JP6337944B2 - Coated tool - Google Patents

Description

  The present invention is, for example, a diamond-like carbon film (hereinafter also referred to as “DLC film”) such as a press mold, a forging mold, a cutting tool such as a saw blade, or a cutting tool such as a drill. It is related with the coated tool which coat | covered.

When a workpiece such as aluminum, copper, or resin is molded with a mold, product abnormalities such as galling or scratching may occur due to part of the workpiece adhering to the surface of the mold. In order to solve this problem, a coated mold in which a DLC film is coated on the surface of the mold has been put into practical use. A DLC film substantially free of hydrogen (Tetrahedral amorphous carbon film: ta-C film) is widely applied to coating dies because it has high hardness and excellent wear resistance.
However, a high-hardness DLC film that does not substantially contain hydrogen is formed by an arc ion plating method using a graphite target, and particles (graphite spheres) having a size of several micrometers, called droplets, are formed. Inevitably mixed into the DLC film, the surface roughness of the DLC film deteriorates.

  In order to solve such a problem, Patent Document 1 applies a filtered arc ion plating method provided with a mechanism for collecting droplets, so that DLC that is substantially free of smooth and hard hydrogen is contained. It is disclosed that the coating can be coated.

JP 2008-297171 A

  By applying a DLC film having a high hardness and a smooth surface state as in Patent Document 1, an improvement in tool characteristics is expected. However, a high hardness DLC film tends to have poor adhesion to the substrate.

  According to the study by the present inventor, especially when cold tool steel such as SKD11 with a large amount of carbide (for example, high carbon steel having a carbon content of 1% by mass or more) is used as a base material, the matrix and carbide. It was confirmed that there was a gap between the DLC films, and the DLC film was likely to be peeled off starting from the gaps.

  This invention is made | formed in view of the above situations, Comprising: It is related with the coated tool excellent in adhesiveness, and its manufacturing method.

The present inventor has found that there is a specific film structure capable of improving the adhesion of a high-hardness DLC film and a coating method effective for realizing it, and has reached the present invention.
Specific means for achieving the above object are as follows.
That is, the present invention is a coated tool in which a surface of a base material is coated with a DLC (diamond-like carbon) film, and the DLC film has a nanoindentation hardness of 50 GPa or more and 100 GPa or less, and the DLC film is formed on the substrate side. The content of hydrogen atoms and nitrogen atoms decreases in the thickness direction (surface side) from the surface, and the surface of the DLC film has a hydrogen atom content of 0.5 atomic% or less and contains nitrogen atoms. This is a coated tool having an amount of 2 atomic% or less and excellent adhesion.

As for the surface roughness of the DLC film, the arithmetic average roughness Ra is preferably 0.03 μm or less, and the maximum height roughness Rz is preferably 0.5 μm or less.
The surface of the substrate of the DLC film preferably has a hydrogen atom content of 0.7 atom% to 7 atom% and a nitrogen atom content of more than 2 atom% and not more than 10 atom%.
The film thickness of the diamond-like carbon film is preferably in the range of 0.1 μm to 1.5 μm.
The substrate is preferably a high carbon steel or cemented carbide having a carbon content of 1% by mass or more.

The method for producing a coated tool of the present invention is a method for producing a coated tool for coating a surface of a substrate with a DLC (diamond-like carbon) film by a filtered arc ion plating method,
A step of introducing a mixed gas containing hydrogen atoms into the furnace and performing a gas bombardment treatment on the surface of the substrate; and then introducing nitrogen gas into the furnace after the gas bombardment treatment and introducing the nitrogen into the furnace Covering the surface of the substrate with a DLC film using a graphite target while reducing the gas flow rate.
The mixed gas is preferably a mixed gas containing argon gas and 4% by mass or more of hydrogen gas with respect to the total mass of the mixed gas.
In the coating step, after the diamond-like carbon film is coated while reducing the flow rate of the nitrogen gas introduced into the furnace, the introduction of nitrogen gas is further stopped (the amount of nitrogen gas introduced is reduced to 0 sccm). It is preferable to coat a diamond-like carbon film.
In the coating step, the flow rate of nitrogen gas introduced into the furnace is preferably 5 sccm or more and 30 sccm or less.

  ADVANTAGE OF THE INVENTION According to this invention, the coating tool excellent in adhesiveness and its manufacturing method are provided.

1 shows a sample No. 1 as an example of the present invention. 1 is a graph showing the results of glow discharge optical emission spectrometry of a DLC film for 1. FIG. 2 shows a sample No. as an example of the present invention. 2 is a graph showing the results of glow discharge emission spectroscopic analysis of a DLC film. 3 shows a sample No. which is an example of the present invention. 3 is a graph showing the results of glow discharge emission spectroscopic analysis of a DLC film. FIG. 1 is a graph showing the results of glow discharge optical emission spectrometry of a DLC film for 1. FIG. 2 is a graph showing the results of glow discharge emission spectroscopic analysis of a DLC film. FIG. 3 is a graph showing the results of glow discharge emission spectroscopic analysis of a DLC film. 7 shows a sample No. 1 as an example of the present invention. 1 is a graph showing the results of Auger electron spectroscopy analysis of a DLC film. 8 shows a sample No. which is an example of the present invention. 3 is a graph showing the results of Auger electron spectroscopy analysis of the DLC film. FIG. 3 is a graph showing the results of Auger electron spectroscopy analysis of the DLC film. FIG. 10 is a schematic view of a T-shaped filtered arc film forming apparatus used in the examples. 11 shows a sample No. which is an example of the present invention. 1-No. 3 is a surface observation photograph of the DLC film of No. 3 by an optical microscope. FIG. 1-No. 6 is a surface observation photograph of the DLC film of No. 6 with an optical microscope. FIG. 13 is a surface observation photograph of each sample, which is an example of the present invention after the ball-on-disk test, using an optical microscope. FIG. 14 is a surface observation photograph by an optical microscope of each comparative sample after the ball-on-disk test.

  The coated tool of the present invention is a coated tool in which the surface of a base material is coated with a diamond-like carbon film, and the nanoindentation hardness measured from the film surface is 50 GPa or more and 100 GPa or less. The coated tool of the present invention has a DLC film having a high hardness having a nanoindentation hardness of 50 GPa or more measured from the film surface on a substrate. When the nanoindentation hardness is low and lower than 50 GPa, the wear resistance is lowered, and the tool life is not sufficient. On the other hand, when the hardness of the film is higher than 100 GPa, the residual stress becomes too high, and the adhesion with the substrate is lowered.

  The nanoindentation hardness of the DLC film in the present invention is more preferably 55 GPa or more, and even more preferably 60 GPa or more, from the viewpoint of good wear resistance and excellent adhesion to the substrate. The nanoindentation hardness of the DLC film is more preferably 95 GPa or less, and still more preferably 90 GPa or less.

  Nanoindentation hardness is the plastic hardness when a probe is pressed into a sample (DLC film) and plastically deformed. A load-displacement curve is obtained from the indentation load and indentation depth (displacement). Calculate the hardness. Specifically, using a nanoindentation device manufactured by Elionix Co., Ltd., the hardness of the coating surface was measured under the measurement conditions of an indentation load of 9.8 mN, a maximum load holding time of 1 second, and a removal rate after loading of 0.49 mN / second. Ten points are measured and obtained from an average value of six points excluding two points having a large value and two points having a small value.

High hardness DLC films tend to have very high internal stress and poor adhesion to the substrate. Therefore, conventionally, a technique has been proposed in which an intermediate film having a lower hardness than the DLC film is provided to ensure adhesion between the base material and the DLC film. However, according to the study of the present inventor, when an intermediate film such as a metal, carbide or nitride is interposed between the base material and the DLC film, the DLC film is preferentially started from the surface defect of the intermediate film. In order to peel, it confirmed that it was not enough to improve adhesiveness.
On the other hand, it is known that a DLC film containing hydrogen atoms or nitrogen atoms has reduced hardness and residual stress. As the content of hydrogen atoms contained in the DLC film increases, the hardness and residual stress decrease. For example, when a DLC film is applied as a coating material for a coating mold, hydrogen contained in the DLC film evaporates due to a temperature rise during molding, resulting in defects such as voids in the mold, resulting in a decrease in mold life. . Also, when the content of nitrogen atoms contained in the DLC film increases, the hardness and residual stress decrease. When a non-ferrous material is processed, welding is likely to occur. Therefore, even if the adhesion is improved by interposing a DLC film containing excessive hydrogen atoms or nitrogen atoms, the tool characteristics are hardly improved.

In view of this, the present inventor has studied a method of reducing the residual stress by providing a DLC film directly on the substrate and continuously changing the film structure in the thickness direction of the DLC film. As a result, if the hydrogen and nitrogen elements are not uniformly contained in the thickness direction but the contents of hydrogen atoms and nitrogen atoms are reduced in the thickness direction from the base material side to the surface side of the DLC film, the residual stress decreases. And when cold tool steel with many carbides was used for a base material, peeling did not generate | occur | produce but it confirmed that adhesiveness was improved.
However, when the content of hydrogen atoms or nitrogen atoms contained in the DLC film on the surface away from the base material increases, welding of the work material occurs, and the tool life tends to be reduced. Therefore, in the coated tool of the present invention, the content of hydrogen atoms and nitrogen atoms is decreased in the thickness direction from the substrate side to the surface side of the DLC film, and the hydrogen atom content on the surface of the DLC film is reduced to 0. The content of nitrogen was 5 atomic% or less, and the nitrogen content was 2 atomic% or less. That is, in the coated tool of the present invention, the content of hydrogen atoms on the surface on the substrate side exceeds 0.5 atomic%, and the content of nitrogen atoms on the surface on the substrate side is 2 atomic%. Indicates that it has exceeded.
By having such a film structure, the high-hardness DLC film provided immediately above the substrate has high adhesion to the substrate, and welding of the workpiece can also be suppressed.
The coated tool of the present invention is preferable because it can greatly improve the mold life by being applied to the coated mold.

Among these, for the same reason as described above, the hydrogen atom content on the surface of the DLC film is preferably 0.4 atomic% or less, and more preferably 0.3 atomic% or less.
Moreover, as content of the nitrogen atom in the surface of a DLC film, 1.5 atomic% or less is preferable and 1.0 atomic% or less is more preferable.

  The “surface” of the coating in the present invention refers to the surface in contact with the workpiece and the vicinity thereof. In addition, the “surface on the substrate side” in the present invention refers to the surface of the film in contact with the substrate and the vicinity of the interface.

  The hydrogen atom content can be determined by the elastic recoil detection method (ERDA analysis). The nitrogen atom content can be determined by Auger electron spectroscopy (AES analysis).

In the DLC film, if the hydrogen content on the substrate side is excessive, the hydrogen content contained in the entire DLC film increases even if the hydrogen content is decreased from the substrate side toward the surface side. As a result, a decrease in hardness and a decrease in tool characteristics due to evaporation of hydrogen during tool use are caused. In order to increase the hydrogen content on the substrate side, it is effective to introduce a hydrocarbon-based gas such as acetylene (C ₂ H ₂ ). However, if a large amount of hydrocarbon-based gas is introduced, soot adhering to the furnace increases, and apparatus maintenance becomes difficult.
Therefore, the surface of the DLC film on the base material side preferably has a hydrogen content of 0.7 atomic% or more and 7 atomic% or less. A more preferable hydrogen content is 0.7 atom% or more and 3 atom% or less, and further 0.7 atom% or more and 2 atom% or less.
In addition, in the DLC film, if the nitrogen content on the base material side increases too much, the nitrogen content contained in the entire DLC film increases even if the nitrogen content decreases from the base material side toward the surface side. . As a result, wear resistance decreases due to a decrease in hardness, and welding tends to occur when non-ferrous materials are processed.
Therefore, the surface of the DLC film on the substrate side preferably has a nitrogen content of more than 2 atomic% and not more than 10 atomic%. More preferable nitrogen content is more than 2 atomic% and 8 atomic% or less, and further more than 2 atomic% and 5 atomic% or less.

  If droplets, impurities or the like are present on the surface of the DLC film, the workpieces are welded starting from these to cause galling or the like. When measured with an arithmetic average roughness Ra (conforming to JIS-B-0601-2001) and maximum height roughness Rz (conforming to JIS-B-0601-2001), which are general surface roughnesses, Ra is 0. When the surface has a smoothness of 0.03 μm or less and Rz of 0.5 μm or less, it is preferable in that a surface defect that is a starting point of welding of the workpiece can be reduced. More preferably, Ra is 0.02 μm or less. More preferably, Rz is 0.3 μm or less.

  When the film thickness of the DLC film becomes too thin, the durability as a tool is insufficient. Moreover, when the film thickness of the DLC film becomes too thick, the surface roughness of the film surface tends to deteriorate. When the film thickness becomes too thick, the possibility that the DLC film partially peels increases. Therefore, the film thickness of the DLC film is preferably 0.1 μm to 1.5 μm, and more preferably 0.1 μm to 1.2 μm. In order to give sufficient wear resistance to the coated tool, the thickness of the DLC film is preferably 0.2 μm or more. In order to achieve smooth surface roughness and excellent wear resistance at the same time, the film thickness of the DLC film is more preferably 0.5 μm to 1.2 μm.

  The base material is not particularly limited, and can be appropriately selected according to the use and purpose. For example, cemented carbide, cold tool steel, high speed tool steel, plastic mold steel, hot tool steel, etc. can be applied. Among the base materials, a high carbon steel or cemented carbide having a carbon content of 1% by mass or more, in which a large amount of carbide of the base material is likely to cause film peeling, is preferable in that the effect of improving adhesion is high. Examples of the high carbon steel include JIS-SKD11.

Then, the manufacturing method of the coated tool of this invention is demonstrated.
The method for producing a coated tool of the present invention is a method for producing a coated tool in which a surface of a substrate is coated with a diamond-like carbon film by a filtered arc ion plating method. Specifically, the method for producing a coated tool according to the present invention includes a step of introducing a gas mixture containing hydrogen into a furnace and performing a gas bombarding process on the surface of the base material, and a nitrogen gas in the furnace after the gas bombarding process. And a step of coating the surface of the base material with a diamond-like carbon film using a graphite target while reducing the flow rate of the nitrogen gas introduced into the furnace.

The DLC film in the coated tool of the present invention can be coated with a conventionally known filtered arc ion plating apparatus. In particular, the use of a T-shaped filtered arc ion plating apparatus is preferable because a smoother DLC film can be coated.
In order to reduce the nitrogen content of the DLC film from the substrate side to the surface side, it can be achieved by coating the DLC film with a graphite target while reducing the flow rate of nitrogen gas introduced into the furnace. . On the other hand, in order to reduce the hydrogen content of the DLC film from the substrate side to the surface side, it is effective to perform a gas bombardment treatment with a mixed gas containing hydrogen gas before coating the DLC film. .

When a conventional gas bombardment process using an argon gas is performed on the base material before coating the DLC film, a large amount of oxygen is present at the interface between the film and the base material, resulting in poor adhesion. Oxygen present at the interface originates from the oxide film formed on the substrate surface from the beginning, and is a residual element that has not been removed by the gas bombardment with argon gas. In contrast, by performing gas bombardment on the surface of the substrate using a mixed gas containing hydrogen, the oxide film on the surface of the substrate is reduced by reacting with hydrogen ions, and the oxide film is formed by gas bombardment treatment. And it becomes possible to remove dirt on the surface.
Hydrogen remains in the furnace after the gas bombardment of the surface of the substrate with a mixed gas containing hydrogen. Therefore, after the gas bombardment process is completed, only nitrogen gas is introduced into the furnace, and power is applied to the graphite target while reducing the gas flow rate to coat the DLC film, so that excessive hydrogen is contained in the DLC film. It is not contained, and a film configuration in which hydrogen and nitrogen are reduced from the substrate side toward the surface side can be achieved.

The mixed gas containing hydrogen gas is preferably a mixed gas containing argon gas and 4% by mass or more of hydrogen gas with respect to the total mass of the mixed gas. When the hydrogen concentration is 4% by mass or more, it is more suitable to remove the oxide film by gas bombardment with a mixed gas. Further, the amount of hydrogen remaining in the furnace after the gas bombardment treatment is reduced, and it is difficult for hydrogen to be contained on the base material side of the DLC film.
When performing the gas bombardment treatment, it is preferable that the negative bias voltage applied to the substrate is -2500V to -1500V in order to improve the adhesion of the high hardness DLC film. When the negative bias voltage applied to the substrate is low, the gas ion collision energy is low, and therefore the etching effect is reduced, and the adhesion of the high hardness DLC film tends to be reduced. In addition, if the negative bias voltage applied to the substrate is large, the plasma may become unstable and abnormal discharge may occur. When abnormal discharge occurs, abnormal discharge (arcing) traces are formed on the tool surface, and unevenness may occur on the tool surface.
In order to remove the oxide on the surface of the substrate uniformly, it is preferable to perform gas bombardment treatment with a mixed gas for 30 minutes or more.
After the gas bombardment with the mixed gas, a hydrocarbon gas such as acetylene may be introduced into the furnace to increase the hydrogen content on the substrate side.

When coating the DLC film, the substrate temperature is preferably 200 ° C. or lower. When the temperature is higher than 200 ° C., the graphitization of the DLC film proceeds and the hardness tends to decrease.
Moreover, it is preferable that the bias voltage applied to the substrate is −300 V to −50 V when the DLC film is coated. When the negative bias voltage applied to the substrate is −50 V or less, the collision energy of carbon ions is not reduced and is easily maintained, and defects such as voids are less likely to occur in the DLC film. Further, when the negative bias voltage applied to the substrate is −300 V or more, abnormal discharge is less likely to occur during film formation.
The bias voltage applied to the substrate is more preferably -200V to -100V.

When coating the DLC film, the substrate temperature is preferably 200 ° C. or lower. When the temperature is higher than 200 ° C., the graphitization of the DLC film proceeds and the hardness tends to decrease.
Further, when the DLC film is coated, it is preferable that the bias voltage applied to the substrate is 50 V to 300 V in absolute value. When the absolute value of the negative bias voltage applied to the substrate is 50 V or more, the collision energy of carbon ions increases, and defects such as voids are less likely to occur in the DLC film. Further, when the absolute value of the negative bias voltage applied to the substrate is 300 V or less, abnormal discharge during film formation is further suppressed.
The bias voltage applied to the substrate is more preferably -200V to -100V.

  The flow rate of nitrogen gas introduced into the furnace after the gas bombardment treatment is preferably 30 sccm or less. When the gas flow rate is higher than 30 sccm, the content of nitrogen contained in the DLC film increases, so that the wear resistance is reduced due to the decrease in hardness, and welding is likely to occur when non-ferrous materials are processed. On the other hand, if the flow rate of nitrogen gas introduced into the furnace is too small, it is not sufficient to reduce the residual compressive stress of the DLC film. For this reason, the flow rate of nitrogen gas introduced into the furnace after the gas bombardment treatment is preferably 5 sccm or more from the viewpoint of lowering the residual compressive stress of the DLC film. The DLC film is coated while gradually reducing the flow rate of the nitrogen gas introduced into the furnace, and then the introduction of the nitrogen gas is stopped, and finally the DLC film is coated without introducing the nitrogen gas. Is preferred.

In the method for producing a coated tool of the present invention, a diamond-like carbon film is coated on the surface of a substrate by a filtered arc ion plating method. Since a filtered arc ion plating apparatus is used, a smooth DLC film can be easily obtained, but the surface roughness may decrease as the film thickness increases. In that case, the surface state of the coated tool can be achieved by polishing the surface of the coated DLC film.
Moreover, about the base material before coat | covering a DLC film, it is preferable that it is smoother in order to improve the adhesiveness of a base material and a DLC film more. Specifically, the surface roughness of the substrate is an arithmetic average roughness Ra (based on JIS-B-0601-2001), which is a general surface roughness, and a maximum height roughness Rz (JIS-B-). In accordance with 0601-2001), Ra is preferably polished to 0.06 μm or less and Rz to 0.1 μm or less. Furthermore, as for the surface roughness of a base material, it is more preferable that Ra is 0.05 micrometer or less and Rz is 0.08 micrometer or less.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof. Unless otherwise specified, “part” is based on mass.

Example 1
<Deposition system>
As the film forming apparatus, a T-shaped filtered arc ion plating apparatus was used. A schematic diagram of the apparatus is shown in FIG. The film forming chamber (6) has an arc discharge evaporation source on which a carbon cathode (cathode) (1) provided with a graphite target is mounted, and a substrate holder (7) for mounting the substrate. There is a rotation mechanism (8) under the substrate holder, and the substrate rotates and revolves through the substrate holder. Reference numeral (2) indicates a carbon film forming beam, and reference numeral (3) indicates spherical graphite (droplet) neutral particles.
When an arc discharge is generated on the surface of the graphite target, only the charged carbon is bent by the magnetic coil (4) and reaches the film forming chamber to cover the substrate with the coating. The droplets without charge are collected in the duct (5) without being bent by the magnetic coil.

<Base material>
For the evaluation of the peeled state and the weldability immediately after the coating of the DLC film, a base material of JIS-SKD11 equivalent steel material tempered to 60 HRC with a dimension of φ20 × 5 mm was used.
For measurement of film thickness by nanoindenter hardness, film analysis, and fracture surface, a substrate made of cemented carbide made of tungsten carbide (WC-10 mass% Co) having a cobalt content of 10 mass% (dimension: 4 mm × 8 mm × 25 mm, average particle size: 0.8 μm, hardness: 91.2 HRA).
For the scratch test, a base material of JIS-SKH51 equivalent steel material having dimensions of 21 mm × 17 mm × 2 mm was used.
Before coating the DLC film, any of the above substrates was polished so that the arithmetic average roughness Ra was 0.01 μm or less and the maximum height roughness Rz was 0.07 μm or less. And after grinding | polishing, it degreased and washed and it fixed to the base-material holder in a chamber.
Each substrate was coated with a DLC film under the following conditions.

<Example 1 (Sample No. 1)>
The film forming chamber was evacuated to 5 × 10 ⁻³ Pa, the substrate was heated to around 150 ° C. with a heater for heating, and held for 90 minutes.
Thereafter, a negative pressure bias voltage applied to the substrate was set to −2000 V, and a gas bombardment treatment with a mixed gas containing 5 mass% hydrogen gas in argon gas was performed for 90 minutes. The flow rate of the mixed gas was 50 sccm to 100 sccm.
After the gas bombardment treatment, 10 sccm nitrogen gas was introduced into the film forming chamber, a bias voltage of −150 V was applied to the substrate, and the substrate temperature was adjusted to 100 ° C. or lower. Then, a 50 A current was applied to the graphite target, and the DLC film was coated for about 10 minutes.
Next, nitrogen gas was set to 5 sccm, and the DLC film was coated for about 10 minutes. Next, the introduction of nitrogen gas was stopped and the DLC film was coated for 30 minutes.

<Example 2 (Sample No. 2)>
Sample No. until gas bombardment treatment. Same as 1. After the gas bombardment treatment, 10 sccm nitrogen gas was introduced into the film forming chamber, a bias voltage of −150 V was applied to the substrate, and the substrate temperature was adjusted to 100 ° C. or lower. Then, the current supplied to the graphite target was increased stepwise from 50A to 80A, and the DLC film was coated for about 30 minutes.
Next, the nitrogen gas flow rate was 5 sccm, and the DLC film was coated for about 30 minutes. Next, the introduction of nitrogen gas was stopped and the DLC film was coated for about 70 minutes.

<Example 3 (Sample No. 3)>
Sample No. until gas bombardment treatment. Same as 1. After the gas bombardment treatment, 20 sccm nitrogen gas was introduced into the film forming chamber, a bias voltage of −150 V was applied to the substrate, and the substrate temperature was adjusted to 100 ° C. or lower. Then, the current supplied to the graphite target was increased stepwise from 50A to 80A, and the DLC film was coated for about 30 minutes.
Next, the nitrogen gas flow rate was changed stepwise from 20 sccm to 5 sccm, and the DLC film was coated for about 30 minutes. Next, the introduction of nitrogen gas was stopped and the DLC film was coated for about 70 minutes.

<Example 4 (Sample No. 4)>
Sample No. until gas bombardment treatment. Same as 1. After the gas bombardment treatment, 5 sccm of C ₂ H ₂ gas was introduced into the film formation chamber for 5 minutes. Thereafter, introduction of C ₂ H ₂ was stopped, 10 sccm nitrogen gas was introduced, a bias voltage of −150 V was applied to the substrate, and the substrate temperature was adjusted to 100 ° C. or lower. Then, a current of 50 A was applied to the graphite target to coat the DLC film for about 10 minutes.
Next, the DLC film was coated for about 10 minutes with a nitrogen gas flow rate of 5 sccm. Next, the introduction of nitrogen gas was stopped, and the DLC film was coated for about 30 minutes.

<Example 5 (Sample No. 5)>
Sample No. until gas bombardment treatment. Same as 1. After the gas bombardment treatment, a mixed gas containing 5% by mass of hydrogen gas in 100 sccm of argon gas was introduced into the film formation chamber for 5 minutes. Thereafter, the introduction of the mixed gas was stopped, 10 sccm nitrogen gas was introduced, a bias voltage of −150 V was applied to the substrate, and the substrate temperature was adjusted to 100 ° C. or lower. Then, the current applied to the graphite target was 50 A, and the DLC film was coated for about 10 minutes.
Next, the nitrogen gas flow rate was 5 sccm, and the DLC film was coated for about 10 minutes. Next, the introduction of nitrogen gas was stopped, and the DLC film was coated for about 30 minutes.

<Example 6 (Sample No. 6)>
Sample No. until gas bombardment treatment. Same as 1. After the gas bombardment treatment, 10 sccm of C ₂ H ₂ gas was introduced into the deposition chamber for 10 minutes. Thereafter, 10 sccm of C ₂ H ₂ gas and 15 sccm of nitrogen gas were simultaneously introduced, and a bias voltage of −150 V was applied to the base material so that the base material temperature was 100 ° C. or lower. Then, the current supplied to the graphite target was increased stepwise from 50A to 80A, and the DLC film was coated for about 6 minutes.
Next, the introduction of C ₂ H ₂ gas was stopped, a nitrogen gas flow rate of 15 sccm was introduced, and the DLC film was coated for about 45 minutes. Next, the nitrogen gas flow rate was changed stepwise from 15 sccm to 5 sscm, and the DLC film was coated for about 45 minutes. Next, the introduction of nitrogen gas was stopped and the DLC film was coated for about 100 minutes.

<Example 7 (Sample No. 7)>
Sample No. until gas bombardment treatment. Same as 1. After the gas bombardment treatment, C ₂ H ₂ gas was introduced into the film formation chamber. Thereafter, introduction of C ₂ H ₂ was stopped, 10 sccm nitrogen gas was introduced, a bias voltage of −150 V was applied to the substrate, and the substrate temperature was adjusted to 100 ° C. or lower. The current applied to the graphite target was 50 A, and the DLC film was coated for about 10 minutes. Next, C ₂ H ₂ gas was again introduced into the furnace. Thereafter, the introduction of C ₂ H ₂ gas was stopped, the nitrogen gas flow rate was set to 5 sccm, and the DLC film was coated for about 10 minutes. Next, the introduction of nitrogen gas was stopped, and the DLC film was coated for about 30 minutes.

<Comparative Example 1 (Comparative Sample No. 1)>
Sample No. until gas bombardment treatment. Same as 1. After the gas bombardment treatment, a nitrogen gas was not introduced, and a bias voltage of −150 V was applied to the substrate to make the substrate temperature 100 ° C. or lower. A DLC film was formed for about 50 minutes with an electric current applied to the graphite target being 50 A.

<Comparative Example 2 (Comparative Sample No. 2)>
The gas bombardment process was performed only with argon gas. After the gas bombardment treatment, 10 sccm nitrogen gas was introduced into the film forming chamber, a bias voltage of −150 V was applied to the substrate, and the substrate temperature was adjusted to 100 ° C. or lower. And the electric current thrown into a graphite target was 50 A, and the DLC film was coat | covered for about 10 minutes. Next, the nitrogen gas flow rate was 5 sccm, and the DLC film was coated for about 10 minutes. Next, the introduction of nitrogen gas was stopped, and the DLC film was coated for about 30 minutes.

<Comparative Example 3 (Comparative Sample No. 3; Conventional Example)>
The gas bombardment process was performed only with argon gas. After the gas bombardment treatment, a nitrogen gas was not introduced, and a bias voltage of −150 V was applied to the substrate to make the substrate temperature 100 ° C. or lower. A DLC film was formed for about 50 minutes with an electric current applied to the graphite target being 50 A.

<Comparative Example 4 (Comparative Sample No. 4; Conventional Example)>
Before coating the DLC film, the substrate surface was gas bombarded with only argon gas to coat about 3 μm of CrN as an intermediate film. After the coating of the intermediate film, nitrogen gas was not introduced, and a bias voltage of −150 V was applied to the substrate to make the substrate temperature 100 ° C. or lower. A DLC film was formed for about 50 minutes with an electric current applied to the graphite target being 50 A.

In addition, any sample mentioned above coat | covered the DLC film, repeating film-forming and cooling so that the temperature of a base material might be 200 degrees C or less.
Each sample coated with the DLC film was subjected to hardness measurement, adhesion evaluation, weldability evaluation, and structural analysis. Hereinafter, the measurement conditions will be described.

<Comparative Example 5 (Comparative Sample No. 5)>
Until gas bombardment processing, sample No. Same as 1. After the gas bombardment treatment, 10 sccm nitrogen gas was introduced into the film forming chamber, a bias voltage of −150 V was applied to the substrate, and the substrate temperature was adjusted to 100 ° C. or lower. Then, a 50 A current was applied to the graphite target, and the DLC film was coated for about 10 minutes.
Next, nitrogen gas was set to 5 sccm, and the DLC film was coated for about 10 minutes. Next, the introduction of nitrogen gas was stopped, 20 sccm of C ₂ H ₂ gas was introduced, and the DLC film was coated for 30 minutes.

<Comparative Example 6 (Comparative Sample No. 6)>
Until gas bombardment processing, sample No. Same as 1. After the gas bombardment treatment, 20 sccm nitrogen gas was introduced into the film forming chamber, a bias voltage of −150 V was applied to the substrate, and the substrate temperature was adjusted to 100 ° C. or lower. Then, the current supplied to the graphite target was increased stepwise from 50A to 80A, and the DLC film was coated for about 30 minutes.
Next, the nitrogen gas flow rate was changed stepwise from 20 sccm to 5 sccm, and the DLC film was coated for about 30 minutes. Next, 5 sccm of nitrogen gas was introduced, and the DLC film was coated for about 70 minutes.

<Measurement and evaluation>
-Measurement of hardness-
The hardness of the coating surface was measured using a nanoindentation device manufactured by Elionix Co., Ltd. 10 points were measured under the measurement conditions of indentation load of 9.8 mN, maximum load holding time of 1 second, and removal speed after load loading of 0.49 mN / second. 6 points were excluded except 2 points with large values and 2 points with small values. Obtained from the average value. It was confirmed that the hardness of the fused quartz as the standard sample was 15 GPa and the hardness of the CVD diamond film was 100 GPa.

-Measurement of surface roughness-
Arithmetic average roughness Ra and maximum height roughness Rz were measured from a roughness curve according to JIS-B-0601-2001 using a contact type surface roughness measuring device SURFCOM 480A manufactured by Tokyo Seimitsu Co., Ltd. The measurement conditions were as follows: evaluation length: 4.0 mm, measurement speed: 0.3 mm / s, cut-off value: 0.8 mm.

-Evaluation of adhesion-
The surface of the DLC film of the sample immediately after coating was observed at a magnification of about 800 times using an optical microscope manufactured by Mitutoyo Corporation to evaluate the peeling state. The evaluation criteria for the surface peeling of the DLC film were as follows.
<Evaluation criteria for surface peeling>
A: No surface peeling B: With micro peeling C: With peeling

The peel load was measured using a CSM scratch tester (REVETEST). The measurement conditions are: measurement load: 0 to 100 N, load speed: 99.25 N / min, scratch speed: 10 mm / min, scratch distance: 10 mm, AE sensitivity: 5, indenter: Rockwell, diamond, tip radius: 200 μm, hard Wear setting: Fn contact 0.9 N, Fn speed: 5 N / s, Fn removal speed: 10 N / s, approach speed: 2% / s.
The initial chipping occurrence load was evaluated as A load, and the load when the substrate at the bottom of the scratch mark was completely exposed was evaluated as B load.

-GD-OES analysis-
In order to confirm the distribution of the nitrogen component, structural analysis was performed by glow discharge emission analysis (GD-OES) from the surface of the DLC film to the substrate. The apparatus used was JY-5000RF type GD-OES manufactured by HORIBA JOBIN YVON. As analysis conditions, Ar is used as a sputtering gas, pressure: 600 Pa, output: 35 W, module: 6 V, phase 4: V, gas replacement time: 20 seconds, pre-sputtering time: 30 seconds, background: 10 seconds, measurement Time: 90 seconds to 120 seconds.
Since the emission intensity of nitrogen was low, the peak intensity was confirmed to be 30 times. As a representative example, Sample No. 1-No. 3 and comparative sample no. 1-No. 1 to 6 show the intensity profiles of GD-OES.

-AES analysis-
The nitrogen component was quantitatively analyzed by Auger electron spectroscopy (AES analysis) from the surface of the DLC film to the substrate. As the apparatus, PHI650 (scanning Auger electron spectrometer) manufactured by Perkin Elmer was used. The analysis was performed under the following analysis conditions.
(Analysis conditions)
・ Primary electron energy: 3 keV
・ Current: about 260nA
-Incident angle: 30 degrees with respect to the sample normal-Analysis area: approx. 5 μm x 5 μm
(Conditions for ion sputtering (Ar ⁺ ))
・ Energy: 3 keV
・ Current: 25mA
-Incident angle: about 58 degrees with respect to the sample normal line-Sputtering speed: about 50 nm / min
As a representative example, FIG. 1 and FIG. 3 and FIG. The measurement result of 3 is shown.

-ERDA analysis-
In order to confirm the distribution of hydrogen components, Elastic Recoil Detection
Hydrogen concentration analysis was performed on the substrate side and the surface side of the DLC film by the analysis of elastic recoil particles (ERDA analysis). As the apparatus, Pelletron 3SDH manufactured by National Electrostatics Corporation was used. He ^{+ +} ions with an energy of 2.3 MeV were incident at an angle of 75 degrees with respect to the normal of the sample surface, and recoiled hydrogen particles (H, H ⁺ ) were detected by a semiconductor detector at a scattering angle of 30 degrees. .

-Ball-on-disk test-
In order to evaluate the weldability, a ball-on-disk tester (Tribometer manufactured by CSM Instruments) was used. The disk-shaped test piece was rotated at a speed of 100 mm / sec while pressing aluminum A5052 balls (diameter 6 mm) with a load of 5 N against the substrate coated with the DLC film. The test distance was 100 m.

The test results are summarized in Table 1. Sample No. which is an example of the present invention. 1-No. 7 had no surface peeling after coating, and the adhesion by the scratch test was also superior to that of the comparative example. Sample No. which is an example of the present invention having a film thickness of 1 μm or more. Sample No. 6 which is an example of the present invention having a film thickness smaller than 6 is shown. 1-No. 5 and no. No. 7 tended to make the DLC film smoother.
11 and 12 show typical examples of the optical microscope observation photograph of the sample surface immediately after coating the DLC film. Comparative sample No. 1, comparative sample No. As for No. 2, fine peeling having a diameter of about 20 μm was confirmed after coating. Among the comparative examples, comparative sample No. 1 containing no hydrogen or nitrogen on the substrate side of the DLC film. 3 and comparative sample No. 1 with a nitride intermediate film interposed between the substrate and the DLC film. For No. 4, large peeling with a diameter of about 100 μm was confirmed after coating the DLC film, and the scratch load was also low.
Regarding the surface observation photograph after the ball-on-disk test, FIG. 13 shows a representative example of the sample of the present invention, and FIG. 14 shows a representative example of the comparative sample. In the examples of the present invention, it was confirmed that no film peeling or welding occurred in the ball-on-disk test. On the other hand, in the comparative examples, there was film peeling, and welding accompanying peeling was also confirmed.
Analysis was performed to confirm the film structure of the DLC film having excellent adhesion. Samples of the present invention and comparative sample No. As for No. 2, it was confirmed from the GD-OES analysis that the nitrogen concentration decreased from the substrate side to the surface side.

As a result of AES analysis, it was confirmed that 2.8 atomic% to 3.7 atomic% of nitrogen was contained on the substrate side surface of the DLC film of the sample of the present invention. On the other hand, the nitrogen content on the surface of the sample DLC film of the present invention was below the detection limit (1.0 at% or less). Note that the peak seen on the substrate side (for example, the peak near the sputtering depth of 1000 nm to 1700 nm in FIG. 7) is due to the interference of the N and W Auger peaks.
From the ERDA analysis, the DLC film of the sample according to the present invention contains 1.0 atomic% to 7.8 atomic% of hydrogen on the surface on the base material side. 2 atomic% or less). As a representative example, Sample No. 4-No. Details of the hydrogen concentration analysis in the film thickness direction of No. 7 are shown in Table 2. In all of the inventive examples, it was confirmed that the hydrogen concentration decreased from the substrate side to the surface side of the DLC film.
From the above analysis, it was confirmed that the nitrogen content and the hydrogen content of the present invention example having excellent adhesion decreased from the base material side to the surface side.

Comparative sample No. 1 to Comparative Sample No. In No. 3, a film structure in which the nitrogen content and the hydrogen content decreased from the substrate side toward the surface side was not confirmed. Therefore, the adhesiveness was lowered and welding occurred as compared with the sample of the present invention.
Comparative sample No. In No. 4, since an intermediate film made of nitride is separately interposed between the base material and the DLC film, the surface of the DLC film is peeled off from the surface defect of the nitride film, and the adhesion by the scratch test is also improved. It became low.
Comparative sample No. In No. 5, the nitrogen content decreases from the substrate side to the surface side, but the hydrogen content increases. Therefore, compared with the sample of the example of the present invention, the film hardness and adhesion were lowered, and welding was also generated.
In Comparative Example 6, the nitrogen content and the hydrogen content decrease from the substrate side toward the surface side, but the surface nitrogen content is large. Therefore, compared with the sample of the example of the present invention, the film hardness and adhesion were lowered, and welding was also generated.

The disclosure of Japanese application 2013-073617 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.

Claims (4)

A coated tool in which a diamond-like carbon film is coated on the surface of a substrate,
The nano-indentation hardness of the diamond-like carbon film is 50 GPa or more and 100 GPa or less,
The diamond-like carbon film has a reduced content of hydrogen atoms and nitrogen atoms in the thickness direction from the substrate side,
The surface of the diamond-like carbon film has a hydrogen atom content of 0.5 atomic percent or less and a nitrogen atom content of 2 atomic percent or less.
The surface of the diamond-like carbon film on the substrate side has a hydrogen atom content of 1.2 atom% or more and 7 atom% or less, and a nitrogen atom content of more than 2 atom% and 8 atom% or less,
A coated tool having a hydrogen atom content of 0.9 atomic % or more at a position of 20.8% of the film thickness in the thickness direction from the substrate-side surface of the diamond-like carbon film.   2. The coated tool according to claim 1, wherein the surface roughness of the diamond-like carbon film is an arithmetic average roughness Ra of 0.03 μm or less and a maximum height roughness Rz of 0.5 μm or less.   The coated tool according to claim 1 or 2, wherein the diamond-like carbon film has a thickness of 0.1 µm to 1.5 µm. The coated tool according to any one of claims 1 to 3, wherein the base material is a high carbon steel or a cemented carbide having a carbon content of 1% by mass or more.