JP2001214269A - Hard carbon laminated film and deposition method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard carbon laminated film excellent in adhesion with a metallic base material, good in wear resistance, lubricity, adhesion resistance or the like and applicable as sliding parts and wear resistant parts. SOLUTION: In a vacuum evaporation chamber, an amorphous silicon carbide film layer 2, a silicon-containing high density carbon film layer 3 having a film density of 2.2 to 3.5 g/cm3 and a silicon-containing low density carbon film layer 4 having a film density of 1.5 to 2.2 g/cm3 are successively laminated on the surface of a base material 1 to obtain a hard carbon laminated film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amorphous hard carbon laminated film such as a diamond-like carbon (hereinafter referred to as "DLC") film and a method for forming the same, and particularly to an excellent adhesion to a metal substrate. ,
The present invention relates to an amorphous hard carbon laminated film having excellent wear resistance, lubricity (low friction coefficient), and adhesion resistance, and applicable to sliding parts and wear resistant parts, and a method for forming the same.

[0002]

2. Description of the Related Art An amorphous hard carbon film formed on a metal substrate by an ion beam evaporation method, a sputtering method, a plasma CVD method, an arc ion plating method, a laser ablation method, or the like has a high hardness (Vickers hardness). 2000-4000Hv), high insulation (specific resistance 1)
0 ¹⁰ to 10 ¹⁴ Ω · cm), low friction coefficient (μ = 0.1 to
0.2), smooth surface morphology (surface roughness Ra)
= 0.3 nm or less), and has excellent properties such as being chemically stable and not attacked by acids or alkalis. Therefore, its application to cutting tools, wear-resistant protective films, sliding parts, etc. has been widely studied. ing.

An amorphous hard carbon film is called a DLC film because its physical properties are similar to those of diamond. It is an amorphous (amorphous) hard carbon film mainly composed of carbon. is there.

[0004]

However, such an amorphous hard carbon film has low adhesion to an iron-based material or a cemented carbide material such as a WC-Co-based material, and has a thickness of about 1 μm. It can only be vapor deposited. Further, with respect to severe sliding parts such as those used in automobiles, there is a problem that the coated film is peeled off by friction, and the performance cannot be satisfied.

In coating an amorphous hard carbon film on the surface of a cemented carbide material such as an iron-based material or a WC-Co-based material,
Several methods have been proposed to improve the various problems described above. For example, JP-A-56-41372 discloses that by providing an intermediate layer made of Si or SiC between a substrate and an amorphous hard carbon film, the adhesion between the substrate and the amorphous hard carbon film is improved. However, in this method, 5 μm is used.
It is specified that when the layer thickness exceeds m, peeling or chipping occurs in the deposited carbon coating layer, and it cannot be applied to a layer thickness exceeding 5 μm. This is considered to be due to the high internal stress of the amorphous carbon film.

Further, when the amorphous hard carbon film is coated on the surface of the base material, as a method of lowering the internal stress of the amorphous hard carbon film, a carbon film is made to contain a group IVa element such as silicon, germanium or tin. This is disclosed in
No. 57602. When a follow-up test was carried out on this content, it was possible to vapor-deposit up to 3 μm, but it was peeled off at a film thickness larger than 3 μm. This is considered to be due to insufficient adhesion at the interface between the amorphous carbon film and the substrate.

In order to ensure the adhesion between the DLC film and the base material, the present inventor coated an intermediate layer made of amorphous silicon carbide, and then formed an amorphous carbon film layer containing silicon. It has been found that by successively laminating, it is possible to obtain an amorphous hard carbon laminated film having high adhesion without peeling even at a film thickness of 15 μm. Then, regarding the adhesion of the laminated film, a scratch tester (CSR-01, manufactured by Resca Corp.)
Was measured as a critical peeling load Lc, which was more than 40 N, and it was confirmed that the adhesion was sufficiently practical.

Various hard carbon laminated films were prepared by this method, and the friction coefficient and the specific wear amount of the laminated film were examined using a ball-on-disk type friction / wear tester (HEIDON-20, manufactured by Shinto Kagaku Co., Ltd.). However, it was found that the friction coefficient and the specific wear amount greatly depend on the density of the silicon-containing amorphous carbon film as shown in FIGS. That is, in a laminated film in which the density of the silicon-containing amorphous carbon film exceeds 2.2 g / cm ³ , the friction coefficient μ is as large as 0.23 and the specific wear amount is Ws = 10 ⁻⁸ m.
It shows a large value of m ³ / N · mm.

On the other hand, when the density of the silicon-containing amorphous carbon film is as small as 1.9 g / cm ³ , the friction coefficient μ is as small as 0.05 and the specific wear amount is Ws = 10.
^It shows a small value of ⁻¹⁰ mm ³ / N · mm. A coating with good tribological properties means that the coefficient of friction is small,
These three conditions must be satisfied that the coating itself does not wear and that the aggressiveness to the counterpart material is low. From this, it can be said that an amorphous carbon film containing silicon and having a low film density is a film having excellent lubricity. However, a silicon-containing amorphous carbon film having a low film density cannot be applied to sliding parts (hydraulic pistons and piston rings, etc.) with a large applied load. However, there is a problem that it cannot withstand practical use.

FIG. 2 shows a conventional lamination structure in which a low-density carbon film layer 4a containing silicon is coated on a substrate surface 1 via an amorphous silicon carbide film layer 2, and FIG. 1 shows a conventional lamination structure in which a silicon-containing high-density carbon film layer 3a is covered with a crystalline silicon carbide film layer 2 interposed therebetween. 2, the thickness of the amorphous silicon carbide film layer 2 is 0.1 μm, and the thickness of the low-density carbon film layer 4a is 1 to 15 μm.
m is representative. In the case of such a low-density carbon film layer 4a, there is no problem when sliding with a light load, but there is a problem that the coating is broken when sliding with a high load. In the case of the high-density carbon film layer 3a shown in FIG. 3, the coating is not broken or peeled even under a high load, but there is a problem that the friction coefficient is large and the coating itself is greatly worn.

In view of the above problems, the present invention provides a hard carbon laminated film having excellent adhesion to a substrate, abrasion resistance and a low coefficient of friction, even for a sliding part with a high load. It is another object of the present invention to provide a method for forming the laminated film.

[0012]

According to a first aspect of the present invention, an amorphous silicon carbide film layer having a film density of 2.2 to 3.5 g / cm ³ is formed on a surface of a substrate. A hard carbon laminated film is formed by sequentially forming a high-density carbon film layer containing silicon and a low-density carbon film layer containing silicon having a film density of 1.5 to 2.2 g / cm ³ .

According to a second aspect of the present invention, in the first aspect, the high-density carbon film layer and the low-density carbon film layer contain 1 to 30 at% of silicon.

According to a third aspect of the present invention, there is provided a method for performing discharge cleaning by plasma of argon gas and hydrogen gas on a substrate disposed in a vapor deposition chamber to which an asymmetric pulse voltage is applied, and introducing the tetramethylsilane gas into the substrate. Forming an amorphous silicon carbide film layer on the material, then introducing a hydrocarbon-based gas in addition to tetramethylsilane gas to form a silicon-containing high-density carbon film layer; And a step of sequentially forming a high-density carbon film layer.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the asymmetrical pulse voltage has a negative voltage having an absolute value larger than an absolute value of a positive voltage and a frequency of 10 kHz.
At a frequency of z to 250 kHz, the minimum value of the time maintained at the positive voltage is 0.1 μs or more, and the maximum value is 40% in terms of duty ratio.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the hard carbon laminated film of the present invention has three layers laminated on the surface of the substrate. That is, an amorphous silicon carbide film layer 2, a silicon-containing high-density carbon film layer 3, and a silicon-containing low-density carbon film layer 4 are sequentially formed on the surface of the substrate 1. The amorphous silicon carbide film layer 2 is an intermediate layer for bonding the base material 1 and the silicon-containing high-density carbon film layer 3 with good adhesion. The silicon contained in the high-density carbon film layer 3 and further in the low-density carbon film layer 4 plays a role in reducing the internal stress (compression stress) of the hard carbon layer. The content of silicon in the hard carbon layer is suitably from 1 to 30 at%, and more preferably from 5 to 15 at%. This is because the silicon content is 3
If it exceeds 0 at%, the coefficient of friction will increase,
This is because when the sliding characteristics are reduced and the content is less than 1 at%, the internal stress is not reduced.

In the present invention, the coating density of the silicon-containing high-density carbon film layer 3 and the silicon-containing low-density carbon film layer 4 constituting the above-mentioned hard carbon laminated film is as follows. It is appropriate that the range is 2.2 to 3.5 g / cm ³ and the low density carbon film layer 4 has a range of 1.5 to 2.2 g / cm ³ . The magnitude of the film density can be controlled by appropriately adjusting the flow rate of the gas introduced into the reaction chamber in plasma CVD, the plasma density, and the ion impact energy to the substrate.

Since the high-density carbon film layer 3 has a high film density,
The distance between the constituent atoms is small. Therefore, it is hardly deformed by a load and is strong. On the other hand, since the low-density carbon film layer 4 has a low film density and a large interatomic distance between constituent atoms, the low-density carbon film layer 4 is easily deformed by a load. However, if there is a high-density carbon film layer 3 that is difficult to deform as a base of the low-density carbon film layer 4, the amount of deformation is small, and there is no breakage. Further, since the low-density carbon film layer 4 has a very small friction coefficient μ of 0.05, the outermost surface in contact with the counterpart material is covered with a film having excellent self-lubricating properties.

In the present invention, the amorphous silicon carbide film layer 2 formed on the surface of the substrate as an intermediate layer for bonding the substrate and the hard carbon laminated film layer with good adhesion has a thickness of 0.01 to 1 μm.
m, preferably 0.1 to 0.3 μm. The thickness of the silicon-containing high-density carbon film layer 3 is determined depending on what kind of sliding component the substrate on which the hard carbon laminated film layer is formed is applied. From the viewpoint of having both good adhesion and abrasion resistance, the film thickness is desirably in the range of 1 to 20 μm. On the other hand, when the thickness of the silicon-containing low-density carbon film layer 4 exceeds 3 μm, the load applied to the low-density carbon film layer 4 hardly affects the high-density carbon film layer 3, The load is absorbed only by the film layer 4, and as a result, the low-density carbon film layer 4 may be broken or peeled. The low-density carbon film layer 4 has a thickness of 0.01 μm.
If the thickness is smaller, the good properties (low friction coefficient, low wear amount) are hardly exhibited because the film thickness is too thin. From such a viewpoint, the low-density carbon film layer 4 has a thickness of 0.01
３3 μm, preferably 0.1-1 μm.

In the hard carbon laminated film according to the present invention, a substrate to which an asymmetric pulse voltage is applied is installed in a vacuum evaporation chamber, and the substrate is subjected to discharge cleaning by a mixed plasma of argon gas and hydrogen gas. A step of introducing silane gas to form an amorphous silicon carbide film layer on the substrate, and then introducing a hydrocarbon-based gas in addition to tetramethylsilane gas to form a silicon-containing high-density carbon film layer The step and the step of forming a low-density carbon film layer containing silicon are sequentially performed by a plasma CVD method.

Plasma CVD of the above-mentioned hard carbon laminated film
For example, the hot cathode P as shown in FIG.
IG (Penning Ionization Gau)
ge) A plasma CVD device may be used. The configuration of the hot cathode PIG plasma CVD apparatus will be briefly described. This apparatus has a vacuum deposition chamber 11 connected to a vacuum pump (not shown) via an exhaust port 12 below. A plasma chamber 13 is provided in the vacuum evaporation chamber 11 so as to cover the opening thereof, and a floating potential (insulation potential) is provided by an insulating plate 14 made of fluororesin or alumina.
Has been maintained. In the plasma chamber 13, a hot cathode 15, an anode 16, an electron injection electrode 17, a gas nozzle 18 are provided.
Is arranged. The hot cathode 15 is made of a tungsten filament and has a DC or AC capacity of 20 V, 100 A
Is maintained at a temperature (2000 ° C. or higher) at which thermoelectrons are emitted by the filament heating power supply.

Anode 1 arranged near hot cathode 15
6 is an anode power supply (capacity 100 V, 30 A, DC) 2
By 0, a positive voltage is applied to the hot cathode 15. In addition, an electron injection electrode 17 disposed close to the anode 16 is connected to an electron injection power supply 21 (capacity 100 V, 3
0A, direct current) and is maintained at the ground potential similarly to the wall of the vacuum deposition chamber 11. Therefore, the potential of the hot cathode 15 is controlled by the electron injection voltage, and its value is 0 to -10 with respect to the ground potential.
It is in the range of 0V. In addition, these hot cathode 15 and anode 1
6. The electron injection electrode 17 is floating from the wall of the plasma chamber 13, and this plasma chamber 13 is maintained at an insulating potential.

A reflecting electrode 24 is provided in the vacuum deposition chamber 11 so as to be opposed to the plasma chamber 13 and to be suspended from the wall of the vacuum deposition chamber 11 and supported by a holder 26 above. Substrate 25 is disposed. An asymmetric pulse power source 28 provided outside the vacuum evaporation chamber 11 is connected to the substrate 25 via a holder 26. The power supply 28 generates a pulse voltage in which the absolute value of the negative voltage is larger than the absolute value of the positive potential at a frequency of 10 to 250 k.
The frequency is applied in the range of Hz.

Reference numeral 23 denotes a nozzle for introducing a material gas into the vacuum evaporation chamber 11. Reference numeral 29 denotes a heater for heating the substrate 25 to a predetermined temperature. 32 and 33 are solenoid coils for controlling the shape of the plasma 35 formed in the vacuum evaporation chamber 11.

The gas used for obtaining the hard carbon laminated film using the plasma CVD apparatus having the above-mentioned structure includes:
Ar gas and H ₂ gas are used for discharge cleaning of the base material, and tetramethylsilane [Si (CH ₃ ) ₄ ] gas (hereinafter referred to as TMS gas) is used for forming an amorphous silicon carbide film as an intermediate layer. However, a TMS gas and a hydrocarbon-based gas are used for forming the silicon-containing carbon film. Examples of the hydrocarbon-based gas include CH ₄ , C ₂ H ₂ , C ₂ H ₄ , and C ₆ H ₆ , and among them, C ₂ H ₂ gas is preferable. As a silicon-based gas, in addition to TMS gas, monosilane (SiH
₄ ) Gas, silicon tetrachloride (SiCl ₄ ) gas, etc., but SiH ₄ gas has spontaneous ignition and explosive properties, and when used, equipment related to special material gas, such as cylinder cabinet, exhaust gas treatment equipment, gas detection It requires equipment and the like, which involves danger and requires high equipment costs. Also,
The SiCl ₄ gas is not explosive, but is corrosive and cannot be used unless special treatment is applied to the piping, vacuum chamber, etc. of the plasma CVD apparatus. TMS gas belongs to Class 4 of Dangerous Goods, Petroleum Class 1 and is handled according to acetone and gasoline, and is flammable but non-corrosive and less toxic. As described above, in the present invention, the TMS gas is used for forming the amorphous silicon carbide film and the silicon-containing carbon film.

In the discharge cleaning of the base material, an oxide layer, an organic contaminant layer, etc. on the base material surface are removed by bombarding an inert gas ion such as Ar gas before the formation of the coating, and the base material and the coating are removed. This is performed for the purpose of improving the adhesion, and is usually performed using only Ar gas, but in the present invention, H ₂ gas is introduced together with Ar gas. This is because plasma using only Ar gas requires time to remove the organic contaminated layer, and depending on the conditions of discharge cleaning, the residual organic gas present in the vacuum deposition chamber is activated by Ar gas plasma,
This is because there is a possibility that the carbon film adheres to the surface of the base material and contaminates the surface of the base material.

In a mixed plasma of Ar gas and H ₂ gas,
Since the oxidized layer and the organic contaminated layer are reduced to water vapor and hydrocarbon-based gas due to the chemical reactivity of hydrogen, the etching rate is large, and the substrate surface is not contaminated by the carbon film. An appropriate flow ratio of Ar gas and H ₂ gas introduced into the vacuum deposition chamber is, for example, Ar: H ₂ = 1: 2.

TMS gas is used for forming an amorphous silicon carbide film formed as an intermediate layer on the surface of a substrate cleaned by electric discharge cleaning, but hydrogen gas may be simultaneously introduced for the purpose of adjusting the film composition. . By introducing hydrogen, the amount of carbon in the amorphous silicon carbide layer can be reduced. However, if hydrogen is introduced more than necessary, the decomposition efficiency of the TMS gas decreases, and the deposition rate decreases.

To form the silicon-containing high-density carbon layer and the silicon-containing low-density carbon layer, TMS gas and hydrocarbon-based gas are simultaneously introduced into a vapor deposition chamber, and plasma CVD is performed. The silicon content can be adjusted by the ratio of the flow rate of the introduced TMS gas to the flow rate of the hydrocarbon-based gas. In particular, when C ₂ H ₂ is used as the hydrocarbon-based gas, the gas flow ratio is used in the range of C ₂ H ₂ : TMS = 1: 0.05 to 1. The film density of the carbon film layer is controlled by the amount and energy of ions incident on the substrate. The amount of ions is proportional to the plasma density and depends on the power for generating the plasma. Energy is controlled by the negative voltage of the asymmetric pulse voltage applied to the substrate. The ion current density is 0.5 mA /
At cm ² or more, the film density tends to decrease as the ion energy increases. On the other hand, when the ion current density is 0.1 mA / cm ² or less, the film density tends to increase as the ion energy increases.

In the discharge cleaning and the formation process of the hard carbon laminated film, an asymmetric pulse voltage is constantly applied to the substrate. In the asymmetric pulse voltage, the absolute value of the negative voltage is larger than the absolute value of the positive voltage, and the frequency is 10 kHz to 25 kHz.
At 0 kHz, the minimum time maintained at a positive voltage is 0.1
μs or more, and the maximum value is 40% in terms of duty ratio.

In the above-described asymmetric pulse power supply, when the absolute value of the positive voltage is larger than the absolute value of the negative voltage, the amount of electrons is larger than the amount of ions incident on the substrate. For this reason, charge is neutralized by making the absolute value of the positive voltage smaller than the absolute value of the pulse negative voltage. Further, the reason why the frequency is set to 10 to 250 kHz is that if the frequency is lower than 10 kHz, a sufficient effect of charge-up cannot be obtained, and if the frequency exceeds 250 kHz, noise is likely to occur, which is not preferable.

It is known that the reason why the time during which the positive voltage is maintained is 0.1 μs or more can prevent charge-up when a high frequency voltage of 13.56 MHz is applied to the base material, and is close to this 13.56 MHz. Frequency 1
The period of 0 MHz is 0.1 μs and is at least 0.1 μs.
This is because if a positive voltage is applied over a period of μs or longer, charge-up can be prevented. Also,
The reason for setting the duty ratio to 40% or less is that when the duty ratio is increased, ions do not enter the base material during that period, and low energy is required to form a dense and high-performance reaction film. This is because it has been found that ion irradiation with a large current is effective, and if the duty ratio is made unnecessarily large, it will be contrary to this.

The specific resistance of the amorphous silicon carbide film and the silicon-containing carbon film formed above is 10 ¹⁰ to 10 ¹³ Ω · c.
m, high resistance and high insulation. In a plasma CVD method for forming an insulating film using ion bombardment, a high frequency of 13.56 MHz is generally used as a substrate bias power supply. In the case of a high frequency, matching adjustment is necessary in order to efficiently supply power to the base material.
If the load of the plasma changes (the kind, flow rate, pressure, plasma density, substrate surface area, quantity, etc. of the gas introduced into the film forming chamber) of the plasma changes, the matching adjustment is always necessary and complicated. Some automatic matching devices can be adjusted automatically, but it takes about a few seconds to stabilize. In a period of about several seconds, film formation is unstable. In addition, since the adhesion of the film depends on the bonding force at the interface between the substrate surface and the film, at the initial stage of film formation and at the interface between the laminated films,
If the RF input power to the base material becomes unstable, a film having high adhesion strength cannot be obtained. There is also a problem in reproducibility.

When a high frequency of 13.56 MHz is used as a substrate bias power source, the above-mentioned unstable element is always present. To avoid this, in the forming method of the present invention, an asymmetrical DC pulse is applied to the substrate. A voltage is applied to the substrate. The asymmetric pulse power supply does not require the matching adjustment required at high frequencies. In addition, the price is 1/3 to 1/4 of that of the high frequency power supply, and the hard carbon laminated film can be formed at low cost.

[0035]

EXAMPLE An amorphous hard carbon laminated film was formed using the hot cathode PIG plasma CVD apparatus shown in FIG. 4 described above. Note that a SUS304 mirror surface plate was used as a base material. The SUS304 mirror surface plate was supported in the holder 26 and placed in the vacuum evaporation chamber 11 as a substrate 25. Ar gas was introduced into the vapor deposition chamber 11 from the gas nozzle 18 of the plasma chamber 13 at a flow rate of 10 mL / min and H ₂ gas at a flow rate of 20 mL / min. The plasma gun output was 500 W, and the substrate pulse bias applied to the substrate was -400 V. Then, discharge cleaning was performed for 10 minutes. Thereafter, while the Ar gas and the H ₂ gas are flowing, a TMS gas is introduced at 30 mL / min from the material gas introducing nozzle 23 into the vapor deposition chamber 11 to form a film for 5 minutes, and the amorphous silicon carbide film is formed to a thickness of 100 nm. Deposited to a thickness of

Next, 150 mL of C ₂ H ₂ gas was introduced into the vapor deposition chamber.
/ Min, the TMS gas flow rate is 20 mL / min,
The H ₂ gas was adjusted to 0 mL / min, a film was formed for 50 minutes, and a high-density carbon film having a film density of 2.4 g / cm ³ was deposited to a thickness of 5 μm. Further, a film was formed for 13 minutes while adjusting the plasma output to 250 W while maintaining the gas flow rate, and a low-density carbon film layer having a film density of 2.0 g / cm ³ was deposited at 1 μm, as shown in FIG. A hard carbon laminated film of the present invention was formed.

COMPARATIVE EXAMPLE 1 In the same manner as in the above embodiment, Ar was transferred from the plasma chamber to the deposition chamber.
Gas at 10 mL / min, H ₂ gas at 20 mL / min
, A plasma gun output of 500 W, a substrate pulse bias applied to the substrate of -400 V, and discharge cleaning for 10 minutes. Thereafter, with the Ar gas and the H ₂ gas flowing, 30 mL / min of TMS gas is supplied to the vapor deposition chamber.
After the introduction, a film was formed for 5 minutes, and an amorphous silicon carbide film was deposited to a thickness of 100 nm. Then C ₂ H ₂ gas 150 mL /
min, the TMS gas flow rate is 20 mL / min, H
_{(2) The} gas flow rate was adjusted to 0 mL / min, the film was formed for 60 minutes, and a high-density carbon film having a film density of 2.4 g / cm ³ was deposited by 6 μm to form a hard carbon film layer shown in FIG.

COMPARATIVE EXAMPLE 2 In the same manner as in the above embodiment, Ar was transferred from the plasma chamber to the deposition chamber.
Gas at 10 mL / min, H ₂ gas at 20 mL / min
And a discharge cleaning was performed for 10 minutes with a plasma gun output of 500 W and a substrate pulse bias applied to the substrate of −400 V. Then, while flowing Ar gas and H ₂ gas, a TMS gas was introduced into the deposition chamber at a rate of 30 mL / min, and a film was formed for 5 minutes.
nm. Next, 150 mL of C ₂ H ₂ gas was introduced into the deposition chamber.
/ Min, the TMS gas flow rate was adjusted to 20 mL / min, the H ₂ gas was adjusted to 0 mL / min, the plasma gun output was adjusted to 250 W, and the film was formed for 80 minutes, and the film density was 2.0 g / cm ³ . The low-density carbon film having a thickness of 6 μm was deposited to form a hard carbon film layer shown in FIG.

In the above Examples and Comparative Examples 1 and 2, SUS3
The silicon content of the low-density carbon film layer and the high-density carbon film layer was measured by an X-ray microanalyzer (EPMA) for the laminated films formed to a thickness of 6.1 μm on each of the 04 base materials. No significant difference was observed at 5 at%. The coating Knoop hardness is 1500 Hk for the low density carbon film layer and 2300 Hk for the high density carbon film layer.
k, and the high-density carbon film layer was harder.

Further, a friction and wear test was performed on these laminated films. The results are shown in Table 1. The friction test was performed using a ball-on-disk type friction and wear tester (HEIDON-20, manufactured by Shinto Kagaku Co., Ltd.). The counterpart material was a hemispherical single-crystal diamond indenter having a radius of 5 mm. The rotation was performed at 150 rpm, the number of repetitions was 20,000, in the atmosphere, and without lubrication. In addition, the adhesion of the coating film was evaluated by increasing the load while sliding, and the value at which the coating film was broken and the friction coefficient suddenly increased.

[0041]

[Table 1]

From Table 1, it can be seen that the coefficient of friction of the hard carbon laminated film of the embodiment of the present invention is about 1/4 as compared with the high density carbon film of Comparative Example 1 which is a prior art. The specific wear amount is about 1
/ 10 and small. Further, the peeling load was about 5 times as large as that of the low-density carbon film of Comparative Example 2 which was the prior art. From the above, it was confirmed that the hard carbon laminated film of the present invention is a film that shows excellent sliding characteristics even in frictional wear under a high load.

[0043]

As described above, the amorphous silicon carbide film layer on the substrate surface, the high-density carbon film layer containing silicon having a film density of 2.2 to 3.5 g / cm ³ , the film density Is 1.5
The hard carbon laminated film of the present invention obtained by sequentially forming a silicon-containing low-density carbon film layer of up to 2.2 g / cm ³ has excellent adhesion to a substrate and has a friction coefficient of about the conventional value. 1/4
Since the specific wear amount is as small as 1/10 and the peeling load is about five times that of the conventional one, the sliding characteristics are stable even with high load frictional wear. further,
According to the forming method of the present invention, such a hard carbon laminated film can be formed with good reproducibility and stably, and is very effective as a solid lubricating film required for various sliding parts. I can say.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a hard carbon laminated film of the present invention.

FIG. 2 is an explanatory view showing a configuration of a conventional hard carbon laminated film.

FIG. 3 is an explanatory view showing a configuration of a conventional hard carbon laminated film.

FIG. 4 is an explanatory view showing one example of a plasma CVD apparatus used for forming a hard carbon laminated film of the present invention.

FIG. 5 is a diagram showing a relationship between a film density of a hard carbon laminated film and a friction coefficient.

FIG. 6 is a diagram showing the relationship between the film density of the hard carbon laminated film and the specific wear amount.

[Explanation of symbols]

 Reference Signs List 1 base material 2 amorphous silicon carbide film 3 silicon-containing high-density carbon film 4 silicon-containing low-density carbon film

Claims (4)

[Claims] An amorphous silicon carbide film layer on a surface of a substrate, a high-density carbon film layer containing silicon having a film density of 2.2 to 3.5 g / cm ³ , and a film density of 1.5 to 2 A hard carbon laminated film characterized by sequentially forming a silicon-containing low-density carbon film layer of 0.2 g / cm ³ . 2. The hard carbon laminated film according to claim 1, wherein the high-density carbon film layer and the low-density carbon film layer contain 1 to 30 at% of silicon. 3. A step of subjecting a substrate disposed in a vacuum evaporation chamber to an asymmetric pulse voltage to be subjected to discharge cleaning by plasma of argon gas and hydrogen gas, and introducing tetramethylsilane gas to form an amorphous layer on the substrate. Forming a silicon carbide film layer, then introducing a hydrocarbon-based gas in addition to tetramethylsilane gas to form a silicon-containing high-density carbon film layer, and further forming a silicon-containing low-density carbon film layer And a step of sequentially performing the steps of forming a hard carbon laminated film by a plasma CVD method. 4. The asymmetric pulse voltage has an absolute value of a negative voltage larger than an absolute value of a positive voltage and a frequency of 10 kHz.
The hard carbon according to claim 3, wherein the minimum value of the time maintained at a positive voltage at 0.1 kHz to 250 kHz is 0.1 μs or more, and the maximum value is 40% in terms of duty ratio. A method for forming a laminated film.