JPS63111105A - Composite sintered body and its production - Google Patents

Abstract

PURPOSE:To produce a composite sintered body having high joint strength of a WC-Co sintered hard alloy supporting layer and diamond powder layer by interposing a sheet consisting of a core part of a high melting metal and outside surface part of the carbide, etc., thereof between the two layers. CONSTITUTION:Substantially WC and Co which is a binder are molded or sintered to obtain the sintered hard alloy supporting layer. The prescribed supporting layer and the diamond powder layer are disposed adjacently to each other via the sheet consisting of >=1 kinds among group 4a, 5a, 6a metals of the periodic table interposed therebetween. The sheet is formed to the sectional area of 70-95% of the opposed sectional area of the two layers and is further formed with a compd. layer of at least one kind among C, N and B on the surface to decrease the wettability with molten iron family metals. The entire part thereof is then sintered within the stable region of the diamond and under the pressure and temp. conditions of about >=1,300 deg.C. The composite sintered body which has the diamond layer exhibiting an excellent hardness characteristic and does not generate exfoliation at all between the diamond and sintered hard alloy layers at the time of the heating operation is thereby obtd.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a compound sintered body useful for cutting tool members, etc., in particular a sintered diamond layer and a cemented carbide layer with an intermediate layer interposed between the two layers. The present invention relates to the improvement of integrated composite rings and dead bodies.

[Prior art and its problems]

A composite sintered body in which a sintered diamond layer with a thickness of one head or less is bonded to a cemented carbide base layer is often used as a high-hardness material such as a cutting tool material for difficult-to-cut materials υROE. From the viewpoint of strength properties, it is preferable to perform the sintering of the diamond layer and the bonding between the layer phases in a single operation (so-called simultaneous sintering), and the following methods have been proposed for this purpose: has been done. rl
) By placing the diamond particle layer and the cemented carbide layer in direct contact with each other and treating them under high temperature and high pressure, the melt phase supplied from the soil-removed cemented carbide is used as a sintering aid. A device that performs sintering of the diamond layer and bonding between the two layers (Tokukō 6
1-24360), (2) The layers are partitioned with a substance with a coefficient of thermal expansion between that of diamond and cemented carbide, and the sintering aid is a powdered metal mixed in the diamond layer in advance or a substance in contact with the diamond layer. This is a method using ferrous metals arranged in such a manner (Japanese Patent Publication No. 60-22680.58-19428, Japanese Patent Application Laid-Open No. 60-85940, etc.).

In method (1) above, it is possible to control the sintering aid OJf that acts during sintering of the diamond layer to a lesser extent than in method (2), and as a result, a harder diamond sintered layer can be obtained. On the other hand, although there is a large difference in coefficient of thermal expansion between the sintered diamond and cemented carbide layers, there is no intermediate layer to absorb this difference, so this sintered body is attached to the support metal by high-temperature brazing. When the IC is near the boundary between both layers,
Due to the large strain of 7JOb, the diamond layer tends to peel off near the interlayers, and this tendency increases as the hardness of the diamond sintered layer increases. On the other hand, in U.S. Patent No. M 4440573, a partition plate made of a high melting point metal is arranged between the diamond and carbide layers, the area of which is slightly smaller than the opposing cross-sectional area of both layers, and a bonding agent supplied from the carbide to the diamond layer is arranged. A method is described for obtaining a composite sintered body with a high diamond-diamond bond density by minimizing melt stitching of the agent (mainly composed of Co).

However, as the intermediate layer in each of these conventional techniques, Ta
Preformed transition metal carbides and nitrides such as C and TiN are used, and interlayers and dividers loaded in the metallic state also tend to convert entirely to carbide during the sintering operation. Therefore, although these intermediate layers act as transition layers regarding the coefficient of thermal expansion in the diamond-carbide composite sintered body, they absorb the strain caused by the difference in coefficient of thermal expansion between the two layers, and completely prevent peeling during high-temperature heating. You can't get rid of it.

[Problem that the invention seeks to solve]

Therefore, one of the main objectives of the present invention is to completely eliminate peeling between the diamond and cemented carbide layers during heating and operation by optimizing the structure of the composite sintered body, thereby improving the yield when making tools. It's about letting people know.

Another object of the present invention is to provide a method for manufacturing a composite sintered body that is free from such delamination and in which the sintered diamond layer exhibits excellent hardness characteristics. According to the knowledge of those who
The process by which these metals change into carbides is a liquid-phase process in which an alloy is first formed by a reaction between the metal and the melt, and then this alloy is carbonized, rather than an in-phase reaction due to the diffusion of carbon into the solid metal. It has been found that intercalated reactions are likely to be predominant, and that it is extremely effective to form a dense compound layer on the surface of the high melting point metal that is poorly wettable with the melt.

Therefore, the gist of the present invention is, firstly, a composite sintered body in which a sintered diamond layer and a cemented carbide layer are integrated with an intermediate layer interposed between the two layers, and this intermediate layer is essentially A core containing a metal with a high melting point and a carbide or nitride of this metal,
It consists of a plate-like body having an outer surface containing carbonitride or boride, and this plate-like body has a cross-sectional area of 70 to 70% of the opposing cross-sectional area of both layers.
The composite sintered body is characterized by having a cross-sectional area of 95%, and the supporting layer and the diamond powder layer are made of at least one metal selected from Groups 4a, 5a, and 6a of the periodic table. These thin plates are arranged adjacent to each other through thin plates made of metal or an alloy mainly composed of metal, and these thin plates have a cross-sectional area slightly smaller than the opposing cross-sections of both layers. Before or after placement, a compound layer is formed on the surface of the metal with at least one of carbon, element, and boron, which have low wettability with respect to the bath-molten iron group metal, and then the whole is placed within the diamond stability region. The present invention provides a method for producing a diamond-cemented carbide composite sintered body, which is characterized by subjecting the diamond-cemented carbide composite sintered body to pressure and temperature conditions of approximately 1300°C or higher.

The high melting point metal constituting the intermediate layer of the present invention is selected from metals in Groups 4a, 5a, and 6a of the periodic table.

The compounds to be formed on the metal surface are Ti, Ti, which have low wetting properties (indicating a wetting angle of f Carbides, nitrides, carbides, borides of Zr, Hf, Ta, Nb, nitrides and borides of Mo are suitable, while Co such as WC and Mo2C are suitable.
Even if a compound exhibiting a wetting angle of 0° with respect to K is formed on the surface of the metal bar, the melt easily passes through the grain boundaries of this compound and reaches the internal structure of the metal. The suitability and unsuitability of various compounds such as these are excluded from Yu, V., and Naideichi's [Contact Phenomena of Molten Metals].
(published by the Krajina Academy of Sciences of the Soviet Union).

The following methods can be used to form the surface layer or surface compound.

Carbide: A solid carburizing method in which a metal plate is sandwiched between graphite plates and heated, a gas carburizing method in which hydrocarbons are thermally decomposed on the surface of the metal plate, or a metal plate between a diamond layer and a cemented carbide layer can be used. A carbide layer can also be formed on the metal surface by placing the metal plate at a temperature below the temperature at which it forms a melt for a certain period of time, and using this method makes it easier to handle the metal plate.

Nitride: A nitride layer can be easily formed by heating a metal plate in N2 gas or MfI5 gas to red heat or above the decomposition temperature of NH5.

Boride: Metal boron powder and high melting point metal are brought into close contact with each other and heated to adhere boron to the surface of the metal plate, and this is further heated to convert it into a boride film, or boron is deposited on the heated metal plate. A method of vapor-depositing can be used.

Carbonitride: Obtained by heating a metal in a mixed gas of CH4 and NH3 above their decomposition temperature.

In addition to the above, it is also possible to form these compounds as a thin film on the same or different metals by known CVD or PVD methods.

The thickness of the intermediate layer (metal + compound layer) used in the present invention is 10
~100 μm, of which the compound layer has a thickness of 1 to 1
It is appropriate to set it to 0 μm.0 [Example] 1. A diameter of 90 mm thick in a Ta capsule with an inner diameter of 90 mm.2
A WC-13% CO alloy substrate of 0.0 mm was placed, a Ta plate with a diameter of 8.4 μm and a thickness of 50 μm was placed thereon, and 0.15 f of diamond powder with a particle size of 3 to 8 μm was placed thereon.

The whole was loaded into a high-temperature, high-pressure device and kept at about 1100°C for 10 minutes under a pressure of about 60 Pa to cause a reaction between carbon and Ta by decarburizing diamond and WCO,
A fine carbide layer with a thickness of about 6 μm was formed on the Ta surface layer, and the temperature was further increased to 1450° C. for 5 minutes to obtain a composite sintered body.

The diamond layer exhibited an average Knoop hardness of 6500 f/-.

2 Outer diameter 9.0m + 4 JL diameter 2.2rm, n 7Qμ
A titanium nitride layer with a thickness of 5 μm was formed on the surface by heating a perforated Ti thin plate with a diameter of 9 m in diameter to 80 °C in a N2 stream.
A WC-Co carbide with an inner diameter of 90mm and a thickness of 2.0mm is placed in the so-called Ta capsule in the same manner as in 1 above, and this thin plate is placed on top of it, and a diamond of 5-12μm in diameter is placed on top of it.
155' was placed, and the whole was subjected to conditions of 6 GPa and 1450°C for 10 minutes.

3. A thin Mo plate with a diameter of 8.0+III+ and a thickness of 100 μm is heated to 500°C in a vapor deposition apparatus to deposit boron thereon, and then further heated to 1000°C to form a MoB2 film with a thickness of about 2 μm. Formed. This thin film is
It was placed in a Ta capsule and treated under the same pressure and temperature conditions to obtain a composite sintered body.

4. A Zr thin plate with a diameter of 8.5 μm and a thickness of 50 μm was heated in a container, and CH4 was introduced thereon at a ratio of 20 μm to form a carbide with a thickness of 10 μm on the surface layer of the thin plate. This thin plate was arranged in the same manner as on each side and treated under the same conditions to obtain a composite sintered body.

The hardness of the sintered bodies obtained in steps 2 to 4 above is 60.
It was within the range of 00kookpf/-.

The above methods 1 to 4 were repeated to obtain 10 sintered bodies for each method. These were placed in a heating device and heated to 1.000° C. at a rate of 300° C./fW in an Ar flow, and no peeling of the diamond layer was observed either during heating or cooling to room temperature.

[Comparative example]

For comparison, 5-12μ in a similar Ta capsule.
A composite sintered body was prepared by directly disposing diamonds o and isr of m in liquid on a cemented carbide substrate and similarly subjecting it to pressure and temperature conditions of 6 GPa and 1450° C. for 10 minutes. For 10 sintered bodies obtained by repeating this operation, the sintered diamond layer was 4500±500kff.
It has a Knoop hardness of 7'-, and in the heating test described above it has a Knoop hardness of 10.
Peeling occurred in 8 of the pieces.

In the above example, for the sake of simplicity, the grade of cemented carbide (C
Although the scales were made the same (concentration), size, diamond particle size, and amount, it is obvious that other scales may be used in the method of the present invention.

Claims (1)

[Claims] 1. A composite sintered body in which a sintered diamond layer and a cemented carbide layer are integrated with an intermediate layer interposed between the two layers, and the intermediate layer is essentially a high-melting point metal. and an outer surface containing carbide, nitride, carbonitride, or boride of this metal, and this plate-like body accounts for 70 to 95% of the opposing cross-sectional area of both layers. A composite sintered body characterized by having a cross-sectional area of . 2. The high melting point metal is at least one metal selected from metals of groups 4a, 5a, and 6a of the periodic table and alloys mainly composed of these metals.
The sintered body according to claim 1, which is a seed. 3. A molded or sintered support layer consisting essentially of WC and Co as binder and a diamond powder layer are combined with at least one metal selected from Groups 4a, 5a and 6a of the Periodic Table of Metals.
They are arranged adjacent to each other through thin plates made of a metal or an alloy mainly composed of the metal, and the thin plates have a cross-sectional area slightly smaller than the opposing cross-sections of both layers. Prior to or after placement, a compound layer of these metals with at least one of carbon, nitrogen, and boron, which has low wettability to molten iron group metals, is formed on the surface, and then the whole is within the diamond stability region and A method for producing a diamond-cemented carbide composite sintered body, the method comprising subjecting it to pressure and temperature conditions of approximately 1300°C or higher.