JPS61111965A - Polycrystal diamond for tool 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 [Field of Industrial Application] The present invention relates to polycrystalline diamond used in tools such as cutting tools, drilling tools, and wire drawing dies, and to a method for producing the same.

[Prior art] Diamond sintered bodies made by sintering Da Diamond fine powder under ultra-high pressure have already been widely used in cutting tools for non-ferrous metals, drill pits, wire drawing dies, etc. .

For example, Japanese Patent Publication No. 52-12126 discloses a method for manufacturing this type of sintered body, in which diamond powder is placed in contact with a compact or sintered body of WC-CO cemented carbide. Sintering is carried out at a temperature above the temperature at which the liquid phase of the cemented carbide occurs and under ultra-high pressure. At this time,
Some of the Go in the cemented carbide penetrates into the diamond powder layer and acts as a bonding agent. The diamond sintered body made by the method disclosed in this prior art has approximately 10 to 1
Contains 5% CO by volume.

[Problems to be Solved by the Invention] The above-described sintered body has sufficient practical performance as a cutting tool for non-ferrous metals and the like. However, it had the drawback of being inferior in heat resistance.

For example, when this sintered body is heated to a temperature of 750°C or higher, a decrease in wear resistance and strength is observed, and a further
At temperatures higher than 0.degree. C., the sintered body will be destroyed. This is thought to be due to graphitization of the diamond occurring at the interface between the diamond particles and the binder CO, 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 CO 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 prior art, the removed portions of the bonded metal phase become pores, so although the heat resistance is improved, there is a problem in that the strength is reduced.

On the other hand, attempts have been made to sinter only diamond powder under ultra-high pressure, but since the diamond particles themselves are difficult to deform, pressure is not transmitted to the gaps between the particles, resulting in graphitization and diamond powder. Only graphite composites have been obtained.

Therefore, an object of the present invention is to provide a sintered diamond for tools that is excellent in both heat resistance and strength, and a method for manufacturing the same.

[Means for Solving the Problems] The inventors of the present application have made the following invention as a result of intensive studies to obtain a diamond for tools that is even more excellent in heat resistance and strength.

That is, in the polycrystalline diamond for tools of the present invention, diamond accounts for [60.0 to 99.9% at 1%],
The remainder is a carbide represented by the formula (Feχ, M+-), C1 (wherein M is one or more elements selected from the group consisting of Or, Mn, MO and W, x is 0.05 to
0.95), and the polycrystalline diamond for tools having the above composition contains 59 carbon-containing substances.
．． Contains 9 to 99.8% by weight, with the remainder being Cr, Mn,
Diamond This is a method for producing polycrystalline diamond for tools, which is characterized by promoting the formation and sintering of metal and forming carbides of the metal.

[Function] It has been found that the polycrystalline diamond for tools according to the present invention has significantly improved heat resistance compared to conventional sintered diamond, and can withstand heating to a temperature of about 1000°C. The reason for the remarkable improvement in heat resistance is that firstly, the binder phase is a carbide represented by the formula (Fe alloy, My-x>7C3 (where M is Or, Mn, Mo, W).
Because it is composed of at least one metal element selected from the group consisting of This is thought to be because the reverse conversion of diamond to graphite does not occur.

The second reason is that these carbides have a smaller difference in coefficient of thermal expansion with diamond than metals such as CO that act as catalysts during diamond formation or alloys of these metals, so the sintered body does not hold up when heated. It is surmised that the thermal stress generated inside is reduced.

In carrying out this invention, 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, and some or all of them are converted into graphite. and mixtures thereof can be used.

Diamonds can be either natural or synthetic.

Among the above carbon-containing materials, the most preferred is one obtained by heating diamond powder to a temperature of 1400° C. or higher in vacuum or in a non-oxidizing atmosphere to convert a part or all of it into graphite.

The above carbon-containing substance is 59.9 to 99.8 in the starting material.
Adjust so that it accounts for a heavy ffi%. This is because if the amount of the carbon-containing substance is less than 59.9% by weight, the wear resistance of the sintered body will decrease, while if it exceeds 99.8% by weight, sintering will become difficult and graphite will remain partially. This is because only a sintered body with low strength can be obtained.

The above-mentioned carbon-containing substance is a small amount selected from Cr, Mn, Mo, and W (all of which include at least one metal and Fe and/or
Alternatively, after mixing with these alloys, the diamond is placed in a high pressure chamber of an ultra-high pressure generating device such as a belt-type device, and the diamond is stabilized at 1>50 kb and exposed to ultra-high pressure and high temperature of 1300° C. or higher to be sintered. Under these conditions, the raw carbon-containing material is a combination of at least one metal selected from Cr, Mn, 1vlo, and W, and Fe and/or
Alternatively, the formation and sintering of diamond progresses due to the action of these alloys.

At the same time, these diamond-forming catalyst metals have the formula (Feχ1ML-X”) according to the blending ratio of metals in the raw materials.
7 Carbide represented by Cs (wherein M is Or.

The binder phase of the sintered body that forms one or more metal elements selected from the group consisting of Mn, Mo, and W, It is composed of the above-mentioned carbide.

Note that when M is at least one metal element selected from Cr, Mn, Mo, and W, M and Fe
The reason why the molar ratio l"e is set to 0.05 to 0.95 is because if it is less than 0.05, the proportion of bonds between diamond particles decreases and a sintered body with high strength cannot be obtained. On the other hand, if it exceeds 0.95, the produced carbide will be at normal pressure and 70
This is because it decomposes into metal and graphite at temperatures above 0°C.

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

Furthermore, instead of pre-mixing the carbon-containing substance and the metal powder during production of the sintered body, it is also possible to laminate the carbon-containing substance and the metal and sinter them under ultra-high pressure. In this case, the melted alloy consisting of the above metal elements penetrates into the layer of the carbon-containing substance, resulting in (Feχ1M,
-x), a bonded phase of C- will be generated.

[Explanation of Examples] Hereinafter, the present invention will be described in detail based on Examples.

Example 1 Synthetic diamond with an average particle size of 10 μm was mixed with metal powder in the proportions shown in Table 1 and filled into a reaction vessel made of gold Jl. Incidentally, for comparison, sintered body E shown in Table 1 is a commercially available sintered body and only Fe is used as a binder.

Table 1 Samples A to E shown in Table 1 were filled in a container made of Ta, and 70kb and 1600
Sintering was carried out for 10 minutes at .degree. All recovered sintered bodies were strong.

Commercially available sintered diamond using CO as a binder as another comparative example and the sintered bodies of samples A to E were heated at 100% in vacuum.
A heating test was conducted at a temperature of 0°C. As a result, no change was observed in the appearance or specific gravity of any of the sintered bodies A to D. On the other hand, cracks occurred in the commercially available sintered body and in the sintered body E using only Fe as a binder. After this heating test, it was confirmed by X-ray analysis that graphite was generated in the cracked sintered bodies, that is, the commercially available sintered bodies and the sintered bodies E.

In the sintered body E, the binding material before heating was FetC5, but it was found that it decomposed into l''e and graphite after heating.

Example 2 The sintered bodies A to D shown in Table 2 and a commercially available sintered diamond made by bonding 80% by weight of diamond with WC-CO were processed to create a cutting tip.
Alumina sintered bodies of No. 00 were cut and their respective performances were evaluated.

The cutting test was conducted under dry conditions: cutting speed: 50 m/min, depth of cut: 0.51, feed: 0.051 m/rpm, and cutting time: 15 minutes.

The results of the cutting test are shown in Table 3, and it was found that the sintered bodies had a high binder phase content and were inferior in wear resistance, but the sintered bodies A to C all showed high wear resistance. Ta.

Example 3 A thin plate made of an alloy of 75Fe-5Cr-20Mn was placed in contact with a layer of diamond powder subjected to the same graphitization treatment as used in Example 2, and this was placed in a bell-type ultra-high pressure generator. 60kb and held at a temperature of 1600°C for 10 minutes. The obtained sintered body has (-+=e, Cr,
Mn)? It had a binder phase of Cs, and no cracks occurred even when heated to a temperature of 1000°C.

[Effects of the Invention] As described above, according to the present invention, diamond accounts for 60.0 to 99.9% by weight, and the remainder is expressed by the formula (FeX
, M, -yo) 70- (wherein, M is O
One or more elements selected from the group consisting of r, Mn, MO and W, x is a number in the range of 0.05 to 0.95)
Polycrystalline diamond for workers with excellent heat resistance and wear resistance can be used as a material for various tools such as cutting tools, drilling tools, wire drawing dies, and dressers. I can do it. In particular, unlike conventional diamond sintered bodies, the heat resistance has been significantly improved without reducing strength, making it possible to dramatically expand the range of applications as tool materials.

Claims (3)

[Claims] (1) Diamond accounts for 60.0 to 99.9% by weight, and the remainder is of the formula (Fe_x, M_1_-_x)_7C_
3 (wherein M is one or more elements selected from the group consisting of Cr, Mn, Mo and W, x is 0
．． polycrystalline diamond for tools, characterized in that it consists of a polycrystalline diamond (number in the range of 0.05 to 0.95). (2) Contains 59.9 to 99.8% by weight of a carbon-containing substance, with the balance being at least one metal selected from the group consisting of Cr, Mn, Mo, and W, and Fe and/or an alloy thereof. A mixture consisting of 60% diamond by weight is exposed to extremely high pressure and high temperature at which diamond is thermodynamically stable, thereby promoting the formation and sintering of diamond and carbonizing the metal. 0-99
．． It accounts for 9%, and the remainder is the formula (Fe_x, Cr_1_−_x
)_7C_3 carbide (wherein, M is Cr, M
A method for manufacturing a polycrystalline diamond for tools, comprising one or more elements selected from the group consisting of n, Mo, and W, x being a number in the range of 0.05 to 0.95. (3) Claim 2 uses a raw material obtained by exposing diamond as a carbon-containing substance to high temperature under thermodynamically stable conditions and converting part or all of it into graphite.
A method for manufacturing polycrystalline diamond for tools as described in Section 1.