JPH0369595A - Production of diamond coated member - Google Patents

Abstract

PURPOSE:To improve adhesion to a substrate and wear resistance by forming plural diamond layers including at least a base layer and a surface layer on the surface of a silicon nitride-based sintered body with plural kinds of prescribed mixed gases. CONSTITUTION:A first mixed gas consisting of >=10vol.% CO and H2 is excited to produce a first active gas. This active gas is brought into contact with the surface of a base material whose surface layer is made of a silicon nitride-based sintered body to form a diamond layer. A second mixed gas consisting of <10vol.% CO and H2 is then excited to produce a second active gas and a diamond layer as a surface layer is formed with the active gas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a diamond-coated member. More specifically, the present invention relates to a method for producing a diamond-based member coated with a diamond-based film that can produce a diamond-based film with excellent adhesion to a base material at a high deposition rate.

[Prior Art] Diamond thin films have excellent hardness, abrasion resistance, electrical insulation, thermal conductivity, infrared transparency, solid lubricity, etc., and are therefore used, for example, in cutting tools, abrasive materials, and wear-resistant materials. It is being used as a hard coat material for various parts such as mechanical parts and optical parts, as well as electrical and electronic materials.

By the way, in order for a diamond-based coated member formed by coating with a thin film of tire cents to exhibit the desired performance, the adhesion between the base material and the diamond-based thin film must be excellent.

Therefore, we have improved the adhesion between the diamond thin film and the base material.
Various proposals have been made in the past for the purpose of achieving this.

Japanese Patent Publication No. Sho Go-59086 discloses Si as a base material.

A technique for forming a diamond film with a film thickness of 0.5 to 5 oJLm on the surface of an N4-based material has been disclosed. However, this publication does not describe the conditions for synthesizing the diamond-like film.

It is true that the Si3N4 material has a coefficient of thermal expansion relatively close to that of diamond, so it has superior adhesion compared to WC cemented carbide and the like. However, Si
Even if it is attempted to coat a 3N4 material with diamond, the problem is that the film formation rate is extremely slow.

For this reason, it is possible to increase the concentration of the carbon source gas, but it is difficult to provide diamond coating with sufficient performance, making it difficult to use it for cutting tools and the like. Various multilayer coatings of diamonds with different properties have also been proposed. (Unexamined Japanese Patent Publication No. 62196371, Unexamined Japanese Patent Publication No. 82-24
1898, JP-A-83-288994, etc.).

However, for 5i3Nn-based materials, no method has yet been proposed that allows rapid film formation and simultaneously improves surface properties such as surface hardness and wear resistance.

The object of the present invention is to form a diamond-like film that has good adhesion to a substrate, has a surface layer that has particularly excellent wear resistance, and has a sufficient thickness at a high deposition rate. An object of the present invention is to provide a method for manufacturing a silicon nitride-based, diamond-coated member that can be coated with silicon nitride.

[Means for Solving the Problems] The invention according to claim 1 of the present application, which is a distant relative of the above object, provides a method for reducing the concentration of carbon monoxide on the surface of a base material, at least the surface layer of which is made of a silicon nitride-based sintered body. An activated gas obtained by exciting a first mixed gas containing carbon monoxide and hydrogen having a carbon monoxide concentration of 10% by volume or more is brought into contact with a substrate to form a diamond layer, and the carbon monoxide concentration is 10% by volume. 2. A method for manufacturing a diamond-coated member, characterized in that a surface diamond layer is formed using an active gas obtained by exciting a second mixed gas containing carbon monoxide and hydrogen that is less than The invention described in claim 3 is a method for manufacturing a diamond-like coated member according to claim 1, wherein the concentration of carbon monoxide in the mixed gas is continuously or intermittently reduced. In the described invention, the thickness of the entire diamond-like film of the diamond-like coated member is 0.5 to 1100p, and the thickness of the uppermost diamond-like film is 50% or less of the thickness of the entire tire cent-like film. A method of manufacturing a diamond-like coated member according to claim 1.

The present invention will be explained in detail below.

A base material The silicon nitride-based sintered body in the present invention refers to a sintered body containing silicon nitride as a main component. Silicon nitride is usually
Si3N4 can be used.

The sintered body contains silicon nitride as a main component and AfL203.
, AIN, MgO, Cab, Y203Zr02, Ti
It can be obtained by appropriately mixing a sintering aid such as O2, B4C, TiN, or WC, and reinforcing material such as whiskers as required, and sintering the mixture by a known method.

This sintered body can be manufactured by a known sintering method,
Among these, pressure sintering methods such as hot press method ()fP), heat 1177 isostatic pressing method (HIP), and gas pressure sintering method are preferred.

The entire base material may be composed of this sintered body, or only the surface layer of the base material may be composed of this sintered body, and the other parts may be composed of other known materials. Sarani is Si3N4
The surface layer portion may be formed by coating a base material.

The known materials here include metals such as silicon, manganese, vanadium, thallium, aluminum, titanium, tungsten, molybdenum, germanium, chromium, and poron, semimetals, and their oxides, nitrides, and carbides; There are alloys of these.

In addition, preferred known materials for use in cemented carbide tools include, for example, WC-Co alloy, WC-Ti
C-Co alloy, WC-TiCTaC-Co alloy, W
C-TiN-Co alloy, W C-T i C-T i
N-Co alloy, TiN-Ni, TiN-Ti
Examples include cermets such as C-Ni.

- Formation of diamond layer - In the present invention, on the surface of the silicon nitride-based sintered body,
It is important to form at least two layers of diamond-like films. In other words, the layer that is in contact with the silicon nitride sintered body is formed at high speed using diamonds that have even higher adhesion to the silicon nitride sintered body, and the surface layer is made of diamond that has even higher wear resistance. At least two layers of diamond-like films are formed on the surface of the base material so that the diamond-like film as a whole has both further improved adhesion to the base material and further improved wear resistance. It forms. Therefore, in the present invention, the diamond layer is in contact with the surface of the base material and has improved adhesion and film formation rate, and the surface layer portion has improved wear resistance. Although the expression "layer" is used here, in the present invention, a "layer" is formed even when there is a clear interface between the two layers, or when there is no clear interface between the two layers. Suppose there is.

The diamond-like layer is made of a plasma gas obtained by exciting a first mixed gas containing carbon monoxide and hydrogen in which the concentration of carbon monoxide is 10% by volume or more, preferably 10 to 80% by volume, as a base material. It is formed by bringing it into contact.

If the concentration of carbon monoxide gas in the first mixed gas is less than 10% by volume, it will take a long time to form diamonds, which is not preferable from the viewpoint of productivity.

Note that the concentration of carbon monoxide in the first mixed gas may vary variously during the formation of the diamond layer as long as it is 10% by volume or more. Specifically, during the formation period of the diamond layer, the concentration of carbon monoxide gas in the first mixed gas may be a constant value of 10% by volume or more, or the concentration of carbon monoxide gas in the first mixed gas may be a constant value of 10% by volume or more. The concentration of carbon monoxide gas is adjusted so that the initial concentration of carbon monoxide gradually decreases during the formation period of the diamond layer, and the concentration of carbon monoxide gas is adjusted so that the initial concentration of carbon monoxide gas gradually decreases during the formation period of the diamond layer.
The concentration may be adjusted so that the concentration of carbon monoxide gas is % by volume.

Note that this first mixed gas may contain other gases within a range that does not impede the object of the present invention.

Other gases include, for example, N2. He, Ne, Ar
Examples include inert gases such as.

In any case, the first mixed gas can be produced using a thermal filament method (including an EACVD method), a direct current plasma CVD method (including a thermal plasma method), a high frequency plasma CVD method (including a thermal plasma method), or a microwave plasma CVD method. Excitation can be performed by a method such as a method (including field-CVD method and ECR-CVD method), a combustion flame method, a photo-CVD method, a sputtering method, or the like.

Among them, various types of plasma C are preferable for the purpose of the present invention.
This is the VD method.

The surface temperature of the base material when the active gas obtained by exciting the first mixed gas using the excitation method is brought into contact with the base material cannot be further determined because it differs depending on the method of excitation of the first mixed gas. is usually 300 to 1,200°C, preferably 800 to 1,100°C.

If this surface temperature is lower than 300° C., the precipitation rate of diamonds will be slowed down, and the crystallinity and homogeneity of the precipitates will be lost. On the other hand, even if the temperature is higher than 1,200℃,
This does not have a commensurate effect, resulting in disadvantages in terms of energy efficiency, and the diamonds formed may be etched away.

The reaction pressure when bringing the active gas into contact with the substrate surface is usually 10-6 to 10" torr, preferably 1O-5t.
orr to 800 torr.

If the reaction pressure is lower than 10-6 torr, the rate of film formation of diamonds may become slow or the diamonds may not precipitate.

On the other hand, even if it is made higher than 103 torr, the corresponding effect may not be achieved.

The reaction time for bringing the excited gas into contact with the base material is appropriately determined depending on the conditions for forming the diamond layer and the thickness of the diamond layer.

After the formation of the diamond layer is completed, a surface diamond layer is formed.

The surface diamond film uses a plasma gas obtained by exciting a second mixed gas containing carbon monoxide and hydrogen in which the concentration of carbon monoxide is less than 10% by volume, preferably 2% by volume or more and less than 10% by volume. , is formed by bringing it into contact with a diamond-like film that has already been formed on the surface of the base material.

If the concentration of carbon monoxide gas in the second mixed gas is 10% by volume or more, a diamond-like film with no improvement in wear resistance is formed.

During the formation of the surface diamond layer, the concentration of carbon monoxide in the second mixed gas may vary from species to species during the formation of the surface diamond layer, as long as it is less than 10% by volume. Specifically, during the formation period of the diamond layer, the concentration of carbon monoxide gas in the second mixed gas is 1.
The concentration of carbon monoxide gas may be set to a constant value of 0% by volume without swirling, or the concentration of carbon monoxide gas may be set such that the initial concentration of carbon monoxide gas in the second mixed gas gradually decreases during the formation period of the surface diamond layer. may be adjusted.

In addition, the carbon monoxide gas concentration in the first mixed gas at the final stage of diamond layer formation and the carbon monoxide gas concentration in the second mixed gas at the initial stage of surface diamond layer formation are made to match 10% by volume. It's okay to stay. in this case,
It can be said that the carbon monoxide concentration in the first mixed gas and the carbon monoxide gas concentration in the second mixed gas are continuously changing.

On the contrary, the carbon monoxide gas concentration in the first mixed gas at the final stage of the diamond layer formation is made to be inconsistent with the carbon monoxide gas concentration in the second mixed gas at the early stage of the surface diamond layer formation. You can leave it there.

Note that these two methods may be used within the scope of not impeding the purpose of the present invention. Other gases may be contained in the second mixed gas.

Other gases are the same as those explained in the formation of the diamond layer. Further, the excitation means for the second mixed gas, the temperature of the base material, the reaction pressure, etc. are also the same as those explained in the formation of the diamond layer.

The diamond-like coated member manufactured by the method of the present invention can be used for various purposes, and is particularly preferably used for processing tools such as cutting tools.

When using the diamond-like coated member of the present invention as a processing tool, it is preferable to adjust the thickness of the diamond-like layer and the thickness of the surface diamond layer as follows.

That is, as shown in FIG. 1, when a diamond layer B is formed on the base material A and a surface diamond layer C is laminated on the diamond layer HB, the diamond layer B is formed on the base material A. The sum of the thickness dl of B and the thickness dl of the surface diamond layer C (dl + d2)
is 0.57hm to 100km, preferably 5km
~30 pLm is good.

If the sum (d++d2) of the film thickness dl of the diamond-like layer B and the film thickness dl of the surface diamond layer C is less than 5 pm, the film thickness will be insufficient, the life of the tool will be shortened, and the diamond-like layer B The sum (dl + d2) of the film thickness dl and the film thickness dl of the surface diamond-like layer C is 1100 pL.
This is because if it exceeds this, the cost of forming the coating increases and chipping becomes more likely to occur.

The film thickness d2 of the surface diamond layer C is 50% or less, preferably 30% or less of the film thickness (d++d2) of the entire diamond-like film.

[Example] Next, the present invention will be explained in more detail with reference to Examples.

(Example 1) Synthesis of diamond-like film Chips made of silicon nitride-based sintered bodies from the same lot (manufactured by Toshiba Tungaloy Corporation, T P G N 1B030BFX
920) as a base material and microwave plasma CVD
The device was installed in a reaction chamber, and a diamond-like film was formed on the surface of the chip under the following synthesis conditions.

Synthesis conditions First, in the first stage, Co/H is used as the raw material gas.

Using a mixed gas, the concentration of CO gas was 20% by volume (constant concentration), the substrate temperature was t, ooo°C, and the reaction pressure was 40 Ta.
rr, synthesis time 4 hours, microwave plasma CV
A diamond-like film was formed on the chip by method D (2,45GH2,400W).

Next, in the second stage, CO/H2 mixed gas was used as the raw material gas, the concentration of CO gas was 5% (constant value), the substrate temperature was 1,000°C, the reaction pressure was 40 Torr, and the synthesis time was 2. Microwave plasma CVD method (2,45G
A diamond film was formed on the surface layer of the chip by heating (H2, 450 W).

The thickness of the entire diamond-like film (bottom layer + top layer) obtained as described above was 12 pm.

Cutting Test Next, a workpiece was cut using the diamond-like film-coated tip obtained under the conditions described in Section 2 under the following conditions.

Cutting conditions ■Chip shape: TPGN1130308 ■Cutting speed V
: 100m/win ■Depth of cut: 1mm ■Feed f: 0.085mm ■Format: wet ■Workpiece material: Ti-6A pattern-4■ Cutting results: flank wear was 1l107p after 80 minutes.

(Comparative Example 1) Synthesis of Diamond-like Film Using the same base material as in Example 1, it was placed in a reaction chamber in a microwave plasma CVD apparatus, and a diamond-like film was formed on the surface of the chip under the following synthesis conditions. 6 was formed.

Synthesis conditions CO/H2 mixed gas was used as the raw material gas, the concentration of CO gas was 20%, the substrate temperature was 1,000°C, and the reaction pressure was 4.
A single diamond-like film was formed on the chip by microwave plasma CVD (2,45 GH2, 400 W) at 0 Torr and for 6 hours for synthesis time.

The thickness of the diamond-like film obtained as described above is 1
It was 4 m.

Cutting test Next, the chip obtained under the above conditions was cut under the same conditions as in Example 1, and the wear on the flank surface was 28% after 80 minutes.
It reached 0Ji,m.

(Comparative Example 2) Synthesis of diamond-based film The same base material as in Example 1 was used, and this was placed in a reaction chamber in a microwave plasma CVD apparatus, and a layer of diamond-based film was formed on the surface of the chip under the following synthesis conditions. A film was formed.

Using a Co/H2 mixed gas as the raw material gas, the concentration of CO gas was 5%, the substrate temperature was 1.000°C, and the reaction pressure was 40°C.
Torr, the synthesis time was set to 6 hours, and a diamond-like film was formed on the chip by microwave plasma (2,45GH2,450W).

The thickness of the diamond-like film obtained in this manner is 6.
It was Im.

Cutting Test Next, the chip obtained under the above conditions was cut under the same conditions as in Example 1, and peeling of the diamond film was observed after 60 minutes of cutting.

(Example 2) Synthesis of a diamond-like film Using the same chip as in Example 1 as a base material, it was placed in a reaction chamber in a microwave plasma CVD apparatus, and a diamond-like film was formed on the surface of the chip under the following synthesis conditions. formed.

Threat conditions First, in the first stage, CO/H? Using a mixed gas, the COO20 concentration was 30% (constant value), the substrate temperature was 1,000°C, the reaction pressure was 40 Torr, the synthesis time was 4 hours, and the microwave plasma CVD method (2,45
A diamond-like film was formed on the chip using GH2, 380W).

Next, in the second stage, a CO/H2 mixed gas was used as the raw material gas, the COO20 concentration was 7%, and the substrate temperature was 1.000.
℃, the reaction pressure was 40 Torr, and the synthesis time was 2 hours.
Microwave plasma CVD method (2,45GH2,450
A diamond film was formed on the bottom layer of the chip using W).

朦1 The total thickness of the diamond-like film obtained as described above was 15 gm.

Cutting Test Next, when the chip obtained under the conditions described in Section 2 was cut under the same conditions as in Example 1, the wear on the flank surface was 1 after 80 minutes.
It was 307 Lm.

9 (Example 3) Synthesis of diamond-like film Using the same chip as in Example 1 as a base material, it was placed in a reaction chamber in a microwave plasma CVD apparatus, and a diamond-like film was formed on the surface of the chip under the following threat conditions. formed.

Synthesis conditions First, in the first stage, a CO/H2 mixed gas is used as the raw material gas, the COO20 concentration is 60%, and the substrate temperature is 900%.
℃, the reaction pressure was 40 Torr, the synthesis time was 3.5 hours, and the microwave plasma CVD method (2,45GH2, 3
50 W) to form a diamond-like film on the chip.

Next, in the second stage, a CO/H2 mixed gas was used as the raw material gas, the COO20 concentration was 4%, and the substrate temperature was 1.000.
℃, the reaction pressure was 40 Torr, the synthesis time was 2.5 hours, and the microwave plasma CVD method (2,45GH2,4
50 W) to form a diamond film on the surface layer of the chip.

The thickness of the entire diamond-like film obtained as described above was 147 tm.

Cutting test Next, the chip obtained under the above conditions was cut under the same conditions as in Example 1, and the wear on the flank surface was 11 after 80 minutes.
It was 00JL.

(Comparative Example 3) Synthesis of a diamond-like film A diamond-like film was formed on a chip in the same manner as in Example 2 except that the COO20 concentration was 20%, the substrate temperature was 1.000°C, and the synthesis time was 30 hours. A diamond film was then formed on the surface layer in the same manner as in Example 2 except that the synthesis time was changed to 10 hours.

The thickness of the entire diamond-like film obtained as described above was Et5 gm.

Cutting Test Next, the chip obtained under the conditions described in Section 2 was cut under the same conditions as in Example 1, and after 5 minutes, it was peeled off by chipping.

[Effects of the Invention] According to the manufacturing method of the present invention, a diamond-like film having good adhesion to a substrate and particularly improved surface wear resistance can be formed in a sufficient thickness in a short time. result,
A diamond-coated member suitable for diamond-coated tools and the like having high wear resistance and chipping resistance can be provided with high productivity.

Therefore, the present invention makes a significant contribution to the fields of cutting tools, dies, wear-resistant members, etc.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a cross section of a diamond-like coated member as an example manufactured by the method of the present invention.

Claims (3)

[Claims] (1) A first mixed gas containing carbon monoxide and hydrogen having a carbon monoxide concentration of 10% by volume or more is excited onto the surface of a base material at least the surface layer of which is made of a silicon nitride-based sintered body. An active gas obtained by contacting a substrate with an active gas to form a diamond layer, and exciting a second mixed gas containing carbon monoxide and hydrogen in which the concentration of carbon monoxide is less than 10% by volume. A method for producing a diamond-coated member, comprising forming a surface diamond layer. (2) The method for producing a diamond-coated member according to claim 1, wherein the concentration of carbon monoxide in the mixed gas is continuously or intermittently reduced. (3) The total film thickness of the diamond-like film of the diamond-like coated member is 0.5 to 100 μm, and the film thickness of the diamond film formed using the second mixed gas is less than the total film thickness of the diamond-like film. The method for manufacturing a diamond-coated member according to claim 1, wherein the diamond-like coating member has a content of 50% or less.