JP5824010B2 - Hard coating coated member - Google Patents

Description

  The present invention relates to a hard film-coated member excellent in wear resistance, adhesion, and high-temperature oxidation and mold releasability in a mold, and particularly relates to a member having a nitrogen-containing chromium film formed on its surface as a hard film. Further, the present invention relates to an aluminum die casting or resin molding mold surface on which the hard film is formed.

  Conventionally, nitrogen-containing chromium is produced by physical vapor deposition such as sputtering on the surfaces of sliding parts and machine parts such as automobiles that require wear resistance and seizure resistance, as well as dies used under high surface pressure. A method of forming a film and improving wear resistance and seizure resistance is known (Patent Document 1).

  In addition, for example, as a mold as a member for a resin molding apparatus, it has an excellent release property and wear resistance, having a modified layer in which carbon and fluorine are ion-implanted on the outermost surface on the surface of the metallic base material in contact with the resin And a mold that can maintain the releasability over a long period of time has been proposed (Patent Document 2). In addition, a method has been proposed in which a chromium nitride film is formed on a mold by ion plating, and then a chromium oxide film is formed to obtain a coating having excellent wear resistance (Patent Document 3).

JP-A-11-217666 JP 2000-61952 A JP-A-8-296033

However, it is difficult to solve a surface-treated film that satisfies all of the characteristics required for aluminum die casting and resin molds, such as wear resistance, adhesion, high-temperature oxidation resistance, and releasability, with a simple system. It is. In addition, methods have been proposed for satisfying all of the above characteristics by composite treatment, multi-element addition, and the like, but it has been difficult to satisfy all of the required characteristics by the method of the above-mentioned patent document, for example.
The conventional nitrogen-containing chromium film has an amorphous structure and no clear grain boundary, so it is said to have high corrosion resistance and alkali resistance. However, the wettability with molten metal and resin molded toward the surface is too good (for example, Patent Document 1).
Moreover, since the strength of the coating on the outermost surface of the coating of Patent Document 2 is relatively small, there is a risk of early peeling and abrasion of the coating in the above-described mold application with a high load. The method of Patent Document 3 is based on ion plating. In order to form a film, it is necessary to heat the mold to at least 300 ° C. or higher, and the base material may be softened.
Furthermore, the prior art has a high manufacturing cost due to complicated equipment and processes. In addition, there was a problem in productivity such as inability to re-process and local processing. In addition, although a mold having a TiAlN film is also known, it is chemically unstable with respect to an alkaline aqueous solution, and there is a risk that problems may occur in mold maintenance.

  Therefore, in view of such conventional problems, the present invention is not only excellent in mechanical strength such as wear resistance and adhesion, but also in chemical stability such as high temperature oxidation resistance, alkali resistance and releasability. Another object of the present invention is to provide an excellent hard coating member.

  As a result of diligent research to solve the above problems, the present inventors have formed a nitrogen-containing chromium film on a base material, and formed a chromium oxide film on the nitrogen-containing chromium film, thereby achieving good resistance to resistance. We have found that we can obtain a hard coating material coated with a hard coating with high hardness, which has excellent mechanical properties such as wear and adhesion, and chemical stability such as high-temperature oxidation resistance, alkali resistance and releasability. The present invention has been completed.

That is, the hard film-coated member according to the present invention includes a base material, a nitrogen-containing chromium film having a thickness of 1 to 30 μm , and a thick peak of CrN by X-ray diffraction sequentially laminated on the base material. And a chromium oxide film having a thickness of 0.1 to 3 μm.

The hard film covering member of the present invention has a base material, a chromium film having a thickness of 0.01 to 3 μm sequentially laminated on the base material, and a thickness 1 in which the peak of CrN by X-ray diffraction is broad. It is characterized by comprising a nitrogen-containing chromium film having a thickness of ˜30 μm and a chromium oxide film having a thickness of 0.1 to 3 μm.

The hard film covering member of the present invention is an intermediate between the nitrogen-containing chromium film and the chromium oxide film in which oxygen and chromium gradually decrease and nitrogen gradually increases between the nitrogen-containing chromium film and the chromium oxide film. It has a graded composition layer having a composition thickness of 0.01 to 1 μm.

The hard film-coated member of the present invention is characterized in that concave dimples are formed on the surface of the chromium oxide film.

  The hard film covering member of the present invention is used as a mold or a sliding part.

  In the present specification, the “nitrogen-containing chromium film” refers to a film in which at least one of nitrogen and chromium nitride is dispersed in the chromium film.

  According to the present invention, a hard coating member excellent in mechanical strength such as wear resistance and adhesion, and excellent in chemical stability such as high temperature oxidation resistance, alkali resistance and releasability, and a low cost hard coating member. It is possible to provide the hard coating member that can be formed. This hard film covering member can be used for a mold, a machine part, an automobile part, etc., and is particularly preferably applied to a mold.

It is sectional drawing of the hard film coating | coated member by this invention. It is the schematic of the processing apparatus for manufacturing the hard film coating | coated member by this invention.

  Hereinafter, with reference to an accompanying drawing, a hard coat covering member by the present invention is explained in detail.

  As shown in FIG. 1, the hard film covering member according to the present invention includes a base material 1, a chromium film as a base layer 2 formed on the base material 1, and a nitrogen-containing material formed on the base layer 2. A chromium film 3, a gradient composition layer 4 formed on the nitrogen-containing chromium film 3, and a chromium oxide film 5 formed on the gradient composition layer 4 are provided. The gradient composition layer 4 is a composition layer having an intermediate composition between the nitrogen-containing chromium film 3 and the chromium oxide film 5, and at least one of nitrogen or chromium nitride and at least one of oxygen or chromium oxide is contained in the chromium film. , Refers to a dispersed film.

Thus, by forming the chromium oxide film 5 which is a chemically stable hard layer on the nitrogen-containing chromium film 3 which is a hard layer having high mechanical strength, wear resistance, adhesion and It is possible to obtain a hard film-coated member formed by coating a high-hardness hard film excellent in alkali resistance. In addition, since the chromium oxide film has already been oxidized and is stable, there is little concern about high temperature oxidation. Furthermore, for example, since these materials have low wettability with respect to molten aluminum or resin, when they are used as a mold for molding them, they have excellent release properties.
That is, by forming a hard and mechanically strong nitrogen-containing chromium film 3 on the substrate 1 and forming a hard and chemically stable chromium oxide film 5 thereon, the wear resistance and adhesion are improved. , High-temperature oxidation resistance, alkali resistance and releasability can be improved, and further, by forming the underlayer 2 and the gradient composition layer 4, between the substrate and the nitrogen-containing chromium film, the nitrogen-containing chromium film and the chromium It is possible to relieve stress generated between oxide films and to secure higher adhesion.

In order to obtain good wear resistance, the thickness of the nitrogen-containing chromium film 3 is preferably 1 to 30 μm, more preferably 1 to 20 μm, and most preferably 2 to 15 μm. . In order to obtain good high-temperature oxidation resistance, alkali resistance, and releasability, the thickness of the chromium oxide film 5 is preferably 0.1 to 3 μm, and more preferably 0.2 to 2 μm.
In order to further improve the adhesion between the base material and the film, it is preferable to form a chromium film having a thickness of 0.01 to 3 μm on the base material 1 as the base layer 2. More preferably, it is 2 μm.
Further, the gradient composition layer 4 may be formed between the nitrogen-containing chromium film 3 and the chromium oxide film 5 in order to further improve the adhesion between the base material and the film and the nitrogen-containing chromium film and the chromium oxide film. Preferably, the thickness is preferably 0.01 to 1 μm, and more preferably 0.05 to 0.5 μm.

  The chromium film and the nitrogen-containing chromium film 3 as the underlayer 2 can be continuously formed in a processing chamber of an apparatus that performs sputtering using a chromium target. That is, when the chromium film as the underlayer 2 is formed, for example, the processing chamber is set to an argon gas atmosphere, and when the nitrogen-containing chromium film 3 is formed, the processing chamber is set to an atmosphere containing argon gas and nitrogen gas. The chromium film as the underlayer 2 and the nitrogen-containing chromium film 3 can be formed continuously.

  Moreover, the film of the present invention has a chromium oxide film on the surface and is poorly wetted with respect to the molten aluminum, that is, it has good releasability when applied to a mold. In addition, it is insoluble in acids and alkalis and is chemically stable.

  The sputtering can be performed by a DC magnetron sputtering method, and can be formed at a temperature lower than the tempering temperature of a steel material used as a base material (for example, 250 ° C. or less), thereby suppressing the softening and thermal distortion of the steel material. It is also more productive than other physical vapor depositions. In addition, in this sputtering, since a lump (droplet) in which the material of the film is melted does not occur as in the case of film formation by an ion plating method, a film having a smooth surface can be formed. Furthermore, since this sputtering forms a chromium film and a nitrogen-containing chromium film, the intermediate layer of other materials (elements) can be eliminated, so that a single target can be used in a conventional sputtering apparatus. The film can be formed by introducing nitrogen gas into the room by switching between ON and OFF. Therefore, it is possible to obtain a nitrogen-containing chromium film having excellent adhesion by relaxing the stress by the relaxation layer while ensuring high hardness. Moreover, since sputtering can be performed with a constant bias voltage, cracking of the film can be prevented.

  The embodiment of the hard film covering member according to the present invention can be manufactured using, for example, the processing apparatus 10 shown in FIG. The processing apparatus 10 includes a vacuum processing chamber 12, a vacuum pump 14 for reducing the pressure in the vacuum processing chamber 12 to form a vacuum, and a rotary table 16 disposed at the center of the bottom of the vacuum processing chamber 12. A base material 20 as a member to be processed placed on the turntable 16 via a jig 18, a target 22 as an evaporation source arranged so as to surround the base material 20, and these targets A DC sputtering power supply 24 connected to each of 22, a DC ion bombard and bias power supply 26 connected to the rotary table 16, and a gas introduction pipe for introducing argon gas and nitrogen gas into the vacuum processing chamber 12. 28. Hereinafter, a method for producing a hard coating member according to the present invention using the processing apparatus 10 will be described.

(Ion bombarding process)
First, a chromium target is disposed as the target 22 of the processing apparatus 10, the vacuum pump 14 is operated to evacuate the vacuum processing chamber 12, and then argon gas is introduced into the vacuum processing chamber 12 through the gas introduction pipe 28. Then, the inside of the vacuum processing chamber 12 is made an argon gas atmosphere, and ion bombarding is performed to activate the surface of the substrate 20. Further, the substrate is heated to 250 ° C. or lower, preferably 200 ° C. to 130 ° C. by a heater (not shown). The heating of the substrate is continued until the subsequent sputtering is completed. Note that heating during film formation (sputtering) is performed largely by the collision energy of particle ions, and a heater may be unnecessary.

(Underlayer formation process ... chrome film formation process)
Next, the introduction of the argon gas is temporarily stopped, the inside of the vacuum processing chamber 12 is evacuated, and then the argon gas is introduced into the vacuum processing chamber 12 through the gas introduction pipe 28 so that the inside of the vacuum processing chamber 12 is argon gas. Make the atmosphere. Thereafter, a predetermined voltage is applied to the target 22 from the sputtering power source 24 to generate glow discharge (low temperature plasma) in the vicinity of the target 22. As a result, the argon gas in the discharge region is ionized and collides with the target 22 at a high speed. As a result of this collision, chromium atoms are struck out from the target 22, and the chrome atoms are struck against the surface of the substrate 20. A chromium film as an underlayer is formed on the surface of 20.

(Nitrogen-containing chromium film forming process)
Next, argon gas and nitrogen gas are introduced into the vacuum processing chamber 12 through the gas introduction pipe 28 to make the inside of the vacuum processing chamber 12 an atmosphere of argon gas and nitrogen gas. Thereafter, a predetermined voltage is applied to the target 22 from the sputtering power source 24 to generate glow discharge (low temperature plasma) in the vicinity of the target 22. As a result, the argon gas in the discharge region is ionized and collides with the target 22 at a high speed, and this collision expels chromium atoms from the target 22, and these chromium atoms together with nitrogen atoms in the atmosphere in the vacuum processing chamber 12. A chromium film (hard layer) containing nitrogen is formed on the surface of the chromium film on the substrate 20 by being struck against the surface of the chromium film on the substrate 20. The nitrogen-containing chromium film is a film in which N is dissolved in chromium, or has at least one of chromium nitride having an amorphous structure in chromium and chromium nitride having fine crystals in chromium.

  In the above sputtering, in order to make the thickness of the coating uniform and to maintain the temperature of the base material 20 below the tempering temperature, the distance between the target 22 and the base material 20 is set to, for example, 70 to 80 mm. It is preferable to hold.

(Chromium oxide film formation process)
Next, the base material on which the nitrogen-containing chromium film is formed is taken out from the sputtering apparatus, and a laser having a predetermined output is irradiated to the nitrogen-containing chromium film for a certain period of time in the atmosphere in a laser processing apparatus. As a result, the nitrogen in the nitrogen-containing chromium film causes thermal diffusion, and the chromium in the film is combined with oxygen having a high potential. A chromium oxide film having a desired thickness can be obtained with the irradiation time and irradiation energy at this time.
The chromium oxide film forming treatment by laser can concentrate the light energy in a very short time by, for example, a femtosecond laser, that is, shorten the irradiation time, so that the substrate is hardly affected by heat.
A stable chromium oxide film having a desired thickness is formed without performing heat treatment at 700 to 900 ° C., which is an oxidation temperature of a normal nitrogen-containing chromium film, by heating by gas combustion or heating by an electric heater. Furthermore, it is possible to prevent the occurrence of distortion accompanying the transformation and softening of hardness as seen in ordinary heat treatment.
Further, as a feature of the formation of a chromium oxide film by laser, a concave dimple structure can be provided over the entire surface by irradiating and scanning the laser in a pulse manner. This dimple is excellent in releasability of the release material and lubricant, that is, when applied to a mold, it improves the releasability and durability, and can provide a structurally excellent film. Further, when applied to sliding parts such as automobiles, the dimples retain lubricating oil and improve the durability of the parts.
Since the nitrogen-containing chromium film and the chromium oxide film thus prepared have a nitrogen and oxygen diffusion layer inclined at the interface between the nitrogen-containing chromium film and the chromium oxide film, adhesion between the nitrogen-containing chromium film and the chromium oxide film It has excellent strength and chemical stability derived from the amorphous structure of the nitrogen-containing chromium film.
Even without using a laser, the heat effect on the substrate is minimized even by a heat treatment in which the substrate on which the nitrogen-containing chromium film is formed is put in a furnace preheated to a predetermined temperature for a short time and then cooled. It is possible to form a chromium oxide film with the limit.

The die steel SKD11 was carburized, quenched, and tempered, and then a mirror-polished base material was prepared. This base material is put in a vacuum processing chamber of a processing apparatus (DC magnetron sputtering apparatus) in which a chromium target is installed, and is evacuated to an ultimate vacuum of 5 × 10 ⁻⁴ Pa or less, and then the pressure in the vacuum processing chamber is 5 × 10. ^-1 Pa Argon gas atmosphere is controlled, argon gas is introduced into the vacuum processing chamber, the substrate is heated with a heater to 200 ° C., and ion bombardment treatment is performed at 1000 V × 2 A for about 180 minutes. The surface of the material was activated.

  Next, the introduction of the argon gas is temporarily stopped, the vacuum processing chamber is evacuated and evacuated, and then the argon gas is evacuated so that the partial pressure of the argon gas in the atmosphere in the vacuum processing chamber becomes 0.061 Pa. In this process, sputtering is performed for about 40 seconds with an input power of 4 kW and a bias voltage of −100 V, and a chromium film having a Vickers hardness of about HV500 and a thickness of about 50 nm (0.05 μm) is formed on the base material. did. Before the sputtering, the heater was turned off and the heating of the heater was stopped in the subsequent processes, but the temperature of the substrate was kept at 200 ° C. during the sputtering process.

  Next, while introducing argon gas into the vacuum processing chamber so that the partial pressure of argon gas in the atmosphere in the vacuum processing chamber becomes 0.042 Pa, nitrogen gas is introduced so that the partial pressure of nitrogen gas becomes 0.054 Pa. While being introduced into the vacuum processing chamber, sputtering was performed for 40 minutes with an input power of 4 kW and a bias voltage of −100 V, and a nitrogen-containing chromium film having a thickness of about 3.2 μm was formed on the substrate (formation of a nitrogen-containing chromium film) Process).

  Next, the substrate on which the nitrogen-containing chromium film was formed was taken out from the sputtering apparatus, and a laser having a predetermined output was irradiated to the nitrogen-containing chromium film for a certain period of time in the air in a laser processing apparatus. Laser irradiation was performed in a pulse manner, and a chromium oxide film having a concave dimple structure was formed on the surface by scanning the entire surface (chromium oxide film forming step).

The surface state of the hard film-coated member of the present invention thus obtained was observed with an SEM (scanning electron microscope), and surface elemental mapping was performed by EDS (energy dispersive spectroscopy). Further, the element profile in the depth direction of the hard coating member was measured by GDS (glow discharge emission spectroscopy).
Moreover, the Vickers hardness of the depth direction of the hard film coating | coated member was measured, and the surface X-ray diffraction analysis was implemented.

  When the surface of the hard film-coated member was observed with an SEM, dimples having a diameter and a depth of about 1 μm were formed on the entire surface at intervals of about 1 μm. Further, O (oxygen) was detected on the entire surface by EDS analysis.

Next, the element profile in the depth direction from the surface of the hard coating member was measured by GDS. As a result, the presence of a chromium oxide film having high chromium and oxygen strength in the range of about 0.2 μm from the surface was confirmed. Slight nitrogen was also detected.
In addition, a layer in which elements of oxygen, nitrogen, and chromium coexist is recognized between the chromium oxide film and the nitrogen-containing chromium film at about 0.2 μm, and oxygen and chromium gradually decrease and nitrogen gradually increases, It exhibits a graded composition layer.
A portion deeper than the gradient composition layer was a nitrogen-containing chromium film in which nitrogen and chromium were present.

The Vickers hardness as the plastic deformation hardness is measured with a Barcovic indenter using a Fischer hardness tester (ultra-micro hardness tester) (FISCHERSCOPEH100C _XY-P manufactured by Fischer Instrument Co., Ltd.) 100 mN / 10s. And was calculated based on the plastic deformation hardness measured at room temperature. As a result, the Vickers hardness HV was 770.

The peak of Cr and the peak of CrN and Cr ₂ O ₃ were confirmed by X-ray diffraction. The peak of CrN is broad, and the nitrogen-containing chromium film is presumed to have at least one of amorphous CrN or fine crystal CrN in Cr. It was also confirmed that an oxide film Cr ₂ O ₃ was formed on the surface.

(Comparative Example 1)

  Except not performing the said chromium oxide film formation process, the hard film coating | coated member was produced by the method similar to Example 1, and it evaluated by the same method.

  When the surface of the hard film-coated member was observed with an SEM, a granular form of about 0.1 to several μm was observed. Further, according to EDS, chromium and nitrogen were confirmed.

  Next, the element profile in the depth direction from the surface of the hard coating member was measured by GDS. As a result, chromium and nitrogen were detected, and it was confirmed that the film was a nitrogen-containing chromium film.

A Cr peak and a CrN peak were confirmed by X-ray diffraction, and a Cr ₂ O ₃ peak was not observed. The peak of CrN is broad, and it is estimated that Cr has at least one of amorphous CrN and fine crystal CrN.

  Vickers hardness HV was measured to examine the strength of the films of the members treated in Example 1 and Comparative Example 1 and as an evaluation of wear resistance. As a result, the Vickers hardness HV of the member surface was about 760 in both cases.

  In order to examine the releasability, durability, and high-temperature oxidation resistance of the members treated in Example 1 and Comparative Example 1 when applied to an aluminum mold, each member was melted at 700 ° C. After being immersed in 1 minute, it was taken out. Aluminum was not observed on the member of Example 1, but aluminum was observed on the member of Comparative Example 1. That is, Example 1 was found to be excellent in releasability and durability.

  Assuming maintenance when applied to the mold, the member of Example 1 was immersed in an aqueous alkali solution of sodium hydroxide, but the film was chemically stable without dissolving.

DESCRIPTION OF SYMBOLS 1 Base material 2 Underlayer 3 Nitrogen-containing chromium film 4 Gradient composition layer 5 Chromium oxide film 10 Processing apparatus 12 Vacuum processing chamber 14 Vacuum pump 16 Rotary table 18 Jig 20 Base material 22 Target 24 Sputter power supply 26 Bias power supply 28 Gas introduction pipe

Claims (5)

A substrate, a nitrogen-containing chromium film having a thickness of 1 to 30 μm, and a chromium oxide film having a thickness of 0.1 to 3 μm , and a peak of CrN by X-ray diffraction sequentially laminated on the substrate; A hard film covering member comprising: A base material, a chromium film having a thickness of 0.01 to 3 μm sequentially laminated on the base material, and a nitrogen-containing chromium film having a thickness of 1 to 30 μm in which the peak of CrN by X-ray diffraction is broad ; A hard film-coated member comprising a chromium oxide film having a thickness of 0.1 to 3 μm. Between the nitrogen-containing chromium film and the chromium oxide film, the thickness of the intermediate composition of the nitrogen-containing chromium film and the chromium oxide film in which oxygen and chromium are gradually decreased and nitrogen is gradually increased is 0.01 to 1 μm. The hard-coated member according to claim 1, wherein the hard-coated member has a gradient composition layer. 4. The hard film covering member according to claim 1, wherein concave dimples are formed on the surface of the chromium oxide film.   The hard film-coated member according to claim 1, 2, 3, or 4, which is used as a mold or a sliding part.

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