JPH06346074A - Sliding member having abrasion-resistant coating - Google Patents

Abstract

PURPOSE:To obtain a sliding member made of an aluminum or iron alloy coated with a coating layer having excellent abrasion resistance and sliding characteristics and resistant to abrasion and peeling even if foreign matters are intruded between the sliding surfaces. CONSTITUTION:A sliding member made of an aluminum alloy (e.g. a high-silicon aluminum alloy) having a sliding face, wherein at least the sliding face of the sliding member is coated with an amorphous hard carbon film having a thickness of 2-20mum and containing silicon and nitrogen. A sliding member made of an iron alloy having a sliding face, wherein at least the sliding face of the sliding member is coated with an amorphous hard carbon film having a thickness of 2-20mum and containing silicon and nitrogen. A sliding member made of an aluminum alloy having a sliding face, wherein at least the sliding face of the sliding member is coated with a silicon-containing amorphous hard carbon film having a thickness of 4-15mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding part made of an aluminum-based or iron-based alloy having a coating excellent in abrasion resistance and sliding characteristics. In particular, the present invention relates to a sliding component that can be suitably used for a compressor or the like used in a CFC substitute refrigerant having a coating having excellent wear resistance and sliding characteristics.

[0002]

2. Description of the Related Art At present, in automobiles and the like, from the viewpoint of reducing fuel consumption, weight reduction is progressing and aluminum-based materials are used for various parts. However, aluminum-based materials have low wear resistance, and parts that require wear resistance have high strength (8-20%) and excellent strength and wear resistance.
Often, high silicon content aluminum alloys containing silicon are used.

For example, the high silicon-containing aluminum alloy is also used in compressors for automobile air conditioners and the like. Further, in the case of a compressor for an automobile air conditioner or the like, good sliding characteristics are required in addition to abrasion resistance. Therefore, a material in which a high silicon content aluminum alloy is compounded with a self-lubricating agent has also been proposed (JP-A-5-43692 and JP-A-5-43693).

[0004]

By the way, in recent years, the destruction of the ozone layer by CFC has become a big social problem. Therefore, as a refrigerant for an automobile air conditioner, an alternative refrigerant instead of CFC has been used. Such alternative refrigerants include chlorine-free refrigerants such as HFC-134a. However, such an alternative refrigerant cannot be expected to have an extreme pressure effect because it does not contain chlorine, and as a result,
The sliding environment of the air conditioner compressor becomes extremely harsh. Therefore, in the present situation, even a high-silicon-containing aluminum alloy having excellent wear resistance causes considerable wear. Therefore, as one proposal, it is performed to reduce the wear of the sliding member of the compressor by mixing an additive such as refrigerating machine oil into the alternative refrigerant. However, it is required to improve the fuel consumption and reduce the wear amount by further reducing the friction loss.

Therefore, the sliding parts made of an aluminum alloy having a high silicon content of the compressor are coated with Ni-P plating or the like on their surfaces. However, in a high silicon aluminum alloy, when the silicon content is 12% or more (eutectic point or more), primary crystal silicon (particle diameter of about 10 to 50 μm) is mixed in the material. This primary crystal silicon projects from the surface or gradually falls off from the surface of the component as the component slides. The primary crystal silicon particles that have fallen off are mixed as foreign matter between the sliding surfaces and cause abrasion and peeling of the protective film such as Ni—P plating provided on the sliding surfaces.

In addition to the dropped primary crystal silicon particles, various foreign substances may be mixed between the sliding surfaces. As a result, the protective film on the sliding surface may be worn and peeled off. Such a problem of foreign matter mixing between the sliding surfaces is not limited to the high silicon content aluminum alloy sliding parts, but may be an aluminum alloy sliding part other than the high silicon content aluminum alloy or an iron-based sliding part. This is a common problem with sliding parts such as alloy sliding parts.

Therefore, an object of the present invention is to provide a sliding part made of an aluminum alloy, which is excellent in wear resistance and sliding characteristics, and which is coated with a coating which is unlikely to be worn and peeled off even when foreign matter is mixed between sliding surfaces. And to provide sliding parts such as iron-based alloy sliding parts.

[0008]

DISCLOSURE OF THE INVENTION The present invention is a sliding part made of an aluminum alloy having a sliding part, wherein at least the sliding part is amorphous containing nitrogen and silicon having a thickness of 2 to 20 μm. The present invention relates to a sliding part coated with a hard carbon film.

Further, the present invention is a sliding component made of an iron-based alloy having a sliding portion, wherein at least the sliding portion has a thickness of 2
A sliding part coated with an amorphous hard carbon film containing nitrogen and silicon having a thickness of 20 μm

The present invention is also an aluminum alloy sliding component having a sliding portion, wherein at least the sliding portion is coated with an amorphous hard carbon film containing silicon having a thickness of 4 to 15 μm. The present invention relates to a sliding component.

The amorphous hard carbon film of the present invention will be described below. C using plasma or ion beam
The amorphous hard carbon film formed by the vapor deposition method such as VD is
Since it has a high hardness (Vickers hardness of about 2000 to 5000), it is attracting attention as a hard coating material. The amorphous hard carbon film is also called an amorphous carbon film, a diamond-like carbon film, an i-carbon film, an aC: H film, or the like, and is a high hardness carbon film mainly composed of amorphous carbon.

In the present invention, as the amorphous hard carbon film, a film containing silicon or a film containing nitrogen and silicon is used. The amorphous hard carbon film containing silicon was developed for the purpose of improving the adhesion to a substrate (JP-A-62-157602). Further, an amorphous hard carbon film containing nitrogen and silicon has not been known so far and has been newly developed by the present inventor.

In the present invention, the amorphous hard carbon film containing silicon has a thickness of 4 to 15 μm from the viewpoint that abrasion and peeling hardly occur even if foreign matter is mixed in between the sliding surfaces.
m range. If the thickness of the film is less than 4 μm, sufficient abrasion resistance cannot be obtained, and if it exceeds 15 μm, peeling easily occurs. Similarly, the amorphous hard carbon film containing nitrogen and silicon has a thickness in the range of 2 to 20 μm from the viewpoint that abrasion and peeling are unlikely to occur even if foreign matter is mixed in between the sliding surfaces. . If the thickness of the film is less than 2 μm, sufficient abrasion resistance cannot be obtained, and if it exceeds 20 μm, peeling easily occurs.

The amorphous hard carbon film containing silicon has already been disclosed in JP-A-62-157602. However, the silicon content of the amorphous hard carbon film containing silicon used in the present invention is preferably in the range of 10 to 35 atom% from the viewpoint that good adhesion and abrasion resistance can be obtained. Is. In addition, as a film forming method, for example, a vapor deposition material is introduced into a vapor deposition chamber in which a substrate is installed, and vapor deposition is performed on the substrate. The vapor deposition method is not particularly limited and can be performed by a conventional method. For example, a vapor deposition method using plasma or an ion beam can be used as appropriate. The thickness of the amorphous hard carbon film can be appropriately changed by adjusting the vapor deposition conditions.

On the other hand, an amorphous hard carbon film containing nitrogen and silicon has not been known so far, and its composition and film forming method will be described below.

Amorphous hard carbon films generally include carbon and hydrogen. Therefore, the amorphous hard carbon film is also called an a (amorphous) -C (carbon): H (hydrogen) film.
In contrast, what is used in the present invention is an amorphous hard carbon film containing silicon and nitrogen in addition to carbon and hydrogen. Whether the carbon film is an amorphous carbon film can be determined from the results of measurement with a Raman spectrophotometer or X-ray diffraction test. Further, this amorphous hard carbon film has a high Vickers hardness of about 2000 to 5000.

The hydrogen content in the carbon film varies depending on the type of raw material used, vapor deposition conditions (high-frequency input power, reaction pressure, etc.), and is, for example, about 0.5 to 5.0 × 10 ²² atoms /
It is cm ³ . Within this range, the adhesion to the substrate is also good. The content of silicon and the content of nitrogen in the carbon film may be about 10 to 35 atom% and 0.1 to 10 atom%, respectively, from the viewpoint of obtaining good adhesion and abrasion resistance. Appropriate.

In the above amorphous hard carbon film, a carbon raw material, a silicon raw material, and a nitrogen raw material are introduced into a vapor deposition chamber in which a base material is installed, and the amorphous hard carbon containing silicon and nitrogen on the base material. It can be manufactured by depositing a film.

Examples of the carbon raw material include hydrocarbons, and the hydrocarbons include methane, acetylene,
Examples thereof include ethylene. A particularly preferred carbon source is methane. Examples of the silicon raw material include organic silicon compounds, and examples of the organic silicon compounds include tetramethylsilane (TMS), SiH ₄ , Si ₂ H ₆ ,
SiCl ₄ , SiH ₂ F, etc. can be exemplified. A particularly preferable silicon raw material is tetramethylsilane from the viewpoints of low toxicity and corrosiveness and good operability. Examples of the nitrogen source include nitrogen (N ₂ ) and nitrogen-containing compounds, and examples of the nitrogen-containing compound include ammonia and amine.

The silicon raw material, carbon raw material, and nitrogen raw material are generally introduced into the vapor deposition chamber in gaseous form. Therefore, what is liquid at room temperature is introduced into the vapor deposition chamber using a suitable carrier gas. For example, tetramethylsilane (TMS), which is a silicon raw material, has a boiling point of 26 ° C. Therefore, for example, in order to keep the vapor pressure constant, in tetramethylsilane maintained at a constant temperature, as a carrier gas,
For example, nitrogen gas that is a nitrogen source can be introduced, and the resulting mixed gas of tetramethylsilane and nitrogen can be introduced into the vapor deposition chamber. Further, when introducing the above raw material into the vapor deposition chamber, an inert gas such as helium or argon can be used as a carrier gas. Further, a mixture of a raw material compound gas and an inert gas can also be used as a carrier gas.

The ratio of silicon raw material, carbon raw material and nitrogen raw material is such that the molar ratio of C: Si: N is 5: 0.05.
It is suitable to set the ratio within the range of 1.0 to 0.4 to 4.0 from the viewpoint of obtaining an amorphous hard carbon film having a desired composition. In particular, when methane is used as a carbon raw material, tetramethylsilane is used as a silicon raw material, and nitrogen is used as a nitrogen raw material, the molar ratio of methane to tetramethylsilane and nitrogen is 5: 0.1 to 1.0 :. 0.2 ~
The range of 2.0 is suitable from the viewpoint of obtaining an amorphous hard carbon film having a desired composition.

The amorphous hard carbon film is deposited on the base material by introducing the raw material into the vapor deposition chamber in which the base material is installed. The vapor deposition method is not particularly limited and can be performed by a conventional method. For example, plasma (eg, high frequency CVD
Method, ECR-CVD method, sputtering method (PVD))
Alternatively, a vapor deposition method using an ion beam (for example, an ion plating method (PVD)) can be used as appropriate. The thickness of the amorphous hard carbon film can be appropriately changed by adjusting the vapor deposition conditions.

Next, the sliding component provided with the amorphous hard carbon film will be described. In the present invention, the sliding parts are made of iron alloy or aluminum alloy. Examples of iron alloys include high speed tool steel and bearing steel. As the aluminum alloy, for example, a high silicon content aluminum alloy containing high concentration (8 to 20%) of silicon, for example, ADC10, ADC1.
2, A390, ASCM and the like. In particular, for sliding parts made of a high silicon content aluminum alloy, an amorphous hard carbon film containing nitrogen and silicon having a thickness of 2 to 20 μm or an amorphous hard carbon film containing silicon having a thickness of 4 to 15 μm is used. By coating the carbon film,
It is possible to effectively prevent abrasion and peeling of the protective film due to mixing of primary crystal silicon particles.

In the present invention, the sliding part is not particularly limited as long as it is a sliding part that requires abrasion resistance and sliding characteristics. However, since the sliding component of the present invention is excellent in wear resistance and sliding characteristics, it is particularly useful as a sliding component of a compressor for an air conditioner that uses a chlorine-free alternative refrigerant. As a compressor, a swash plate type compressor (for example, Japanese Utility Model Laid-Open No. 57-42180) or a vane type rotary compressor (for example, Japanese Patent Laid-Open No. 64-32).
No. 087) and the like.

The swash plate compressor generally includes a swash plate that is inclined and fixed to a rotating shaft, pistons fitted in a plurality of cylinders provided in parallel with the rotating shaft, and the piston and the swash plate. The swash plate is interposed between the swash plate and the swash plate, and the sphere plate is provided with a spherical portion and a flat surface portion, and the spherical surface portion is in sliding contact with a spherical concave portion provided on the piston. The rotation of the piston causes the piston to reciprocate through the shoe to compress the refrigerant. Then, examples of the sliding portion in such a swash plate compressor include a contact surface between the swash plate and the shoe and a contact surface between the piston and the shoe. Regarding the contact surface between the swash plate and the shoe, a high silicon content aluminum alloy is generally used for the swash plate, and an iron-based alloy such as bearing steel is used for the shoe. Either one of the contact surfaces is coated with the amorphous hard carbon film. Also, regarding the contact surface between the piston and the shoe, in general,
Since it is structurally impossible to form a film on the piston side, the spherical surface of the shoe is covered with the amorphous hard carbon film.

Further, the vane type rotary compressor has a cylinder made of an aluminum alloy sandwiched between two side blocks, a rotor rotatably provided in the cylinder, and a vane groove of the rotor in a radial direction. The vane is inserted into and retracted from the vane, and the refrigerant is sucked and compressed by the rotation of the rotor and the vane accompanying the vane. The rotor, vane, cylinder, and side block are made of high silicon content aluminum alloy. And as a sliding part in such a vane type rotary compressor, for example,
Examples thereof include a sliding portion between the vane groove of the rotor and the vane, a sliding portion between the cylinder inner wall and the vane, and a sliding portion between the side block and the vane. In this case, the amorphous hard carbon film can cover the sliding surface of the vane (at least the sliding surface or the entire vane). Further, there is a sliding portion between the side surface of the rotor and the side block, and in this case, either the side surface of the rotor or the side block is covered with the amorphous hard carbon film.

[0027]

According to the present invention, a sliding component made of an aluminum alloy, which is excellent in wear resistance and sliding characteristics, and which is coated with a coating that is unlikely to wear or peel off even if foreign matter is mixed between sliding surfaces. Also, sliding parts such as iron-based alloy sliding parts can be provided. Such a sliding component of the present invention has a low friction coefficient even in the alternative refrigerant containing no chlorine, has a small amount of wear of the mating material and the amorphous carbon film, and has a low heat generation due to sliding. Furthermore, by using the sliding component of the present invention, it is possible to reduce fuel consumption in an automobile air conditioner or the like.

Since the amorphous hard carbon film used in the present invention is formed by the plasma CVD method or the like, the processing temperature is low (for example, 200 ° C. or lower) and the coating is performed without changing the properties of the base material. It is possible to
Another feature is that the processing time required for coating is short (for example, about 1 to 2 hours).

[0029]

EXAMPLES The present invention will be described in more detail below with reference to examples.

EXAMPLE 1 Methane as a source gas and a mixed gas of TMS and nitrogen obtained by bubbling TMS kept at 0 ° C. with nitrogen gas by the parallel plate high frequency plasma CVD method shown in FIG. Introduced in. High speed tool steel (SKH51) was used as the substrate. Methane flow rate is 5 sccm, nitrogen flow rate is 1 sccm, reaction pressure is 8P
a, input power was 100W. Under this condition, the amorphous hard carbon film is formed into a high silicon content aluminum alloy (ASC
A film was formed on M). At this time, the film thickness was 5 μm and the film formation rate was 6 μm / hr.

The spectrum of this carbon film was measured by a Raman spectrophotometer. The results are shown in Figure 2. from this result,
It was found that the obtained carbon film was an amorphous carbon film.
The Vickers hardness of this carbon film was 2700. Therefore, it was found that the obtained carbon film was an amorphous hard carbon film. Further, the hydrogen content in the amorphous hard carbon film was determined by FT-IR, and was found to be 1 × 10 5.
^{It was 22} atoms / cm ³ . The silicon content in the amorphous hard carbon film was quantified by Auger spectroscopy,
It was 20 atomic%. The presence of nitrogen in the obtained amorphous hard carbon film was confirmed by EPMA and FT-IR.

Example 2 A carbon film having a thickness of 8 μm was prepared in the same manner as in Example 1 except that TMS was introduced into the plasma by using helium gas instead of nitrogen gas. Obtained. As a result of analyzing this carbon film by Raman spectroscopy, it was an amorphous carbon film. The Vickers hardness of this carbon film is 250.
It was 0. Therefore, it was found that the obtained carbon film was an amorphous hard carbon film. Further, the hydrogen content in the amorphous hard carbon film was quantified by FT-IR,
It was 1 × 10 ²² atoms / cm ³ . Furthermore, FT-IR
As a result of analysis by, the amorphous hard carbon film did not contain silicon. In addition, as a result of confirmation by EPMA and FT-IR, nitrogen was not present in the obtained amorphous hard carbon film.

Test Example 1 (Sliding Property and Wear Property) ASCM coated with the amorphous hard carbon film obtained in Example 1 and A39 which is a high silicon aluminum alloy.
0 (Si content 16%, primary crystal Si grain size 20 μm) was subjected to a friction wear test by a high pressure atmosphere wear tester in an alternative refrigerant HFC134a + refrigerator oil atmosphere. The result is shown in FIG. FIG. 2 shows Ni-P tested under the same conditions.
The results for the plated ASCM are also shown. As is clear from FIG. 2, the friction coefficient of Example 1 is remarkably improved as compared with the Ni-P plated ASCM.

Further, the ASCM coated with the amorphous hard carbon film of Example 1 was subjected to a wear test for 10 hours in the above atmosphere at a surface pressure of 15 MPa. As a result, the wear amounts of both the amorphous hard carbon film and A390 were out of the detection limit (0.0001 g or less).

Example 3 (Influence of film thickness) In Example 1, the AS was coated with amorphous hard carbon films of various thicknesses shown in Table 1 by changing the film formation time.
I got a CM. The surface pressure of the obtained ASCM is 15MP
The abrasion test was performed for 10 hours in the atmosphere of the alternative refrigerant HFC134a + refrigerating machine oil in a. Table 1 shows the relationship between the film thickness and the presence or absence of peeling during the abrasion test. When the film thickness was less than 2 μm, streak-like peeling due to the drop of the primary crystal Si from the mating material (A390) was apparent, and when it exceeded 20 μm, cracks due to yielding were confirmed in the hard carbon film. Film thickness is 2 to 20 μm
No peeling or cracking was observed between the two, and good sliding characteristics were exhibited. Further, more preferably, the film thickness was between 4 and 8 μm.

[0036]

[Table 1]

Example 4 (Influence of film thickness) In Example 2, the AS was coated with amorphous hard carbon films of various thicknesses shown in Table 2 by changing the film formation time.
I got a CM. A wear test was performed on the obtained ASCM in the same manner as in Example 3. Table 2 shows the relationship between the film thickness and the presence or absence of peeling during the abrasion test. When the film thickness is less than 4 μm, streak-like peeling due to the drop of the primary crystal Si from the mating material (A390) is apparent, and when it exceeds 15 μm, cracks due to yielding in the hard carbon film were confirmed. When the film thickness was 4 to 15 μm, neither peeling nor cracking was observed, and good sliding characteristics were exhibited. Further, more preferably, the film thickness was between 5 and 8 μm.

[0038]

[Table 2]

[Brief description of drawings]

FIG. 1 is a parallel plate type RF plasma CVD used in Examples.
It is a schematic explanatory drawing of the apparatus of the method.

FIG. 2 shows a friction wear test result by a high pressure atmosphere wear tester performed in Test Example 1.

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Claims (4)

[Claims] 1. An aluminum alloy sliding component having a sliding portion, wherein at least the sliding portion has a thickness of 2 to 20.
A sliding part coated with an amorphous hard carbon film containing nitrogen and silicon having a thickness of μm. 2. The sliding component according to claim 1, wherein the aluminum alloy is a high silicon content aluminum alloy. 3. An iron-based alloy sliding part having a sliding part, wherein at least the sliding part is coated with an amorphous hard carbon film containing nitrogen and silicon having a thickness of 2 to 20 μm. Sliding parts characterized by 4. An aluminum alloy sliding component having a sliding portion, wherein at least the sliding portion has a thickness of 4 to 15.
A sliding part coated with an amorphous hard carbon film containing silicon having a thickness of μm.