JPH0762540A - Wear resistant member - Google Patents

Abstract

PURPOSE:To provide a member excellent in adhesion to the substrate, capable of withstanding sliding over a long time and having superior wear resistance. CONSTITUTION:When the surface of a substrate made of a silicon nitride-based sintered compact is coated with a hard carbon film having 1-20mum thickness to obtain a wear resistant member, a layer of a mixture of hard carbon with silicon or a silicon compd. is formed in the hard carbon film at a part adjacent to the substrate especially in 0.1-5mum thickness corresponding to <=4S% of the total thickness of the hard carbon film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wear resistant member coated with a hard carbon film such as a diamond film or a diamond-like carbon film having high strength and excellent adhesion to a substrate.

[0002]

2. Description of the Related Art Since diamond is excellent in hardness, wear resistance, solid lubricity, electric insulation, thermal conductivity, etc., for example, cutting tools, abrasives, wear resistant mechanical parts, optical parts, etc. It is being used as a hard coat material for various members, as well as electrical and electronic materials.

In recent years, it has become possible to synthesize a hard carbon film such as diamond by a vapor phase growth method under a low pressure, and such a hard carbon film can be used in various fields such as sliding members, cutting tools, and abrasives. Is being used by.

On the other hand, in order to exhibit the characteristics of the hard carbon film such as the diamond film, the adhesion between the film and the substrate must be excellent. However, there has been a problem that the hard carbon film formed by these vapor phase synthesis methods is not always sufficient in terms of adhesion to the substrate.

The adhesion between such a hard carbon film and the substrate can be evaluated to some extent by the difference in thermal expansion coefficient between the two, and the smaller the difference, the stronger the adhesion. This is because the film peels from the substrate due to the stress generated by the difference in thermal expansion between the film and the substrate. Therefore, there is a method of reducing the difference in thermal expansion coefficient between the film and the substrate as one of means for improving the adhesion between the film and the substrate. Based on this idea, a method of forming an intermediate film made of SiC, for example, on a substrate and then forming a diamond film is disclosed in JP-A-63-286576.
It is proposed in the issue. Further, JP-A-5-5179 proposes to form an intermediate layer made of diamond and a metal compound between a base made of cemented carbide and a diamond film.

[0006]

However, regarding the adhesion to the substrate, according to the method of forming the intermediate layer of SiC between the substrate and the carbon film, the thermal expansion of both is higher than that in the case where the intermediate layer is not formed. Since the difference is relaxed, the adhesion can be increased to some extent and the life as a wear resistant member can be extended, but it is still satisfactory in terms of slidability and wear resistance as a wear resistant member. Characteristics are not obtained. Moreover, since a work process for forming the intermediate film is required before the process for forming the hard carbon film, the number of processes is increased and the productivity is low.

Further, according to JP-A-5-5179, since the difference in thermal expansion between diamond and cemented carbide is large,
Only the layer structure for increasing the adhesiveness between the two has been studied, but not enough from the viewpoint of the characteristics as a wear resistant member.

Therefore, the present invention is intended to solve the above problems and to provide a wear resistant member having a low coefficient of friction and capable of withstanding long-term sliding as a wear resistant member.

[0009]

As a result of repeated studies on the above problems, the present inventors have selected a silicon nitride sintered body as a base material for forming a hard carbon film, and It has been found that the above object can be achieved by providing a mixed layer of hard carbon and silicon or a silicon compound adjacent to the substrate side in the carbon film. In particular, the thickness of the mixed layer is set to 0.1 to 5 μm, and the thickness of the mixed layer is controlled to be 45% or less of the total thickness of the hard carbon film.

The present invention will be described in detail below. The wear resistant member of the present invention is characterized in that a silicon nitride sintered body is used as a substrate for forming the hard carbon film. The coefficient of thermal expansion of silicon nitride itself is about 2 to 5 × 1
A 0 ^-6 / ℃, 2~ thermal expansion coefficient of the hard carbon film is approximately
4 × 10 ⁻⁶ / ° C., which are close to each other. In particular, since the silicon nitride-based sintered body contains various sintering aids in addition to silicon nitride, the coefficient of thermal expansion will change somewhat depending on the sintering aid to be added, and the hard carbon film will also have a diamond crystal or amorphous structure. The coefficient of thermal expansion changes depending on the constituents of the hard carbon film such as carbon, diamond-like carbon and graphite. Therefore, the difference in thermal expansion between the substrate and the hard carbon film is 2 ×
It is desirable to combine them so as to be 10 ^-6 / ° C or less.

Further, the silicon nitride-based sintered body used as the substrate is Y, Yb, E as a sintering aid for silicon nitride.
an oxide of a Group 3a element of the periodic table such as r, Sc, La, or the like,
Al ₂ O ₃ , MgO, etc. are contained at a ratio of 1 to 20% by weight, the relative density is 95% or more, the bending strength at room temperature (by four-point bending) is 50 kg / mm ² or more, and the toughness (K It is desirable that ₁ c) is 5 MPa · m ^1/2 or more.

Further, according to the present invention, even if the thermal expansion of the substrate and the hard carbon film are approximated, excellent characteristics as a wear resistant member cannot be obtained. Therefore, according to the present invention, a major feature is that a mixed layer of hard carbon and silicon or a silicon compound is present adjacent to the substrate side in the hard carbon film. Due to the existence of this mixed layer, there is no large inflection point on the thermal expansion between the hard carbon film and the substrate, and the adhesion between the substrate and the hard carbon film can be further enhanced and the toughness of the hard carbon film can be enhanced. This mixed layer, a phase made of hard carbon,
It is a layer in which silicon or a silicon compound, for example, a compound phase such as SiC or Si ₃ N ₄ is mixed.

This mixed layer is adjacent to the side of the substrate in the film.
The hard carbon film is preferably formed with a thickness of 1 to 5 μm, and the outermost surface of the hard carbon film is preferably substantially composed of hard carbon. Therefore, it is desirable to control the thickness of the mixed layer to be 45% or less of the total thickness of the hard carbon film. This is because when the thickness of the mixed layer is less than 0.1 μm, the effect of improving the adhesion and the toughness of the hard carbon film due to the presence of the mixed layer is small, and when the thickness is more than 5 μm, the hardness of the entire hard carbon film becomes low. This is because distortion or the like is likely to occur in the film, resulting in problems such as deterioration in durability. Furthermore, when the thickness of the mixed layer exceeds 45% of the total thickness of the hard carbon film, the excellent properties of the hard carbon film are not fully exhibited on the film surface, and the wear resistance and sliding characteristics of the wear resistant member are reduced. This is because the

In order to manufacture the wear resistant member of the present invention, a hard carbon film is formed on the surface of the above-mentioned silicon nitride sintered body as a substrate by a general vapor phase growth method. As a method for forming a hard carbon film, a carbon source gas containing carbon is used as a raw material gas, which is excited by microwaves or high frequency waves and brought into contact with the base to form a hard carbon film on the surface of the base. Can be deposited. Specific methods for producing such a hard carbon film are described in, for example, JP-A-53-10394 and JP-A-56-2261.
6 and JP-A-58-91100.

In order to form a mixed layer of hard carbon and silicon or a silicon compound according to the present invention, a gas containing silicon element is mixed as a raw material gas in addition to the carbon source gas, and at the same time N ₂ gas or the like is mixed. By introducing the above, hard carbon and silicon or a silicon compound can be simultaneously deposited.

The silicon element-containing gas mixed in the raw material gas at this time has an amount of 0.5 to 1 with respect to the carbon source gas.
It is desirable to mix them in a proportion of 0%, particularly 0.5 to 5%. If it is less than 0.5%, it is difficult to form a mixed layer, and if it exceeds 10%, a large amount of compound phase is formed.
This is because the performance as a hard carbon film is deteriorated.

The carbon source gas used to form the hard carbon film includes, for example, alkanes such as methane, ethane, propane, butane, pentane and hexane,
Alkenes such as ethylene, propylene, butene, pentene and butadiene, alkynes such as acetylene, aromatic hydrocarbons such as benzene, toluene, xylene, indene, naphthalene and phenanthrene, cycloparaffins such as cyclopropane and cyclohexane, cyclopentene And cycloolefins such as cyclohexene. In addition, carbon monoxide, carbon dioxide, oxygen-containing carbon compounds such as methyl alcohol, ethyl alcohol and acetone, and nitrogen-containing carbon compounds such as mono (di, tri) methylamine and mono (di, tri) ethylamine are also used as carbon source gases. Can be used. Among these, paraffin hydrocarbons such as methane, ethane and propane, oxygen-containing carbon compounds such as carbon monoxide, carbon dioxide, methyl alcohol and acetone, and nitrogen-containing carbon compounds such as trimethylamine are preferable. These may be used alone or in combination of two or more.

As the silicon-containing gas to be used, in addition to halides such as silicon tetrafluoride, silicon tetrachloride and silicon tetrabromide, oxides such as silicon dioxide, mono (di, tri, tetra, penta) is also used. Silane compounds such as silane, mono (di, tri, tetra) methylsilane, methylchlorosilane, phenylchlorosilane, trimethylsilanol,
Examples thereof include silanol compounds such as triethylsilanol and triphenylsilanol. In this case, monosilane and mono (di, tri, tetra) methylsilane are preferable. These may be used alone or in combination of two or more.

In addition to the above, the raw material gas may contain hydrogen gas or a diluting gas such as argon gas or helium gas.

Preferably, first, a mixed layer of hard carbon and silicon or a silicon compound is formed by the above method, and then,
A film having a hard carbon layer formed on the mixed layer can be obtained by stopping the introduction of the silicon-containing gas and forming only hard carbon. Further, the amount of silicon-containing gas in the mixed layer is gradually decreased from the initial stage when the mixed layer is formed so that the amount of silicon or silicon compound deposited in the mixed layer gradually decreases from the substrate side toward the film surface side. By forming the mixed layer in which the concentration of the compound is changed, the thermal expansion difference between the substrate and the hard carbon film can be continuously changed without an inflection point.

[0021]

According to the present invention, the type of the substrate, the film quality, etc. of the member having the hard carbon film formed can be changed with respect to the special evaluation items such as slidability, friction coefficient and specific wear amount as the wear resistant member. As a result, it was found that the silicon nitride sintered body was superior in slidability to the cemented carbide generally used as the substrate.

As a method for improving the adhesion between the hard carbon film and the substrate, a substance having a coefficient of thermal expansion and an intermediate substance between the substrate and the hard carbon film is interposed between the substrate and the hard carbon film. Alternatively, there are methods such as forming a mixed layer of hard carbon and a compound containing a base component. However, forming the mixed layer was superior in slidability to the method of forming the intermediate layer.

Moreover, based on the above knowledge, when a silicon nitride sintered body was used as a base material and a mixed layer of hard carbon and silicon or a silicon compound was formed in the hard carbon film to be formed, sliding characteristics, etc. Is greatly improved. This is because when an intermediate layer or a mixed layer is formed in order to improve adhesion, peeling due to thermal expansion between the base and the hard carbon film can be suppressed, but when a cemented carbide is used as the base. In the first place, since the difference in thermal expansion between the cemented carbide and the hard carbon film is large in the first place, the thermal expansion characteristics change drastically at the interface between the base and the hard carbon film as compared with the case of the silicon nitride sintered body base. It will be. If there is such a rapid change in thermal expansion characteristics, it is not possible to alleviate the generation of stress due to frictional heat generated when used as a wear resistant member,
Stress accumulates and the life of the member is shortened.

On the other hand, when the silicon nitride sintered body is used as the substrate, the coefficient of thermal expansion with the hard carbon film is very close to each other. Since no stress is accumulated, the life of the member can be extended.

Further, according to the present invention, when a silicon nitride sintered body is selected as the base and a predetermined mixed layer is formed in the hard carbon film, an intermediate layer different from the base and the hard carbon film is formed. Since there is no interface due to a material difference as compared with the above case, shear stress is applied to the interface between the film and the substrate, especially in a member involving sliding, but the durability against this stress is improved. Further, in the mixed layer, grain growth during precipitation of the hard carbon component can be suppressed and a film having a fine crystal structure can be formed, so that the toughness of the hard carbon film can be enhanced.
Therefore, in addition to the toughness of the substrate itself, the toughness at the interface of the hard carbon film with the substrate can be increased due to the presence of the mixed layer, so that the durability against external stress is increased and the abrasion resistance of the film is improved. It is possible to improve the property.

[0026]

【Example】

Example 1 Si (CH ₃ ) ₄ -H ₂ mixed gas containing Si (CH ₃ ) ₄ at a concentration of 500 ppm in a reaction chamber at a flow rate of 20 SCCM and N ₂ —H ₂ mixed gas (N ₂ concentration 1%). To 10S
CCM, CH ₄ gas 1.0 SCCM, H ₂ gas 170
Each was introduced at a flow rate of SCCM (CH ₄ gas concentration was 0.5%), and the reaction chamber pressure was set to 0.30 kPa. Then, an output of 400 W was input from a microwave power source of 2450 MHz, and Si ₃ N ₄ was used as a main component and 2% by weight of Y ₂ O ₃ and Al ₂ O were supplied by a microwave plasma CVD method.
Sintered body containing 5% by weight of ₃ (coefficient of thermal expansion 4 × 10 ^-6 /
The film on the substrate made of ° C.) to obtain a diamond film containing Si ₃ N ₄ and SiC (first layer), then, Si (CH
₃ ) Stop the supply of _4- H ₂ mixed gas, and add CH ₄ gas to 1.
A diamond film (second layer) was formed by introducing 0 SCCM and H ₂ gas 200 SCCM. Samples No. 1 and No. 2 in Table 1 were prepared by changing the film forming times of the first layer and the second layer.

The sliding characteristics of each of the obtained coated members were evaluated based on the pin-on-disk method. The sliding test conditions were room temperature, air, and no lubrication under a load of 39.2N,
The sliding speed was 2 m / sec and the time was 24 hours. The pins used were made of aluminum.

In the measurement, the sliding distance until the film peels off,
The friction coefficient and the specific wear amount of the disk surface were measured. In addition, the specific wear amount is shown only when the film peeling did not occur even in the 24-hour sliding test. The respective measurement results are shown in Table 1.

Example 2 As a source gas, 20 SC of Si (CH ₃ ) ₄ -H ₂ mixed gas containing Si (CH ₃ ) ₄ at a concentration of 500 ppm was used.
At a flow rate of CM, 1.0 sccm of CH ₄ gas, H ₂ gas 180 sccm, and introduced respectively at flow rates of H ₂ gas 170 sccm (CH ₄ concentration is 0.5%), identical to the substrate used in Example 1 A diamond film (first layer) containing SiC is formed on the surface of the Si ₃ N ₄ sintered body, and CH
₄ gas 1.0 SCCM and H ₂ gas 200 SCCM were introduced to form a diamond film (second layer). The first
A layer having a thickness of 0.1 to 6 μm and a second layer having a thickness of 2 to 8 μm was formed as in Sample Nos. 3 to 8 in Table 1, and the obtained covering member was formed in the same manner as in Example 1. The sliding characteristics were evaluated by the method, and the results are shown in Table 1.

Example 3 In Example 1, the Si (CH ₃ ) ₄ concentration was set to 5 at the initial stage of film formation.
00ppm of Si (CH _{3) 4} -H ₂ mixed gas 20sc
cm, CH ₄ gas 1.0sccm, N ₂ -H ₂ gas 10
From the ratio of SCCM and H ₂ gas 170 SCCM, the gas flow rate is gradually changed so that the flow rate becomes H ₂ 200 SCCM and CH ₄ 1.0 SCCM at 5 hours.
C, Si ₃ N ₄ and diamond, SiC,
After forming a mixed layer (first layer) in which the amount of Si ₃ N ₄ gradually decreases from the substrate toward the film surface, 1
A diamond film (second layer) was formed for 5 hours (Sample No.
14). The obtained covering member was evaluated for sliding characteristics in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 1 CH ₄ gas was introduced as a source gas into the reaction chamber at a flow rate such that CH ₄ concentration was 0.5% with respect to H ₂ gas, and the same Si ₃ N ₄ quality as the substrate used in Example 1 was used. Only the diamond film was formed on the surface of the sintered body (Sample No. 9).

Further, the raw material gas as _{Si (CH 3) 4 Si (} CH 3) at a concentration of 1000ppm of by introducing ₄ -H ₂ mixed gas at a flow rate of 200SCCM of Example 1 S
After the SiC film (first layer) is formed on the surface of the base body of the i ₃ N ₄ -based sintered body, CH ₄ gas is introduced into H ₂ gas at a CH ₄ concentration of 0.5% to form a diamond film (first layer). Two layers) were deposited (Sample No. 10). Then, the sliding characteristics of each of the above samples were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 2 As a substrate for forming a hard carbon film, a cemented carbide substrate made of WC94%, TiC1% and Co5% (coefficient of thermal expansion 5 × 10 ⁻⁶ / ° C.) was used instead of the silicon nitride sintered body. And TiC
N50%, NbC9%, WC9% , Mo 2 C16%, N
For cemented carbide and cermet consisting of i16%,
Sample N, which is the optimum hard carbon film configuration in Example 2
A hard carbon film was formed with the same film configuration as in o.4. The obtained coated members (Sample Nos. 12 and 13) were evaluated for sliding properties in the same manner as in Example 1, and the results are shown in Table 1.

[0034]

[Table 1]

According to Table 1, when comparing the sample No. 4 using the silicon nitride sintered body as the base and the samples No. 12 and 13 using the cemented carbide or cermet as the base, the friction coefficient is Although there is no big difference, it is understood that it is better to use the silicon nitride sintered body as the base in the sliding distance.

Further, even when the silicon nitride sintered body is used as the substrate, Sample Nos. 9 and 1 in which the substrate alone, the diamond film only, and the SiC layer formed between the diamond film and the substrate are formed.
Both 0 and 11 had low sliding characteristics as compared with the product of the present invention. Furthermore, according to the samples No. 1 to 8, the hard carbon film has a thickness of more than 20 μm.
In the abrasion test, peeling of the film was observed. Also,
According to a comparison between Sample Nos. 6 and 7 in which the thickness of the first layer, which is a mixed layer, exceeds 45% of the total film, and Samples No. 1 to 5 in which the thickness of the first layer is 45% or less, Sample Nos. 1 to 5 are It can be seen that the friction coefficient and the specific wear amount are small and the sliding characteristics are excellent.

[0037]

As described in detail above, according to the present invention,
It is possible to provide a member that has excellent adhesion to a substrate and can withstand long-term sliding, and that has excellent wear resistance. Thereby, the application as a member coated with the hard carbon film can be further expanded.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 7, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

Further, as a method for improving the adhesion between the hard carbon film and the substrate, an intermediate material between the substrate and the hard carbon film is used so that the thermal expansion coefficient between the substrate and the hard carbon film becomes small. Intervening or forming a mixed layer of hard carbon and a compound containing a substrate component. However, the mixed layer is superior in slidability to the intermediate layer. It was

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

[0026]

EXAMPLES Si (CH _{3) 4} -H ₂ mixed gas at a concentration of 500ppm of Si (CH _{3) 4} in Example 1 reaction chamber at a flow rate of 20SCCM, N ₂ -H ₂ mixed gas (N ₂ concentration 1%) to 10 SC
CM, CH ₄ gas 1.0 SCCM, H ₂ gas 170S
Each of them was introduced at a flow rate of CCM (CH ₄ gas concentration was 0.
5%), and the reaction chamber pressure was set to 0.30 kPa. Next, output 400 from the microwave source of 2450 MHz
Charge W and apply Si ₃ by microwave plasma CVD
N ₄ was used as a main component Y ₂ O ₃ 2% by weight, the Al ₂ O ₃ 5
A diamond film (first layer) containing Si ₃ N ₄ and SiC in the film is formed on the surface of the substrate made of a sintered body (coefficient of thermal expansion 4 × 10 ⁻⁶ / ° C.) containing wt%, and thereafter, Si
(CH ₃₎ stopping the supply of ₄ -H ₂ mixed gas was deposited diamond film (second layer) of CH ₄ gas 1.0 sccm, by introducing H ₂ gas 200 SCCM. Samples No. 1 and No. 2 in Table 1 were prepared by changing the film forming times of the first layer and the second layer.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

[0029] As Example 2 source gas, the Si (CH _{3) 4} -H ₂ mixed gas containing Si and (CH _{3) 4} in a concentration of 500 ppm 20SCC
CH ₄ gas was introduced at a flow rate of 1.0 SCCM and H ₂ gas was introduced at a flow rate of 180 SCCM (CH ₄ concentration was 0.5%) to obtain the same Si ₃ N ₄ as the substrate used in Example 1.
Diamond film containing SiC on the surface of the porous sintered body (first
Layer) and CH ₄ gas 1.0 SCCM, H
₂ gas 200SCCM was introduced to the diamond film (second
Layer) was deposited. The first layer is 0.1 to 6 μm and the second layer is
The thickness of the layer is 2 to 20 μm, and the sample No. 3 to 8 in Table 1 is used.
The coated member thus obtained was evaluated for sliding characteristics in the same manner as in Example 1 and the results are shown in Table 1.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

Example 3 In Example 1, the Si (CH ₃ ) ₄ concentration was set to 5 at the initial stage of film formation.
00ppm of Si (CH _{3) 4} -H ₂ mixed gas 20sc
cm, CH ₄ gas 1.0 sccm, H ₂ gas 180 SC
From the ratio of CM, H ₂ 200SCCM, C at 5 hours
After gradually changing the flow rate of the gas so that the flow rate of H ₄ becomes 1.0 SCCM, the mixed layer (first layer) is formed so that the amount of SiC gradually decreases from the substrate toward the film surface, and then continues. A diamond film (second layer) was formed for 15 hours (Sample No. 14). The obtained covering member was evaluated for sliding characteristics in the same manner as in Example 1, and the results are shown in Table 1.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction content]

[0034]

[Table 1]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C23C 28/04 // B23B 27/14 A 9326-3C

Claims (3)

[Claims] 1. A wear-resistant member comprising a hard carbon film having a thickness of 1 to 20 .mu.m coated on the surface of a base body made of a sintered body containing silicon nitride as a main component, and adjacent to the base side of the hard carbon film. A wear resistant member, characterized in that a mixed layer of hard carbon and silicon or a silicon compound is present. 2. The wear resistant member according to claim 1, wherein the thickness of the mixed layer is 0.1 to 5 μm. 3. The wear resistant member according to claim 1, wherein the thickness of the mixed layer is 45% or less of the total thickness of the hard carbon film.