JPH05214532A - Coated sintered body - Google Patents

Abstract

PURPOSE:To improve the adhesion, durability or the like of a sintered body coated with a diamond or hard carbon film. CONSTITUTION:In a coated sintered body in which a sintered body of cemented carbide, ceramics or the like obtd. by sintering tungsten carbide, titanium carbide or the like by the use of cobalt and nickel as a binder is used as a base material and a diamond or hard carbon film is formed on the surface, an aluminum nitride film is used for an intermediate layer. Moreover, the aluminum nitride film of the intermediate layer is formed by a reactive ion plating method. This coated sintered body can be used as ones excellent in durability as well as wear resistance as cutting tools, wear resistant tools, wear resistant parts or the like, and furthermore, as ornaments.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a coated sintered body used for cutting tools, wear resistant tools, wear resistant parts, ornaments and the like.

[0002]

2. Description of the Related Art For high-performance and high-wear resistant tools and the like, a so-called cemented carbide or cermet sintered body material containing tungsten carbide, titanium carbide or the like as a main component has been widely used. Ceramic materials such as alumina and silicon nitride have also been widely used.

On the other hand, in recent years, a chemical vapor deposition method (CVD method)
With the progress of the physical vapor deposition method (PVD method) and the like, ceramic materials such as titanium carbide and titanium nitride and diamond or hard carbon coating have been widely applied to the above materials in order to further improve the performance of the above tools. There is.

[0004]

A chemical vapor deposition method (CV) for a sintered body containing tungsten carbide or titanium carbide as a main component.
When a diamond or hard carbon coating is formed by the D method), carbon deposited in cobalt or nickel used as a binder of a sintered body diffuses and forms a solid solution, so that the characteristics of the coating such as adhesion and crystallinity are obtained. It had the drawback of getting worse.

On the other hand, when the base material is ceramics, the compatibility with the base material prevents the diamond or desired hard carbon film from being deposited, peels off the film due to the difference in the coefficient of thermal expansion, and deteriorates the adhesion. It had the drawback of coming.

[0006]

In order to solve the above problems, the present invention uses an aluminum nitride layer as an intermediate layer between a substrate and a diamond or hard carbon coating. Further, in forming an excellent diamond or hard carbon film, a chemical vapor deposition method (CVD method), particularly a microwave CVD method or a hot filament CVD method is used as a forming method, and further, as an aluminum nitride layer forming method. Is the one using the reactive ion plating method.

[0007]

The formation of diamond or a hard carbon coating close to the physical properties of diamond by chemical vapor deposition is generally carried out by a microwave CVD method or a hot filament CVD method using a gaseous carbon compound and excess hydrogen gas as raw materials. However, in any method, 700 to 1
There are two major problems because the base material is exposed to a high temperature of 000 ° C. That is, at such a high temperature, a substance that forms a solid solution with carbon forms a solid solution, and a substance that forms a compound with carbon forms a carbide.
There is a problem of peeling of the film due to the difference in coefficient of thermal expansion between the base material and the diamond coating. Regarding the former, it is difficult to deposit diamond on the surface of a substance that dissolves carbon.
Further, when such a substance is contained in the base material, diffusion and solid solution occur deep inside the base material, so that not only diamond precipitation does not occur but also the base material is altered. Therefore, this phenomenon occurs remarkably in the cemented carbide that uses as a binder cobalt or nickel that forms a solid solution with carbon, and does not occur in a substance that does not react with carbon. Generally, 700-1000 ° C
Ceramic materials such as alumina and silicon nitride are conceivable as materials that can withstand the high temperatures of 1. However, since the coefficient of thermal expansion of alumina is very different from that of diamond, the latter problem, that is, film peeling occurs. Further, it is known that silicon nitride, aluminum nitride and the like do not cause these two problems, but have problems in strength and workability as a base material.

It is known that aluminum nitride has a thermal expansion coefficient close to that of diamond among heat resistant materials, but as described above, bulk materials have problems in strength and workability. .. However, the problem of the diamond-coated tool can be solved by using this aluminum nitride as a thin film having an appropriate film thickness and as an intermediate layer. That is, when using a substance that dissolves carbon as the base material, by forming an aluminum nitride film on the base material, it is possible to prevent the diffusion or solid solution of carbon that occurs during the formation of the diamond or hard carbon coating, Also, by using aluminum nitride as a thin film,
A highly reliable surface state is formed without causing deterioration of mechanical strength due to microscopic defects such as bulk aluminum nitride produced by sintering with a commonly used sintering aid. can do. By forming a diamond or hard carbon coating on this surface, it is possible to achieve coating with excellent adhesion and reliability.

As a method of forming this aluminum nitride film, a CVD method and a PVD method can be considered.
In the method, expensive organometallic compounds such as trimethylaluminum and halides such as aluminum chloride are used as the aluminum source, but these aluminum compounds have ignitability, flammability, toxicity, etc., and are troublesome substances to handle. In addition to the above, it is necessary to raise the substrate temperature to a high temperature of about 1000 ° C. when synthesizing aluminum nitride, which causes a problem because the substrate is damaged by the temperature and by-products.

On the other hand, in the PVD method, the sputtering method and the reactive ion plating method are widely applied to the formation of an aluminum nitride film. However, the aluminum nitride film formed by the sputtering method has problems in film quality such as adhesion, hardness and crystallinity. In contrast,
In the reactive ion plating, especially the method of synthesizing an aluminum nitride film from metallic aluminum and nitrogen gas,
The film quality such as adhesion and crystallinity of the synthesized film is excellent,
It is possible to make the diamond film formed on the aluminum nitride film later excellent in adhesion and crystallinity.

[0011]

EXAMPLES The present invention will be described below based on examples. An aluminum nitride film of about 2 μm was formed by a reactive ion plating method on a so-called cemented carbide throwaway chip of tungsten carbide-cobalt system (cobalt 4% by weight, JIS standard K-10 equivalent product). The frequency is 2.54 with methane and hydrogen gas as raw materials.
An example in which a diamond film having a thickness of about 5 μm is formed by using a so-called microwave plasma CVD apparatus that uses discharge by microwave of GHz will be described.

FIG. 1 is a vertical cross-sectional view of a hollow cathode type ion plating apparatus for forming an aluminum nitride film which is an intermediate layer. First, the vacuum chamber 1 is evacuated to the vacuum exhaust system 2
Vacuum evacuation to 1 × 10 ^-5 Torr by a direct current discharge of 30V-300A between the hollow cathode electron gun 3 and the evaporation metal aluminum 5 contained in the water-cooled copper crucible 4 to melt the aluminum 5.・ Evaporate. At this time, most of the evaporated aluminum is 30V-300A.
Is ionized and activated by the electrons present during the large current discharge. Nitrogen gas was added to this state at 100 cc / mi
After introducing the gas at a flow rate of n from the gas introduction system 6 and stabilizing it, the shutter 7 was opened, and an aluminum nitride film was synthesized and formed on the throw-away chip 8 made of a carbide. At this time, a high-frequency power of 13.56 MHz was applied as a DC component of -50 V from the high-frequency power source 9 to the carbide throw-away chip 8 as the substrate. At this time, the temperature of the cemented carbide throw-away tip 8 was set to about 200 ° C. After cooling, the carbide throw-away tip 8 was taken out.

Next, the carbide throw-away tip 14 coated with this aluminum nitride film is placed in the microwave plasma CVD apparatus shown in FIG. 2, the apparatus is evacuated, and methane is removed from the gas introducing system 10. Introducing hydrogen gas containing 0.5%, a microwave generating power source 11 generates a microwave of 500 W at 2.54 GHz, and a discharge plasma is generated in the reaction tube 13 made of a quartz tube through the waveguide 12 to generate aluminum nitride. A diamond film was formed on the carbide-made throw-away tip 14 with a film thickness of about 5 μm at a film forming rate of 0.3 μm / hr.

The throw-away tip coated with this diamond film was analyzed by the X-ray diffraction method and found to be superior in crystallinity to the one coated directly with the diamond film without using the aluminum nitride film as the intermediate layer. It was
In addition, the so-called diamond-structured SP3-bonded carbon component was also present in a larger amount than the latter by laser Raman spectroscopic analysis. In addition, a cubic electron crystal growth peculiar to the diamond film was observed by observation with a scanning electron microscope.

Using the diamond-coated cemented carbide throw-away tip produced in this way, Al-
When a cutting test of a Si alloy was performed using an NC lathe under the conditions shown in Table 1, an uncoated cemented carbide throwaway tip A and a cemented carbide throwaway tip in which a diamond film was directly formed without an intermediate layer The results regarding flank wear shown in FIG. 3 were obtained for B and the cemented carbide throw-away tip C having the diamond film coating using the aluminum nitride film as the intermediate layer. The uncoated carbide throw-away tip caused seizure immediately after the start of the cutting test, resulting in large wear. In addition, in the case of the cemented carbide throw-away tip directly coated with the diamond film, chipping and peeling occurred immediately after the start of the cutting test, and there was no coating effect of the diamond film. On the other hand, in the case where the aluminum nitride film was formed on the intermediate layer, phenomena such as chipping and peeling did not occur and extremely high machinability was exhibited.

[0016]

[Table 1]

[0017]

As described above, according to the present invention, a sintered body including a tungsten carbide-cobalt sintered body having high versatility as a material for tools, wear-resistant tools, dies, wear-resistant parts, ornaments, etc. It is possible to provide a coated sintered body coated with an excellent diamond film or a hard carbon film as a substrate and a method for producing the same. That is, by using an aluminum nitride film as an intermediate layer between a sintered body such as a tungsten carbide-cobalt sintered body and a diamond film, a diamond-coated sintered body having excellent adhesion and crystallinity can be obtained. Of. Further, by synthesizing an aluminum nitride film exhibiting excellent performance as the intermediate layer by the reactive ion plating method, the base material is not attacked, and unlike the CVD method, the dangerous gas is not used and the cost is low. It becomes possible to synthesize.

In the embodiment, the indexable insert made of carbide is taken up, but it is obvious that the present invention can be applied to other materials and parts. Further, although the microwave plasma CVD method was used in the synthesis of the diamond film, it is also apparent that the same effect can be obtained by a method such as a hot filament method or a plasma jet method.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a hollow cathode type ion plating apparatus used for forming an aluminum nitride film.

FIG. 2 is a vertical sectional view of a microwave plasma CVD apparatus used for forming a diamond film.

FIG. 3 is an explanatory diagram showing a result of a cutting test.

[Explanation of symbols]

 1 Vacuum Tank 2 Vacuum Exhaust System 3 Hollow Cathode Electron Gun 4 Water-Cooled Copper Crucible 5 Aluminum for Evaporation 6 Gas Introducing System 7 Shutter 8 Carbide Throw-Away Chip 9 High Frequency Power Supply 10 Gas Introducing System 11 Microwave Generation Power Supply 12 Waveguide 13 Reaction tube 14 Carbide throw-away tip

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location C23C 28/04 (72) Inventor Jun Tsuneyoshi 6-31-1 Kameido, Koto-ku, Tokyo Seiko Denshi Industry Co., Ltd.

Claims (1)

[Claims] 1. A surface of a base material is a cemented carbide obtained by sintering tungsten carbide, titanium carbide or the like with cobalt or nickel as a binder, or a ceramics sintered body containing alumina or silicon nitride as a main component. In a coated sintered body on which a diamond or hard carbon coating is formed,
A coated sintered body comprising an aluminum nitride layer as an intermediate layer between the substrate and the diamond or hard carbon coating.