JP5126867B2 - Carbon film manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a carbon film useful as a sliding member of a drive machine.

  Carbon films have excellent properties such as wear resistance and low friction, and have been applied as protective films, solid lubricating films, or sliding materials. In particular, with the growing awareness of environmental protection issues in recent years, there has been a strong demand for hydraulically driven machines that use water with less environmental impact. There is an urgent need to develop excellent carbon films. In addition, the weight of drive machines has been reduced, and carbon films using aluminum or magnesium-based alloys as base materials are being studied.

  However, in general, a carbon film material based on an iron-based metal may cause the carbon film to peel off from the substrate under water or severe conditions, and a lightweight alloy such as aluminum or a magnesium-based alloy may be used as the substrate. The carbon film material to be used has a problem that the adhesion between the base material and the carbon film is inferior.

  In order to solve such a problem, an intermediate layer made of a carbon film containing the same metal composition as that of the base material and having a higher metal element concentration toward the base metal side is formed between the base metal and the carbon film. (Patent Document 1) and “Sliding member having a bond layer, an intermediate layer, a hard bond layer, and an outermost hard carbon coating layer” (Patent Document 2) ) Etc. have been proposed.

  However, the former requires the use of an expensive sublimable organometallic compound such as ferrocene, necessitates the installation of a heating means for introducing this, and further uses a different organometallic compound depending on the substrate. A large number of gas introduction units are required, and there are problems such as high cost and complicated processes. Moreover, since the latter has a multi-layer structure, it is necessary to use various kinds of gases as the source gas, and there is a problem that the process and operation management become complicated.

JP-A-10-72287 JP 2004-169137 A

  The present invention has been made in view of the above-described prior art, and the purpose thereof is an intermediate layer provided by a simple and inexpensive process, which has excellent adhesion to a substrate and is resistant to peeling and abrasion. Another object of the present invention is to provide a method capable of industrially advantageously producing a carbon film excellent in low friction.

As a result of earnestly examining the manufacturing method of the carbon film, the present inventors have prepared an intermediate layer interposed between the base material and the carbon film by a combination of physical vapor deposition and chemical vapor deposition. Surprisingly, it has been found that the above problems can be solved, and the present invention has been completed.
That is, this application provides the following invention.
(1) As the metal substrate side high metal component concentration, via an intermediate layer having a concentration gradient such that the concentration of carbon and silicon as diamond-like carbon film side becomes high, diamond-like, which is provided on a metal substrate the method of manufacturing a carbon film, a diamond-like carbon film, which created by applying a DC bias to the metal substrate by a combination of physical vapor deposition and chemical vapor deposition the intermediate layer Production method.
(2) The method for producing a diamond-like carbon film according to (1), wherein the DC bias is −30 to −200V .
(3) Physical the vapor deposition and the chemical vapor deposition is characterized by being performed in parallel (1) or (2) the production method of diamond-like carbon film according to.

According to the method of the present invention, a carbon film excellent in peeling resistance, wear resistance and low friction is industrially advantageously produced through an intermediate layer excellent in adhesion to a substrate by a simple and inexpensive process. it can.
In addition, the carbon film obtained by the method of the present invention has improved peeling resistance of the carbon film in an air or water environment, and is slid in a place where a mechanical sliding mechanism exists, particularly in a water environment. It can be widely applied as lubrication and protective material for moving parts. Currently, the application of carbon film as a solid lubricant film has limited applications and has many problems such as adhesion to the substrate, but the carbon film of the present invention has adhesion and peeling resistance to the substrate. It is excellent in property, more base materials can be used, further contributes to resource saving and energy saving, suppresses adverse effects on the environment, and is useful for environmental conservation.

  The method for producing a carbon film of the present invention comprises a carbon provided on a metal substrate via an intermediate layer having a concentration gradient such that the metal component concentration is higher on the metal substrate side and the nonmetal component concentration is higher on the carbon film side. In the film manufacturing method, the intermediate layer is formed by a combination of physical vapor deposition and chemical vapor deposition.

  Any conventionally known metal substrate can be used as the metal substrate, and in addition to iron-based substrates such as iron, cobalt, nickel, stainless steel, and alloy steel, lightweight alloy-based substrates such as aluminum and magnesium can also be used.

The intermediate layer of the present invention is formed on this metal substrate by a combination of physical vapor deposition (PVD) and chemical vapor deposition (CVD).
A single metal component is deposited on the base material by the former PVD method, and a compound or composite of a metal component and a non-metallic component is deposited on the base material by the latter CVD method. The concentration gradient is such that the concentration of the nonmetallic component increases as the carbon film side increases. In the present invention, the physical vapor deposition method (PVD method) and the chemical vapor deposition method (CVD method) are used in combination. The former method may be preceded, and then the latter method may be performed. Both methods may be carried out in parallel, but a method carried out in parallel is preferred.
In the preparation of the intermediate layer only by chemical vapor deposition (CVD) without using physical vapor deposition (PVD) and chemical vapor deposition (CVD), adhesion to the substrate However, it is difficult to achieve the intended purpose of the present invention.

Examples of the single metal component forming the intermediate layer include iron-based alloys such as chromium, titanium, tungsten, cobalt, iron, and stainless steel. Among these, chromium, titanium, tungsten, stainless steel, etc. are preferable.
These simple metal components are made on a metal substrate by PVD method targeting iron alloys such as chromium, titanium, tungsten, cobalt, iron or stainless steel.

In addition, examples of the compound or composite of the metal component and the nonmetal component that form the intermediate layer include CrC, TiC, CoC, and SiC.
These components are made on a metal substrate by CVD using silicon organic compounds such as tetramethylsilane and hexamethyldisiloxane, and hydrocarbon compounds such as methane, ethylene, benzene, and toluene as source gases. Is done. Hexamethyldisiloxane is preferred as the silicon organic compound, and methane and toluene are preferred as the hydrocarbon compound.

Examples of the PVD method used in the present invention include a sputtering method, a laser ablation method, and an ion beam evaporation method. From the viewpoint of convenience and good adhesion in combination with the CVD method, the sputter PVD method can be used. Is preferably used.
In addition, examples of the CVD method used in the present invention include a thermal CVD method, a laser CVD method, a plasma CVD method, and the like. From the viewpoint of properties, it is preferable to use a plasma CVD method.

  Regarding the metal coating conditions by the PVD method, it is preferable to use argon as a sputtering gas, and the pressure of the argon gas is 0.1 to 100 Pa, and preferably 0.2 to 20 Pa. When the PVD method and the CVD method are used in combination to form the intermediate layer, the amount of silicon organic compound or hydrocarbon compound is 1/100 to 1/2 of argon, and preferably 1/50 to 1/5. In addition, when creating an intermediate layer by using the PVD method and CVD method together, the intermediate layer can be created without applying a bias, but since the adhesion with the substrate is further improved by applying a bias, It is preferable to apply a bias of −30 to −200 V. In this case, the value of the current flowing through the substrate by applying a bias is preferably 3 mA or more.

Next, in the present invention, a carbon film is formed on the intermediate layer prepared by such a method by a thermionic excitation CVD method, a PVD method, or the like.
In addition, the carbon film as used in the field of this invention means the film which has carbon with a comparatively large hardness produced by the physical vapor deposition method (PVD method) or the chemical vapor deposition method (CVD method) as a main component. and such other carbon film da ear Mondo-like carbon (DLC) film as a carbon film, a carbon film or the like containing heteroatoms such as nitrogen and metals together with carbon as such as carbon nitride film Ru are included.

The pressure of the chamber when forming the carbon film is 0.05 to 100 Pa, preferably 20 Pa or less. In addition, the temperature of the base material at the time of carbon film creation naturally increased when cleaning the base material using argon plasma and when coating the carbon film only by the CVD method.
It is below ℃.

  The pressure of the silicon organic compound or hydrocarbon compound when the uppermost carbon film is formed only by the CVD method is 0.05 to 20 Pa. At this time, the bias applied to the substrate is -200 to -7000 V, preferably -500 to -5000 V.

  Since the obtained DLC film has excellent peeling resistance in air and water, it is used as a material for lubrication and protection of sliding parts in a mechanical environment, particularly in sliding parts under water environment. Can be widely applied.

  The thickness of the intermediate layer is 0.1 to 3 μm, preferably 0.3 μm or more. The thickness of the uppermost carbon film is 0.5 to 10 μm.

A typical apparatus for carrying out the method for producing a carbon film of the present invention is shown in FIG.
In FIG. 1, 1 is a base material, 2 is a base material holder with a rotation mechanism. Thereby, the direction of a base material can be changed. That is, when the intermediate layer is formed, the base material is changed to the target, and when the DLC film is formed, the base material is changed to face the ion gun. Reference numeral 3 denotes a target, and reference numeral 4 denotes a magnetron sputtering power source, which is a power source that converts a gas such as argon introduced by the generated high frequency into plasma and further converts the target metal into plasma. Reference numeral 5 denotes an inlet for argon or source gas, and reference numeral 6 denotes an ion gun, which comprises a filament unit 7 for generating thermoelectrons and an anode unit 8 for extracting thermoelectrons and giving energy to the electrons. A power source 9 applies a pulse or a DC bias to the substrate and draws plasma into the substrate.

  Next, the operation principle of the apparatus shown in FIG. 1 will be described. First, the chamber in which the substrate is installed is evacuated to 0.04 Pa or less. Next, an inert argon gas is introduced, and the substrate is cleaned using argon plasma generated by a thermionic excitation method. The substrate after cleaning faces the target, and a metal layer such as chromium or titanium is coated on the substrate by the PVD method. Subsequently, a silicon organic compound such as hexamethyldisiloxane or a hydrocarbon compound such as toluene is introduced. The gas can be introduced in a constant amount, but it is preferable to introduce the gas by increasing the introduction amount stepwise. In addition, a bias is applied to the substrate being coated as necessary. After that, the coating of the metal component by PVD method is stopped, the base material is directed to the ion gun, and a carbon film is formed by CVD method or the like.

  Next, an example of a preferable method for producing a carbon film according to the present invention will be described. First, the cleaned stainless steel substrate is coated with a metal component such as chromium or titanium of the intermediate layer by sputtering PVD. Next, while coating chromium and titanium, a silicon organic compound such as hexamethyldisiloxane and a hydrocarbon compound such as toluene are introduced in a gas state, and a carbon system containing chromium or titanium by a plasma CVD method, or A carbon-based composite material layer having silicon is also prepared. Moreover, the amount of each element can be graded by introducing raw material gases that are non-metallic components such as silicon organic compound and hydrocarbon compound gas in a stepwise manner from a small amount to a large amount. In this way, an inclined structure intermediate layer can be created in which the amount of carbon or silicon increases as the amount of chromium or titanium decreases as the substrate goes to the surface layer. Then, a carbon film is formed thereon by a CVD method or the like.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
The film forming apparatus shown in FIG. 1 was used as the apparatus. For the preparation of the intermediate layer, first, chromium was coated as a target on a 5 mm-thick stainless steel SUS 630 substrate by RF excitation type PVD method in an argon gas atmosphere for 15 min. Hexamethyldisiloxane (HMDS) was introduced. The introduction of HMDS was gradually increased from 5 to 5 in small steps, and kept at 10 minutes for each step. Since the introduction of HMDS, a DC bias of -120 V was applied to the substrate. The pressure at the time of forming the intermediate layer was 10 Pa or less, and the temperature was 100 ° C. or less. Thus, the PVD method and the CVD method were used in combination, and an intermediate layer having a thickness of about 0.7 μm was created with the amount of chromium, silicon, and carbon inclined.
Next, on this intermediate layer, a carbon-based thin film DLC film was prepared by toluene as a source gas by an electron excitation type CVD method. The total thickness of the film was 5.0 μm.
The peel resistance of the DLC film was evaluated by a friction test in purified water using a ball-on-disk reciprocating friction tester at room temperature. A 3/16 inch SUS 440C ball was used as an opponent. The friction conditions were a load of 100 N, a stroke of 10 mm, a reciprocating speed of 60 cycles / min, and a friction time of 120 min. The result is shown in FIG.
In addition, a 0.2 μm silicon-containing carbon film was formed on an intermediate layer separately formed on a silicon wafer under the same conditions, and the intermediate layer was analyzed by XPS. From the XPS analysis results shown in FIG. 3, the intermediate layer has an elemental composition in the depth direction of the intermediate layer that is substantially pure chromium on the substrate side, and the amount of chromium decreases as it goes to the surface layer side. And the amount of silicon increased. This intermediate layer has no obvious interface between the metal substrate and the surface Si-DLC, and is considered to play a role in mitigating chemical composition changes. In addition, the XPS analysis result of FIG. 4 shows that the chromium / silicon / carbon intermediate layer of the present invention is a composite material of a carbon-based material and a metal carbide according to the XPS analysis result inside the intermediate layer after etching to some extent. I understood.

Comparative Example 1
For comparison, a carbon film (DLC thin film) was prepared in the same manner as in Example 1 except that a Si-DLC-based intermediate layer prepared by thermionic excitation CVD method was used. It was used for. However, the load was 40 N. The result is shown in FIG.

As shown in FIG. 2 (b), the DLC film of Comparative Example 1 was confirmed to be remarkably peeled under a load of 40 N in purified water. On the other hand, as shown in FIG. 2 (a), the DLC film of Example 1 showed no film peeling even under a load of 100N. In addition, the coefficient of friction was a stable low value of 0.1 or less. The specific wear amounts of DLC film and ball are 10 and 3 × 10 ^-8 mm ³ / Nm, respectively, and the maximum contact pressure reaches 2.7 GPa in the calculation based on Hertz contact theory. ing.

Example 2
A DLC film was prepared in the same manner as in Example 1 except that a Si-DLC film having a thickness of about 0.2 μm was further formed on the intermediate layer formed on the SUS 630 stainless steel substrate. However, the bias voltage at the time of forming the intermediate layer was −110 V, and the current was 39 mA. This DLC film does not peel off even under a load of 40 N in air and a load of 110 N in water, and exhibits excellent adhesion.

Example 3
In Example 1, a DLC film was prepared in the same manner except that the base material was changed to an aluminum / magnesium alloy (AZ91D) and the thickness of the uppermost carbon film was changed to 2/3. However, the bias voltage at the time of creating the intermediate layer was −160 V, and the current was 40 mA. This DLC film was also excellent in peel resistance.

Example 4
A DLC film was prepared in the same manner as in Example 1 except that the target chromium was replaced with titanium. However, the bias voltage at the time of creating the intermediate layer was −150 V, and the current was 35 mA. This DLC film was also excellent in peel resistance.

Example 5
In Example 1, a DLC film was prepared in the same manner except that the raw material gas was replaced with toluene and introduced in four stages. However, the bias voltage at the time of forming the intermediate layer was −110 V, and the current was 37 mA. This DLC film does not peel off even under a load of 110 N in water, and exhibits excellent adhesion.

Explanatory drawing of the film-forming apparatus preferably used in the manufacturing method of this invention. (A) is a wear scar optical micrograph of the carbon film according to Example 1. (B) is an abrasion micrograph of a carbon film according to Comparative Example 1. The element concentration profile of the depth direction of the intermediate | middle layer obtained in Example 1. FIG. The XPS spectrum of C1s inside the intermediate layer obtained in Example 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Base material holder with a rotation mechanism 3 Target 4 Magnetron sputtering power source 5 Argon or source gas inlet 6 Ion gun 7 Filament unit 8 Anode unit 9 Power source for applying pulse or DC bias to the base material

Claims (3)

The diamond-like carbon film provided on the metal substrate has an intermediate layer having a concentration gradient such that the metal component concentration is higher on the metal substrate side and the carbon and silicon concentrations are higher on the diamond-like carbon film side. A method for producing a diamond-like carbon film , wherein the intermediate layer is formed by applying a DC bias to a metal substrate by a combination of physical vapor deposition and chemical vapor deposition. The method of manufacturing a diamond-like carbon film according to claim 1, wherein the DC bias is −30 to −200V . The method for producing a diamond-like carbon film according to claim 1 or 2 , wherein physical vapor deposition and chemical vapor deposition are performed in parallel.