst metal appears to exist as spherical or plate-shaped precipitates within the crystal grains rather than at the grain boundaries. was observed.

On the other hand, in conventional sintered bodies, the catalyst metal exists in the form of a thin film at the interface between diamond particles.

This is because the binder phase is what invades the gaps between the diamond powder during sintering.

Even in the hard diamond and mondo sintered bodies of this invention, there is a slightly thin film of metal at the diamond grain boundaries, but this is due to the Z
At least one metal selected from among r, 1-ff, ■, positive, Ta, Cr, Mo, W, etc. diffuses into the raw material during sintering, is not contained in the diamond particles, and remains at the grain boundaries. It is an intermetallic compound produced by reacting with a catalytic metal.

As a result, in the sintered body of the present invention, most of the catalytic metal exists dispersed within the diamond particles, so it is thought that graphitization due to heating is unlikely to occur.

In addition, the metal phase slightly present in the grain boundaries is an intermetallic compound between the metal constituting the reaction vessel and the catalyst metal contained in the raw diamond, and is more difficult to form in diamond than in the metals that act as catalysts or their alloys. It is presumed that the thermal stress generated in the sintered body during heating is reduced when the difference in the coefficient of thermal expansion is small.

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 synthetic diamond used as a starting material contains 0.01 to 10% by weight of a catalyst metal or an alloy containing the same in its crystals.

Here, the catalyst metal or alloy containing it contained in the synthetic diamond is in the range of o, oi to 10w% by weight.
This is because if it is less than 0.01% by weight, sintering becomes difficult, and if it is more than 10% by weight, the heat resistance of the sintered body decreases, which is not preferable.

Graphitization of starting materials is necessary to improve sinterability.

The diamond powder is heated to 1400° C. or higher in vacuum or in a non-oxidizing atmosphere.

Next, this partially or completely graphitized raw material is Z
A reaction vessel made of at least one metal selected from Y, Hf, ■, positive, Ta, Cr, Mz, W, etc. is filled and heated to 5X 10 torr by means such as electron beam welding.
The sample is sealed in a high vacuum. The degree of vacuum is 5X1 (Iorr
If it is less than this, the sinterability will be lowered due to the influence of the gas adsorbed on the raw material, which is not preferable.

The sintering process is carried out using an ultra-high pressure device such as a belt-type ultra-high pressure device, under conditions where diamonds with a small amount (5σ kb or more, 1400'C or more) are stable, preferably 70 kb or more, 16
It is preferable to carry out the process under high pressure and high temperature of 00°C or higher.

After sintering, a black diamond bowl can be obtained by dissolving the recovered capsules in heated hydrochloric acid.

(6) Example of implementation The present invention will be explained in detail below with reference to Examples.

Example 1 Various diamond powders containing metal impurities as shown in Table 1 below and having an average particle size of 30 μm were used as raw materials.

Table 1 The numerical values in Table 1 above are the amounts of metals contained in the diamond powder analyzed using a mass spectrometer.

Each of the above powders was treated in vacuum at 1600° C. for 1 hour. When the graphitization ratio of the taken powder was examined by X-ray diffraction, it was found that A was about 90%, B was 50%, C was 8%, and D
was 0.3%.

These powders were filled into a molybdenum reaction vessel and 5x
It was sealed in a high vacuum of 10 torr.

For comparison, the natural diamonds listed in Table 1, which do not contain any metals, were not graphitized and similarly sealed in the reaction vessel. These samples were sintered by holding them at a pressure cuff temperature of 1,800° C. for 10 minutes using a belt-type high-pressure device.

As a result, those made from powdered diamond and natural diamond had poor sinterability and cracked.

When X-ray diffraction was performed on each of the obtained sintered bodies, no residual graphite was observed in those made from powders A, B, and C, but those made from powdered powder and natural diamond. A small amount of graphite was detected.

Next, a cutting tip was prepared by processing a sintered body made of powder A and BSC as raw materials, and the performance was evaluated by cutting an alumina sintered body having a Vickers hardness of 2000.゛Table 2 summarizes the results of a cutting test conducted with a commercially available sintered body containing about 10% of elastomer as a comparison material, as tool flank wear width.

The cutting test Cutting speed 50m/min Cut depth 0.5mm Feed: 0.05 mm/rDm Cutting time: 15 minutes dry Cutting was performed under these conditions.

Table 2 Example 2 Powder C shown in Table 1 was sealed in a vanadium reaction vessel and held under the conditions shown in Table 3 for 5 minutes to perform sintering. Table 3 also shows the characteristics of the sintered bodies obtained.

From the results in Table 3 above, it is thought that graphite remains in N001 because both pressure and temperature are insufficient, and graphite remains in N004 because the temperature is too high and it moves out of the diamond stability region. it is conceivable that.

Next, in the above table, for NO92, 3, 5, and 6, which did not leave graphite and had good sintering, 30
A heating test was conducted for 1 minute, but no changes were observed in appearance, hardness, or specific gravity.

(Sword effect) The hard diamond sintered body produced by the method of the present invention has excellent heat resistance and wear resistance as a tool material for cutting tools, drilling tools, wire drawing dies, dressers, etc.
In particular, the heat resistance, which was a drawback of conventional diamond sintered bodies, has been significantly improved without reducing the strength, so the range of application performance as tool materials has been dramatically improved.

Patent applicant Sumitomo Electric Industries Co., Ltd. Agent Patent attorney Kazu 1) Showa procedural amendment (voluntary) April 3, 1985

Claims (2)

[Claims] (1) Synthetic diamond powder containing 0.01 to 10% by weight of a diamond synthesis catalyst made of a metal from Group 8 of the periodic table, Cr, Mn, Ta, or an alloy containing these used during diamond synthesis The raw material is exposed to high temperature under stable conditions to graphitize part or all of it, and the raw material is used as a raw material for ZrHf, V, and Nb.
A diamond sintered body filled in a reaction vessel made of at least one metal selected from , Ta, Cr, Mo, W, etc., and sintered under ultra-high pressure and high temperature where the diamond is stable; A hard diamond sintered body characterized by containing 0.02 to 12% by weight of an intermetallic compound consisting of a metal contained in raw diamond or an alloy thereof and a metal constituting a reaction vessel. (2) Synthetic diamond powder containing 0.01 to 10% by weight of a diamond synthesis catalyst made of a metal from Group 8 of the periodic table, Cr, Mn, Ta, or an alloy containing these used during diamond synthesis The raw material is exposed to high temperature under stable conditions to graphitize part or all of it, and the raw material is used to produce Zr, Hf, V, N
b, filled in a reaction vessel made of at least one metal selected from Ta, Cr, Mo, W, etc., and the diamond is sintered under stable ultra-high pressure and high temperature, and at the same time reacts from the reaction vessel into the raw material. By diffusing the metal constituting the container, an intermetallic compound is formed with the catalyst metal or its alloy remaining at the interface of the diamond particles, and the compound is contained in the sintered body in an amount of 0.02 to 12% by weight. A method for producing a hard diamond sintered body, characterized by: