JP2003095743A - Diamond sintered compact and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diamond sintered compact which is improved in the bonding strength of diamond particles to each other or the bonding strength by matrix material and exhibit such bonding strengthes, particularly at a high temperature, and a method of efficiently manufacturing the same. SOLUTION: The diamond particles and the particles of a first metallic material containing metal capable of forming a carbide are densely and uniformly mixed to form a sintered material. This sintered material is housed into a high melting metal vessel and is exposed to the temperature at which the first metallic material melts under the pressure and temperature conditions within a region where diamond is thermodynamically stable, by which the first metallic material of a liquid phase and ht diamond are brought into contact with each other and a coating of the carbide of the carbide forming metal and a matrix phase containing the carbide are formed on the surfaces of the diamond particles and the integration of the sintered material by sintering is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diamond-containing sintered body, particularly to a diamond sintered body having high temperature strength and high toughness, which is suitable for use in throw away chips and various wear resistant materials, and a method for producing the same.

[0002]

2. Description of the Related Art A material obtained by baking diamond particles is
It is a general name for sintered diamond (PCD) and is widely used as a high-performance cutting tool and wear-resistant material. This kind of material is a polycrystalline or direct bond type sintered body in which diamond particles are mutually bonded by covalent bond,
It is roughly classified into a dispersion type sintered body in which diamond particles are dispersed and held in a matrix. In the former case, it is usually sintered together with a cemented carbide backing material (substrate), and in the latter case, the matrix is generally WC-Co of cemented carbide composition.
System and other ceramic systems.

The direct-bonding type sintered body has a wide range of uses as a cutting tool because it can withstand severe use conditions, but on the other hand, the hardness of the diamond-containing layer is high.
Particularly in a diamond sintered body, a large number of man-hours are required to process a cutting tool.

On the other hand, the dispersion type sintered body has the advantage that molding such as cutting out is relatively easy, but the bonding strength between the diamond abrasive grains and the matrix material is not sufficiently large. Insufficiency of strength due to is a problem that needs to be solved. The problem is that finer surfaces are required as tools and wear-resistant materials, and the toughness of the sintered body itself is required, so that the grain size of diamond abrasive grains used tends to become smaller. Therefore, urgent measures are required.

Further, cobalt which is used as an infiltrant in the direct bond type sintered body and remains in a small amount between the diamond particles, and which is usually used as a matrix constituent material in the dispersed type sintered body and contributes to the toughness, is cut. When used as a cutting edge, when it is exposed to high temperatures during use, it has the effect of promoting the graphitization of diamond in addition to lowering its strength. For this reason, graphitization proceeds on the surface of the diamond particles in contact with cobalt, and the cutting edge performance tends to be significantly reduced.

[0006]

SUMMARY OF THE INVENTION In the above situation, the main object of the present invention is to improve the bonding force between diamond particles in a direct bonding type and dispersion type sintered body of diamond or the holding force by a matrix material. In particular, it is to provide a diamond sintered body that exhibits such a binding force or a holding force even at a high temperature.

[0007]

Means for Solving the Problems The diamond sintered body according to the present invention is one in which diamond is integrated by a sintering process in a thermodynamically stable pressure / temperature region. , Adjacent diamond particles,
It is characterized in that they are joined at least partially through the carbide of the carbide forming metal formed on the surface of the diamond particles in the sintering step.

In the second aspect of the invention, the diamond particles are coated with a carbide of a carbide forming metal formed by the reaction with diamond during the sintering step, and the diamond particles are at least partially in a matrix phase. And the matrix phase contains carbides of the carbide-forming metal formed by reaction with diamond.

The diamond sintered body of the present invention can be effectively obtained as follows. That is, the diamond particles and the particles of the first metal material containing a metal capable of forming a carbide are densely and uniformly mixed to obtain a sintered material, and the sintered material is housed in a refractory metal container, The diamond is subjected to the pressure and temperature conditions within the thermodynamically stable region and the temperature at which the first metal material melts. Although the reaction of forming a carbide by the reaction between the first metal material and diamond proceeds even between solid phases, the reaction proceeds rapidly due to the formation of the liquid phase of the first metal material, and the first metal material on the surface of the diamond particles This is for forming a carbide coating of a metal material and forming particles of the carbide, and at the same time, sintering and integrating the sintered material.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In each of the above-mentioned sintered bodies, the content of diamond particles coated with carbide is suitably 10% or more and 90% or less in terms of volume ratio to the entire sintered body.

In the above-mentioned inventions, Ti, Si, Zr, Mo, W and T which show remarkable carbide forming ability as the first metal material.
Suitable are a, Nb, Cr, etc., which may be used alone or in combination.

In the dispersion type sintered body, the matrix is made of Fe, Co, Ni, Cu, Al in addition to the first metal.
Alternatively, the melting point or liquid phase generation temperature can be lowered by adding an alloy containing these metals as a main component alone or in combination as an additional metal material. When Cu is used, for example, Monel metal, Hastelloy, Cu-
When used as an alloy such as Be alloy, Cu
To prevent its release in the matrix.

In the sintered body of the present invention, the matrix essentially forms a solid solution with a carbide forming metal such as Ti, Si and Cr and an additive metal, and a carbide forming metal (such as Fe, Co and Ni). ) Carbide. This carbide is formed by the reaction between the carbide forming metal in which the added metal is dissolved and the diamond particles during the sintering process, and is distributed in the matrix as a coating layer on the surface of the diamond particles or as the carbide particles to reinforce the matrix. .

Fe, Co, which is contained as an additive metal,
Ni has originally been thought to be unsuitable for use as a tool because it originally has an action of promoting graphitization of diamond under normal pressure and high temperature, but in the present invention, a metal coated with diamond particles is used. Since the carbide functions as a protective film at high temperatures, it can be used without problems.

Distributing a metal nitride or boride formed during the sintering process to the matrix is also useful because it also has a reinforcing effect. For this purpose, hexagonal (low-pressure phase) or cubic or wurtzite (high-pressure phase) boron nitride is mixed as a nitrogen source and a boron source in the above-mentioned sintered material together with the first metal material.

[0116] When forming a metal carbide, or further a nitride and / or a boride in the sintering process, these reactions are exothermic reactions, and thus the heat of reaction can be utilized for melting the metal.

In the sintered body having a low diamond content, for the purpose of strengthening the matrix, for example, tungsten carbide (WC), titanium carbide, tantalum carbide, niobium carbide, vanadium carbide, etc. are formed in the form of preformed carbide. It is also effective to add to the sintered material alone or in combination. In this case, powder of cobalt or nickel as a binder metal for bonding these carbide particles is sufficiently mixed with the powder of carbide.

The particle size of the diamond particles used in the present invention is not particularly limited, but the nominal particle size is 0.3 to 200 μm.
m, especially in the range of 0.5 to 50 μm, the bonding strength is remarkably improved.

The diamond sintered body constructed as described above is further wholly, as a whole, with a substrate made of a material having specific properties such as high toughness, high melting point and brazing property during the sintering process or after being taken out from the press. It is also useful to join them by brazing under normal pressure to form a hard member. The material of the substrate and the bonding method may vary depending on the application.

Materials include cemented carbide, high speed steel, die steel, SKD steel, monel metal, Ti-4Al-4Mn, Ti-6A
High (tensile) strength alloy materials such as l-4V and Ti-6Al-2Sn-4Zr-2Mo can be used. For example, when the above-mentioned titanium alloy substrate is used, a hard structural material having both toughness, lightness and wear resistance can be obtained.

Next, the present invention will be described in more detail by way of examples.

[0022]

Example 1 (Direct Bonding Type) A mixture of diamond particles having a name of 30-40 μm and Ti-8.5mass% Si powder at a volume ratio of 85:15 was prepared as a sintering material. 450g of this sintered material
The inner diameter, height, and wall thickness are 75 mm, 50 mm, and 0.15, respectively.
Put in a cylindrical container of mm, diameter 75mm on top, thickness 0.2mm
The metal titanium disc was placed on the container, and the tip of the container was bent and sealed.

The above container was placed in a refractory reaction chamber, and a graphite heater was placed around it. The whole was loaded into a uniaxial pressure type press, and was subjected to a temperature / pressure condition of 1400 ° C. and 6 GPa for 15 minutes. . After cooling and depressurizing, the reaction product was recovered from the press.
The refractory and the like were removed to isolate the sintered body.

The hardness of the surface of the sintered body obtained by polishing and removing the container material has a micro Vickers hardness of 4570 kgf / m.
It was m ² , and when observed by a microscope, the diamond particles were well bonded to each other via the carbide phase on the surface of the diamond particles.

[0025]

Example 2 (Dispersion type) A sintering reaction was carried out by combining various types of carbide forming metals and additional metals. The pressure and temperature conditions of the sintering process were all 5.5 GPa and 1300 ° C., and the thickness of the sintered body was 1 mm or less in the reaction for forming the diamond sintered body integrated with the substrate. The compounding conditions used and the results are summarized in the table below along with the types of tools produced. In the table, D represents diamond and M represents metal.

[0026]

[Table 1]

[0027]

EFFECTS OF THE INVENTION In the present invention, by forming a carbide coating on the surface of diamond, chemical bonds can be obtained between the diamond particles or between the diamond particles and the matrix material through the coating layer. The joint strength between the diamond particles and the binder or matrix material is improved, and the strength and wear resistance of the sintered body are improved.

Further, since the carbide coating formed on the surface of the diamond functions as a protective film for preventing the conversion of diamond into graphite, when the sintered body of the present invention is applied to a cutting tool, Even in, the performance of the cutting edge is maintained.

Claims (15)

[Claims] 1. A sintered body in which a plurality of diamond particles are integrated in a sintering step under the pressure and temperature conditions in which diamond is thermodynamically stable, and adjacent diamond particles are at least partially A diamond sintered body, characterized in that it is bonded via a carbide of a carbide forming metal formed on the surface of diamond particles during the sintering step. 2. A sintered body in which a plurality of diamond particles are integrated in a sintering step under a pressure and temperature condition in which diamond is thermodynamically stable, wherein the diamond particles are combined with diamond during the sintering step. Of the carbide-forming metal formed by the reaction of, and the diamond particles are bonded to each other at least partially through a matrix phase, and the matrix phase is formed by the reaction with diamond. A diamond sintered body comprising a metal carbide. 3. Diamond particles coated with the carbide are 10% or more and 90% or less (volume ratio to the whole, the same applies hereinafter),
The diamond sintered compact according to claim 1, wherein the balance is the matrix. 4. The carbide forming metal is Ti, Si, Zr, M.
The diamond sintered body according to each of claims 1 and 2, containing at least one selected from o, W, Ta, Nb, and Cr. 5. The matrix is Fe, Co, Ni, Cu,
3. An additive metal containing Al selected from the group consisting of Al and Al.
The diamond sintered body according to each item. 6. The diamond sintered body according to claim 1, wherein the matrix contains a carbide of the carbide forming metal formed by a reaction with diamond during the sintering step. 7. The diamond sintered body according to claim 1, wherein the diamond particles have a particle size of 0.3 to 200 μm. 8. The matrix further comprises high pressure phase boron nitride particles and nitrides and / or borides of carbide forming metals formed in the sintering process.
And the diamond sintered body according to each item of 2. 9. The diamond sintered body as a whole,
A hard member integrally bonded to a substrate made of a material containing the above-mentioned carbide forming metal. 10. A hard member formed by integrally bonding the diamond sintered body in layers on both sides of a plate surface with a plate-shaped hard metal material interposed therebetween. 11. Diamond particles and particles of a first metal material containing a metal capable of forming carbide are densely and uniformly mixed to obtain a sintered material, and the sintered material is housed in a refractory metal container. Then, the diamond is brought into contact with the first metal material in the liquid phase by subjecting it to a temperature / temperature condition in which the diamond is thermodynamically stable and at a temperature at which the first metal material melts. And forming a coating of the carbide of the first metal material and a matrix phase containing the carbide on the surface of the diamond particles, and performing the sintering integration of the sintering material. Manufacturing method. 12. The diamond sintered body according to claim 11, wherein the first metal material contains at least one selected from Ti, Si, Zr, Mo, W, Ta, Nb and Cr as a carbide forming metal. Body manufacturing method. 13. The first metal material is further Fe, Co, N.
The method for producing a diamond sintered body according to claim 11, further comprising an additive metal selected from i, Cu and Al. 14. A preformed carbide containing at least one selected from tungsten carbide, titanium carbide, tantalum carbide, niobium carbide, and vanadium carbide as the first metal material, and a binder with the carbide which is a binder of the carbide. The method for producing a diamond sintered body according to claim 11, which contains at least one binder selected from cobalt, nickel, and an alloy containing these as main components, which are mixed with each other. 15. The method for producing a diamond sintered body according to claim 11, wherein the first metal material further contains low-pressure phase or high-pressure phase boron nitride particles.