JPH0733301B2 - Diamond coating member and method for manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diamond-coated member and a method for producing the same, and more specifically, it has excellent adhesion between a substrate and a diamond film coating the substrate,
The present invention relates to a diamond-coated member that exhibits high performance and excellent durability in practical use, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, cemented carbide, sintered diamond, single crystal diamond, etc. have been used for cutting tools, dies and other tools that require high hardness and wear resistance. ing.

Of these, diamond tools are particularly preferred because of their outstanding hardness and wear resistance.

Conventionally, this diamond tool has been used in which a sintered diamond or single crystal diamond is mounted on the surface of a base material made of a cemented carbide or a metal having a high hardness by brazing or the like.

On the other hand, in recent years, a vapor deposition diamond synthesis technique such as a CVD method or a PVD method is used to deposit a diamond film on the surface of a base material made of a cemented carbide or a metal having a high hardness. Methods have been studied, and attempts have been made to apply the diamond-coated member obtained thereby to the above-mentioned uses.

By the way, since diamond is the hardest substance, a diamond-like film formed on the surface of a base material such as cemented carbide is a coating material for imparting high hardness and wear resistance to the base material. Alternatively, it can be effectively used as a protective film.

For example, if a surface of a base material made of a cemented carbide used for a cemented carbide tool such as a cutting tool or a die is coated with a diamond film, a further excellent cemented carbide tool should be obtained.

However, the surface of the cemented carbide and the diamond-like film generally have poor adhesion, and it has not been successful to obtain a tool that can be used practically.

Therefore, in order to improve the adhesion between the surface of the cemented carbide and the diamond film, a technique of forming an intermediate layer between them has been proposed.

For example, in Japanese Unexamined Patent Publication (Kokai) No. 58-126972, the surface of a cemented carbide is first formed of one or more intermediates selected from carbides, nitrides, borides and oxides of IVa, Va and VIa group metals. A cemented carbide with a diamond film formed by forming a layer and then coating a diamond film on the intermediate layer is described.

However, in the method described in such a publication, since the stepwise film coating method of forming the intermediate layer and coating the diamond-like film is adopted, the manufacturing process becomes complicated and the adhesiveness is improved. While trying to improve
It cannot be said that the adhesion between the cemented carbide and the diamond film is sufficiently improved to a practical level.

On the other hand, there has been proposed a technique for improving the adhesion between a diamond film and a base material made of cemented carbide or the like without forming an intermediate layer.

For example, in Japanese Patent Laid-Open No. 63-100182, a diamond film formed by coating a tungsten carbide carbide alloy containing a specific amount of Co and having a specific grain size of tungsten carbide with a diamond film. Cemented carbide is described.

However, even in this publication, it cannot be said that the adhesion between the cemented carbide and the diamond film is at a sufficiently practical level.

In particular, when the amount of Co added is increased, the thermal expansion coefficient is increased, and carbon is diffused into Co, which makes it difficult to coat a good diamond film, and the adhesiveness is lowered. Durability cannot be obtained.

Generally, if the coefficient of thermal expansion of the base material is very different from that of the diamond-like film, a large thermal stress is generated during cooling after coating with the diamond-like film, which causes a decrease in adhesiveness, resulting in a cemented carbide tool. It is considered that damage such as peeling of the diamond film is likely to occur when used as.

Then, recently, in order to improve the adhesion in consideration of such a point, a new type of base material [a hard material, especially a ceramics, which has a thermal expansion coefficient close to that of diamond and is easy to directly coat a diamond-like film The base material consisting of (sintered body)] has been actively developed and selected.

For example, as an attempt to obtain a diamond-coated member having a diamond film having excellent adhesion,
Si ₃ N ₄ or silicon nitride-based ceramics (sintered body) containing Si ₃ N ₄ as a main component is used as a base material, or a superhard material having a controlled thermal expansion coefficient [many of these are Si ₃ N ₄
It is a sintered body or silicon nitride ceramics. It should be noted that silicon nitride is used in the sintering conditions, TiN, TiC, ZrN, and S.
It is known that addition of iC, ZrO ₂ , Al ₂ O ₃ , Y ₂ O ₃ or the like changes various physical properties such as a thermal expansion coefficient. ] Is proposed (Japanese Patent Publication No. 60-5).
No. 9086, No. 60-122785, No. 61-109628, No. 61-252004, No. 61-291493, No. 62-10706.
7 gazette, the same 63-20478 gazette, the same 63-204.
No. 79, No. 63-33570, No. 63-30.
6805 publication).

However, all of the diamond-coated members using these conventional base materials still have insufficient adhesion, so that there still remains a problem that sufficient performance as a cemented carbide tool, particularly durability cannot be obtained. Have As one specific example of this problem, it can be mentioned that the cutting life is short when used as a cutting tool.

The present invention has been made to improve the above circumstances.

An object of the present invention is to improve the adhesion between a base material made of a hard material and a diamond film,
It is an object of the present invention to provide a diamond coated member having a long life which can be used as a carbide tool such as a cutting tool having high performance and excellent durability and a wear resistant member.

[0022]

[Means for Solving the Problems] In order to solve the above problems, the present inventors first conducted extensive studies on a guideline for selecting a hard base material that exhibits sufficient adhesion to a diamond film.

As a result, the silicon nitride-based sintered body is generally a hard material whose surface is directly coated with a diamond-like film by a vapor phase synthesis method, although the conventional one has insufficient adhesion. However, even if the base material has the same coefficient of thermal expansion as that of diamond, it does not have to be a silicon nitride base material because of the composition of the material. Since the adhesiveness between the base material and the base material may be different, when a member formed by coating the surface of a base material with a diamond film is used as a cutting tool, a large difference may occur in the cutting life depending on the material of the base material. Therefore, in order to improve the adhesion between the diamond film and the base material, it is difficult to control the single unitary factor of the thermal expansion coefficient, and the composition and structure of the sintered body used as the base material (the components in the sintered body). , The type of phase, the composition of the structure, etc.) need to be more closely controlled. Also, when examining various conventional silicon nitride-based base materials, the types and ratios of additives, Furthermore, we obtain basic knowledge that the composition and structure of the sintered body can be changed by the sintering conditions and the treatment before and after the sintering, and that not only the thermal expansion coefficient but also various physical properties and characteristics can be controlled. Came to.

Based on these findings, the present inventors have designed silicon nitride ceramics (sintered body), which has been proposed as a conventional substrate, in order to design a substrate excellent in the adhesion of diamond films. As a result of various examinations mainly on the composition and structure of the sintered body, the following important facts have been found.

That is, conventionally, since ceramics mainly composed of nitride of silicon are difficult-to-sinter substances, these ceramics are usually sintered by adding a sintering aid for forming a glass phase.

However, the constituents of these sintering aids remain in the sintered body as a grain boundary glass phase even after sintering, deteriorating the heat resistance of the sintered body.

Therefore, when these sintered bodies are used as the base material of the diamond coating member as in the prior art, due to the high temperature at the time of coating the diamond coating, the grain boundaries may be formed before or at the same time as the coating of the diamond coating. It was found that the adhesion between the base material and the diamond film is poor because the components volatilize and deteriorate.

Therefore, the inventors of the present invention carry out a crystallization treatment on the above-described silicon nitride sintered body having a grain boundary glass phase to obtain a sintered body having a crystalline grain boundary phase, and then a diamond film. When coated, a diamond-coated member having excellent adhesion is obtained. Such a diamond-coated member is a high-performance and durable cemented carbide tool or wear-resistant member such as a cutting tool with a long cutting life. As a result, the present invention has been completed by finding that it can be advantageously used as the above.

That is, the present invention is a diamond-coated member, characterized in that the surface of a silicon nitride-based ceramic substrate having a crystalline grain boundary phase has a diamond film coated by a vapor phase synthesis method.

In the present invention, the silicon nitride ceramics base material having a grain boundary glass phase is crystallized, and then a vapor phase is formed on the surface of the silicon nitride ceramics base material having a crystalline grain boundary phase. A method for manufacturing a diamond-coated member, which comprises coating a diamond film by a synthetic method.

The present invention will be described in detail below.

In the present invention, the silicon nitride ceramics means silicon nitride (Si ₃ which is identified by X-ray diffraction.
Β-by X-ray diffraction by solid solution of aluminum (Al) or oxygen (O) in a sintered body containing N ₄ ) crystal particles as a main component or Si ₃ N ₄ crystal.
Sialon [Si _6-Z Al _z N _8-z O _z (where Z is 0
.About.4.2)] as a main component.

In the present invention, among the silicon nitride ceramics, one having a crystalline grain boundary phase (hereinafter, this is referred to as a crystalline grain boundary phase-containing sintered body or simply a sintered body [I]. There is) as a base material.

In the present invention, the silicon nitride-based ceramic (sintered body [I]) used as the base material is mainly composed of silicon nitride and contains a crystalline grain boundary phase. , Various compositions can be used. The method for producing the above-mentioned sintered body [I] is not particularly limited and can be produced by various methods. Usually, the sintered body is mainly composed of silicon nitride and has a grain boundary glass phase. (Hereinafter, this sintered body may be referred to as a grain boundary glass phase-containing sintered body or a sintered body [II].) It can be suitably manufactured by subjecting it to a crystallization treatment.

As the sintered body [II], known compositions having various compositions can be used as long as the sintered body is mainly composed of silicon nitride and contains a grain boundary glass phase. , A component that promotes crystallization of the grain boundary glass phase in order to effectively perform the crystallization treatment (for example,
Crystal nucleating agent) is preferably contained.

That is, the sintered body [II] is not particularly limited in its production method, and can be produced by various methods such as known methods. As a starting material component of the sintered body, a crystal nucleating agent is used. It is desirable to add and crystallize a crystallization promoting component such as the above or a precursor thereof.

As the crystallization promoting component, various compounds such as a known crystal nucleating agent can be used, and usually, a Ti compound such as TiN or a Zr compound can be preferably used, and among them, Ti is particularly preferable. Compounds are preferred,
TiN is particularly preferable.

It is sufficient that the crystallization promoting component is added to such an extent that the grain boundary glass phase can be effectively converted into the crystalline grain boundary phase. When a Ti compound such as TiN that acts as a crystal nucleating agent is used as a crystallization promoting component, the Ti compound is usually contained in an amount of 1 to 30% by weight, preferably 2 to 20% by weight in terms of TiN. Is good.

When the ratio of the crystallization promoting component in the sintered body [II] is too small, it takes a long time for the heat treatment for crystallization and the crystallization of the grain boundary glass phase is not sufficiently performed. On the other hand, if the amount is too large, the coefficient of thermal expansion of the obtained substrate may increase, and the adhesion of the diamond film to the substrate may decrease.

As the silicon component used as a starting material for the sintered body [II] or the sintered body [I], various kinds of silicon nitrides can be used, and Si ₃ N ₄ is usually used. It is suitable.

The proportion of silicon nitride, such as Si ₃ N ₄ , in the sintered body [II] and the sintered body [I] is usually 50% by weight or more, preferably 60 to 9%.
It is about 0% by weight. If the content ratio of this silicon nitride is too low, its properties will not be fully exhibited, making it difficult to control the coefficient of thermal expansion of the base material to a value close to that of the diamond type film, or vapor phase synthesis. It may be difficult to smoothly coat the diamond film by the method, and the object of the present invention may not be achieved.

The sintered body [I] or the sintered body [II] is used as a silicon nitride such as Si ₃ N ₄ and a crystallization promoting component (or as a crystallization promoting component) such as the Ti compound. In addition to the above components), various other additive components may be contained, if desired, within a range that does not hinder the purpose of the present invention.

As various other additive components, various components including those used as additive components of known silicon nitride-based sinters proposed as conventional silicon nitride-based sinters are listed. it can. Specific examples include oxides such as Y, Al, Zr, and Mg (for example, ZrO ₂ , MgO, Al ₂ O ₃ and Y ₂ O ₃ ), or nitrides, carbides, borides, and silicates. Acids and the like, or compound compounds and compositions thereof, other than the above, compounds and compositions of silicon other than the above (for example, carbides, oxides, etc. or composite compounds and compositions of silicon), compounds and compositions of Ti other than the above Alternatively, composite compounds or compositions of these may be mentioned.

There are no particular restrictions on these various starting raw material components, and normally, those conventionally used for producing a sintered body by sintering conventional silicon nitride ceramics can be appropriately used. it can.

Among these, ZrO ₂ , MgO,
Y ₂ O _3, the _Al 2 _{O 3} or _the like can be suitably used.

In the present invention, the sintered body [II] is not particularly limited in its production method, and a sintered body such as a known silicon nitride sintered body which has been proposed as a base material for a conventional diamond coating member. Can be manufactured by various methods such as the manufacturing method of.

This production method is usually carried out by using, as a starting material, a suitable Ti compound, preferably TiN, which acts as a crystallization promoting component, preferably TiN, and a suitable silicon nitride, preferably Si ₃ N _4, or these, and the above-mentioned desired compounds. Using the respective compounds (preferably ZrO ₂ , MgO, Y ₂ O ₃ and Al ₂ O ₃ ) suitable as starting materials for various other components used accordingly, a mixture of these in predetermined proportions is used. For example, it is molded into a desired shape by an appropriate molding method such as compression molding, and this is sintered under an appropriate sintering condition to obtain a silicon nitride sintered body (sintered body [II]) having the predetermined composition. The method can be preferably adopted.

Each of the above-mentioned components used as a starting material for this sintering can be used in the form of powder, fine powder, ultrafine particles, whiskers, or other various shapes, The average particle size is usually 0.
05-4.0 μm, preferably 0.05-2.0 μm
Fine particles or ultrafine particles, or whiskers having an aspect ratio of about 20 to 200 can be preferably used.

The sintering temperature is usually from 1,500 to
2,000 ° C, preferably 1,600 to 1,800 ° C
It is suitable to be within the range.

The sintering time is usually 0.2 hours or more, preferably 0.3 to 10 hours.

It should be noted that it is usually desirable to carry out the sintering under nitrogen gas and / or an inert atmosphere. Also,
Sintering is performed by normal pressure sintering, pressure sintering, or gas pressure sintering.

In the present invention, the sintered body [I] used as the base material is the sintered body [II] produced as described above under appropriate conditions and the grain boundary glass in the sintered body [II]. It can be suitably produced by subjecting at least a part of the phase, preferably substantially all, to a crystallization treatment and converting it into a crystalline grain boundary phase.

This crystallization treatment can be carried out by various methods, but usually it can be suitably carried out by heating the sintered body [II] at an appropriate temperature.

The crystallization treatment by heating cannot be uniformly defined because it depends on other conditions such as the composition of the sintered body [II] to be used, but the sintered body [II] is generally specified. ], Usually 1,400 to 1,700 ° C.,
Preferably within a temperature range of 1,500 to 1,600 ° C.,
Usually, 0.5 hours or more, preferably about 1 to 10 hours,
It can be effectively performed by heat treatment.

As another method of obtaining the sintered body [I] having a crystalline grain boundary phase, there is a method by selecting cooling conditions after the sintering treatment, for example, decooling conditions.

As described above, the predetermined sintered body [I] used for the base material can be obtained.

This sintered body [I] can be obtained by forming it into a desired shape in advance for the above-mentioned sintering, or after the above-mentioned sintering or after the above-mentioned crystallization treatment, it can be formed into a desired shape if necessary. It can be processed and used as a base material for the diamond-coated member of the present invention.

In the present invention, a sintered body that can be particularly preferably used among the silicon nitride ceramics (sintered body [I]) used as the base material, for example, Si ₃ N ₄ as a starting material, TiN and Zr
A mixture of at least one kind, preferably two or more kinds of oxides selected from O ₂ , MgO, Y ₂ O ₃ and Al ₂ O _{3 in} a predetermined ratio is used, and the mixture is appropriately molded by press molding or the like. , A silicon nitride sintered body (sintered under the appropriate conditions described above, containing a grain boundary glass phase, and having a peak of Si ₃ N ₄ and / or β-sialon and TiN observed by X-ray diffraction (sintered) Body [II]), which was subjected to crystallization treatment by X-ray diffraction to obtain Si ₃ N ₄ and / or
Or, peaks with β-sialon and TiN are observed, and a melilite phase (Y ₂ S
i ₃ N ₄ O ₃ ) can be mentioned as a sintered product [I]. The predetermined ratio of each component in the mixture is 60 to 90% by weight for Si ₃ N ₄ , 1 to 30% by weight in terms of TiN for Ti-based compound, ZrO ₂ , Mg.
10 to 40% by weight can be mentioned for at least one oxide selected from the group consisting of O, Y ₂ O ₃ and Al ₂ O ₃ .

The diamond-covered member of the present invention is obtained by coating the desired surface of the sintered body [I] (silicon nitride ceramics having a crystalline grain boundary phase) with a diamond film by a vapor phase synthesis method. Is.

Moreover, this diamond film can be efficiently and easily formed with a uniform thickness. By the way, even when the vapor phase synthesis method is applied to the conventional WC-based superalloy substrate, there is a problem that plasma is not uniformly concentrated and the thickness of the diamond film is likely to be nonuniform.

In the diamond-coated member of the present invention, the thickness of the diamond film is such that it is difficult to determine a clear boundary surface between the diamond film and the substrate (the sintered body [I]). However, in the case of a cutting tool, it is usually about 0.5 to 100 μm, preferably about 2 to 50 μm.

If the diamond film is too thin, the surface of the substrate may not be sufficiently covered,
On the other hand, if the thickness of the diamond film is too large, the diamond film may peel off from the substrate.

In the present invention, when simply referred to as diamonds, it includes diamond and diamond-like carbon partially containing diamond-like carbon, in addition to diamond. As a method for coating the diamond film, as long as a vapor phase synthesis method is used,
Various methods such as known methods can be applied, but usually, the following method can be preferably used.

That is, a desired diamond film can be preferably formed on the base material by the following method.

The diamonds film can be formed by a known diamond synthesis method, and among them, a vapor phase diamond synthesis method in which a plasma gas obtained by exciting a carbon source gas is brought into contact with a substrate is preferable.

Specifically, there is a method of forming a diamond film on a substrate by bringing a gas obtained by exciting a raw material gas containing a carbon source gas into contact with the substrate in the reaction chamber. preferable.

The source gas may contain at least a carbon source gas, but is preferably a gas containing carbon atoms and hydrogen atoms.

Specifically, as the raw material gas, for example, a mixed gas of a carbon source gas and hydrogen gas can be mentioned.

If desired, a carrier gas such as an inert gas may be used together with the raw material gas.

As the carbon source gas, various hydrocarbons,
A gas such as a halogen-containing compound, an oxygen-containing compound or a nitrogen-containing compound, or a gasified carbon such as graphite can be used.

Examples of the hydrocarbon compound include methane,
Paraffin hydrocarbons such as ethane, propane, butane;
Olefinic hydrocarbons such as ethylene, propylene and butylene; acetylene hydrocarbons such as acetylene and allylene; diolefinic hydrocarbons such as butadiene; cycloaliphatic hydrocarbons such as cyclopropane, cyclobutane, cyclopentane and cyclohexane; cyclobutadiene ,benzene,
Examples thereof include aromatic hydrocarbons such as toluene, xylene, and naphthalene.

Examples of the halogen-containing compound include halogenated methane, halogenated ethane, halogenated hydrocarbon such as benzene, carbon tetrachloride and the like.

Examples of the oxygen-containing compound include alcohols such as methanol, ethanol, propanol and butanol; methyl ether, ethyl ether, ethyl methyl ether, methyl propyl ether, ethyl propyl ether, phenol ether, acetal, cyclic ether (dioxane). , Ethylene oxide etc.); acetone, diethyl ketone, pinacholine, aromatic ketones (acetophenone, benzophenone etc.), diketone, cyclic ketone etc. ketones; formaldehyde, acetaldehyde, butyraldehyde, benzaldehyde etc. aldehydes; formic acid, Organic acids such as acetic acid, propionic acid, succinic acid, butyric acid, oxalic acid, tartaric acid and stearic acid; acid esters such as methyl acetate and ethyl acetate; ethylene glycol, diethylene Dihydric alcohols such as recall; carbon monoxide can be mentioned carbon dioxide.

Examples of the nitrogen-containing compound include amines such as trimethylamine and triethylamine.

Among these carbon source gases, paraffinic hydrocarbons such as methane, ethane and propane which have a high gas or vapor pressure at room temperature; ketones such as acetone and benzophenone; alcohols such as methanol and ethanol; and monoxide. Oxygen-containing compounds such as carbon and carbon dioxide gas are preferable, and carbon monoxide is particularly preferable.

The concentration of the carbon source gas in all gases is usually 0.1 to 80% by volume.

The hydrogen constituting the hydrogen gas forms atomic hydrogen when excited.

Although the detailed mechanism of this atomic hydrogen is unknown, it is considered to act as a catalyst for activating the diamond forming reaction. Further, it has a function of removing non-diamond components such as graphite and almorphus carbon which are deposited at the same time as the deposition of diamond.

Means for exciting the source gas include, for example, microwave plasma CVD method, RF plasma CV
D method, DC plasma CVD method, magnetic field plasma CVD method (including ECR condition), hot filament method, thermal plasma CVD method, photo CVD method, laser induced CVD method, combustion flame method, sputtering method, ion beam method, cluster The ion beam method, the ion plating method, etc. can be mentioned.

Of these, various CVDs are preferable.
Method, and more preferably a plasma CVD method.

In the combination of each source gas and each excitation means described above, particularly preferable for the purpose of the present invention is a mixed gas of carbon monoxide gas and hydrogen gas and a microwave plasma CVD method (with a magnetic field CVD method). Including).

In the vapor phase method, the temperature of the base material at the time of coating the diamond film is different depending on the method of exciting the raw material gas, and therefore cannot be unconditionally determined, but it is usually 300 to 1,200. ℃, preferably 500 ~
It is 1100 degreeC.

If the temperature is lower than 300 ° C., the deposition rate of diamond may slow down or the crystallinity of the deposit may be lost.

On the other hand, even if the temperature is higher than 1,200 ° C., the effect commensurate with the temperature rise is not obtained, which is disadvantageous in terms of energy efficiency and the coated diamond may be etched.

The reaction pressure for coating the diamond film is usually 10 ^-6 to 10 ³ Torr, preferably 10 ^{-5 to} 800 Torr. Reaction pressure is 10 ^-6 To
When it is lower than rr, the deposition rate of diamond becomes slow, or it does not deposit. On the other hand, 1
When it is higher than 0 ³ Torr, the amount of generated graphite increases.

The reaction time varies depending on the surface temperature of the substrate, the reaction pressure, the required film thickness, etc., and therefore cannot be determined unconditionally, but may be determined appropriately.

The thickness of the diamond film thus formed is not particularly limited because it varies depending on the use of the coating member formed by coating the diamond film, but is usually 0.3 μm or more, preferably Is 0.5-5
It is preferably 1 to 100 μm, more preferably 00 μm.

The diamond-coated member of the present invention can be manufactured as described above.

The diamond-coated member of the present invention is the same as a conventional diamond-coated member obtained by forming a diamond film on a known ceramic-based substrate such as a silicon nitride sintered body or a cemented carbide substrate. In comparison, the adhesion between the diamond film and the sintered body (sintered body [I]), which is the base material, is remarkably excellent. For example, various tools such as cutting tools that require hardness and wear resistance. It can exhibit high performance and excellent durability when it is put into practical use as a member, and can significantly extend its cutting life, especially when used as a cutting tool used under severe conditions. it can.

Therefore, the diamond-coated member of the present invention can be used as a cutting tool such as a cutting tool, an end mill, a drill, and a cutter, a die, a wire drawing die, a gauge, a cemented carbide tool such as a head of a bonding tool, a wear-resistant tool, and a wear-resistant tool. It can be suitably used as an abradable member or the like, or as various functional materials that utilize the characteristics or functions of diamond type films such as electronic materials.

[0091]

EXAMPLES Examples of the present invention will be described below.

Example 1 71% by weight of Si ₃ N ₄ powder,
Y ₂ O ₃ powder was wet mixed at a ratio of 11% by weight, Al ₂ O ₃ powder at 3% by weight and TiN powder at a ratio of 15% by weight, dried, molded, and then sintered under atmospheric pressure in a nitrogen atmosphere at 1,70%.
Sintered at 0 ° C. for 1 hour.

The obtained sintered body was treated with a nitrogen atmosphere at 1,55
A crystallization heat treatment is performed by heating at 0 ° C. for 2 hours,
Cutting tool shaped sintered tip (shape: SPGN421)
Was produced.

The sintered body which had been subjected to this crystallization heat treatment was analyzed by X-ray diffraction. As a result, the peaks of β-sialon and TiN and the melilite phase (Y ₂ Si ₃ N
₄ O ₃ ) peak was observed, the crystallization of the grain boundary glass phase was progressing, and it was confirmed that this sintered body was a silicon nitride-based ceramic having a crystalline grain boundary phase.

The sintered chips subjected to this crystallization heat treatment were placed as a base material in a reaction vessel of a microwave plasma CVD apparatus, and the raw material for the reaction vessel was placed under the conditions of a base material temperature of 1,000 ° C. and a pressure of 40 Torr. The gas flow rate was set to 15 sccm of carbon monoxide gas and 85 sccm of hydrogen gas, the output of microwave (frequency 2.45 GHz) was set to 400 W, the reaction was carried out for 5 hours, and the thickness of the substrate was about 10
Coated with μm diamonds.

When Raman spectroscopic analysis was carried out on this coating film, a peak due to diamond was observed at around 1,333 cm ^{−1 in the} Raman scattering spectrum, and it was confirmed that the diamond was almost free of impurities.

Next, using the diamond-coated tip thus obtained, a wet cutting test was conducted under the following conditions,
The cutting characteristics of each chip were investigated.

Work Material: Aluminum Alloy (Silicon 8% by Weight) Cutting Speed: 1,500 m / min Feed: f = 0.1 mm / rev Depth of Cut: 0.25 mm Working Fluid: Aqueous Emulsion Oil As a result, 30,000 m After the cutting test, no abnormalities such as peeling and chipping of the diamond film were observed.

After this cutting test, the diamond film /
When the interface of the base material was observed with a scanning electron microscope, the interface between the diamond film and the base material having excellent continuity was observed.

Further, using the diamond-coated chips, a dry cutting test was conducted under the following conditions to examine the cutting characteristics of each chip.

Work Material: Aluminum Alloy (8% by Weight of Silicon) Cutting Speed: 800 m / min Feed: f = 0.1 mm / rev Depth of Cut: 0.25 mm As a result, the diamond film peels off even after a cutting test of 50,000 m. No abnormalities such as chipping were observed.

After the cutting test, the diamond film /
When the interface of the base material was observed with a scanning electron microscope, the interface between the diamond film and the base material having excellent continuity was observed.

Comparative Example 1 A sintered chip having the same cutting tool shape was produced in the same manner as in Example 1 except that the crystallization heat treatment was not performed.

When this sintered body was analyzed by X-ray diffraction, peaks of β-sialon and TiN were observed, but no other peaks were observed.
That is, it was confirmed that this sintered body did not have a crystalline grain boundary phase.

A diamond film was formed on the surface of the base material by the same method as in Example 1 using the sintered chip having no crystalline grain boundary phase as the base material.

When a wet cutting test was conducted using the obtained diamond-coated member under the same conditions as in Example 1, the diamond film was peeled off after only cutting 3,000 m.

After the cutting test, the diamond film / substrate interface was observed with a scanning electron microscope. As a result, a gap that was thought to be generated due to the volatilization of grain boundary components was observed at the interface portion.

(Examples 2 to 6) Si ₃ N ₄ powder, Y ₂ O ₃ powder, Al ₂ O ₃ powder and TiN powder were mixed in the proportions shown in Table 1, and the crystallization treatment time was as shown in Table 1. A sintered chip (shape: SPGN421) was manufactured by performing the same operation as in the above-described example except that the above was changed to.

When this sintered chip was analyzed by X-ray diffraction, it was found that β-sialon and TiN
Peaks (excluding Example 5) and melilite phase (Y ₂ Si)
₃ N ₄ O ₃ ) peak was observed, crystallization of the grain boundary glass phase proceeded, and it was confirmed that this sintered body was a silicon nitride-based ceramic having a crystalline grain boundary phase.

A diamond-coated chip was manufactured in the same manner as in Example 1 using the sintered chip as a base material.

Using this diamond-coated tip, a wet cutting test was conducted under the same cutting conditions as in Example 1 to determine the cutting length until the diamond film was peeled off. The results are shown in Table 1.

[0112]

[Table 1]

[0113]

According to the present invention, since a specific silicon nitride ceramics (sintered body) having a crystalline grain boundary phase is used as a base material for coating a diamond film, the base material (sintered body). It is possible to remarkably improve the adhesion between the diamond film and the diamond film, when it is put into practical use as various cemented carbide tools including cutting tools, wear resistant members, etc.
It is possible to significantly reduce damage due to peeling or abrasion of the diamond film, and it is possible to provide a diamond-coated member having high performance, excellent durability, and long life.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location // B23P 15/28 A 7528-3C C04B 35/584 (72) Inventor Toshimichi Ito Chiyoda-ku, Tokyo Marunouchi 3-1-1 1-1 Idemitsu Petrochemical Co., Ltd. (72) Inventor Masaya Tsubokawa 1660 Kamisen, Sodegaura-cho, Kimitsu-gun, Chiba Idemitsu Petrochemical Co., Ltd.

Claims (2)

[Claims] 1. A diamond-coated member comprising a silicon nitride ceramic substrate having a crystalline grain boundary phase and a diamond film formed by a vapor phase synthesis method on the surface thereof. 2. A silicon nitride ceramics base material having a grain boundary glass phase is crystallized, and the surface of the base material made of a silicon nitride ceramics having a crystalline grain boundary phase is crystallized.
A method for producing a diamond-coated member, comprising coating a diamond film by a vapor phase synthesis method.