TW201512434A - Coated tool and method for producing the same - Google Patents

Abstract

The present invention provides a coated tool, in which a surface of a substrate is coated with a diamond-like carbon film, the nano-indentation hardness of the diamond-like carbon film being from 50 GPa to 100 GPa, the content of hydrogen atoms and nitrogen atoms in the diamond-like carbon film decreasing from the substrate side in a thickness direction of the film, the content of hydrogen atoms at the surface of the diamond-like carbon film being no more than 0.5 atomic%, and the content of nitrogen atoms at the surface of the diamond-like carbon film being no more than 2 atomic%.

Description

Covered tool and method of manufacturing same

The present invention relates to a coating tool such as a die for press working, a die for forging, a cutting tool such as a saw blade, or a cutting tool such as a drill, which is coated with a diamond-like carbon film (hereinafter also referred to as "DLC film"). Its manufacturing method.

When a material to be processed such as aluminum, copper, or resin is molded by a mold, the product may be scratched or damaged due to a part of the material to be processed being attached to the surface of the mold. In order to solve this problem, a coated mold in which a surface of a mold is covered with a DLC film has entered a practical stage of use. A DLC film (Tetrahedral amorphous carbon film, ta-C film, tetrahedral amorphous carbon film) which does not substantially contain hydrogen is widely used for a coated mold because of its 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 called particles having a size of several micrometers (graphite balls) are inevitably mixed into the DLC film to form a DLC film. The surface roughness deteriorates.

In order to solve such problems, Patent Document 1 discloses that a DLC film which is smooth, high in hardness, and substantially free of hydrogen can be coated by a filter arc ion plating method using a mechanism for trapping and collecting fine particles.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2008-297171

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

According to the review by the present inventors, it has been found that, in particular, when a cold-worked tool steel such as SKD11 having a large amount of carbide (for example, a high-carbon steel having a carbon content of 1% by mass or more or more) is used for a substrate, it is easy to be used in the mother. A gap is formed between the material and the carbide, and the DLC film tends to peel off from the gap. Therefore, the DLC film after the coating may be peeled off.

In view of the above problems, the present invention relates to a coated tool excellent in adhesion and a method for producing the same.

The present inventors have found a specific film structure capable of improving the adhesion of a DLC film having a high hardness and a coating method for realizing the structure, and completed the present invention. The specific means of solving this problem are as follows. That is, the present invention is a coating tool in which a surface of a substrate is coated with a DLC film (diamond-like carbon film) having a nanoindentation hardness of 50 GPa or more and 100 GPa or less, and hydrogen atoms and nitrogen atoms of the DLC film. The content of the DLC film is reduced from the substrate side to the thickness direction (surface side), and the content of hydrogen atoms is 0.5 atom% or less on the surface of the DLC film, and the content of nitrogen atoms is 2 atom% or less, which is a coating tool excellent in adhesion. .

In the surface roughness of the DLC film, the arithmetic mean roughness Ra is preferably 0.03 μm or less, and the maximum height roughness Rz is preferably 0.5 μm or less. The content of hydrogen atoms in the surface of the substrate side of the DLC film is preferably 0.7 atom% or more and 7 atom% or less, and the content of the nitrogen atom is preferably more than 2 atom% and not more than 10 atom%. Further, 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 a super hard alloy having a carbon content of 1% by mass or more.

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

According to the present invention, it is possible to provide a coated tool excellent in adhesion and a method for producing the same.

1‧‧‧Carbon cathode

2‧‧‧Carbon film bundle

3‧‧‧Spherical graphite (microparticles) neutral particles

4‧‧‧Electromagnetic coil

5‧‧‧ catheter

6‧‧‧ Film processing room

7‧‧‧Substrate support

8‧‧‧Rotating mechanism

Fig. 1 is a graph showing the results of glow discharge emission spectrum analysis of a DLC film of sample No. 1 of the present invention.

Fig. 2 is a graph showing the results of glow discharge emission spectrum analysis of the DLC film of sample No. 2 of the present invention.

Fig. 3 is a graph showing the results of glow discharge emission spectrum analysis of the DLC film of sample No. 3 of the present invention.

Fig. 4 is a graph showing the results of glow discharge emission spectrum analysis of the DLC film of Comparative Sample No. 1.

Fig. 5 is a graph showing the results of glow discharge emission spectrum analysis of the DLC film of Comparative Sample No. 2.

Fig. 6 is a graph showing the results of glow discharge emission spectrum analysis of the DLC film of Comparative Sample No. 3.

Fig. 7 is a graph showing the results of the Auger electron spectroscopy analysis of the DLC film of sample No. 1 of the present invention.

Fig. 8 is a graph showing the results of the Auger electron spectroscopy analysis of the DLC film of sample No. 3 of the present invention.

Fig. 9 is a graph showing the results of the analysis of the Auger electron spectroscopy of the DLC film of Comparative Sample No. 3.

Fig. 10 is a schematic view showing a T-shaped filter arc film forming apparatus used in the embodiment.

Fig. 11 (a) to (c) are surface observation images of an optical microscope of a DLC film of samples No. 1 to No. 3 of the present invention.

Fig. 12 (a) to (f) are surface observation images of an optical microscope of a DLC film of Comparative Sample Nos. 1 to 6.

Fig. 13 is a (a) to (f) surface observation image of an optical microscope of each sample of the present invention after the ball-to-disk test.

[Fig. 14] (a) to (e) are surface observation images of optical microscopes of respective comparative samples after the ball-to-disk test.

The coated tool of the present invention is a coated tool in which a diamond-like carbon film is coated on the surface of a substrate, and the nanoindentation hardness measured from the surface of the film is 50 GPa or more and 100 GPa or less. The coating tool of the present invention is a coating tool having a high-hardness DLC film having a nanoindentation hardness of 50 GPa or more measured from the surface of the film on the substrate. If the nanoindentation hardness is less than 50 GPa, the tool life will not be long enough due to the low wear resistance. On the other hand, if the hardness of the film is higher than 100 GPa, the residual stress is too high, and the adhesion to the substrate is lowered.

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

The nanoindentation hardness is a plastic hardness when the probe is pressed into the sample (DLC film) to be plastically deformed, and a load-displacement curve is obtained from the press-in load and the press-in depth (displacement) to calculate the hardness. specific In the nanoindentation apparatus manufactured by ELIONIX Co., Ltd., the hardness of 10 points on the surface of the film was measured under the measurement conditions of a load of 9.8 mN, a maximum load holding time of 1 second, and a load removal speed of 0.49 mN/sec. The two points with the largest value and the two points with the smallest value are eliminated, and the average of the six points is obtained.

The high-hardness DLC film tends to have poor adhesion to a substrate having an extremely high internal stress. Therefore, there has been proposed a technique for ensuring adhesion between a substrate and a DLC film by providing an intermediate film having a lower hardness than the DLC film. However, according to the review by the present inventors, it has been confirmed that when an intermediate film of a metal, a carbide or a nitride is provided between the substrate and the DLC film, the DLC film is peeled off first from the surface defect of the intermediate film. The degree of improvement in adhesion is still insufficient. On the other hand, a DLC film containing a hydrogen atom or a nitrogen atom is known to have a lowered hardness and residual stress. The more the content of hydrogen atoms contained in the DLC film, the lower the hardness and residual stress. For example, when a DLC film is used as a coating material for a coating mold, an increase in temperature during molding causes evaporation of hydrogen contained in the DLC film, and defects such as voids are generated in the mold to shorten the life of the mold. Further, the more the content of the nitrogen atom contained in the DLC film, the lower the hardness and the residual stress. In the case of processing non-ferrous materials, melting and sticking tend to occur. Therefore, even if the adhesion is improved, the DLC film containing too many hydrogen atoms or nitrogen atoms is not easily improved.

Then, the inventors of the present invention have devised a method of providing a DLC film directly above the substrate and changing the continuity of the film structure in the thickness direction of the DLC film to reduce the residual stress. As a result, it was confirmed that when hydrogen and nitrogen elements are not uniformly contained in the thickness direction, and the content of hydrogen atoms and nitrogen atoms decreases in the thickness direction from the substrate side to the surface side of the DLC film, the residual stress is lowered. Even if the substrate is made of cold-worked tool steel with a large amount of carbide, peeling does not occur, and the density is further Improved access. However, when the content of hydrogen atoms or nitrogen atoms contained in the DLC film located on the surface leaving the substrate is large, fusion of the material to be processed occurs, and the tool life is easily shortened. Therefore, in the coating tool of the present invention, the content of hydrogen atoms and nitrogen atoms is gradually decreased in the thickness direction from the substrate side to the surface side of the DLC film, and the content of hydrogen atoms on the surface of the DLC film is 0.5 atom% or less. At the same time, the content of the nitrogen atom is 2 atom% or less. In other words, in the coated tool of the present invention, the content of hydrogen atoms on the surface of the substrate side exceeds 0.5 atom%, and the content of nitrogen atoms on the surface of the substrate side exceeds 2 atom%. By having such a film structure, the high-hardness DLC film disposed directly above the substrate has high adhesion to the substrate, and the problem of melt adhesion of the material to be processed can be prevented. The coated tool of the present invention is applied to a coated mold to greatly extend the life of the mold, which is a preferred aspect.

Among these, for the same reason as described above, the content of hydrogen atoms on the surface of the DLC film is preferably 0.4 atom% or less, more preferably 0.3 atom% or less. Further, the content of the nitrogen atom on the surface of the DLC film is preferably 1.5 atom% or less, more preferably 1.0 atom% or less.

Further, the "surface" of the film of the present invention means a surface in contact with a material to be processed and a portion in the vicinity thereof. In addition, the "surface on the substrate side" of the present invention means the surface of the film which is in contact with the substrate and the portion in the vicinity of the interface.

The content of hydrogen atoms can be determined by elastic recoil detection analysis (ERDA). Further, the content of the nitrogen atom can be determined by Auger electron spectroscopy analysis (AESA).

In the DLC film, if the hydrogen content on the substrate side is too large, even if the hydrogen content is decreased from the substrate side to the surface side, the hydrogen content of the entire DLC film is still large. As a result, the hardness is lowered and the tool characteristics are deteriorated due to evaporation of hydrogen in the use of the tool. In order to increase the hydrogen content on the substrate side, it is effective to introduce a hydrocarbon gas such as acetylene (C ₂ H ₂ ). However, if a hydrocarbon gas is introduced in a large amount, the amount of carbon black adhering to the furnace increases, and maintenance of the apparatus becomes difficult. Therefore, the hydrogen content is preferably 0.7 atom% or more and 7 atom% or less on the surface of the substrate side of the DLC film. The hydrogen content is more preferably 0.7 atom% or more and 3 atom% or less, more preferably 0.7 atom% or more and 2 atom% or less. Further, in the DLC film, if the nitrogen content on the substrate side is too large, even if the nitrogen content is decreased from the substrate side to the surface side, the nitrogen content of the entire DLC film is still large. As a result, there is a problem that the hardness is lowered to cause a decrease in wear resistance and melting and adhesion when processing a non-ferrous material. Therefore, the nitrogen content on the surface of the substrate side of the DLC film is preferably more than 2 atom% and not more than 10 atom%. The nitrogen content is more preferably more than 2 atom% and not more than 8 atom%, more preferably more than 2 atom% and not more than 5 atom%.

When particles such as fine particles or impurities are present on the surface of the DLC film, the material to be processed is melted and adhered to the surface of the DLC film, and scratches such as scratches occur. When measuring the general surface roughness, that is, the arithmetic mean roughness Ra (according to JIS-B-0601-2001) and the maximum height roughness Rz (based on JIS-B-0601-2001), if Ra is A smoothness of 0.03 μm or less and an Rz of 0.5 μm or less can reduce surface defects which become a starting point of melting and bonding of a workpiece, and this is a preferable aspect. Ra is more preferably 0.02 μm or less. Further, Rz is more preferably 0.3 μm or less.

If the film thickness of the DLC film is too thin, the durability of the tool may be insufficient. Further, if the film thickness of the DLC film is too thick, the surface roughness of the film tends to deteriorate. When the film thickness is too thick, the possibility of partial peeling of the DLC film also becomes large. Therefore, the film thickness of the DLC film is preferably from 0.1 μm to 1.5 μm, more preferably from 0.1 μm to 1.2 μm. In order to impart sufficient abrasion resistance to the coated tool, the film thickness of the DLC film is preferably 0.2 μm or more. In order to obtain a smooth surface roughness and excellent wear resistance at the same time, the film thickness of the DLC film is preferably from 0.5 μm to 1.2 μm.

The substrate is not particularly limited and may be appropriately selected depending on the purpose or purpose. For example, super hard alloy, cold worked tool steel, high speed tool steel, plastic mold steel, hot work tool steel, or the like can be used. In the case of the base material, since the effect of improving the adhesion is high, if the carbide of the base material is too much, peeling of the film is likely to occur. Therefore, it is preferable to use a high carbon steel having a carbon content of 1% by mass or more. Superhard alloy. High carbon steel, such as JIS-SKD11.

Next, a method of manufacturing the coated tool of the present invention will be described. The method for producing a coated tool according to the present invention is a method for producing a coated tool in which a diamond-like carbon film is coated on a surface of a substrate 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 mixed gas containing hydrogen into a furnace, performing a gas bombardment treatment on the surface of the substrate, and introducing the nitrogen gas into the furnace after the gas bombardment treatment. The diamond-like carbon film is coated on the surface of the substrate with a graphite target while reducing the flow rate of the nitrogen gas introduced into the furnace.

The DLC film of the coated tool of the present invention can be coated with a conventional filter arc ion plating apparatus. In particular, if a T-shaped filter arc ion plating device is used, it can be coated with a smoother DLC film. Therefore, it is a better aspect. In order to reduce the nitrogen content of the DLC film from the side of the substrate to the surface side, it is possible to coat 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, gas bombardment treatment of a mixed gas containing hydrogen gas before the DLC film is coated has an effect.

When the conventional argon gas bombardment treatment is performed on the substrate before the DLC film is coated, a large amount of oxygen is present at the interface between the film and the substrate, and the adhesion is deteriorated. The oxygen present at this interface is entirely due to the oxide film initially formed on the surface of the substrate, and is a residual element that is not completely removed by gas bombardment with argon gas. On the other hand, when the surface of the substrate is subjected to gas bombardment treatment using a mixed gas containing hydrogen, the oxide film on the surface of the substrate is reacted with hydrogen ions to be reduced, and the oxide film and the surface can be treated by gas bombardment treatment. The dirt is removed. After the gas bombardment treatment is performed on the surface of the substrate with a mixed gas containing hydrogen, hydrogen remains in the furnace. Therefore, after the gas bombardment treatment is completed, nitrogen gas is introduced into the furnace, and the gas flow rate is reduced to face the input power of the graphite target to coat the DLC film, whereby the DLC film does not contain excessive hydrogen, and thus can be formed. A film structure in which hydrogen and nitrogen are reduced from the side of the substrate to the surface side.

The mixed gas containing hydrogen gas is preferably a mixed gas containing argon gas and hydrogen gas having a total mass of 4% by mass or more based on the total mass of the mixed gas. If the hydrogen concentration is 4% by mass or more, the effect of removing the oxide film by the gas bombardment treatment of the mixed gas is better. Further, after the gas bombardment treatment, the amount of hydrogen remaining in the furnace is reduced, and hydrogen is less likely to be present on the substrate side of the DLC film. At the time of gas bombardment treatment, from the viewpoint of improving the adhesion of the high-hardness DLC film, the bias voltage of the negative pressure applied to the substrate is preferably -2500 V to -1500 V. If the bias voltage of the negative pressure applied to the substrate is small, the impact energy of the gas ions will be lower, so the etching effect It will be small, and the adhesion of the high hardness DLC film tends to decrease. Further, if the bias voltage of the negative pressure applied to the substrate is large, the plasma may be unstable, and an abnormal discharge phenomenon may occur. When an abnormal discharge occurs, an abnormal discharge (arc discharge) mark is formed on the surface of the tool, so that unevenness may occur on the surface of the tool. In order to uniformly remove the oxide on the surface of the substrate, the gas bombardment treatment of the mixed gas is preferably 30 minutes or more. After the gas bombardment treatment of 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 the DLC film is coated, the substrate temperature is preferably 200 ° C or less. If the temperature is higher than 200 ° C, the DLC film will be further graphitized and the hardness tends to decrease. In addition, when the DLC film is coated, the bias voltage applied to the substrate should be -300V to -50V. When the bias voltage of the negative pressure applied to the substrate is -50 V or less, the impact energy of the carbon ions is not so small and is easily maintained, and the DLC film is less likely to cause defects such as voids. Further, when the bias voltage of the negative pressure 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 preferably between -200V and -100V. When the DLC film is coated, the substrate temperature is preferably 200 ° C or less. If the temperature is higher than 200 ° C, the DLC film will be further graphitized and the hardness tends to decrease. Further, when the DLC film is coated, the absolute value of the bias voltage applied to the substrate is preferably 50V to 300V. When the absolute value of the bias voltage applied to the substrate is 50 V or more, the impact energy of the carbon ions is large, and the DLC film is less likely to cause defects such as voids. Further, when the absolute value of the bias voltage applied to the negative pressure of the substrate is 300 V or less, the abnormal discharge phenomenon during film formation can be prevented. The bias voltage applied to the substrate is preferably between -200V and -100V.

The flow rate of the nitrogen introduced into the furnace after the gas bombardment treatment is preferably 30 sccm or less. If the flow rate of the gas is larger than 30 sccm, the nitrogen content of the DLC film will increase, and the hardness will easily decrease to cause wear resistance. Reduced properties and problems such as melting and adhesion when processing non-ferrous materials. On the other hand, if the flow rate of the nitrogen gas introduced into the furnace is too small, the degree of reduction of the residual compressive stress of the DLC film may be insufficient. Therefore, the flow rate of the 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. Then, it is preferable that the DLC film is coated while gradually reducing the flow rate of the nitrogen gas introduced into the furnace, and then the introduction of nitrogen gas is stopped, and finally it is preferable to coat the DLC film without introducing nitrogen gas.

In the method for producing a coated tool of the present invention, a diamond-like carbon film is coated on the surface of the substrate by a filtered arc ion plating method. Since a filtered arc ion plating apparatus is used, it is easy to obtain a smooth DLC film, but when the film thickness is thick, the surface roughness may be lowered. At this time, by coating the surface of the coated DLC film, the coated tool can be brought to a better surface state. Further, in order to improve the adhesion between the substrate and the DLC film, it is preferred to make the substrate before the DLC film is coated more smoothly. Specifically, the surface roughness of the substrate is determined by measuring the general surface roughness, that is, the arithmetic mean roughness Ra (according to JIS-B-0601-2001) and the maximum height roughness Rz (by JIS-B-0601). When -2001 is the standard, it is preferable to grind to Ra of 0.06 μm or less and Rz of 0.1 μm or less. Then, the surface roughness of the substrate is more preferably Ra of 0.05 μm or less and Rz of 0.08 μm or less.

[Examples]

Hereinafter, the present invention will be more specifically described by the examples, but the present invention is not limited to the following examples without departing from the spirit of the invention. In addition, as long as it is not specifically denied, "part" is the quality standard.

(Example 1)

<film forming apparatus>

The film forming apparatus uses a T-shaped filter arc ion plating apparatus. A schematic view of the device is shown in FIG. In the film formation processing chamber (6), an arc discharge evaporation source in which a carbon cathode (1) provided with a graphite target is mounted, and a substrate holder (7) for mounting a substrate are provided. A rotating mechanism (8) is disposed under the substrate holder, and the substrate is rotated and revolved through the substrate holder. Symbol (2) represents a carbon film-forming bundle, and symbol (3) represents spherical graphite (fine particles) neutral particles. When an arc discharge occurs on the surface of the graphite target, only the carbon having the electric charge is bent by the electromagnetic coil (4) and reaches the film processing chamber, and the film is coated on the substrate. The particles without charge are not bent by the electromagnetic coil and are captured and collected in the catheter (5).

<Substrate>

The peeling state and the melt adhesiveness after the DLC film coating were evaluated using a substrate equivalent to JIS-SKD11 steel material having a size of φ20 × 5 mm and a thickness of 60 HRC. For the measurement of the nanoindentation hardness, the film analysis, and the rupture film thickness, a substrate made of a superhard alloy composed of tungsten carbide (WC-10% by mass Co) having a cobalt content of 10% by mass (size: 4 mm × 8 mm) × 25 mm, average particle size: 0.8 μm, hardness: 91.2 HRA). In the scratch test, a substrate equivalent to JIS-SKH51 steel having a size of 21 mm × 17 mm × 2 mm was used. Any of the above-mentioned substrates is polished until the arithmetic mean roughness Ra is 0.01 μm or less and the maximum height roughness Rz is 0.07 μm or less before being coated with the DLC film. Then, after grinding, it is degreased and washed and fixed to the substrate holder in the processing chamber. The DLC film was coated on each of the substrates under the following conditions.

<Example 1 (Sample No. 1)>

The film forming process chamber was vacuum-absorbed to 5 × 10 ^-3 Pa, and the substrate was heated to around 150 ° C by a heater for 90 minutes. Thereafter, the bias voltage of the negative pressure applied to the substrate was set to -2000 V, and gas bombardment treatment of a mixed gas containing 5% by mass of hydrogen gas in argon gas was performed for 90 minutes. The flow rate of the mixed gas is 50 sccm to 100 sccm. After the gas bombardment treatment, 10 sccm of nitrogen gas was introduced into the film formation processing chamber, and a bias voltage of -150 V was applied to the substrate, and the substrate temperature was set to 100 ° C or lower. Then, a current of 50 A was input to the graphite target, and the DLC film was coated for about 10 minutes. Next, nitrogen gas was made 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)>

The sample was the same as the sample No. 1 until the gas bombardment treatment. After the gas bombardment treatment, 10 sccm of nitrogen gas was introduced into the film formation processing chamber, and a bias voltage of -150 V was applied to the substrate, and the substrate temperature was set to 100 ° C or lower. Then, the current input to the graphite target was gradually increased from 50A to 80A, and the DLC film was coated for about 30 minutes. Next, a nitrogen gas flow rate of 5 sccm was applied, 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)>

The sample was the same as the sample No. 1 until the gas bombardment treatment. After the gas bombardment treatment, 20 sccm of nitrogen gas was introduced into the film forming processing chamber, and a bias voltage of -150 V was applied to the substrate, and the substrate temperature was set to 100 ° C or lower. Then, the current input to the graphite target was gradually increased from 50A to 80A, and the DLC film was coated for about 30 minutes. Next, the nitrogen 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)>

The sample was the same as the sample No. 1 until the gas bombardment treatment. After the gas bombardment treatment, 5 sccm of C ₂ H ₂ gas was introduced into the film forming chamber for 5 minutes. Thereafter, the introduction of C ₂ H ₂ was stopped, 10 sccm of nitrogen gas was introduced, and a bias voltage of -150 V was applied to the substrate to set the substrate temperature to 100 ° C or lower. Then, a current of 50 A was applied to the graphite target, and the DLC film was coated for about 10 minutes. Next, the flow rate of 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 about 30 minutes.

<Example 5 (Sample No. 5)>

The sample was the same as the sample No. 1 until the gas bombardment treatment. After the gas bombardment treatment, 100 sccm of a mixed gas containing 5% by mass of hydrogen gas in argon gas was introduced into the film forming chamber for 5 minutes. Thereafter, the introduction of the mixed gas was stopped, 10 sccm of nitrogen gas was introduced, a bias voltage of -150 V was applied to the substrate, and the substrate temperature was set to 100 ° C or lower. Then, the current input to the graphite target was 50 A, and the DLC film was coated for about 10 minutes. Next, a nitrogen gas flow rate of 5 sccm was applied, 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)>

The sample was the same as the sample No. 1 until the gas bombardment treatment. After the gas bombardment treatment, 10 sccm of C ₂ H ₂ gas was introduced into the film forming 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 substrate, and the substrate temperature was set to 100 ° C or lower. Then, the current input 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 the C ₂ H ₂ gas was stopped, a flow rate of nitrogen of 15 sccm was introduced, and the DLC film was coated for about 45 minutes. Next, the nitrogen flow rate was changed stepwise from 15 sccm to 5 sccm, 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)>

The sample was the same as the sample No. 1 until the gas bombardment treatment. After the gas bombardment treatment, C ₂ H ₂ gas was introduced into the film forming process chamber. Thereafter, the introduction of C ₂ H ₂ was stopped, 10 sccm of nitrogen gas was introduced, and a bias voltage of -150 V was applied to the substrate to set the substrate temperature to 100 ° C or lower. Then, the current input to the graphite target was 50 A, and the DLC film was coated for about 10 minutes. Next, the C ₂ H ₂ gas was again introduced into the furnace. Thereafter, the introduction of the C ₂ H ₂ gas was stopped, the flow rate of the nitrogen gas 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 1 (Comparative Sample No. 1)>

The sample was the same as the sample No. 1 until the gas bombardment treatment. After the gas bombardment treatment, nitrogen gas was not introduced, a bias voltage of -150 V was applied to the substrate, and the substrate temperature was 100 ° C or lower. Then, the current input to the graphite target was 50 A, and a DLC film was formed for about 50 minutes.

<Comparative Example 2 (Comparative Sample No. 2)>

The gas bombardment treatment was carried out only with argon gas. After the gas bombardment treatment, 10 sccm of nitrogen gas was introduced into the film formation processing chamber, and a bias voltage of -150 V was applied to the substrate, and the substrate temperature was set to 100 ° C or lower. Then, the current input to the graphite target was 50 A, and the DLC film was coated for about 10 minutes. Next, a nitrogen gas flow rate of 5 sccm was applied, 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 treatment was carried out only with argon gas. After the gas bombardment treatment, nitrogen gas was not introduced, a bias voltage of -150 V was applied to the substrate, and the substrate temperature was 100 ° C or lower. Then, the current input to the graphite target was 50 A, and a DLC film was formed for about 50 minutes.

<Comparative Example 4 (Comparative Sample No. 4; Conventional Example)>

Before the DLC film was coated, the surface of the substrate was subjected to gas bombardment treatment with only argon gas, and CrN of about 3 μm was coated as an intermediate film. After the intermediate film was coated, nitrogen gas was not introduced, a bias voltage of -150 V was applied to the substrate, and the substrate temperature was 100 ° C or lower. Then, the current input to the graphite target was 50 A, and a DLC film was formed for about 50 minutes.

Further, in any of the above samples, the DLC film was coated while repeating film formation and cooling so that the substrate temperature was 200 ° C or lower. For each sample coated with the DLC film, hardness measurement, adhesion evaluation, melt adhesion evaluation, and structural analysis were performed. Hereinafter, the measurement conditions will be described.

<Comparative Example 5 (Comparative Sample No. 5)>

The sample was the same as the sample No. 1 until the gas bombardment treatment. After the gas bombardment treatment, 10 sccm of nitrogen gas was introduced into the film formation processing chamber, and a bias voltage of -150 V was applied to the substrate, and the substrate temperature was set to 100 ° C or lower. Then, a current of 50 A was input to the graphite target, and the DLC film was coated for about 10 minutes. Next, nitrogen gas was made 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)>

The sample was the same as the sample No. 1 until the gas bombardment treatment. After the gas bombardment treatment, 20 sccm of nitrogen gas was introduced into the film formation processing chamber, and a bias voltage of -150 V was applied to the substrate to bring the substrate temperature to 100 ° C or lower. Then, the current input to the graphite target was gradually increased from 50A to 80A, and the DLC film was coated for about 30 minutes. Next, the nitrogen 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>

- Determination of hardness -

The hardness of the surface of the film was measured using a nanoindentation device manufactured by ELIONIX Co., Ltd. Ten points were measured under the measurement conditions of a load of 9.8 mN, a maximum load holding time of 1 second, and a load removal speed of 0.49 mN/sec, and the two points with the largest value and the two points with the smallest value were eliminated, and six were obtained. The average of the points. It was confirmed that the hardness of the fused silica as a standard sample was 15 GPa, and the hardness of the CVD diamond film was 100 GPa.

- Determination of surface roughness -

The arithmetic mean roughness Ra and the maximum height roughness Rz were measured using a roughness curve according to JIS-B-0601-2001 using a contact surface roughness measuring device SURFCOM480A manufactured by Tokyo Seimitsu Co., Ltd. The measurement conditions were: evaluation length: 4.0 mm, measurement speed: 0.3 mm/s, and critical value: 0.8 mm.

- Evaluation of adhesion -

The surface of the DLC film of the sample after coating was observed with an optical microscope manufactured by MITUTOYO Co., Ltd. at a magnification of about 800 times, and the peeling state was evaluated. The evaluation criteria of the surface peeling of the DLC film are as follows.

<Evaluation criteria for surface peeling>

A: no surface peeling, B: slight peeling, C: peeling.

Further, the peeling load was measured using a CSM scratch tester (REVETEST). The measurement conditions are: measuring load: 0~100N, load speed: 99.25N/min, scratch speed: 10mm/min, scratch distance: 10mm, AE sensitivity: 5, indenter: Rock hardness, diamond, front end radius: 200 μm, hardware setting: Fn contact 0.9 N, Fn speed: 5 N/s, Fn removal speed: 10 N/s, approach speed: 2%/s. The load at the initial chip generation was regarded as the A load, and the load when the substrate was completely exposed at the bottom of the scratch was regarded as the B load, and was evaluated.

-GD-OES Analysis -

In order to confirm the distribution of the nitrogen component, a structural analysis of a glow discharge emission spectrometer (GD-OES) was performed from the surface of the DLC film to the substrate. The device uses JY-5000RF type GD-OES manufactured by HORIBA JOBIN YVON. The analysis conditions were as follows: Ar was used as the sputtering gas, pressure: 600 Pa, output: 35 W, module: 6 V, phase 4: V, gas replacement time: 20 seconds, preliminary sputtering time: 30 seconds, background: 10 seconds, Measurement time: 90 seconds to 120 seconds. Since the luminescence intensity of nitrogen was low, it was confirmed that the peak intensity was 30 times. As a representative example, the strength profiles of the samples No. 1 to No. 3 of the present invention and the GD-OES of the comparative samples No. 1 to No. 3 are shown in FIGS. 1 to 6 .

-AES analysis -

Quantitative analysis of the nitrogen component of the Auger electron spectroscopy (AES analysis) was carried out from the surface of the DLC film to the substrate. The device used PHI650 (scanning type Auger electron spectroscopy analyzer) manufactured by PERKIN ELMER. The analysis was carried out under the following analysis conditions.

(analysis conditions)

Energy of primary electron: 3 keV, current: about 260 nA, incident angle: 30 degrees with respect to the normal of the sample, and analysis area: about 5 μm × 5 μm.

( conditions for ion sputtering (Ar ⁺ ))

Energy: 3 keV, current: 25 mA, incident angle: about 58 degrees with respect to the normal of the sample, and sputtering rate: about 50 nm/min.

As a representative example, FIG. 7 shows the measurement result of sample No. 1 of the example of the present invention, FIG. 8 shows the measurement result of sample No. 3 of the example of the present invention, and FIG. 9 shows the measurement result of the comparative sample No. 3 of the comparative example.

-ERDA analysis -

In order to confirm the distribution of the hydrogen component, the hydrogen concentration analysis was performed on the substrate side and the surface side of the DLC film by an elastic recoil detection analysis method (ERDA analysis). The apparatus used Pelletron 3SDH manufactured by National Electrostatics Corporation. The He ⁺⁺ ion having an energy of 2.3 MeV was incident at an angle of 75 degrees with respect to the normal to the sample surface, and the recoiled hydrogen particles (H, H ⁺ ) were detected by a semiconductor detector at a position where the scattering angle was 30 degrees.

- Ball to disk test -

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

The test results were compiled and shown in Table 1. In the samples No. 1 to No. 7 of the examples of the present invention, the surface after coating was not peeled off, and the adhesion of the scratch test was also superior to the comparative example. In the sample No. 6 of the present invention having a film thickness of 1 μm or more, the samples No. 1 to No. 5 and No. 7 of the present invention having a thin film thickness have a smoother DLC film. tendency. Fig. 11 and Fig. 12 show optical microscope observation images of the surface of the sample after the DLC film of the representative example is coated. Comparative sample No. 1 and Comparative sample No. 2 were confirmed to have minute peeling having a diameter of about 20 μm after coating. In the comparative example, Comparative Sample No. 3, which was not contained in hydrogen or nitrogen on the substrate side of the DLC film, or Comparative Sample No. 4 in which the intermediate film of the nitride was interposed between the substrate and the DLC film. After the DLC film was coated, a large peeling having a diameter of about 100 μm was also confirmed, and the scratch load was also low. Fig. 13 shows a surface observation image after the ball-to-disk test of a representative example of the sample of the present invention, and Fig. 14 shows a surface observation image after the ball-to-disk test of a representative example of the comparative sample. In the examples of the present invention, it was confirmed in the ball-to-disk test that no peeling or fusion of the film occurred. On the other hand, in the comparative examples, peeling of the film occurred, and the melt adhesion accompanying the peeling was also confirmed. In order to confirm the film structure of the DLC film excellent in adhesion, the analysis was performed. According to the GD-OES analysis, the sample of the present invention and the comparative sample No. 2 confirmed that the nitrogen concentration gradually decreased from the substrate side to the surface side.

As a result of the AES analysis, it was confirmed that the surface of the DLC film of the sample of the present invention contained 2.8 atom% to 3.7 atom% of nitrogen on the surface of the substrate side. On the other hand, the nitrogen content of the surface of the DLC film of the sample of the present invention is not more than the detection limit (1.0 atom% or less). In addition, the peak observed on the substrate side (example As shown in Fig. 7, the sputtering depth is around 1000 nm to 1700 nm, which is caused by the interference of the peaks of N and W. According to the ERDA analysis, it was confirmed that the DLC film of the sample of the present invention contained 1.0 atom% to 7.8 atom% of hydrogen on the surface of the substrate side, and the hydrogen content of the surface was not more than the detection limit (0.2 atom% or less). The details of the hydrogen concentration analysis in the film thickness direction of Sample Nos. 4 to 7 of the present invention are shown in Table 2 as a representative example. It was confirmed that the hydrogen concentration in the examples of the present invention gradually decreased from the side of the substrate to the surface side of the DLC film. According to the above analysis, it was confirmed that the example of the present invention excellent in adhesion has a gradually reduced nitrogen content and hydrogen content from the side of the substrate to the surface side.

In Comparative Sample No. 1 to Comparative Sample No. 3, the film structure from which the nitrogen content and the hydrogen content gradually decreased from the substrate side to the surface side was not confirmed. Therefore, the adhesion is lower than that of the sample of the present invention, and fusion and adhesion also occur. In addition, in Comparative Sample No. 4, since an intermediate film made of nitride is provided between the substrate and the DLC film, the surface of the nitride film is peeled off from the surface defect of the nitride film. The adhesion of the test is also low. In Comparative Sample No. 5, the nitrogen content gradually decreased from the side of the substrate to the surface side, but the hydrogen content gradually increased. Therefore, the hardness and adhesion of the film are lower than those of the sample of the present invention, and fusion and adhesion also occur. In Comparative Example 6, the nitrogen content and the hydrogen content gradually decreased from the side of the substrate to the surface side, but the nitrogen content of the surface was large. Therefore, the hardness and adhesion of the film are lower than those of the sample of the present invention, and fusion and adhesion also occur.

【Table 1】

【Table 2】

The disclosure of Japanese Patent Application No. 2013-073617, the entire contents of which is incorporated herein by reference. All of the documents, patent applications, and technical specifications described in the specification are incorporated by reference to the respective documents, patent applications, and technical specifications to the extent that they are specifically and individually described. The reference is incorporated into this specification.

Claims (9)

A coating tool coated on a surface of a substrate with a diamond-like carbon film, characterized in that the diamond indentation hardness of the diamond carbon film is 50 GPa or more and 100 GPa or less; hydrogen atoms and nitrogen atoms of the diamond carbon film The content is reduced from the side of the substrate in the thickness direction; on the surface of the diamond-like carbon film, the content of hydrogen atoms is 0.5 atom% or less, and the content of nitrogen atoms is 2 atom% or less. The coated tool according to the first aspect of the invention, wherein the surface roughness of the diamond carbon film is: an arithmetic mean 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 content of the hydrogen atom is 0.7 atom% or more and 7 atom% or less, and the content of the nitrogen atom is more than 2 atom% on the surface of the substrate side of the diamond carbon film. And below 10 atom%. The coated tool according to claim 1 or 2, wherein the diamond carbon film has a film thickness of 0.1 μm to 1.5 μm. The coated tool according to claim 1 or 2, wherein the substrate is a high carbon steel or a super hard alloy having a carbon content of 1% by mass or more. A method for manufacturing a coated tool, which is coated with a diamond-like carbon film on a surface of a substrate by a filtered arc ion plating method, comprising: a step of introducing a mixed gas containing hydrogen into the furnace to perform a gas bombardment treatment on the surface of the substrate; and introducing nitrogen into the furnace after the gas bombardment treatment, while reducing the flow rate of the nitrogen gas introduced into the furnace A step of coating a diamond-like carbon film on the surface of the substrate with a graphite target. The method for producing a coated tool according to the sixth aspect of the invention, wherein the mixed gas is a mixed gas containing argon gas and hydrogen gas having a total mass of 4% by mass or more based on the total mass of the mixed gas. The method for producing a coated tool according to the sixth or seventh aspect of the present invention, wherein the covering step is performed by introducing a diamond-like carbon film while reducing the flow rate of the nitrogen gas introduced into the furnace, and further stopping introduction of nitrogen gas and coating Diamond carbon film. The method for producing a coated tool according to claim 6 or 7, wherein in the covering step, the flow rate of the nitrogen gas introduced into the furnace is 5 sccm or more and 30 sccm or less.