JPH01103992A - Production of diamond film - Google Patents

Abstract

PURPOSE:To improve the adhesiveness of a cemented carbide to a diamond film by previously subjecting the cemented carbide to heat treatment in a vacuum at the time of forming the film by bringing the cemented carbide into contact with an activated gaseous raw material. CONSTITUTION:The gaseous raw material contg. a carbon source gas is introduced from an introducing port 1 into a reaction vessel 2 and is cracked and activated by the microwaves or high frequencies led out by a waveguide 3. The carbon in the excitated state contained in said gas is deposited on a substrate 4 consisting of a super alloy having the surface previously cleaned by a heat treatment in a vacuum, by which the diamond film is formed thereon. The above-mentioned heat treatment is preferably executed at 10<-7>-10<-3>Torr degree of vacuum and 900-1,200 deg.C. Etching progresses to the inside of the cemented carbide and the loss of the intrinsic performance of the alloy and the degraded adhesiveness of the diamond are caused in some cases if the degree of vacuum is below 10<-7>Torr and the temp. exceeds 1,200 deg.C. The cemented carbide is oxidized if the degree of vacuum exceeds 10<-3>Torr and the sufficient cleaning effect is not obtainable in some cases if the temp. is below 900 deg.C.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a diamond film, and more specifically, the present invention relates to a method for manufacturing a diamond film, and more specifically, a diamond film useful as a protector for various cutting tools such as bits, end mills, drills, and cutters. The present invention relates to a method for producing a diamond film that can be formed on a cemented carbide with good adhesion.

[Prior art and its problems] In recent years, diamond synthesis technology has made remarkable progress, and diamond has come to be widely used, for example, as various protective films, optical materials, electronic materials, chemical industrial materials, and the like.

In particular, in the field of various cutting tools such as bits, end mills, cutters, etc., the maintenance of cutting tools made of a hard alloy is
By using a diamond film as FgII, a cutting tool with excellent wear resistance can be obtained, so there is an increasing demand for a cutting tool formed by forming a diamond film on a cemented carbide.

Conventionally, methods for forming a diamond film on cemented carbide include, for example, activating the surface of the cemented carbide by subjecting the cemented carbide to ion etching treatment prior to forming the diamond film. Method of bringing cemented carbide into contact with activated raw material gas (JP-A-60-2
04695), or before forming a diamond film on a substrate made of cermet, the cermet is etched with, for example, an acid solution to remove the bonding phase on the surface, and then the cermet and the activated raw material are etched. A method of bringing the material into contact with a gas (see Japanese Unexamined Patent Publication No. 61-52363) has been proposed.

However, in cutting tools using cemented carbide formed with a diamond film obtained by these methods,
The problem is that wear and chipping (partial damage) of the cutting edge are still observed, and the adhesion of the diamond film is still far from satisfactory.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a diamond film that solves the above-mentioned problems and can form a strongly adhesive diamond film on a cemented carbide.

[Means for Solving the Problems] In order to solve the above-mentioned problems, as a result of intensive studies, the inventor has developed a method for producing a diamond film in which a diamond film is deposited on a cemented carbide. The present invention was achieved by discovering that a diamond film firmly adhered to the cemented carbide can be obtained by heat-treating the cemented carbide in advance in a vacuum. That is, in the method of forming a diamond film on a cemented carbide, the configuration of the present invention is to heat-treat the cemented carbide in advance in a vacuum, and then activate a raw material gas containing a carbon source gas to This is a method for producing a diamond film characterized by bringing it into contact with a cemented carbide.

In the method of this invention, the cemented carbide is used as a substrate on which a diamond film is formed.

There are no particular restrictions on the cemented carbide that can be used, and examples include WC-Go alloy, WC-Tie-Go alloy, and VC-
It can be appropriately selected from among Tie-TaC-Go alloys and the like.

An important point in the method of the present invention is that, prior to forming the diamond film, the cemented carbide is previously heat treated in a vacuum to clean the surface of the cemented carbide.

This heat treatment is preferably performed under the following conditions.

That is, the degree of vacuum is 101 torr −1 O−3 tor
r, preferably 10-6 to 10-'torr. If the degree of vacuum is less than 10-7 torr, etching will progress to the inside of the cemented carbide, impairing the original performance of the cemented carbide, and reducing the diamond film obtained on the cemented carbide. Adhesion may decrease. On the other hand, if it exceeds 10''3 torr, the cemented carbide may be oxidized.

The heat treatment temperature is 900°C to 1200°C, preferably 1000°C to 1200°C. If this temperature is less than 900°C, the heat treatment may not produce a sufficient cleaning effect. On the other hand, if the temperature exceeds 1200° C., etching may progress to the inside of the cemented carbide, impairing the inherent performance of the cemented carbide and reducing the adhesion of the resulting diamond film to the cemented carbide.

The heat treatment time is usually 10 minutes to 60 minutes.

If the heat treatment time is less than 10 minutes, sufficient heat treatment effects may not be achieved. On the other hand, if it exceeds 60 minutes,
Etching may progress to the inside of the cemented carbide, impairing the inherent performance of the cemented carbide and reducing the adhesion of the diamond film obtained on the cemented carbide.

In the method of the present invention, the cemented carbide whose surface has been cleaned by the heat treatment is brought into contact with a gas obtained by activating a raw material gas containing a carbon source gas.

The raw material gas contains at least a carbon source gas, and may contain hydrogen gas and an inert gas in addition to the carbon source gas.

Examples of the carbon source gas include paraffinic hydrocarbons such as methane, ethane, propane, and butane; ethylene;
Olefinic hydrocarbons such as propylene and phthylene; Acetylene hydrocarbons such as acetylene and arylene; Diolefinic hydrocarbons such as butadiene; Alicyclic hydrocarbons such as cyclopropane, cyclobutane, cyclopentane, and cyclohexane, didichlorobutadiene , benzene, toluene,
Aromatic hydrocarbons such as xylene and naphthalene;
Ketones such as diethyl ketone and benzophenone; alcohols such as methanol and ethanol; amines such as nitrimethylamine and triethylamine; carbon dioxide gas and -carbon oxide; Class 1 petroleum, Class 2 petroleum such as kerosene, turpentine oil, ginger oil, and pine oil, Class 3 petroleum such as heavy oil, and Class 4 petroleum such as gear oil and cylinder oil can also be effectively used. . It is also possible to use a mixture of the various carbon compounds mentioned above.

Among these ranges, preferred are paraffinic hydrocarbons such as methane, ethane, and propane, ketones such as acetone and benzophenone, amines such as trimethylamine and triethylamine, carbon dioxide gas, and carbon oxide.

Hydrogen gas can be used as a diluent gas for the carbon source gas and as a plasma generation gas when plasma decomposing a raw material gas. When this hydrogen gas is used, the content of hydrogen gas in the raw material gas is 99.9 mol% or less, preferably 0.1 to 99.9 mol%. If this content exceeds 99.9 mol%, the formation rate of the diamond film may be significantly slowed or diamond may not precipitate.

The inert gas can be used as a carrier gas for the carbon source gas or a mixed gas of the carbon source gas and hydrogen gas.

Examples of this inert gas include nitrogen gas, argon gas, neon gas, and xenon gas.

As the means for activating the raw material gas, any method can be used from among the various methods conventionally used for diamond synthesis. Specifically, for example, there are methods for plasma decomposition by applying a DC voltage between the electrodes, methods for plasma decomposition by applying high frequency between the electrodes, methods for plasma decomposition by applying a micro wave between the electrodes, or methods for plasma decomposition by applying a microwave between the electrodes. Examples include various plasma decomposition methods such as an ion beam method in which ions are extracted using an ion chamber or an ion gun, and pyrolysis methods in which thermal decomposition is performed by heating with a hot filament. Among these, various plasma decomposition methods are preferred.

In the method of the present invention, the reaction usually proceeds under the following conditions, and a diamond film is formed on a substrate made of cemented carbide that has been pretreated.

That is, the temperature of the surface of the substrate made of the cemented carbide varies depending on the means of activating the raw material gas, so it cannot be determined generally, but for example, in the case of plasma decomposition, it is usually 400 to 1,200°C. , preferably 450
~1,100°C. If this temperature is lower than 400° C., the formation rate of the diamond film may be slowed down.

On the other hand, if the temperature exceeds 1,200°C, the diamond film deposited on the cemented carbide may be etched away, resulting in a slow diamond film formation rate.

The reaction pressure is 10-3 to 103 torr, preferably 1
The reaction pressure is ~800 torr and the reaction pressure is 1O-3 torr.
If it is lower than r, the formation rate of the diamond film may become slow. On the other hand, even if it is made higher than 10' torr, no corresponding effect will be achieved, and in some cases, the formation rate of the diamond film may be reduced.

The reaction time can be appropriately set depending on the desired thickness of the diamond film and the formation rate of the diamond film.

Furthermore, the plasma output when plasma decomposing the raw material gas is usually 0.1 kW or more. If the plasma output is less than 0.1 kW, sufficient plasma may not be generated.

The reaction under the above conditions can be carried out using, for example, a reaction apparatus as shown in FIG.

m1m is a conceptual diagram of a reaction apparatus that can be used in the method of this invention.

That is, the raw material gas containing the carbon source gas is introduced into the reaction vessel 2 from the raw material gas inlet 1. The raw material gas introduced into the reaction vessel z is plasma decomposed and activated by microwaves or high frequency waves guided by the waveguide 3, and the excited carbon contained in this activated gas is
A diamond film is formed by depositing on a substrate 4 made of cemented carbide whose surface has been cleaned by pretreatment.

The diamond film that can be obtained by the method of the present invention can be particularly suitably used as a surface protective film for various cutting tools such as bits, cutters, and end mills.

[Example J] Next, Examples and Comparative Examples of the present invention will be shown to further specifically explain the present invention.

(Example 1) Cutting tip made of cemented carbide (JIS K 105PG
N422) at a pressure of 10-6 torr and a temperature of 1000°C.
The surface layer of this cutting tip was removed by heat treatment under conditions of a treatment time of 30 minutes.

Next, this cutting chip was placed as a substrate in a reaction chamber, and under conditions of a substrate temperature of 900°C and a pressure of 50 torr in the reaction chamber, the output of a microwave power source with a frequency of 2.45 GHz was set to 400 W, and the power into one reaction chamber was set to 400 W. The raw material gas flow rate is 10 scc for carbon monoxide gas and 90 scc for hydrogen gas.
sccm and the reaction was carried out for 1 hour to obtain a deposit having an average thickness of 6 pm on the substrate controlled at the above temperature.

When the obtained deposit was subjected to Raman spectroscopic analysis, a peak attributed to diamond was observed near 1333 cm-1 in the Raman scattering spectrum, confirming that it was diamond without impurities.

Furthermore, a cutting test was conducted on the cutting tip formed with this diamond film under the following conditions.

Work material: A-8% by weight Si alloy.

Cutting speed: 800m/min, feed;
0.1mm/rev.

Cut depth: 0.25 mist.

Cutting time: 10 minutes.

After the test, the deposits on the material to be cut were removed with dilute hydrochloric acid, and the condition of the cutting edge of the cutting tip was examined using a scanning electron microscope (manufactured by JEOL Ltd.).
J5M840).

No wear or chipping was observed, confirming that it was normal.

(Comparative Example 1) A diamond film was formed in the same manner as in Example 1 except that the cutting tip was not heat-treated to obtain a diamond film with an average thickness of 6 #Lm, and A cutting test was conducted under the same conditions as in Example 1 above.

As a result, peeling of the diamond film was observed on the cutting edge of the cutting tip, confirming that the adhesion of the diamond film obtained in this comparative example was poor.

[Effects of the Invention] According to the present invention, (1) A diamond film with superior adhesion compared to conventional methods can be formed on a cemented carbide.

(2) If this diamond film is used, for example, as a protective film for a cutting tool, it can be made into a protective film that has excellent wear resistance and does not peel off.

It is possible to provide an industrially advantageous method for manufacturing a diamond film having the following effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a reaction apparatus used in the method of the present invention. Patent applicant: Idemitsu Petrochemical Co., Ltd. Representative: Mr. Ukimura: 1t ・1st 1st
Figure yo

Claims (1)

[Claims] (1) In a method for forming a diamond film on a cemented carbide, the cemented carbide is heat-treated in a vacuum in advance, and then a gas obtained by activating a raw material gas containing a carbon source gas is brought into contact with the cemented carbide. A method for producing a diamond film, characterized in that: