JPH0776146B2 - Diamond film manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a diamond film, and more specifically, a diamond film useful as a protective film for various cutting tools such as cutting tools, end mills, drills and cutters. Relates to a method for producing a diamond film, which 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 for example, diamond has come to be widely used as various protective films, or as optical materials, electronic materials, chemical industrial materials, and the like.

In particular, in the field of various cutting tools such as cutting tools, end mills and cutters, by using a diamond film as a protective film for a cutting tool made of cemented carbide, it is possible to obtain a cutting tool with excellent wear resistance. There is an increasing demand for cutting tools having a diamond film formed on a hard alloy.

Then, conventionally, as a method for forming a diamond film on a cemented carbide, for example, after activating the surface of the cemented carbide by subjecting the cemented carbide to an ion etching treatment prior to forming the diamond film, A method of contacting a cemented carbide with an activated source gas (JP-A-60-2046)
See Publication No. 5. ), Or prior to forming a diamond film on a cermet substrate, the cermet is etched with, for example, an acid solution to remove the binder phase on the surface, and then the cermet is contacted with an activated source gas. A method (see JP-A-61-52363) has been proposed.

However, in a cutting tool using a cemented carbide formed by forming a diamond film obtained by these methods,
The cutting edge is still worn and chipping (partially missing) is observed, and there is a problem that the diamond film adhesion is not sufficient.

An object of the present invention is to solve the above problems and to provide a method for producing a diamond film capable of forming a strongly adhered diamond film on a cemented carbide.

[Means for Solving the Problems] In order to solve the above problems, as a result of extensive studies by the present inventor, a diamond film manufacturing method for depositing a diamond film on a cemented carbide It was found that a diamond film firmly adhered to this cemented carbide can be obtained by subjecting the above to a heat treatment in vacuum in advance to reach the present invention. That is, the structure of the present invention, in the method for forming a diamond film on a cemented carbide, after heat-treating the cemented carbide in vacuum in advance, the gas obtained by activating the source gas containing the carbon source gas, This is a method for producing a diamond film, which is characterized in that it is brought into contact with a cemented carbide.

In the method of the present invention, the cemented carbide is used as a substrate for forming a diamond film.

There is no particular limitation on the cemented carbide used, for example
WC-Co type alloy, WC-TiC-Co type alloy, WC-TiC-TaC-Co
It can be appropriately selected and used from among system alloys.

An important point in the method of the present invention is that prior to forming the diamond film, the cemented carbide is preliminarily vacuumed at 10 ⁻⁷ torr to 10
^In a vacuum of ^-3 torr, temperature 900 ℃ ~ 1200 ℃, processing time 10 minutes ~ 6
It is to clean the surface of the cemented carbide by heat treatment under the condition of 0 minutes.

This heat treatment has the action of removing the layer containing impurities on the surface of the cemented carbide under the heat treatment conditions to clean the surface, but if heat treatment is performed under conditions other than the heat treatment conditions, only the surface of the cemented carbide will be removed. As a result, inconveniences such as etching progressing to the inside of the cemented carbide occur. This heat treatment is preferably performed under the following conditions.

That is, the degree of vacuum is 10 ^-7 torr to 10 ^-3 torr, preferably 10
^-6 to 10 ^-4 torr. If the degree of vacuum is less than 10 ^-7 torr, etching progresses to the inside of the cemented carbide, impairing the original performance of the cemented carbide and the diamond film obtained on the cemented carbide The adhesiveness to may decrease. On the other hand, if it exceeds 10 ⁻³ torr, the cemented carbide may be oxidized.

Heat treatment temperature is 900 ℃ ~ 1200 ℃, preferably 1000 ℃
~ 1200 ℃. If this temperature is lower than 900 ° C, the heat treatment may not provide a sufficient cleaning effect. On the other hand, if the temperature exceeds 1200 ° C, the etching may proceed to the inside of the cemented carbide, impairing the original performance of the cemented carbide, and the adhesion of the obtained diamond film to the cemented carbide may deteriorate.

The heat treatment time is usually 10 minutes to 60 minutes. If the heat treatment time is less than 10 minutes, a sufficient heat treatment effect may not be obtained. On the other hand, if it exceeds 60 minutes, the etching may proceed to the inside of the cemented carbide, impairing the original performance of the cemented carbide and reducing the adhesion of the diamond film obtained on this cemented carbide. .

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

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

Examples of the carbon source gas include paraffin hydrocarbons such as methane, ethane, propane and butane; ethylene,
Olefin hydrocarbons such as propylene and butylene; Acetylene hydrocarbons such as acetylene and allylene; Diolefin hydrocarbons such as butadiene; Alicyclic hydrocarbons such as cyclopropane, cyclobutane, cyclopentane, cyclohexane; Cyclobutadiene, benzene , Toluene, xylene, naphthalene, and other aromatic hydrocarbons; acetone, diethyl ketone, benzophenone, and other ketones, methanol, ethanol, and other alcohols, trimethylamine,
Amines such as triethylamine; carbon dioxide, carbon monoxide; and, although not a simple substance, such as gasoline, etc., Fire Hazardous Substances Class 4 and Class 1, kerosene, turpentine oil, camphor oil, pine oil, etc. It is also possible to effectively use the second petroleum, the third petroleum such as heavy oil, and the fourth petroleum such as gear oil and cylinder oil. Further, the various carbon compounds may be mixed and used.

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

Hydrogen gas can be used as a dilution gas of the carbon source gas, and as a plasma generating gas when the raw material gas is decomposed by plasma. 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%. This content is 9
If it exceeds 9.9 mol%, the formation rate of the diamond film may be remarkably slowed or diamond may not be precipitated.

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 a means for activating the source gas, a plasma method conventionally used for synthesizing diamond is adopted. Specifically, for example, a method of applying a DC voltage between the electrodes for plasma decomposition, a method of plasma decomposition by high frequency,
Examples thereof include a method of performing plasma decomposition by microwaves, and various plasma decomposition methods such as an ion beam method in which plasma decomposition is performed in an ion chamber or an ion gun and ions are extracted by an electric field.

In the method of the present invention, the reaction usually proceeds under the following conditions to form a diamond film on a substrate made of cemented carbide which has been pretreated in advance.

That is, since the temperature of the substrate surface made of the cemented carbide differs depending on the activation means of the raw material gas, it cannot be unconditionally determined, but, for example, in the case of plasma decomposition, it is usually 400 to 1,200 ° C., preferably It is 450-1,100 ℃. If this temperature is lower than 400 ° C, the formation rate of the diamond film may be slow. On the other hand, if the temperature exceeds 1,200 ° C, the diamond film deposited on the cemented carbide may be scraped off by etching, resulting in a slow diamond film formation rate.

The reaction pressure is 10 ⁻³ to 10 ³ torr, preferably 1 to 800 torr. If the reaction pressure is lower than 10 ⁻³ torr, the formation rate of the diamond film may slow down. On the other hand, even if it is higher than 10 ³ torr, the effect equivalent to that is not exhibited, and in some cases, the formation rate of the diamond film may be lowered.

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

Further, the plasma output when the raw material gas is decomposed by plasma is usually 0.1 kw or more. Plasma output is 0.1
If it is less than kw, plasma may not be sufficiently generated.

The reaction under the above conditions can be carried out using a reactor as shown in FIG. 1, for example.

FIG. 1 is a conceptual diagram of a reaction apparatus that can be used in the method of the present 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 2 is plasma-decomposed and activated by the microwave or high frequency guided by the waveguide 3, and the excited carbon contained in the activated gas is
A diamond film is formed by depositing it on a substrate 4 made of cemented carbide whose surface has been cleaned in advance 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 a cutting tool, a cutter, and an end mill.

EXAMPLES Next, examples and comparative examples of the present invention will be shown to more specifically describe the present invention.

(Example 1) Cutting tip made of cemented carbide (JIS K 10 SPGN 422)
Was heat-treated under conditions of a pressure of 10 ⁻⁶ torr, a temperature of 1000 ° C. and a treatment time of 30 minutes to remove the surface layer of the cutting tip.

Then, this cutting tip was installed as a substrate in the reaction chamber, and the output of the microwave power source of frequency 2.45 GHz was set to 400 W under the conditions of substrate temperature of 900 ° C. and pressure of 50 torr in the reaction chamber, and raw materials into the reaction chamber. The gas flow rate was set to 10 sccm of carbon monoxide gas and 90 sccm of hydrogen gas, the reaction was carried out for 1 hour, and the average film thickness was 6 μm on the substrate controlled to the above temperature.
A deposit of

When Raman spectroscopic analysis was performed on the obtained deposit, a peak due to diamond was observed at around 1333 cm ^{−1 in the} Raman scattering spectrum, and it was confirmed that the diamond was free of impurities.

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

Work material: Al-8 wt% Si alloy. Cutting speed: 800m / min. Feed: 0.1mm / rev. Depth of cut: 0.25mm. Cutting time: 10 minutes. After the test, the deposits on the material to be cut were removed with dilute hydrochloric acid, and the state of the cutting edge of the cutting tip was measured with a scanning electron microscope (manufactured by JEOL Ltd.,
Observation with JSM840) showed no wear or chipping, confirming that it was normal.

Comparative Example 1 A diamond film was formed in the same manner as in Example 1 except that the heat treatment of the cutting tip was not performed in the above Example 1 to obtain a diamond film having an average film thickness of 6 μm. A cutting test was performed under the same conditions as in Example 1.

As a result, a peeling phenomenon of the diamond film was observed at the cutting edge of the cutting tip, and it was confirmed that the diamond film obtained in this comparative example had poor adhesion.

[Advantages of the Invention] According to the present invention, (1) a diamond film having excellent adhesion can be formed on a cemented carbide as compared with a conventional method, and (2) this diamond film is used, for example, as a cutting tool. If it is used as the protective film, it is possible to provide an industrially advantageous method for producing a diamond film, which has effects such as excellent protection against abrasion and removal of the protective film.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a reaction apparatus used in the method of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Watanabe 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi, Aichi Nihon Special Ceramics Co., Ltd. (56) References JP-A-60-186499 (JP, A)

Claims (1)

[Claims] 1. A method for forming a diamond film on a cemented carbide, wherein the cemented carbide is previously vacuumed at a pressure of 10 ⁻⁷ torr to 10 ⁻³ to.
In the vacuum of rr, after the heat treatment under the conditions of a temperature of 900 ° C to 1200 ° C and a treatment time of 10 minutes to 60 minutes, a gas obtained by activating a raw material gas containing a carbon source gas by a plasma method is used as the cemented carbide. A method for producing a diamond film, which comprises contacting.