JP3214937B2 - Method for producing diamond-coated member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a diamond-coated member, and more particularly, to a method for producing a diamond-coated member having excellent adhesion on a tungsten carbide cemented carbide. The present invention relates to a method for manufacturing a diamond-coated member that can be suitably used for a sliding member, a cutting tool, and the like.

[0002]

2. Description of the Related Art Conventionally, cutting tools that require high surface hardness and abrasion resistance,
2. Description of the Related Art Diamond, which is remarkably excellent in hardness and wear resistance, is used for wear-resistant members such as tools such as grinding tools and polishing tools and mechanical parts. For example, in general, CVD
There is known a method in which diamond is deposited on the surface of a base material such as tools and wear-resistant members by using a diamond synthesis technique based on a gas phase method such as a PVD method or a PVD method to form a diamond film. By coating the base material with the diamond coating as described above, a high degree of surface hardness and wear resistance can be imparted to tools and wear-resistant members.

However, the surface of the substrate and the diamond coating generally have poor adhesion. This is because when a diamond thin film is formed on the surface of a substrate, a large thermal stress is generated between the substrate and the diamond thin film due to a difference in thermal expansion coefficient. Therefore, various proposals have been made to improve the adhesion.

For example, Japanese Patent Application Laid-Open No. 60-208473 discloses a method of providing an intermediate layer made of a metal carbide, nitride or boron compound between a substrate and a diamond coating. However, in this method, practically sufficient adhesion has not been obtained.

Japanese Patent Application Laid-Open No. S61-106493 proposes a method in which a mixture of a base material component and diamond is used as an intermediate layer. However, also in this case, sufficient adhesion has not been obtained.

Japanese Patent Application Laid-Open No. 62-47480 proposes a method in which the surface of a cermet substrate is treated with an acid to remove metal components. However, this method has a disadvantage that the substrate surface becomes brittle. There is also known a method of coating a base material with a diamond film and thereafter heat-treating the obtained diamond-coated member. However, in this method, even if it is possible to obtain a diamond-coated member suitable for precision processing by removing fine cracks on the surface,
The effect of improving the adhesion between the substrate and the diamond film can hardly be achieved.

Further, Japanese Patent Application Laid-Open No. HEI 1-103992 proposes a method in which a substrate made of a cemented carbide is heat-treated in a vacuum in advance, and a diamond thin film is formed thereon. As described above, the adhesiveness can be improved by preliminarily heat-treating the base material; however, in this case, the degree of improvement has not yet been satisfied.

On the other hand, Japanese Patent Application Laid-Open No. 2-293385 discloses a technique for improving the adhesion by treating the surface of a sintered body containing tungsten carbide as a main component in a decarburized atmosphere to form fine tungsten carbide on the surface. Have been. However, this method has the drawback that the composition of the substrate is limited to a relatively narrow range, and that the substrate can be formed only by a high-cost method such as hot pressing.

Further, JP-A-1-246361, JP-A-3-115711, and JP-A-4-231428.
Japanese Patent Application Laid-Open Publication No. H11-163,045 discloses an invention in which the adhesion between a diamond film and the substrate is improved by pre-heating the substrate for a diamond cutting tool. However, in the heat treatment described in JP-A-1-246361, there is a description that a non-oxidizing atmosphere is used as an atmosphere gas, and in JP-A-4-231428, there is no description that a normal pressure inert gas atmosphere is used. However, there is no description that nitrogen gas is used, and there is no description that nitrogen gas acts on a substrate. Atmosphere gases described in these publications are merely used as an inert gas atmosphere to the extent that they become tired.

After all, in the above-mentioned conventional method, the adhesion between the surface of the substrate and the diamond film is not yet sufficient, and the coated diamond film is easily peeled off.
There is a problem that the life of a cutting tool, a polishing tool, or the like using the diamond-coated member is not sufficient.

An object of the present invention is to eliminate the above-mentioned conventional problems. That is, an object of the present invention is to provide a method for producing a diamond-coated member in which a normal tungsten carbide cemented carbide is coated with a diamond film with good adhesion.

[0012]

[Means for Solving the Problems]

According to a first aspect of the present invention, a substrate made of a tungsten carbide cemented carbide is placed in a nitrogen gas atmosphere of 1 to 300 Torr . After applying a heat treatment at 1,200 to 1,600 ° C. while allowing nitrogen in the atmosphere to act on the base material, a diamond-like film is formed on the surface of the base material by a vapor phase method. The method according to claim 2 is a method of manufacturing a substrate comprising a tungsten carbide cemented carbide, a rare gas and a partial pressure of 1 to 760 T.
orr gas, under an atmosphere containing nitrogen gas.
While the nitrogen in the atmosphere acts on the substrate,
A method of manufacturing a diamond-coated member, comprising forming a diamond film on the surface of the base material by a vapor phase method after heat treatment at 1600 ° C. Atmospheric pressure during heat treatment is 760
The method for producing a diamond-coated member according to claim 2, wherein the pressure is from Torr to 3,000 atm. The invention according to claim 4, wherein the tungsten carbide cemented carbide is 50 to 95% by weight of tungsten carbide. And titanium carbide 1-3
The method for producing a diamond-coated member according to any one of claims 1 to 3, comprising 0% by weight and 2 to 20% by weight of cobalt. The hard alloy is tungsten carbide 60-9
The diamond-coated member according to any one of claims 1 to 3, comprising 5% by weight, 1 to 10% by weight of tantalum carbide, 0 to 20% by weight of niobium carbide, and 3 to 10% by weight of cobalt. The method according to claim 6, wherein
The tungsten carbide cemented carbide is 50 to 95% by weight of tungsten carbide, the total of 3 to 35% by weight of titanium carbide, titanium nitride, tantalum carbide, tantalum nitride, niobium carbide and niobium nitride is 2 to 15% by weight of cobalt. %. The method for producing a diamond-coated member according to any one of claims 1 to 3, comprising the steps of:
Forming at least one selected from the group consisting of carbides, nitrides and carbonitrides of two or more metals selected from the group consisting of metals belonging to group a, metals belonging to group Va and metals belonging to group VIa And then 1 to 300 To
under a nitrogen gas atmosphere rr, while the action of <br/> nitrogen in the nitrogen gas atmosphere to a substrate, 1,200~1,600 ℃
The method according to claim 8, wherein a diamond-like film is formed on the surface of the base material by a vapor phase method after the heat treatment.
On a substrate made of a tungsten carbide cemented carbide, a carbide, nitride and carbonitride of two or more metals selected from the group consisting of metals belonging to Group IVa, metals belonging to Group Va and metals belonging to Group VIa At least one selected from the group consisting of a rare gas and a partial pressure of 1 to
Under an atmosphere containing nitrogen gas of 760 Torr, while allowing nitrogen in the gas atmosphere to act on the base material,
A method for producing a diamond-coated member, comprising forming a diamond film on the surface of the base material by a vapor phase method after heat treatment at 1,200 to 1,600 ° C.

Hereinafter, the method of the present invention will be described in detail.

The base material used in the method of the present invention may be a tungsten carbide cemented carbide.

Specific examples of the tungsten carbide cemented carbide include W, W-WC, WC-C, and W-WC-C.
-C system, WC-Co, WC-Co-W, WC-Co-
C, WC-Co-WC and other W-Co-based materials, WC-TaC
-Co, WC-TaC-Co-C and other W-Ta-Co
System, WC-TiC-Co, WC-TiC-Co, WC-
W-Ti-Co system such as TiCN-Co, WC-Nb-C
o, W-Ta-Nb-Co such as WC-Ta-Nb-Co
System, WC-TiC-Nb-Co system, WC-TiC-Ta
C-Co-C, WC-TiC-TaC-NbC-Co-
And a cemented carbide such as W-Ti-Ta-Nb-Co-C such as C. The tungsten carbide cemented carbide used in the present invention includes Ti, Co, Ta, Nb,
Those containing metals such as Mo, Cr, and Ni are preferable.

In the method of the present invention, of the tungsten carbide cemented carbide used as the substrate, specific examples of preferred compositions include WC-TiC-Co and WC-TaC-
NbC-Co, WC-TiC-TiN-TaC-TaN
-NbC-NbN-Co and WC-Co cemented carbides can be mentioned. These hardmetals actually contain unavoidable impurities.

The cemented carbide having the composition of WC-TiC-Co includes tungsten carbide of 50 to 95% by weight, preferably 70 to 94% by weight, and titanium carbide of 1 to 30% by weight, preferably 2 to 20% by weight. And 2 to 20% by weight, preferably 4 to 10% by weight of cobalt.

The cemented carbide having the composition of WC-TaC-NbC-Co includes tungsten carbide of 60 to 95% by weight, preferably 85 to 92% by weight, and tantalum carbide of 1 to 95% by weight.
Those having 20% by weight, preferably 2 to 10% by weight, 0 to 20% by weight of niobium carbide, preferably 1 to 10% by weight, and 3 to 10% by weight, preferably 4 to 6% by weight of cobalt are listed. be able to.

WC-TiC-TiN-TaC-TaN-
As the cemented carbide having the composition of NbC-NbN-Co, 50 to 95% by weight, preferably 70 to 94% by weight of tungsten carbide, titanium carbide, titanium nitride, tantalum carbide, tantalum nitride, niobium carbide, and niobium nitride Those having a total of 3 to 35% by weight, preferably 5 to 20% by weight and cobalt of 2 to 15% by weight, preferably 4 to 10% by weight can be mentioned.

As a cemented carbide having a composition of WC-CO, 90 to 98% by weight, preferably 9% by weight of tungsten carbide is used.
Those having 4 to 97% by weight and 2 to 10% by weight, preferably 3 to 6% by weight of cobalt can be mentioned.

As the tungsten carbide, those used in conventional tools and the like can be used. Specifically, WC, WCx (where x represents a positive real number other than 1; X is a number greater than 1 or less than 1.) The stoichiometric compound and the non-stoichiometric compound represented by
Substitution or intrusion can be mentioned. Of these, WC is particularly preferably used.

These may be used alone or in combination of two or more, or may be used as a mixture, solid solution or composition of two or more.

The titanium carbide is not particularly limited, and those used for producing ordinary alloys can be used. Specifically, TiC, TiCy (where y represents a positive real number other than 1;
Greater than or less than 1. And stoichiometric compounds and non-stoichiometric compounds represented by the formula (1), or compounds in which other elements such as oxygen are bonded, substituted or invaded. Among them, usually, TiC
Is particularly preferably used.

The tantalum carbide is not particularly limited, and those used for producing ordinary alloys can be used. More specifically, TaC, TaCz (where z represents a positive real number other than 1;
Greater than or less than 1. And stoichiometric compounds and non-stoichiometric compounds represented by the formula (1), or compounds in which other elements such as oxygen are bonded, substituted or invaded. Among these, usually, TaC
Is particularly preferably used.

The niobium carbide is not particularly limited, and any niobium carbide used for producing an ordinary alloy can be used. Specifically, NbC, NbCz (where z represents a positive real number other than 1;
Greater than or less than 1. And stoichiometric compounds and non-stoichiometric compounds represented by the formula (1), or compounds in which other elements such as oxygen are bonded, substituted or invaded. Among these, usually NbC
Is particularly preferably used.

The cobalt is not particularly limited, but a simple metal can be suitably used.

In the method of the present invention, the tungsten carbide, the titanium carbide, the tantalum carbide, the niobium carbide, and the cobalt do not need to be particularly pure, as long as the object of the present invention is not hindered. It may contain impurities.

For example, the tungsten carbide may contain a trace amount of excess carbon, excess metal, impurities such as oxides and the like.

By setting the proportions of the respective components within the above ranges, the strength of the substrate itself can be improved and the adhesion between the diamond film and the surface of the substrate can be improved.

The substrate used in the method of the present invention is not particularly limited as long as the above components are blended in the above ratio, and commercially available substrates can be used.

Among the commercially available substrates, a particularly preferred example is a WC-based cemented carbide suitable for cutting tools (specifically, for example, JIS B410).
4, use classification symbols P01, P10, P20, P3
P series such as 0, P40, P50, M10, M20,
M series such as M30, M40, K01, K10, K2
Cemented carbide chips for cutting tools such as K series such as 0, K30, K40, etc., Cemented carbide chips for wire drawing dies such as V series such as V1, V2, V3, center, and cutting tools, etc. W-Co-C based cemented carbide such as WC-Co based, W-Ti-Ta such as WC-TiC-TaC-Co based
-Co-C cemented carbides, or those in which part of Ta is changed to Nb, etc.). These may contain other elements and additional components other than the above. What kind of material and shape of cemented carbide should be adopted may be appropriately selected according to the purpose of use and the like.

When a commercially available material is used, the base material can be obtained by a method such as sintering after blending the above components in the above ratio.

Prior to sintering, together with the above components,
If necessary, an auxiliary binder containing ethylene glycol, ethylene-vinyl acrylate, polybutylene methacrylate, adamantane or the like as a main component may be contained.

The sintering method is not particularly limited, and can be performed according to a conventionally known sintering method.

In the sintering method, each of the above components can be used in the form of powder, fine powder, ultrafine particles, whiskers, or other various shapes. Usually, fine particles or ultrafine particles having a particle size of about 0.05 to 4.0 μm, preferably about 0.05 to 2.0 μm, or whisker particles having an aspect ratio of about 20 to 200 are suitably used. be able to.

The sintering temperature is usually from 1,300 to 1,
It is suitable to set the temperature to 600 ° C., preferably about 1,350 to 1,550 ° C.

The sintering time is usually at least 0.5 hour, preferably in the range of about 1 to 2 hours.

The shape of the substrate used in the method of the present invention is not particularly limited.

For example, the substrate can be sintered after being formed into a desired shape at the time of sintering. Alternatively, after the sintering, the substrate can be processed into a desired shape as required. Can be used as a base material for a diamond-coated member.

When the content of the effective components such as titanium carbide, tantalum carbide, niobium carbide and the like on the surface of the substrate is small, it is preferable to form a predetermined coating layer on the surface of the substrate.

The coating layer is made of Group IVA of the periodic table, V
At least one metal selected from the group A and group VIA metals and Si; selected from the group IVA, group VA and group VIA metals of the periodic table and Si carbides, nitrides and carbonitrides And at least one selected from the group consisting of at least one metal compound.

More preferable among the group of substances forming these coating layers are metallic titanium, titanium nitride, titanium carbide and titanium carbonitride, and metallic tantalum, tantalum nitride, tantalum carbide and tantalum carbonitride.
These may be used singly or may be used with two or more kinds of various compositions.

As the titanium nitride, for example, Ti
N, or the like can be given those represented by TiN _x, TiN-Ti, TiN or the like. As the titanium carbide, for example, TiC or TiC
_{C x, TiC-C, TiC} -Ti, TiC-TiC,
One represented by Ti-C or the like can be given. Examples of the titanium carbonitride include TiCN,
TiC / TiN, TiC _X / TiN _x , TiC / TiN
-C, TiC.TiN-Ti, TiC.TiN-Ti-
Examples thereof include those represented by C, Ti-NC, and the like.

That is, the titanium-containing coating layer is usually preferably represented by Ti, TiN, TiC or TiCN, but may be composed of two or more of these. One or more of them may contain excessive amounts of Ti, C and / or N components. In addition, the coating layer containing titanium includes Ti, C within a range that does not impair the object of the present invention.
And N or other elements or components other than N.

As a method for forming the coating layer on the surface of the substrate, a generally used method, for example, a generally used ion plating method or a sputtering method can be adopted. The thickness of the coating layer is not particularly limited, but is usually 100 to 50,000 ，,
It is preferably selected from the range of 1,000 to 30,000 ° so as to obtain a solid solution layer having a desired thickness. When the thickness is less than 100 °, the effect of the intermediate layer is hardly expected.
On the other hand, if it exceeds 50,000 °, the strength of the intermediate layer itself decreases.

In the method of the present invention, the base material is heat-treated to modify the surface of the base material before coating the base material with the diamond-like film, whether or not there is a coating layer on the surface. I do.

In the method of the present invention, as the heat treatment, a nitrogen-containing gas is caused to act on the surface of the substrate at a high temperature.

When the nitrogen-containing gas is 100% nitrogen gas, the pressure of the nitrogen gas is 1 to 300 Torr.
r, preferably 10 to 200 Torr.
Therefore, when the gas containing 100% nitrogen is used as the nitrogen-containing gas, the heat treatment is performed under reduced pressure.

When the nitrogen-containing gas is a mixed gas of nitrogen gas and another inert gas such as a rare gas, the partial pressure of nitrogen in the mixed gas should be 1 to 760 Torr, preferably 10 to 500 Torr. good. Among the rare gases, an argon gas can be particularly preferably used. The total pressure of the mixed gas is not particularly limited as long as the partial pressure of the nitrogen gas is within the above range.
It may be 0 Torr to 3,000 atm.

Regardless of the pressure under which the heat treatment is performed,
When nitrogen acts on the substrate surface during the heat treatment, it is considered that the substrate surface undergoes physical or chemical alteration.For example, a nitride or carbonitride layer is formed on the substrate surface, and the substrate layer surface becomes fine. Forming irregularities or C in the substrate layer
For example, the o component is reduced, which is advantageous for improving the adhesion between the diamond-like thin film described below and the substrate.

The heating temperature during the heat treatment is usually
The temperature is preferably from 1,200 to 1,650 ° C, particularly preferably from 1,300 to 1,550 ° C. When the temperature is out of the above range, the surface of the base material is not sufficiently modified.

The heat treatment time is from 1 minute to 50 minutes.
0 minutes is preferable, and particularly preferable is 15 minutes to 300 minutes. When the time for the heat treatment is less than 1 minute, the surface of the base material is insufficiently modified. Further, when the heat treatment time exceeds 500 minutes, the surface modification proceeds excessively, so that irregularities increase on the surface of the substrate, and evaporation of the components contained in the substrate causes the substrate to undergo evaporation. This is not preferable because it involves a risk of causing deformation of the.

In the method of the present invention, the content of carbonitride is increased on the surface of the base material without deforming the base material by performing the heat treatment while applying nitrogen to the base material surface. Fine surface irregularities are formed, the affinity for the diamond film formed thereafter is improved, and the diamond film is formed in a form penetrating into the pores on the substrate surface, so the adhesion to the substrate is high The base material can easily form a diamond film.

In the present invention, a diamond thin film can be coated on the surface of the base material that has been heat-treated as described above, and the base material contains titanium, tantalum, niobium or the like. When the amount is small, it is preferable that after subjecting the substrate to plasma treatment under specific conditions, a diamond thin film is coated on the surface of the substrate.

The plasma treatment is performed in a mixed gas atmosphere of carbon dioxide gas and hydrogen gas at 10 to 100 torr.
Plasma treatment is performed at 500 to 1,100 ° C.

In the mixed gas, carbon dioxide gas 60 is usually used.
A mixing ratio of 90% and hydrogen gas 40% to 10% is preferable. The pressure during the plasma treatment is 10 to 100 to
It is preferably within the range of rr. When the pressure is higher than the above range, the controllability of the processing is poor, and when the pressure is lower, the processing takes time. The substrate temperature is in the range of 500 to 1,100 ° C.,
Preferably it is 700-900 degreeC. If the temperature is higher than the above range, the controllability of the process is poor and reproducibility is poor, and if the temperature is low, the process takes time. Processing time is 1 minute to 2
00 minutes, preferably 60 minutes.

In order to generate plasma of a mixed gas of carbon dioxide gas and hydrogen gas, a CVD method can be suitably employed. As the CVD method for performing the plasma processing, for example, a microwave plasma CVD method, a high-frequency plasma CV
A wide variety of methods such as a D method, a hot filament CVD method, and a DC arc CVD method are known. In the method of the present invention, any of these methods can be applied, and particularly, a microwave plasma CVD method, a high-frequency plasma CVD method, and the like can be given. Also,
C used in the vapor phase synthesis of diamond described below
If the same CVD method as the VD method is adopted, it is convenient in terms of the apparatus configuration.

As described above, in the method of the present invention, by performing the above-described plasma treatment, the surface of the substrate is activated, and the bonding force between the substrate and diamond is increased.

In addition to the plasma treatment, the substrate surface may be subjected to a scratching treatment.

As the scratching treatment, for example, a surface scratching treatment with diamond abrasive grains or the like can be mentioned. This surface damage treatment can be performed according to a known method. By performing such a surface damage treatment (particularly, a surface damage treatment with diamond abrasive grains), favorable effects such as further improving the adhesion between the base material and the diamond thin film can be obtained.

In the present invention, a diamond-like thin film is coated on the surface of the cemented carbide substrate which has been heat-treated as described above or has been subjected to the heat treatment and plasma treatment.

The diamonds mentioned here include, in addition to diamond, diamond partially containing diamond-like carbon and diamond-like carbon.

The formation of the diamond film can be performed by various vapor phase synthesizing methods such as a conventional vapor phase synthesizing method. Among them, a method by a CVD method is suitably employed.
CV as a vapor phase synthesis method of such diamond thin films
As the method D, for example, microwave plasma CVD
Method, high frequency plasma CVD method, hot filament CVD
Various methods such as a DC arc CVD method and the like are known. In the method of the present invention, any of these methods can be applied. Among them, a microwave plasma CVD method, a high-frequency plasma CVD method and the like are particularly preferably applied.

It is also known that in such a gas phase synthesis method of diamond films by the plasma CVD method, various types and compositions of source gases including at least a carbon source gas can be used as source gases. I have. As the source gas, for example, a source gas containing a hydrocarbon as a carbon source gas, such as a mixed gas of CH ₄ and H ₂ , and a carbon compound other than a hydrocarbon, such as a mixed gas of CO and H ₂ , as a carbon source Raw material gas, etc.
Various source gases can be mentioned.

In the method of the present invention, as long as a diamond film can be formed, various source gases such as the above-mentioned source gases and the like used in the conventional method are appropriately used. To form a diamond film. Among them, a mixed gas of CO and H ₂ or a mixed gas of CH ₄ and H ₂ is preferable. In particular, CO and H
_The use of a mixed gas of ₂ as a raw material gas is superior in that the deposition rate of diamonds is higher than in the case of using a hydrocarbon, and that a film can be formed efficiently.

Hereinafter, as a particularly preferable example of the method of forming a diamond film, a method using CO and H ₂ as source gases will be described.

That is, in the method of the present invention, the diamond film is formed by using a mixed gas of carbon monoxide and hydrogen gas as a raw material gas (hereinafter, this method is referred to as method I). In particular).

That is, in this method I, carbon monoxide and hydrogen are mixed at a rate such that the carbon monoxide gas becomes 1% by volume or more.
A diamond synthesis method characterized by contacting a gas obtained by exciting a contained gas mixture with a substrate.

In this method I, there is no particular limitation on the carbon monoxide to be used. For example, the furnace gas and water gas obtained by hot-reacting coal or coke with air or steam are sufficiently purified. Can be used.

The hydrogen to be used is not particularly limited, and can be obtained by, for example, gasification of petroleum, conversion of natural gas, water gas, etc., electrolysis of water, reaction of iron with steam, complete gasification of coal, and the like. A sufficiently purified product can be used.

In this method I, carbon monoxide and the hydrogen are used as raw material gases, and the content of carbon monoxide gas is 1
A gas obtained by exciting a mixed gas contained in a ratio of at least 3% by volume, preferably at least 3% by volume, more preferably at least 5% by volume, is brought into contact with the base material (sintered base material). Then, diamonds are deposited on the predetermined surface. The content of carbon monoxide gas in the mixed gas is 1
If it is less than the volume percentage, no diamond is formed, or even if diamond is formed, the deposition rate is extremely low.

Means for exciting the source gas to obtain the source gas containing carbon in an excited state include, for example, a plasma CVD method, a sputtering method, an ionization evaporation method, an ion beam evaporation method, a hot filament method, and a chemical transport method. For example, a conventionally known method such as the above can be used.

When using the above-mentioned plasma CVD method,
The hydrogen forms plasma by irradiation with high frequency or microwave, and in the case of using a CVD method such as the chemical transport method and the hot filament method, the hydrogen forms atomic hydrogen by heat or discharge. This atomic hydrogen is
It has the function of removing the graphite-structured carbon that is deposited simultaneously with the deposition of diamond.

In the method I, an inert gas can be used as a carrier for the raw material gas. Specific examples of the inert gas include an argon gas, a neon gas, a helium gas, a xenon gas, and a nitrogen gas. These may be used alone or in combination of two or more.

In this method I, the reaction proceeds under the following conditions, and diamonds precipitate on the substrate made of tungsten carbide cemented carbide. That is, since the temperature of the surface of the substrate made of the tungsten carbide cemented carbide differs depending on the means for exciting the source gas, it cannot be determined unconditionally. 400 ° C. to 1,000 ° C., preferably 4
50 ° C to 950 ° C. If the temperature is lower than 400 ° C., the deposition rate of diamond may be reduced, or excited carbon may not be generated. On the other hand,
If the temperature is higher than 0 ° C., diamond deposited on the base material may be removed by etching, and the deposition rate may not be improved. The reaction pressure is usually from 10 ^-3 to 1
0 ³ torr, preferably 1～800Torr.
If the reaction pressure is lower than 10 ^-3 torr, the deposition rate of diamond will be slow or diamond will not precipitate. On the other hand, even if the pressure is higher than 10 ³ torr, the corresponding effect cannot be obtained.

As described above, it is possible to suitably form a diamond film on the predetermined base material surface which has been subjected to the sintering process. In the method of the present invention, the formation of the diamond film may, of course, be performed by a method other than the method I described above.

The thickness of the diamond film to be formed may be appropriately determined according to the purpose of use and the like, and is not particularly limited in this sense.
It is better to select within the range of μm. If the film thickness is too small, the coating effect of the diamond film may not be sufficiently obtained.On the other hand, if the film thickness is too large, separation such as peeling of the diamond film may occur depending on use conditions. is there. In addition, when using under severe conditions, such as a cutting tool, normally, it is preferable to select this thickness in the range of 10 to 30 μm.

As described above, according to the method of the present invention,
A substrate made of a tungsten carbide cemented carbide can be coated with a diamond film with good adhesion. The diamond film-coated member thus obtained is suitably used for a sliding member, a cutting tool, and the like. be able to.

[0079]

【Example】

 (Examples 1 and 2) The base materials used are as follows.

The main component is 92.5% by weight of tungsten carbide, 2.5% by weight of titanium carbide and 5% by weight of cobalt.
A substrate having a size of 2.7 mm × 12.7 mm was used as a substrate (A).

12.7 mainly containing 89% by weight of tungsten carbide, 5% by weight of tantalum carbide and 6% by weight of cobalt.
A substrate of mm × 12.7 mm was used as a substrate (B).

On a substrate of the type shown in Table 1 placed in the heating furnace, pure nitrogen gas at the pressure shown in Table 1 was applied.
At the temperature shown in Table 1 for the time shown in Table 1. Observe the substrate surface treated with pure nitrogen gas with an electron microscope,
As a result of energy dispersive elemental analysis, no Co phase was found on the surface of the base material, and fine irregularities were formed. When the substrate surface was analyzed using an X-ray dispersive elemental analyzer, the characteristic peak of the metal carbide was shifted to the peak side of the nitride, indicating that nitride or carbonitride was formed on the surface. It turned out that it was.

Next, the processed substrate is placed on a substrate support in a diamond synthesis reaction tube, and a mixed gas of carbon monoxide gas containing 20% by volume of carbon monoxide gas and hydrogen gas flows through the reaction tube. I let it. After that, the frequency 2.45G
A microwave of Hz was introduced to form diamond by a plasma CVD method.

The pressure in the reaction tube was 40 torr, the temperature of the substrate was 925 ° C., and the reaction was carried out for 10 hours. As a result, a diamond film having a thickness of about 25 μm was formed on the surface of the substrate.

The resulting diamond-coated member was evaluated for adhesion between the diamond film and the surface of the substrate by an indentation method.

The evaluation method by the indentation method means that a diamond indenter shaped into a hemisphere or a pyramid is pressed against a sample to be evaluated to deform the surface of the sample, and the state of the sample after the deformation is changed. Is observed and the adhesion of the sample is evaluated.

In the embodiment of the present invention, since the sample is a diamond-like film-coated member, a pyramid-shaped indenter is pressed into the substrate with an appropriate load to deform the substrate, and the portion where the substrate rises from the original state is described. Observe. In this part, the deformed base material pushes up the diamond-like film formed on the surface, so that if the adhesion between the diamond-like film and the base material is poor, the diamond-like film is separated from the base material. The area of the part to be peeled increases. Therefore, by measuring the magnitude of the area of the peeled diamond film, it is possible to evaluate whether the adhesion between the substrate and the diamond film formed on the surface is good or bad.

In the embodiment of the present invention, the load on the Rockwell indenter was set at 100 kg · f
The peeled area of the diamond film by the indenter was determined, and the magnitude of the adhesion was evaluated based on the measured value. The evaluation criteria are shown below, and the evaluation results are shown in Table 1.

Evaluation criteria A: 0.05 mm ² or less O: 0.05 to 0.5 mm ² Δ; 0.5 to 2.0 mm ² ×; 2.0 mm ² or more

[0090]

[Table 1]

(Examples 3 to 8) The same substrates (A) and (B) as used in Example 1 and a substrate (C) having the following composition were used.

Substrate (C): 12.7 mm × 12.7 mm substrate containing 91 wt% of tungsten carbide, 3 wt% of niobium carbide, and 6 wt% of cobalt as main components. The substrate was placed. Next, after the inside of the heating furnace was once evacuated, nitrogen gas was introduced into the heating furnace to adjust the pressure in the heating furnace to the pressure shown in Table 2.
This pressure indicates the pressure of the nitrogen gas. Further, argon gas was introduced into the heating furnace to adjust the total pressure in the heating furnace to a value shown in Table 2. While heating the base material in the heating furnace at the temperature shown in Table 2 over the time shown in Table 2, nitrogen gas in the heating furnace was allowed to act on the base material.

The surface of the base material plate thus treated was observed with an electron microscope and analyzed by an energy dispersive elemental analyzer. As a result, no Co phase was found on the surface of the base material and fine irregularities were formed. I was When the surface of the substrate was analyzed using an X-ray dispersion elemental analyzer, it was found that nitride or carbonitride was formed and contained on the surface of the substrate.

A diamond thin film was formed on the surface of the substrate in the same manner as in Example 1 to obtain a diamond-coated member.

The adhesion of the diamond film was measured and evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0096]

[Table 2]

(Examples 9 to 12) Commercially available WC-Co based cemented carbide K10 (W: 87% by weight, Co: 7% by weight, C:
The substrate (D) was a 12.7 mm × 12.7 mm substrate having a surface coated with 1.5 μm thick TiC.

A commercially available WC-Co cemented carbide K10 (W:
87% by weight, Co: 7% by weight, C: 6% by weight) The surface of which was coated with 1.5 μm thick TiCN was 12.7.
A substrate of mm × 12.7 mm was used as a substrate (E).

A commercially available WC-Co cemented carbide K10 (W:
87% by weight, Co: 7% by weight, C: 6% by weight) coated with 1.5 μm thick TaC 12.7m
A substrate of mx 12.7 mm was used as a substrate (F).

A commercially available WC-Co cemented carbide K10 (W:
87% by weight, Co: 7% by weight, C: 6% by weight) 12.7 m coated with 1.5 μm thick NbC on the surface
A substrate of mx 12.7 mm was used as a substrate (G).

A pure nitrogen gas having a pressure shown in Table 3 was introduced into a substrate of the type shown in Table 3 placed in the heating furnace, and an Ar gas was further introduced into the heating furnace to obtain a total pressure. The values shown in FIG. The nitrogen gas was allowed to act on the substrate while heating the substrate in the heating furnace at the temperature shown in Table 3 over the time shown in Table 3. Observation of the substrate surface and cross section treated in this manner with an electron microscope revealed that impregnation of the coating phase into the substrate had occurred, and that there was no Co phase, and that fine irregularities were formed. .

A diamond thin film was formed on the surface of the substrate in the same manner as in Example 1 to obtain a diamond-coated member.

The adhesion of the diamond film was measured and evaluated in the same manner as in Example 1. Table 3 shows the results.

[0104]

[Table 3]

Comparative Example 1 The same base material (A) as used in the above example was used.

After the base material (A) was placed in the heating furnace, the inside of the heating furnace was set to the pressure shown in Table 4, and then the base material was heated to the temperature shown in Table 4 and heat-treated for the time shown in Table 4. .

A diamond film was formed on the surface of the base material after the heat treatment in the same manner as in Example 1, and the adhesion of the diamond film was measured in the same manner as in Example 1. Spontaneously separated from the substrate surface.

(Comparative Examples 2 to 5) The same substrates (A), (D) and (E) as used in the above Examples were used as the substrates.

After the base material was placed in the heating furnace, the gas shown in Table 4 was introduced into the heating furnace to adjust the pressure to the one shown in Table 4, and then the base material was heated to the temperature shown in Table 4, Heat treatment was performed for the time shown in FIG.

A diamond film was formed on the surface of the substrate after the heat treatment in the same manner as in Example 1, and the adhesion of the diamond film was measured in the same manner as in Example 4. Table 5 shows the results.

[0111]

[Table 4]

[0112]

According to the method of the present invention, it is possible to provide a method for producing a diamond-coated member in which a diamond film is coated on a normal cemented carbide with good adhesion. The diamond-coated member according to the present invention has excellent durability,
Since the service life has been remarkably improved, it can be suitably used for sliding members, cutting tools and the like.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toshio Isozaki 1660 Kamiizumi, Sodegaura-shi, Chiba Idemitsu Petrochemical Co., Ltd. (56) References JP-A-4-231428 (JP, A) JP-A-62-47480 (JP, A) JP-A-60-208473 (JP, A) JP-A-61-106493 (JP, A) JP-A-1-103992 (JP, A) JP-A-2-293385 (JP, A) JP-A-1-246361 (JP, A) JP-A-3-115711 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C30B 1/00-35/00 H01L 21/205

Claims (8)

(57) [Claims] 1. A substrate made of a tungsten carbide cemented carbide is placed in a nitrogen gas atmosphere of 1 to 300 Torr in a nitrogen gas atmosphere .
While allowing nitrogen in the raw gas atmosphere to act on the substrate,
After heat treatment at 200 to 1,600 ° C,
A method for producing a diamond-coated member, comprising forming a diamond-like film on the surface of the substrate. 2. A substrate made of a tungsten carbide cemented carbide is placed in an atmosphere containing a rare gas and a nitrogen gas having a partial pressure of 1 to 760 Torr while allowing nitrogen in the gas atmosphere to act on the substrate. A method for producing a diamond-coated member, comprising forming a diamond film on the surface of the base material by a vapor phase method after heat treatment at 1,200 to 1,600 ° C. 3. The pressure of the atmosphere in the heat treatment is 76.
3. The method for producing a diamond-coated member according to claim 2, wherein the pressure is 0 Torr to 3,000 atm. 4. The tungsten carbide cemented carbide comprises 50 to 95% by weight of tungsten carbide and 1 to 3 parts of titanium carbide.
The method for producing a diamond-coated member according to any one of claims 1 to 3, comprising 0% by weight and 2 to 20% by weight of cobalt. 5. The tungsten carbide cemented carbide comprises 60 to 95% by weight of tungsten carbide and 1 to 1% of tantalum carbide.
The method for producing a diamond-coated member according to any one of claims 1 to 3, comprising 10% by weight, 0 to 20% by weight of niobium carbide, and 3 to 10% by weight of cobalt. 6. The tungsten carbide-based cemented carbide comprises 50 to 95% by weight of tungsten carbide, and a total of 3 to 35% by weight of titanium carbide, titanium nitride, tantalum carbide, tantalum nitride, niobium carbide and niobium nitride, Cobalt 2
The method for producing a diamond-coated member according to any one of claims 1 to 3, comprising 15% by weight. 7. A substrate comprising a tungsten carbide cemented carbide, a carbide of two or more metals selected from the group consisting of a metal belonging to Group IVa, a metal belonging to Group Va and a metal belonging to Group VIa, and nitriding. At least one member selected from the group consisting of
Under a nitrogen gas atmosphere of 300Torr, the nitrogen gas Kiri囲
While the nitrogen in the air acts on the substrate,
A method for producing a diamond-coated member, comprising forming a diamond film on the surface of the base material by a vapor phase method after heat treatment at 1600 ° C. 8. A substrate made of a tungsten carbide cemented carbide, comprising a carbide of two or more metals selected from the group consisting of a metal belonging to Group IVa, a metal belonging to Group Va and a metal belonging to Group VIa; At least one selected from the group consisting of nitrogen and carbon nitride, and then, in an atmosphere containing a rare gas and a nitrogen gas having a partial pressure of 1 to 760 Torr, use nitrogen as a base material in the gas atmosphere. A method for producing a diamond-coated member, comprising: forming a diamond film on the surface of the base material by a vapor phase method after performing a heat treatment at 1,200 to 1,600 ° C.