JPS6257802A - Parts coated with hard carbon - Google Patents

Abstract

PURPOSE:To obtain a low-priced diamond tool, by forming a thin film of hard carbon on a base material coated with a thin film of a compound from W and C, mainly composed of W2C, in a thickness of 0.1mum or more. CONSTITUTION:Adhesive strength of a film of hard carbon is remarkably improved by providing an intermediate thin film layer of a compound of W and C, mainly composed of W2C, to exist between a base material and the film of hard carbon. According to the experiment, said intermediate layer, even if it is formed by a material of plural phases of W2C+W, W2C+WC+W, etc. except W2C of single phase, generates no difference in the effect. While said intermediate layer, in which thickness of 0.1-5mum is preferable, is recognized no effect for the thickness of 0.1mum or less. While the layer is recognized no particular difference in the effect for the thickness of 5mum or more. In this way, a tool of strength about that of the expensive sintered diamond tool can be manufactured by coating the too with the cheaper hard carbon from a low pressure gas phase.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application] The present invention relates to hard carbon-coated parts, and more specifically, in diamond-coated parts in which diamond is deposited on the surface of a base material from a low-pressure gas phase, the diamond coating and film are combined with the base material. The present invention relates to a new hard carbon-coated component with improved adhesive strength to materials.

[Conventional technology]

Diamond is the hardest material on earth, is extremely chemically inert, has high thermal conductivity, and has a small coefficient of thermal expansion, making it an ideal material for cutting tools, so it is widely used as a cutting tool. It is provided. Conventional natural diamond tools had 9 openness and lattice defects, which caused concerns about toughness, but sintered diamond tools have solved this problem, and have recently been used in cutting tools for A/gold alloys. It has reached the point where it occupies the main fft. However, the sintered diamond tool requires extremely high pressure and high temperature for its manufacture, so it has the disadvantage that the manufacturing cost is very high.

Recently, a technique has been developed in which hydrocarbons in a low-pressure gas phase are decomposed using plasma or the like, and hard carbon such as diamond is precipitated on the surface of a base material for inspection. If a tool is made according to this method, it is thought that there is a possibility that a diamond tool can be provided at a very low cost without requiring ultra-high pressure or high temperature.

[Problem that the invention seeks to solve]

However, when hard carbon was actually deposited on the surfaces of various base materials using the above-mentioned method under low pressure and in a gas phase, hardly any materials were obtained that could be used as cutting tools. The reason for this is that the adhesive strength between the hard carbon coating film and the base material is insufficient, and as a result, the hard carbon coating film peels off at the initial stage of cutting.

Therefore, various studies have been made in order to improve the adhesive strength between the hard carbon-free Φ film and the base material6.

In particular, the interposition of various intermediate layers between the hard carbon coating film and the base material has been studied, particularly Nb and Ta.

It has been proposed that it would be extremely effective to use metals such as Mo and W as the intermediate layer. In accordance with this proposal, the present inventors actually created a machine J1 in which Nb was interposed between the cemented carbide base material and the hard carbon coating film to a thickness of 1 μm, and conducted cutting tests. The effect was hardly recognized.

This fact is due to the fact that Nb is very soft compared to hard carbon and cemented carbide, so Nb deforms plastically during cutting, and the hard carbon coating cannot follow this deformation, resulting in It is considered that this is a precautionary measure as it may have peeled off after all.

In view of the above-mentioned current situation, the present invention aims to propose a new hard carbon-coated component having an intermediate layer that improves the adhesive strength between the base material surface and the hard carbon-free aF film, thereby reducing the cost. This makes it possible to commercialize the production of tool materials by coating hard carbon from the gas phase at low pressure.

[Means for solving problems]

The present invention provides a hard carbon-covered part coated with a hard carbon thin film deposited on the surface of a base material from a vapor phase, in which a thin film of a compound of W and C mainly composed of Vcw2C is formed between the hard carbon thin film and the base material. It is a hard carbon coated part characterized by having a thickness of 0.1 μm or more, which improves the adhesive strength of the hard carbon removal film and provides a practical hard carbon coated part at a low cost. is.

First, the circumstances that led to the present invention will be explained.

The reason why adhesion strength improves when a metal such as Nb, Ta, Mo, or W is interposed between the base material and the hard carbon coating is because these metals are carbide-forming metals. This is thought to be due to the formation of a metal carbide layer at the interface due to carbon diffusion. Therefore, even when Wa having sufficient hardness was used instead of W, almost no improvement in adhesive strength was observed.

The present inventors have discovered that W2C has a hardness comparable to that of W2C, and that when a hard carbon film is coated on W2C, a diffusion intermediate layer called we is formed at the interface between the hard carbon and W2C. It occurred to me that it might be possible to improve strength.

Based on this idea, chemical K
After coating W2C to a thickness of 2μm using the N method, we made a prototype by cutting out hard carbon to a thickness of 2μm using the microwave plasma CVD method, and conducted a cutting test.As a result, the results were as great as expected. Obtained.

In the present invention, the material used as the base material is not particularly limited, but cemented carbide, ceramic sintered body, etc. are preferable.

In the present invention, a compound thin film of W and C containing W2C as a main component is used as the intermediate layer.

It goes without saying that there is no difference in the effect even if the substance has multiple phases such as W2C+w c + W. Further, the thickness of the intermediate layer is preferably 0.1 μm or more and 5 μm or less,
No effect was observed when the thickness was 0.1 μm or less. Also 5μ
No particular difference in effectiveness was observed in the above cases.

In the present invention, for example, WF6. W2 was applied to the surface of the base material heated to 500~toooC in a CH4, H2 mixed air flow.
A so-called chemical vapor deposition method (CVD method) in which carbon is precipitated and coated is generally used. It can also be formed by a sputtering method using 12C as a target in an argon + acetylene atmosphere.

In the present invention, in order to form a hard carbon coating in contact with the above-mentioned intermediate layer, μ waves (high frequency of 300 Mm or more, generally 2.45 G &), RF ( High frequency below 300MHz, generally 13.56MILz, 27.12MHz
) Apply an electric field to turn the mixed air flow into plasma.
A plasma CVD method is generally used in which hard carbon is coated on base soil heated to a temperature of C to 1200 UK. In addition, after ionizing the methane + argon mixed gas with an ion source, carbon ions are ionized in a high vacuum (t
Another well-known method is the ion beam deposition method (IBD method), in which hard carbon is coated on a substrate by extracting it as a K ion beam and irradiating the ion beam onto a substrate held in a high-vacuum container. .

〔Example〕

EXAMPLES The present invention will be specifically explained below with reference to Examples, and its effects will be shown.

Example 1 Commercially available cemented carbide base material [manufactured by Sumitomo Electric Industries (a-), material H
1, model number 5K (1, N 421, :l) was held in a CVD reactor and heated to a temperature of 650DK, WF6.0
M4. After flowing a H2 mixed gas flow at 40 Torr Ic for 2 hours, the sample was taken out and examined, and it was found that the surface was coated with W2C to a thickness of about 2 μm. This sample was held in a microwave plasma CVD apparatus, and I(2 and CH4
A mixed air flow of 40 Torr was applied for 2 hours. The obtained sample was examined by X-ray diffraction i*, and it was confirmed that diamond was fixed on the surface. The samples obtained above are A (product of the present invention), l, , W2
B (comparative product) and W
A cutting test was conducted under the following conditions with samples A, B, and OK, using a 2C glue with W as an intermediate layer and the same as A (comparison product).

Test conditions: Rigid material AQ4C Cutting speed 10001/win Feed F) 0.1 0111/rev
Including cutting 0.5 xx As a result, after cutting A for 100 minutes, the flank wear was 0.
Compared to 08 fins, B and C had flank wear of 0J2 and 0.1'$01 after cutting for 10 minutes, respectively.

Example 2 Commercially available cemented carbide base material [Sumitomo Electric Industries, Ltd. M, material H1
, model number 5DaNa 22), DC bias R
Coating was performed using an F magnetron sputtering device in a C2H2 atmosphere using W as a target. When the sample was taken out and examined, a mixture of W and W2C was punched out to a thickness of 1 μm on the surface of the base material. This sample was held in an ion beam evaporator and irradiated with a C ion beam to form hard carbon (amorphous state) into a 1 μm thick nuclide.

Sample D (product of the present invention) obtained as described above, Sample E (comparison product) with only unsupported base material for comparison, and Sample F (comparison product) with a sintered diamond tool were prepared under the following conditions. A cutting test was conducted.

Test conditions: wt cutting material A C4Cj (]Qm X
100fII corner cutting speed 800ml min Feed rate 0.0 5mm/depth of cut 0.5 Dragon cutter APG4080B The specimen of the present invention showed 0 flank wear after cutting for 100 minutes.
．． However, after cutting for 100 minutes, the flank wear of sample E and sample was 0-2211II, o, and o, respectively.
It was 40. It was found that the product of the present invention has a strength close to that of a sintered diamond tool.

〔Effect of the invention〕

As is clear from the above description and examples, the hard carbon-coated parts of the present invention have a base material surface and a hard carbon coating film firmly adhered to each other by an intermediate layer, and have a strength similar to that of expensive sintered diamond tools. Ak, it is possible to manufacture it by a cheaper hard carbon coating from low pressure and gas phase.

Claims (1)

[Claims] In a hard carbon-coated component in which a thin carbon film harder than the gas phase is deposited on the surface of a base material, a thin film of a compound of W and C containing W_2C as a main component is provided between the hard carbon thin film and the base material with a thickness of 0. A hard carbon coated part characterized by having a carbon coating of 1 μm or more.