CN110616399B

CN110616399B - Covering tool and method for manufacturing same

Info

Publication number: CN110616399B
Application number: CN201910844177.2A
Authority: CN
Inventors: 沙勒·阿布苏里克; 井上谦一
Original assignee: Hitachi Metals Ltd
Current assignee: Proterial Ltd
Priority date: 2013-03-29
Filing date: 2014-03-27
Publication date: 2022-05-24
Anticipated expiration: 2034-03-27
Also published as: WO2014157560A1; TWI616544B; MY173635A; TW201512434A; KR20150121173A; PH12015502188A1; CN110616399A; KR101860292B1; JP2017013136A; JP6103040B2; CN105102665A; JPWO2014157560A1; PH12015502188B1; KR20180030253A; JP6337944B2

Abstract

The present invention provides a method for manufacturing a coated tool in which a diamond-like coating is coated on the surface of a base material by a filtered arc ion plating method, the method including the steps of: a gas bombardment treatment process: introducing a mixed gas containing hydrogen into the furnace, and performing a gas bombardment treatment on the surface of the base material; and a covering step: and a step of introducing nitrogen gas of 5sccm or more and 30sccm or less into the furnace after the gas bombardment treatment, and covering the surface of the substrate with a diamond-like coating film having a film thickness of 0.1 to 1.5 μm by using a graphite target while reducing the flow rate of the nitrogen gas introduced into the furnace.

Description

Covering tool and method for manufacturing the same

(this application is a divisional application filed on even date with 2014.3.27, 201480018973.6, entitled covering tool and method for manufacturing the same.)

Technical Field

The present invention relates to a coated tool coated with a diamond-like coating film (hereinafter referred to as "DLC coating film") 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, and a method for manufacturing the coated tool.

Background

When a workpiece such as aluminum, copper, or resin is molded with a mold, a part of the workpiece adheres to the surface of the mold, and thus product abnormalities such as seizing and scratches may occur. In order to solve such a problem, a covering mold having a DLC coating film covered on the surface of the mold is used. DLC films (Tetrahedral amorphous carbon films: ta-C films) substantially free of hydrogen have been widely used for covering molds because of their high hardness and excellent wear resistance.

However, a DLC film having a high hardness and containing substantially no hydrogen is formed by an arc ion plating method using a graphite target, and particles (graphite nodules) having a size of several micrometers called droplets (droplets) are inevitably mixed into the DLC film, thereby deteriorating the surface roughness of the DLC film.

In order to solve such a problem, patent document 1 discloses that a DLC coating which is smooth and has high hardness and does not substantially contain hydrogen can be coated by applying a Filtered Arc Ion Plating (Filtered Arc Ion Plating) method having a mechanism for collecting droplets.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2008-297171

Disclosure of Invention

Problems to be solved by the invention

By applying a DLC coating having a high hardness and a smooth surface state as in patent document 1, improvement of tool characteristics can be expected. However, the adhesion between the DLC coating having high hardness and the substrate tends to be poor.

According to the study of the present inventors, it was confirmed that: in particular, when cold-work tool steel such as SKD11 (e.g., high-carbon steel having a carbon content of 1 mass% or more) containing a large amount of carbide is used as a base material, a gap tends to be formed between the base and the carbide, and peeling of the DLC coating tends to occur from the gap as a starting point, and the DLC coating may peel off immediately after coating.

The present invention has been made in view of the above circumstances, and relates to a coated tool having excellent adhesion and a method for manufacturing the same.

Means for solving the problems

The present inventors have found a specific film structure capable of improving the adhesion of a DLC film having high hardness and an effective coating method for realizing the structure, and have completed the present invention.

Specific means for achieving the above object are as follows.

That is, the present invention is a coated tool having excellent adhesion, which is a coated tool in which a DLC (diamond-like carbon) coating is coated on a surface of a substrate, wherein the nano-indentation hardness of the DLC coating is 50GPa or more and 100GPa or less; the content of hydrogen atoms and nitrogen atoms in the DLC film decreases from the substrate side in the thickness direction (surface side); the DLC film has a hydrogen atom content of 0.5 atomic% or less and a nitrogen atom content of 2 atomic% or less on the surface.

The surface roughness of the DLC film is preferably such that the arithmetic mean roughness Ra is 0.03 μm or less and the maximum height roughness Rz is 0.5 μm or less.

The DLC film preferably has a hydrogen atom content of 0.7 atom% or more and 7 atom% or less on the substrate side surface, and a nitrogen atom content of more than 2 atom% and 10 atom% or less.

The thickness of the diamond-like coating is preferably in the range of 0.1 to 1.5. mu.m.

As the substrate, high carbon steel or cemented carbide having a carbon content of 1 mass% or more is preferable.

The method for manufacturing a coated tool according to the present invention is a method for manufacturing a coated tool in which a DLC (diamond-like carbon) coating is coated on a surface of a base material by a filtered arc ion plating method, and includes the steps of:

a gas bombardment treatment process: introducing a mixed gas containing hydrogen atoms into the furnace to perform a gas bombardment treatment on the surface of the base material; and a covering step: and then, introducing nitrogen gas into the furnace after the gas bombardment (gas board) treatment, and coating the surface of the substrate with a DLC film by using a graphite target while reducing the flow rate of the nitrogen gas introduced into the furnace.

The mixed gas is preferably a mixed gas containing argon gas and hydrogen gas in an amount of 4 mass% or more based on the total mass of the mixed gas.

In the coating step, it is preferable that the diamond-like carbon coating is coated while reducing the flow rate of the nitrogen gas introduced into the furnace, and then the introduction of the nitrogen gas is stopped (the introduction amount of the nitrogen gas is reduced to 0sccm) to coat the diamond-like carbon coating.

In the coating step, the flow rate of nitrogen gas introduced into the furnace is preferably 5sccm or more and 30sccm or less.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a coated tool having excellent adhesion and a method for manufacturing the same can be provided.

Drawings

FIG. 1 is a graph showing the results of glow discharge emission spectrum analysis of the 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 result of Auger electron spectroscopy analysis of the DLC film of sample No.1 of the present invention.

FIG. 8 is a graph showing the result of 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 Auger electron spectroscopy analysis of the DLC coating film of comparative sample No. 3.

FIG. 10 is a schematic view of a T-shaped arc film deposition apparatus used in examples.

FIG. 11 is a photograph of a surface observation with an optical microscope of DLC coatings of samples Nos. 1 to 3 of the present invention.

FIG. 12 is a photograph of a surface observation with an optical microscope of the DLC coating films of comparative samples No.1 to No. 6.

Fig. 13 is a surface observation photograph of each sample of the present invention example after the ball-and-socket test with an optical microscope.

Fig. 14 is a surface observation photograph of each comparative sample after the ball-and-socket test with an optical microscope.

Detailed Description

The coated tool of the present invention is a coated tool in which a diamond-like coating is coated on the surface of a base material, and the nanoindentation hardness measured from the coating surface is 50GPa or more and 100GPa or less. The coated tool of the present invention is a coated tool having a DLC film with a high hardness, as measured from the film surface, of 50GPa or more as a nanoindentation hardness. If the nanoindentation hardness is low at less than 50GPa, the wear resistance is lowered, and thus the tool life becomes insufficient. On the other hand, if the hardness of the coating is high, which is greater than 100GPa, the residual stress becomes too high, and the adhesion to the substrate is lowered.

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

The nanoindentation hardness is a plastic hardness when a probe is pressed into a sample (DLC coating) and plastically deformed, and a load-displacement curve is obtained from the press-in load and the press-in depth (displacement), and the hardness is calculated. Specifically, the hardness of the film surface at 10 points was measured under the measurement conditions of an indentation load of 9.8mN, a maximum load retention time of 1 second, and a removal rate after the load of 0.49 mN/second using a nanoindenter manufactured by eirix co.

The DLC coating with high hardness tends to have extremely high internal stress and lack adhesion to the substrate. Therefore, a technique has been proposed in the past in which an intermediate coating having a lower hardness than the DLC coating is provided to ensure adhesion between the substrate and the DLC coating. However, according to the studies of the present inventors, it was confirmed that when an intermediate coating such as a metal, carbide, or nitride is interposed between the base material and the DLC coating, the DLC coating is peeled off first from the surface defects of the intermediate coating, and thus the adhesion is not sufficiently improved.

On the other hand, it is known that the hardness and residual stress of the DLC coating film containing hydrogen atoms or nitrogen atoms are reduced. If the content of hydrogen atoms contained in the DLC film is increased, hardness and residual stress decrease. For example, when a DLC coating is used as a coating material for coating a mold, the temperature during molding increases, and hydrogen contained in the DLC coating evaporates, which causes defects such as voids in the mold and decreases the life of the mold. In addition, even if the content of nitrogen atoms contained in the DLC film is increased, hardness and residual stress are reduced. When a non-ferrous material is processed, fusion easily occurs. Therefore, even if the adhesion is improved by the inclusion of the DLC film containing hydrogen atoms or nitrogen atoms in an excessive amount, the tool characteristics are difficult to be improved.

In view of the above, the present inventors have studied a method of reducing residual stress by providing a DLC film directly above a substrate and continuously changing the film structure of the DLC film in the thickness direction. As a result, it was confirmed that when the content of both hydrogen atoms and nitrogen atoms is reduced in the thickness direction from the substrate side to the surface side of the DLC film without uniformly containing hydrogen and nitrogen elements in the thickness direction, the residual stress is reduced, and even when a cold-work tool steel containing a large amount of carbide is used for the substrate, peeling does not occur, and the adhesion is improved.

However, if the content of hydrogen atoms or nitrogen atoms contained in the DLC coating layer on the surface remote from the substrate is increased, welding of the workpiece occurs, and the tool life is likely to be reduced. In contrast, in the coating tool of the present invention, the content of hydrogen atoms and nitrogen atoms is reduced in the thickness direction from the substrate side to the surface side of the DLC coating, and the content of hydrogen atoms and the content of nitrogen atoms on the surface of the DLC coating are 0.5 atomic% or less and 2 atomic% or less, respectively. That is, this means that the content of hydrogen atoms in the surface on the substrate side of the coating tool of the present invention is more than 0.5 atomic%, and the content of nitrogen atoms in the surface on the substrate side is more than 2 atomic%.

By having such a film structure, the DLC film having high hardness provided directly above the substrate has high adhesion to the substrate, and welding of the material to be processed can be suppressed.

The covering tool of the present invention is preferably used for covering a mold, since the life of the mold can be greatly prolonged.

Among these, the content of hydrogen atoms on the surface of the DLC film is preferably 0.4 atomic% or less, and more preferably 0.3 atomic% or less, for the same reason as described above.

The content of nitrogen atoms on the surface of the DLC film is preferably 1.5 atomic% or less, and more preferably 1.0 atomic% or less.

The "surface" of the coating film of the present invention means a surface in contact with a workpiece and its vicinity. In the present invention, the "surface on the substrate side" means the surface of the coating film in contact with the substrate and the vicinity of the interface thereof.

The content of hydrogen atoms can be determined by elastic recoil detection analysis (ERDA analysis). The content of nitrogen atoms can be determined by auger electron spectroscopy (AES analysis).

If the hydrogen content on the substrate side becomes too high in the DLC coating, the hydrogen content contained in the entire DLC coating increases even if the hydrogen content is reduced from the substrate side to the surface side. Resulting in a decrease in hardness and a decrease in tool characteristics due to vaporization of hydrogen in use of the tool. In order to increase the hydrogen content on the substrate side, it is effective to introduce acetylene (C)₂H₂) And hydrocarbon-based gases. However, when a large amount of hydrocarbon-based gas is introduced, dust attached to the furnace increases, making maintenance of the apparatus difficult.

Therefore, the hydrogen content of the surface of the DLC film on the substrate side is preferably 0.7 atomic% or more and 7 atomic% or less. The hydrogen content is more preferably 0.7 atom% or more and 3 atom% or less, and still more preferably 0.7 atom% or more and 2 atom% or less.

In addition, if the nitrogen content on the substrate side becomes too high in the DLC coating, the nitrogen content contained in the entire DLC coating increases even if the nitrogen content is reduced from the substrate side to the surface side. As a result, wear resistance is reduced due to the reduction in hardness, and welding is likely to occur when a nonferrous material is processed.

Therefore, the nitrogen content of the surface of the DLC coating on the substrate side is preferably greater than 2 atomic% and 10 atomic% or less. The nitrogen content is more preferably more than 2 atomic% and 8 atomic% or less, and still more preferably 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 material to be processed welds from these droplets as a starting point, and seizing or the like occurs. When the average roughness Ra (in accordance with JIS-B-0601-2001) and the maximum height roughness Rz (in accordance with JIS-B-0601-2001) which are normal surface roughness are measured, it is preferable that the surface defects which become the starting points of welding of the materials to be processed are reduced by having smoothness in which Ra is 0.03 μm or less and Rz is 0.5 μm or less. More preferably, Ra is 0.02 μm or less. Further, Rz is more preferably 0.3 μm or less.

If the film thickness of the DLC coating is too thin, the durability as a tool is insufficient. Further, 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 of peeling off the DLC coating portion also increases. Therefore, the film thickness of the DLC film is preferably 0.1 to 1.5 μm, more preferably 0.1 to 1.2 μm. The film thickness of the DLC coating is preferably 0.2 μm or more in order to impart sufficient wear resistance to the coated tool. In order to achieve both smooth surface roughness and excellent wear resistance, the film thickness of the DLC film is more preferably 0.5 to 1.2 μm.

The substrate is not particularly limited and may be appropriately selected depending on the application, purpose, and the like. For example, cemented carbide, cold work tool steel, high speed tool steel, plastic mold steel, hot work tool steel, and the like can be used. Among the base materials, high carbon steel and cemented carbide having a carbon content of 1 mass% or more, in which the base material has a large amount of carbide and peeling of the coating easily occurs, are preferable because of their high effect of improving adhesion. Examples of the high carbon steel include JIS-SKD 11.

Next, a method for manufacturing the coated tool of the present invention will be described.

The method for manufacturing a coated tool according to the present invention is a method for manufacturing a coated tool in which a diamond-like coating is coated on the surface of a base material by a filtered arc ion plating method. Specifically, the method for manufacturing a coated tool according to the present invention includes the steps of: a gas bombardment treatment process: introducing a hydrogen-containing mixed gas into the furnace to perform a gas bombardment treatment on the surface of the base material; and a covering step: and a step of introducing nitrogen gas into the furnace after the gas bombardment treatment, and coating the surface of the base material with a diamond-like carbon coating film by using a graphite target while reducing the flow rate of the nitrogen gas introduced into the furnace.

The DLC coating of the coated tool of the present invention can be coated by a conventionally known arc-filtered ion plating apparatus. In particular, the use of a T-shaped filtered arc ion plating apparatus is preferable because a smoother DLC coating can be coated.

In order to reduce the nitrogen content of the DLC film from the substrate side to the surface side, the DLC film can be covered 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 the DLC film is coated.

When a conventional gas bombardment treatment using argon gas is performed on a substrate before the DLC coating is coated, a large amount of oxygen is present at the interface between the coating and the substrate, and adhesion is poor. The oxygen present at the interface is mainly caused by an oxide film formed on the surface of the substrate from the beginning, and is a residual element that is not completely removed by the gas bombardment treatment with argon gas. On the other hand, by performing a gas bombardment treatment on the surface of the base material using a mixed gas containing hydrogen, the oxide film present on the surface of the base material is reduced by reacting with hydrogen ions, and the oxide film and the stains on the surface can be removed by the gas bombardment treatment.

After the surface of the base material is subjected to gas bombardment treatment with a mixed gas containing hydrogen, hydrogen remains in the furnace. Therefore, after the gas bombardment treatment is completed, only nitrogen gas is introduced into the furnace, and electric power is applied to the graphite target while reducing the gas flow rate to coat the DLC film, whereby the DLC film can be formed into a film in which hydrogen and nitrogen are reduced from the substrate side to the surface side without containing excessive hydrogen.

The hydrogen-containing mixed gas is preferably a mixed gas containing argon gas and hydrogen gas in an amount of 4 mass% or more based on the total mass of the mixed gas. When the hydrogen concentration is 4 mass% or more, the oxide film is more preferably removed by a gas bombardment treatment using a mixed gas. Further, after the gas bombardment treatment, the amount of hydrogen remaining in the furnace is reduced, and it is difficult to contain hydrogen on the substrate side of the DLC film.

In the gas bombardment treatment, the bias of the negative pressure applied to the substrate is preferably set to-2500V to-1500V in order to improve the adhesion of the DLC film having high hardness. When the bias of the negative pressure applied to the substrate is small, the collision energy of the gas ions is low, and therefore the etching effect is reduced, and the adhesion of the DLC coating having high hardness tends to be lowered. In addition, when the bias voltage of the negative pressure applied to the substrate is large, the plasma may become unstable and abnormal discharge may occur. If abnormal discharge occurs, an abnormal discharge (arcing) mark may be formed on the tool surface, and unevenness may be generated on the tool surface.

The gas bombardment treatment with the mixed gas is preferably performed for 30 minutes or more in order to uniformly remove the oxide on the surface of the base material.

After the gas bombardment treatment with the mixed gas is performed, a hydrocarbon gas such as acetylene may be introduced into the furnace to increase the hydrogen content on the substrate side.

When the DLC coating is coated, the substrate temperature is preferably 200 ℃. If the temperature is higher than 200 ℃, the hardness tends to decrease because the graphitization of the DLC coating film progresses.

In addition, the bias voltage applied to the substrate during the coating of the DLC film is preferably-300V to-50V. When the bias voltage of the negative pressure applied to the substrate is-50V or less, the collision energy of the carbon ions is not reduced and is easily maintained, and defects such as pores are less likely to occur in the DLC film. When the bias voltage of the negative pressure applied to the substrate is-300V 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.

The substrate temperature for covering the DLC coating is preferably 200 ℃. If the temperature is higher than 200 ℃, the hardness tends to decrease because the graphitization of the DLC coating film progresses.

In the DLC film coating, the absolute value of the bias applied to the substrate is preferably 50V to 300V. When the absolute value of the bias voltage of the negative pressure applied to the substrate is 50V or more, the collision energy of the carbon ions increases, and defects such as pores are less likely to occur in the DLC film. In addition, if the absolute value of the bias of the negative pressure applied to the substrate is 300V or less, abnormal discharge during film formation can be 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 30sccm or less. If the flow rate of the gas is more than 30sccm, the content of nitrogen contained in the DLC film increases, the wear resistance decreases due to the decrease in hardness, and welding easily occurs when processing a nonferrous material. On the other hand, if the flow rate of nitrogen gas introduced into the furnace is too low, the residual compressive stress of the DLC film cannot be sufficiently reduced. Therefore, from the viewpoint of reducing the residual compressive stress of the DLC film, the flow rate of nitrogen gas introduced into the furnace after the gas bombardment treatment is preferably 5sccm or more. Further, it is preferable that the DLC film is covered while the flow rate of nitrogen gas introduced into the furnace is gradually reduced, and then the introduction of nitrogen gas is stopped, and finally the DLC film is covered without introducing nitrogen gas.

In the method for manufacturing a coated tool according to the present invention, a diamond-like coating film is coated on the surface of a substrate by filtered arc ion plating. Since the filtered arc ion plating apparatus is used, a smooth DLC coating is easily obtained, but when the film thickness becomes thick, the surface roughness may decrease. In this case, the surface of the DLC coating after coating is polished, whereby a preferable surface state of the coated tool can be achieved.

Further, the substrate before being coated with the DLC film is preferably a smoother substrate in order to further improve the adhesion between the substrate and the DLC film. Specifically, the surface roughness of the substrate is preferably ground to 0.06 μm or less in Ra and 0.1 μm or less in Rz when measured by the arithmetic average roughness Ra (in accordance with JIS-B-0601-2001) and the maximum height roughness Rz (in accordance with JIS-B-0601-2001), which are typical surface roughness. Further, the surface roughness of the base material is more preferably Ra of 0.05 μm or less and Rz of 0.08 μm or less.

Examples

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Unless otherwise specified, "part" means a mass basis.

(example 1)

< film Forming apparatus >

The film forming apparatus used a T-shaped filtered arc ion plating apparatus. A schematic of the apparatus is shown in figure 10. The film forming chamber (6) has an arc discharge evaporation source to which a carbon cathode (cathode) (1) provided with a graphite target is attached, and a substrate holder (7) for mounting a substrate. A rotating mechanism (8) is arranged below the substrate support, and the substrate rotates and revolves through the substrate support. The symbol (2) represents a carbon film bundle, and the symbol (3) represents spherical graphite (droplet) neutral particles.

When arc discharge occurs on the surface of the graphite target, only the carbon having electric charge is bent toward the magnet coil (4) and reaches the film formation chamber, thereby covering the base material with a film. The droplets without electric charge are not collected into the pipe (5) by the bending of the magnetic coil.

< substrate >

In the evaluation of the peeled state and weldability immediately after the DLC coating was coated, a base material corresponding to JIS-SKD11 steel material was used which was hardened to 60HRC with a size of φ 20X 5 mm.

In the nanoindenter hardness, film coating analysis, and measurement of the film thickness on the fracture surface, a base material (size: 4 mm. times.8 mm. times.25 mm, average particle size: 0.8 μm, hardness: 91.2HRA) made of cemented carbide made of tungsten carbide (WC-10 mass% Co) having a cobalt content of 10 mass% was used.

The scratch test used a base material corresponding to JIS-SKH51 steel having dimensions of 21 mm. times.17 mm. times.2 mm.

Any of the above substrates is polished so that the arithmetic average roughness Ra is 0.01 μm or less and the maximum height roughness Rz is 0.07 μm or less before the DLC film is coated. After polishing, the substrate holder was fixed in the chamber by degreasing and washing.

Each substrate was covered with a DLC coating under the following conditions.

< example 1 (sample No.1) >

Vacuumizing the film-forming chamber to 5 x 10^-3Pa, the substrate was heated to around 150 ℃ by a heater for heating and held for 90 minutes.

Thereafter, the negative pressure applied to the substrate was set to-2000V, and a gas bombardment treatment with a mixed gas containing 5 mass% of hydrogen in argon gas was performed for 90 minutes. The flow rate of the mixed gas is set to 50sccm to 100 sccm.

After the gas bombardment treatment, 10sccm of nitrogen gas was introduced into the film formation chamber, and a bias of-150V was applied to the substrate, so that the substrate temperature was 100 ℃ or lower. Then, a current of 50A was applied to the graphite target to coat the DLC film for about 10 minutes.

Next, the nitrogen gas was set to 5sccm, and the DLC film was coated for about 10 minutes. Subsequently, the introduction of nitrogen gas was stopped, and the DLC film was covered for 30 minutes.

< example 2 (sample No.2) >

The same operation as in sample No.1 was carried out before the gas bombardment treatment. After the gas bombardment treatment, 10sccm of nitrogen gas was introduced into the film formation chamber, and a bias of-150V was applied to the substrate, so that the substrate temperature was 100 ℃ or lower. Then, the current to be applied to the graphite target was increased in stages from 50A to 80A, and the DLC coating was applied for about 30 minutes.

Next, the nitrogen flow rate was set to 5sccm, and the DLC film was coated for about 30 minutes. Subsequently, the introduction of nitrogen gas was stopped, and the DLC film was coated for about 70 minutes.

< example 3 (sample No.3) >

The same operation as in sample No.1 was carried out before the gas bombardment treatment. After the gas bombardment treatment, 20sccm of nitrogen gas was introduced into the film formation chamber, and a bias of-150V was applied to the substrate, so that the substrate temperature was 100 ℃ or lower. Then, the current to be applied to the graphite target was increased in stages from 50A to 80A, and the DLC coating was applied for about 30 minutes.

Next, the nitrogen flow rate was changed stepwise from 20sccm to 5sccm, and the DLC film was coated for about 30 minutes. Subsequently, the introduction of nitrogen gas was stopped, and the DLC film was coated for about 70 minutes.

< example 4 (sample No.4) >

The same operation as in sample No.1 was carried out before the gas bombardment treatment. After the gas bombardment treatment, 5sccm of C was introduced into the film formation chamber₂H₂Gas for 5 minutes. Then, stop C₂H₂10sccm of nitrogen gas was introduced, and a bias of-150V was applied to the substrate to set the substrate temperature to 100 ℃ or lower. Then, a current of 50A 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 flow rate of 5 sccm. Subsequently, the introduction of nitrogen gas was stopped, and the DLC film was coated for about 30 minutes.

< example 5 (sample No.5) >

The same operation as in sample No.1 was carried out before the gas bombardment treatment. After the gas bombardment treatment, a mixed gas of 100sccm of 5 mass% hydrogen in argon was introduced into the film formation chamber for 5 minutes. Thereafter, the introduction of the mixed gas was stopped, 10sccm of nitrogen gas was introduced, and a bias of-150V was applied to the substrate to set the substrate temperature to 100 ℃ or lower. Then, the current applied to the graphite target was set to 50A, and the DLC coating was applied for about 10 minutes.

Next, the DLC film was coated for about 10 minutes with a nitrogen flow of 5 sccm. Subsequently, the introduction of nitrogen gas was stopped, and the DLC film was coated for about 30 minutes.

< example 6 (sample No.6) >)

The same operation as in sample No.1 was carried out before the gas bombardment treatment. After the gas bombardment treatment, 10sccm of C was introduced into the film formation chamber₂H₂Gas was allowed to flow for 10 minutes. Then, C of 10sccm was introduced simultaneously₂H₂A bias of-150V was applied to the substrate with a gas of 15sccm and nitrogen gas, and the substrate temperature was set to 100 ℃ or lower. Then, the current to be applied to the graphite target is increased in stages from 50A to 80AThe DLC coating was applied for about 6 minutes.

Then, stop C₂H₂The gas was introduced at a flow rate of 15sccm of nitrogen gas, and the DLC film was coated for about 45 minutes. Next, the nitrogen flow rate was changed stepwise from 15sccm to 5sccm, and the DLC film was coated for about 45 minutes. Subsequently, the introduction of nitrogen gas was stopped, and the DLC film was coated for about 100 minutes.

< example 7 (sample No.7) >

The same operation as in sample No.1 was carried out before the gas bombardment treatment. After the gas bombardment treatment, C is introduced into the film forming chamber₂H₂A gas. Then, stop C₂H₂10sccm of nitrogen gas was introduced, and a bias of-150V was applied to the substrate to set the substrate temperature to 100 ℃ or lower. Then, the current applied to the graphite target was set to 50A, and the DLC coating was applied for about 10 minutes. Then, C is introduced into the furnace again₂H₂A gas. Then, stop C₂H₂The gas was introduced at a nitrogen flow rate of 5sccm, and the DLC film was coated for about 10 minutes. Subsequently, 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 same operation as in sample No.1 was carried out before the gas bombardment treatment. After the gas bombardment treatment, a bias of-150V was applied to the substrate without introducing nitrogen gas, and the substrate temperature was set to 100 ℃ or lower. Then, the DLC film was formed for about 50 minutes with the current applied to the graphite target set to 50A.

< comparative example 2 (comparative sample No.2) >

The gas bombardment treatment was performed with argon only. After the gas bombardment treatment, 10sccm of nitrogen gas was introduced into the film formation chamber, and a bias of-150V was applied to the substrate, so that the substrate temperature was 100 ℃ or lower. Then, the current applied to the graphite target was set to 50A, and the DLC film was coated for about 10 minutes. Next, the DLC film was coated for about 10 minutes with a nitrogen flow of 5 sccm. Subsequently, 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 performed with argon only. After the gas bombardment treatment, a bias of-150V was applied to the substrate without introducing nitrogen gas, and the substrate temperature was set to 100 ℃ or lower. Then, the DLC film was formed for about 50 minutes with the current applied to the graphite target set to 50A.

< comparative example 4 (comparative sample No. 4: conventional example) >

Before the DLC film was coated, the surface of the substrate was subjected to a gas bombardment treatment using only argon gas, and a CrN film having a thickness of about 3 μm was coated as an intermediate film. After the intermediate coating was coated, a bias of-150V was applied to the substrate without introducing nitrogen gas, and the substrate temperature was set to 100 ℃ or lower. Then, the DLC coating was formed for about 50 minutes with the current applied to the graphite target set to 50A.

In any of the above samples, the DLC film was coated while repeating film formation and cooling so that the temperature of the substrate became 200 ℃.

Each sample coated with the DLC film was subjected to hardness measurement, adhesion evaluation, weldability evaluation, and structural analysis. The measurement conditions will be described below.

< comparative example 5 (comparative sample No.5) >

The same operation as that of sample No.1 was performed before the gas bombardment treatment. After the gas bombardment treatment, 10sccm of nitrogen gas was introduced into the film formation chamber, and a bias of-150V was applied to the substrate, so that the substrate temperature was 100 ℃ or lower. Then, a current of 50A 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 nitrogen gas at 5 sccm. Next, the introduction of nitrogen gas was stopped, and 20sccm of C was introduced₂H₂The DLC film was coated with the gas for 30 minutes.

< comparative example 6 (comparative sample No.6) >

Next, the nitrogen flow rate was changed stepwise from 20sccm to 5sccm, and the DLC film was coated for about 30 minutes. Next, 5sccm of nitrogen gas was introduced to cover the DLC film for about 70 minutes.

< measurement and evaluation >

Determination of the hardness-

The hardness of the film surface was measured using a nanoindentation device manufactured by Elionix co. 10 points were measured under the measurement conditions of an indentation load of 9.8mN, a maximum load retention time of 1 second, and a removal rate after load of 0.49 mN/second, and 2 points having a large removal value and 2 points having a small removal value were determined from the average of 6 points. It was confirmed that the hardness of fused silica as a standard sample was 15GPa and the hardness of the CVD diamond film was 100 GPa.

Determination of surface roughness-

The arithmetic average roughness Ra and the maximum height roughness Rz were measured by a roughness curve in accordance with JIS-B-0601-2001 using a contact surface roughness measuring instrument SURFCM 480A manufactured by Tokyo precision Co. The measurement conditions were set as evaluation length: 4.0mm, measurement speed: 0.3mm/s, cut-off value: 0.8 mm.

Evaluation of adhesion-

The peeling state of the DLC coating surface of the sample immediately after coating was observed at a magnification of about 800 times using an optical microscope manufactured by Mitutoyo co. Evaluation criteria for surface peeling of the DLC coating are as follows.

< evaluation criteria for surface peeling >

A: without surface peeling

B: with micro-peeling

C: with peeling-off

Further, the peeling load was measured using a scratch tester (REVETEST) manufactured by CSM co. The measurement conditions were set to the measurement load: 0-100N, load speed: 99.25N/min, scratch speed: 10 mm/min, scratch distance: 10mm, AE sensitivity: 5. pressure head: rockwell, diamond, nose radius: 200 μm, hardware settings: fn-contact 0.9N, Fn speed: 5N/s, Fn removal rate: 10N/s, approach speed (approximate speed): 2%/s.

The load at which initial peeling occurred was evaluated as a load, and the load at which the base material at the bottom of the scratch was completely exposed was evaluated as B load.

-GD-OES analysis-

In order to confirm the distribution of nitrogen components, structural analysis was performed from the surface of the DLC film to the substrate by glow discharge emission spectroscopy (GD-OES). The device used JY-5000RF model GD-OES manufactured by HORIBA JOBIN YVON. The analysis conditions were set to use Ar as a sputtering gas, pressure: 600Pa, output: 35W, module (module): 6V, phase: 4V, gas replacement time: 20 seconds, pre-sputtering time: 30 seconds, background (background): 10 seconds, measurement time: 90-120 seconds.

Since the emission intensity of nitrogen was low, it was confirmed that the peak intensity was 30 times. As representative examples, the GD-OES intensity distributions of the inventive samples Nos. 1 to 3 and the comparative samples Nos. 1 to 3 are shown in FIGS. 1 to 6.

AES analysis-

Quantitative analysis of nitrogen component was performed from the surface of the DLC film to the substrate by auger electron spectroscopy (AES analysis). The apparatus used was PHI650 (scanning auger electron spectroscopy apparatus) manufactured by Perkin Elmer co. The analysis was performed under the following analysis conditions.

(analysis conditions)

Energy of primary electron: 3keV

Current: about 260nA

Angle of incidence: 30 degrees relative to the normal of the sample

Analysis area: about 5 μm.times.5 μm

(ion sputtering (Ar)⁺) Condition (2)

Energy: 3keV

Current: 25mA

Angle of incidence: about 58 degrees from the normal to the sample

Sputtering rate: about 50 nm/min

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

ERDA assay

In order to confirm the distribution of hydrogen components, the substrate side and the surface side of the DLC coating were analyzed for hydrogen concentration by Elastic Recoil Analysis (ERDA Analysis). The apparatus used Pelletron 3SDH manufactured by National Electrical Corporation. He of energy 2.3MeV⁺⁺The ions are incident at an angle of 75 degrees with respect to the normal of the sample surface, and the recoiled hydrogen particles are detected by a semiconductor detector at a scattering angle of 30 degrees (H, H)⁺) And (6) detecting.

Ball and disk test

For evaluation of weldability, a ball and socket tester (CSM Instruments co., Tribometer manufactured by ltd.) was used. The disc-shaped test piece was rotated at a speed of 100 mm/sec while pressing an aluminum A5052 ball (diameter 6mm) against the DLC film-coated substrate at a load of 5N. The test distance was set at 100 m.

Summary the test results are shown in table 1. The samples Nos. 1 to 7 of the present invention were also superior to the comparative examples in adhesion by the scratch test, in the case of surface peeling after no coating. The DLC coatings of samples Nos. 1 to 5 and 7 of the present invention examples, which had a small film thickness, tended to be smoother than sample No.6 of the present invention example, which had a film thickness of 1 μm or more.

Fig. 11 and 12 show representative examples of optical microscope observation photographs of the surface of a sample immediately after being coated with a DLC coating. In comparative samples No.1 and No.2, it was confirmed that there was slight peeling with a diameter of about 20 μm after the coating. In the comparative example, it was also confirmed that, in comparative sample No.3 in which neither hydrogen nor nitrogen was contained on the substrate side of the DLC film, or comparative sample No.4 in which an intermediate film of nitride was interposed between the substrate and the DLC film, peeling was large in diameter of about 100 μm after the DLC film was coated, and the scratch load was also reduced.

Fig. 13 shows a representative example of the sample of the present invention example, and fig. 14 shows a representative example of the comparative sample, respectively, in the surface observation photographs after the ball pan test. In the present example, it was confirmed that neither peeling off of the coating nor welding occurred in the ball pan test. On the other hand, in the comparative examples, peeling of the coating and fusion bonding accompanied by peeling were confirmed.

The analysis was performed to confirm the film structure of the DLC film having excellent adhesion. The inventive sample and comparative sample No.2 were analyzed by GD-OES, and it was confirmed that the nitrogen concentration decreased from the substrate side to the surface side.

As a result of AES analysis, it was confirmed that the sample of the present invention contained 2.8 atomic% to 3.7 atomic% of nitrogen on the substrate side surface of the DLC film. On the other hand, the nitrogen content of the surface of the DLC coating of the sample of the present invention example was not more than the detection limit (not more than 1.0 atomic%). The peaks observed on the substrate side (for example, peaks near the sputtering depth of 1000nm to 1700nm in fig. 7) are caused by the interference of auger peaks of N and W.

The ERDA analysis confirmed that the DLC coating of the sample of the present invention contains 1.0 atomic% to 7.8 atomic% of hydrogen on the surface on the substrate side, and the hydrogen content on the surface was not more than the detection limit (not more than 0.2 atomic%). Table 2 shows the details of the analysis of the hydrogen concentration in the film thickness direction of samples Nos. 4 to 7 of the present invention as representative examples. In the examples of the present invention, it was confirmed that the hydrogen concentration decreased from the substrate side to the surface side of the DLC coating film.

From the above analysis, it was confirmed that the nitrogen content and the hydrogen content decreased from the substrate side to the surface side in the example of the present invention having excellent adhesion.

In comparative samples No.1 to No.3, the film structure in which the nitrogen content and the hydrogen content were reduced from the substrate side to the surface side could not be confirmed. Therefore, the adhesion was reduced compared to the sample of the present invention, and welding was also caused.

In comparative sample No.4, since an intermediate film made of nitride was additionally interposed between the base material and the DLC film, surface peeling of the DLC film occurred from the surface defects of the nitride film as starting points, and the adhesion by the scratch test was also reduced.

In comparative sample No.5, the nitrogen content decreased from the substrate side to the surface side, but the hydrogen content increased. Therefore, the film hardness and adhesion were reduced and welding was also caused as compared with the sample of the present invention.

In comparative example 6, the nitrogen content and the hydrogen content decreased from the substrate side to the surface side, but the nitrogen content of the surface was large. Therefore, the film hardness and adhesion were reduced and welding was also caused as compared with the sample of the present invention.

[ Table 1]

1 nano indentation hardness

[ Table 2]

The disclosure of japanese application 2013-073617 is incorporated in its entirety by reference into this specification.

All documents, patent applications, and technical standards cited in the present specification are incorporated by reference herein to the same extent as if each individual document, patent application, or technical standard were specifically and individually indicated to be incorporated by reference.

Claims

1. A method for manufacturing a coated tool in which a diamond-like coating is coated on the surface of a base material by filtered arc ion plating, comprising the steps of:

a gas bombardment treatment process: introducing a mixed gas containing hydrogen gas into the furnace to perform a gas bombardment treatment on the surface of the base material, wherein the bias of the negative pressure applied to the base material is-2500V to-1500V; and

a covering procedure: a step of introducing nitrogen gas of 5sccm or more and 30sccm or less into the furnace after the gas bombardment treatment, and covering the surface of the base material with a diamond-like coating film having a film thickness of 0.1 to 1.5 μm by using a graphite target while reducing the flow rate of the nitrogen gas introduced into the furnace,

the diamond-like coating film has a nanoindentation hardness of 50GPa or more and 100GPa or less, a content of hydrogen atoms and a content of nitrogen atoms of the diamond-like coating film decrease from the substrate side to the surface side, and the diamond-like coating film has a surface hydrogen atom content of 0.5 atomic% or less and a nitrogen atom content of 2 atomic% or less.

2. The method for manufacturing a coating tool according to claim 1, wherein the mixed gas contains argon gas and hydrogen gas in an amount of 4 mass% or more based on the total mass of the mixed gas.

3. The method of manufacturing a coated tool according to claim 1 or 2, wherein in the coating step, after the diamond-like coating is coated while reducing the flow rate of the nitrogen gas introduced into the furnace, the introduction of the nitrogen gas is stopped to coat the diamond-like coating.

4. The method for manufacturing a coated tool according to claim 1 or 2, wherein the diamond-like coating has a surface on the substrate side having a hydrogen atom content of 0.7 atomic% or more and 7 atomic% or less, and a nitrogen atom content of more than 2 atomic% and 10 atomic% or less.