KR101862526B1 - Method for manufacturing coated mold for die casting - Google Patents

Abstract

It is an object of the present invention to provide a method for producing a die casting coated metal mold which is excellent in content adhesion and durability against molten metal. A method of manufacturing a die-casting mold, comprising the steps of: coating a substrate surface of a die-casting mold with a first hard coating by an arc ion plating method; smoothing a surface of the first hard coating; And a step of coating the second hard coating film by a plating method.

Description

METHOD FOR MANUFACTURING COATED MOLD FOR DIE CASTING [0002]

The present invention relates to a die casting method for casting various kinds of iron and non-ferrous metals typified by steel, aluminum, magnesium, zinc and alloys thereof, especially for casting aluminum or an alloy thereof, And to a method of manufacturing a mold for a mold.

In recent years, the precision of a die with respect to the product dimension shape and the thermal stress conditions applied to the surface of the die have become stricter each year, and the life of the die becomes unstable, with the light weight, high performance, . The surface of the die casting mold is repeatedly subjected to heating by molten metal and cooling by spraying the releasing agent, thereby causing fatigue cracking due to thermal stress. In addition, at the same time, contact with the molten metal leads to the occurrence of melting and seizing on the mold surface.

Therefore, in order to prevent or suppress such problems, a coating die for die casting in which a hard coating such as nitride, carbonitride, oxynitride, or oxide is coated is proposed. Of the coating means, the arc ion plating method is effective in that the thermal load on the substrate is small and therefore the dimensional change of the metal mold is small and the adhesion of the hard coating is excellent.

For example, Patent Document 1 proposes coating a nitride of Cr with a single layer by the arc ion plating method. Patent Document 2 proposes that a metal or an alloy and a carbide, a nitride, an oxide, or a carbonitride are laminated by an ion plating method. In addition, Reference 3 discloses the application of a chemically stable oxide film, and specifically, it has been proposed to provide an oxide of AlCr on the Cr oxide by the arc ion plating method.

Japanese Patent Application Laid-Open No. 10-237624 Japanese Patent Application Laid-Open No. 2008-188609 Japanese Patent Application Laid-Open No. 2010-58135

The inventor of the present invention has found that even if a coated mold for die casting is coated with an arc ion plating method having excellent coating adhesion, local melting or seizing occurs. The cause of the occurrence of the melting and seizing in the die-casting mold was examined. As a result, a local melting or seizing occurred due to a gap defect such as a void or the like originating from the unevenness of the droplet or particles included in the hard coating And that the

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a die casting mold having excellent properties of a molten metal and excellent corrosion resistance in view of the above problems.

The present invention relates to a method for producing a die-cast coated mold in which a hard film is coated on the surface of a substrate of a die-casting mold by an arc ion plating method, wherein a first hard film is coated on the surface of the substrate by arc ion plating A step of smoothing the surface of the first hard coating and a step of coating the second hard coating on the smoothed first hard coating by an arc ion plating method Lt; / RTI >

Here, the smoothing treatment is preferably a spring wetting treatment.

In the method for producing a die cast casting mold of the present invention, it is preferable that the first hard coating or the second hard coating is a chromium nitride.

In the method for producing a die-cast coated metal mold of the present invention, it is preferable that the second hard coating has a multilayer structure of at least two layers.

According to the present invention, it is possible to provide a die casting mold capable of exhibiting excellent content adhesion and durability against molten metal such as aluminum.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a photograph of an appearance observation by an optical microscope after the melting loss test of Examples 1 to 4 of the present invention. Fig.
Fig. 2 is a photograph of appearance of Comparative Examples 1 and 2 by an optical microscope after the melting loss test. Fig.
Fig. 3 is a photograph of the appearance observation by an optical microscope after the melting test of Examples 10 to 12 of the present invention. Fig.
Fig. 4 is a photograph of the external appearance observed by an optical microscope after the melting loss test of Examples 13 to 15 of the present invention. Fig.
Fig. 5 is a photograph of an appearance observation by an optical microscope after the melting test of Examples 16 to 18 of the present invention. Fig.
Fig. 6 is a photograph of appearance of Comparative Examples 10 to 12 by an optical microscope after the melting test. Fig.
Fig. 7 is a photograph of the appearance observation by an optical microscope after the melting test of Comparative Examples 13 and 14. Fig.

The present inventors have found out that it is effective to provide a smoothing treatment during the coating process of the hard coating by the arc ion plating method in order to reduce the local melting loss and seizure of the die cast coating mold, Respectively.

The inventors of the present invention have confirmed that droplets or particles included in the inside of the hard coating are a cause of local melting and seizing. In addition, it is impossible to remove defects originating from liquid droplets or particles included in the coating film only by smoothing the outermost hard coating film, and it is impossible to suppress the melting and seizing of the die casting mold Respectively. It has been found that it is effective to provide a smoothing treatment during the formation of the hard coating in order to suppress the melting and sticking of the die casting die.

In the present invention, the first hard coating is coated by the arc ion plating method, and the surface of the first hard coating is smoothed. The surface of the first hard coating can be smoothed to smooth the surface by adapting the surface irregularities due to droplets or particles on the surface of the coating. After the surface of the first hard coating is smoothed, it is important to coat the second hard coating with the arc ion plating method. By coating the second hard coating on the smoothed first hard coating with the arc ion plating method, fine irregularities caused by the smoothed finish existing on the surface of the first hard coating are also buried. As a result, The irregularities of the surface starting from the liquid droplets or particles contained are reduced, and local melting and seizure can be suppressed.

In the present invention, the above-mentioned "smoothing treatment" refers to a treatment for reducing the surface roughness of the surface of the hard coating, such as mechanical polishing, spring-wetting treatment and the like.

As the parameters of the surface roughness, the arithmetic average roughness Ra and the maximum height Rz according to JIS-B-0601-2001 can be used. By the smoothing process, it is preferable that the arithmetic average roughness Ra of the surface of the first hard coating film is 0.05 mu m or less and the maximum height Rz is 1.00 mu m or less, and Rz is more preferably 0.50 mu m or less.

In the case of the spring bedding treatment, a spring bedding treatment using a gas such as argon or a spring bedding treatment using a metal ion can be applied. The application of the spring-wetting treatment is preferable to the mechanical polishing described later because it can be continuously treated in the same furnace.

However, if the time for the treatment of the spring burdens becomes too long, the irregularities on the surface of the first hard coating film tend to increase, and the content loss tends to deteriorate. In order to exert a superior content property, it is preferable to set the treatment time to 40 minutes or less in the spring wetting treatment. More preferably 30 minutes or less. However, if the processing time is too short, it is difficult to obtain an effect of improving the content handover. Therefore, it is preferable to set the treatment time to 5 minutes or more in the spring wetting treatment. It is also preferable to set it to 10 minutes or longer.

It is preferable that the gas-plasma bombardment treatment is carried out at a negative bias voltage applied to the substrate at -700 V or more and -400 V or less. If the negative bias voltage applied to the substrate is larger than -400 V (on the plus side of -400 V), the smoothing of the first hard coating is not sufficient, and the content scratch resistance and waterproofing tend to be lowered. Further, when the negative bias voltage applied to the substrate is smaller than -700 V (on the minus side from -700 V), a large amount of unevenness is likely to be formed on the surface of the first hard coating film, so that the content damage and durability are likely to deteriorate.

On the other hand, the following mechanical polishing is effective for eliminating the unevenness of the surface due to the droplet to obtain a smooth surface state.

(1) A method of polishing the surface of a hard coating with an abrasive cloth having an abrasive such as a diamond paste

(2) a polishing method using a so-called AEROLAP (registered trademark) or the like which polishes by a generated frictional force by using an abrasive containing diamond particles and water at high speed on a coating film coated on a substrate

(3) Polishing method by so-called SMAP (Mirror Surface Shot Machine of Kamei Iron Works), which polishes by spraying an abrasive having elasticity and tackiness without using air

Further, after such mechanical polishing, more preferable smoothing can be realized by polishing the diamond paste to 3 탆 or less.

In order to mechanically polish the surface of the first hard coating, it is necessary to remove the sample from the furnace after coating the first hard coating. After the first hard coating is smoothed by mechanical polishing, the sample may be returned to the furnace to coat the second hard coating.

The mechanical polishing can achieve a smoother surface state, and is also preferable to improve the content abrasion resistance and the waterproofness.

Nitride, carbide, carbonitride, carbon nitride, oxynitride, and oxide can be applied to the first hard coating and the second hard coating of the present invention.

In the present invention, the first hard coating and the second hard coating may be single-layered, but preferably have a multi-layered structure. By making the second hard coating a multilayer structure, excellent mechanical properties can be imparted to the second hard coating. For example, high hardness can be added to the second hard coating layer by laminating a chromium nitride excellent in adhesion and a chromium nitride added with a third element such as Si or B to the chromium nitride.

The first hard coating is preferably a nitride or a carbonitride. If the first hard coating on the substrate side is a nitride or a carbonitride, the adhesion with the substrate tends to be better, which is preferable. It is more preferable that it is a nitride. It is more preferable that the first hard film is a chromium nitride or carbonitride containing 50% or more of Cr at an atomic ratio (atomic%) of a metal (including semi-metal) portion, more preferably at least 70% Is more preferable.

In order to improve the content stability and durability of the die-cast coated mold, it is preferable that the second hard coating on the surface side is a nitride, a carbonitride, an oxynitride, or an oxide. It is also preferably a nitride or an oxynitride. In particular, it is preferably a nitride. The second hard film is preferably a chromium nitride or carbonitride containing 50% or more of Cr in terms of atomic percentage (atomic%) of the metal (including semi-metal) portion, more preferably at least 70% Is more preferable.

It is preferable that the second hard coating contains at least one or more of Si and B. By containing at least one of Si and B, the film structure becomes finer, and wear resistance and content dependency are further improved. In order to sufficiently exhibit these effects, the second hard coating preferably contains at least 3% of at least one of Si and B in an atomic ratio (atomic%) of the metal (including semimetal) It is more than 5%. However, if the content of Si and B is too large, the toughness of the coating decreases. Therefore, the second hard coating preferably contains at least 15% of at least one of Si and B in atomic ratio (atomic%) of the metal (including semi-metal) portion, and at least one of Si and B Is preferably 10% or less.

In the present invention, it is preferable to smooth the surface of the second hard coating. In this case, the surface of the second hard film is polished so that the arithmetic mean roughness Ra (in accordance with JIS-B-0601-2001) is 0.05 占 퐉 or less and the maximum height Rz (in accordance with JIS-B-0601-2001) Mu m or less, and more preferably, Rz is 0.60 mu m or less.

Although the substrate of the present invention is not particularly defined, it is preferable to use hot tool steel represented by SKD61 of JIS-G-4404 (2006) or its modifier. It is preferable to use hot tool steel containing C and Cr, which determine the basic characteristics of the tool steel, in mass%, in the range of 0.35 to 0.45% of C, and 4.0 to 6.0% of Cr as a base material.

The substrate may be subjected to surface hardening treatment using diffusion such as nitriding treatment or carburizing treatment in advance. The use of a nitrided base material is preferable because it tends to further improve the property of losing the contents and the durability to corrosion.

In order to further improve the adherence of the hard film, the surface roughness Ra (in accordance with JIS-B-0601-2001) of 0.05 탆 or less and the maximum height Rz (in accordance with JIS B-0601-2001) Is preferably used.

In order to smoothly adjust the surface roughness of the first hard coating film or the second hard coating film, it is preferable that the surface roughness of the substrate before coating is also smoothly polished. Specifically, assuming that the substrate surface roughness before coating the hard coating is A, the surface roughness before smoothing treatment of the first hard coating is B, and the surface roughness after smoothing treatment of the first hard coating is C, It is preferable that the roughness Ra and the maximum height Rz satisfy a relation of A < C < B.

In the present invention, it is preferable that the second hard coating is subjected to a smoothing treatment in addition to smoothing the surface of the first hard coating. In this case, the surface roughness after smoothing treatment of the second hard coating is D, It is more preferable that the relationship of Ra and Rz in the relation of A < C < D < B.

By smoothing the surface of the substrate, it is possible to suppress coating defects attributable to the unevenness of the surface of the substrate. Defective film directly above the substrate causes direct corrosion of the substrate itself, and it is more preferable that the coating film defect on the near side of the substrate is small. Therefore, it is preferable that the surface roughness of the first hard coating is smooth than the surface roughness of the second hard coating after polishing, and it is preferable that the roughness of the substrate surface before coating is the smoothest.

The degree of removal, that is, the surface roughness C after the smoothing treatment is preferably in the range of C (Ra) to Ra (Ra) before the smoothing treatment, / B is less than 1.0, and C / B is less than 0.5 in Rz. By satisfying these formulas, it is possible to further reduce defects in the hard coating.

When the total film thickness of the hard film becomes too thin, the content damage and the waterproofing property may not be sufficient. Therefore, it is preferable that the total thickness of the hard coating is 3 mu m or more. The total thickness of the hard film is more preferably 5 m or more, and more preferably 10 m or more. On the other hand, if the total thickness of the hard coating becomes too thick, peeling of the coating tends to occur. Therefore, the total thickness of the hard film is preferably 40 탆 or less, and more preferably 30 탆 or less.

In the present invention, another coating film may be provided between the first hard coating and the substrate. Further, another coating film may be provided on the second hard coating film. When another coating film is provided on the second hard coating film, the surface of the second hard coating film may be smoothed to provide the third and subsequent hard coating films.

Example 1

A sample for evaluating the content property required for a die casting die was prepared. The substrate used was a steel equivalent to SKD61 of JIS-G-4404 (2006), which is generally used as hot tool steel having a hardness of 46 HRC. The dimensions of the evaluation base material were cylindrical with a diameter of 10 mm and a length of 120 mm and the surface was polished to obtain an arithmetic mean roughness Ra of 0.01 탆 and a maximum height Rz of 0.07 탆. All the samples were subjected to gas nitriding in advance.

Then, the hard coating was coated using a general arc ion plating apparatus. The surface-ground substrate was degreased and cleaned, and fixed to the substrate holder. Then, the substrate temperature was heated to about 500 占 폚, and heat degassing was performed in a vacuum of 1 占^10-3 Pa. Subsequently, Ar gas was introduced, a bias voltage of -500 V was applied to the base material, and Ar bombardment treatment was performed for 20 minutes. Subsequently, a bias voltage of -800 V was applied to the substrate, and the Ti sputtering treatment was performed for about 5 minutes. The spring pad treatment of the substrate was carried out in the same manner as in any of the samples.

CrN was selected as the first hard coating and CrSiBN was selected as the second hard coating, and the coating was applied to the substrate. The smoothing treatment contents of the first hard coating and the second hard coating of Example 2 are shown in Tables 1 and 2. Details of sample preparation conditions will be described in detail below.

&Lt; Inventive Sample No. 1 &

Nitrogen gas was introduced into the furnace, and a bias voltage of -120 V was applied to the substrate, and CrN of about 5.0 탆 which was the first hard film was coated at a base temperature of 500 캜 and a reaction gas pressure of 3.0 Pa. Subsequently, for the smoothing treatment of the first hard coating film, the base material was taken out of the chamber and polished using an aerowave apparatus (AERO LAP YT-300) manufactured by Yamashita Works, and the first hard coating film was smoothed. Then, the surface roughness of the first hard coating was measured. After degreasing cleaning, the wafer was returned to the chamber and covered with the second hard coating. First, in order to remove the oxide film and the like on the surface of the first hard coating film, the Ar bombardment treatment and the Ti bombardment treatment were performed to clean the surface. Thereafter, nitrogen gas was introduced and a bias voltage of -120 V was applied to the base material to coat a second hard film made of CrSiBN with a base temperature of 500 DEG C and a reaction gas pressure of 3.0 Pa at about 4.0 mu m. The target had a composition of Cr ₉₂ Si ₃ B ₅ .

Then, the coated second hard coating was polished using an aerial apparatus, and then subjected to polishing treatment by polishing using a 3 μm diamond paste.

&Lt; Inventive Sample No. 2 &

Up to coating of the first hard coating was the same as in the first example of the present invention. For the smoothing treatment of the first hard coating, the base material was taken out of the chamber, polished using a lapping apparatus (AERO LAP YT-300) manufactured by Yamashita Works, and polished with a diamond paste of 1 탆. The step after the smoothing treatment of the first coating film was performed in the same manner as in the first example of the present invention.

&Lt; Inventive Sample No. 3 >

Up to coating of the first hard coating was the same as in the first example of the present invention.

In order to smooth the surface of the first hard coating film by the spring pad treatment after the first hard film was coated, the negative bias voltage applied to the substrate was set to -500 V and the spring pad treatment using Ar gas was performed for 30 minutes Respectively. Then, the substrate after the smoothing treatment was taken out from the chamber, and the surface roughness of the first hard coating film was measured.

After the surface roughness of the first hard coating film was measured, the substrate was returned into the chamber, and the same surface cleaning as that of the first embodiment of the present invention was carried out. Then, a nitrogen gas was introduced, and a bias voltage of -120 V was applied to the substrate. Under the conditions of the base temperature of 500 ° C and the reaction gas pressure of 3.0 Pa, about 4.0 μm of CrSiBN (target composition: Lt; 2 &gt;). The smoothing processing method of the second hard coating is the same as that of the first embodiment.

&Lt; Inventive Sample No. 4 >

Up to coating of the first hard coating was the same as in the first example of the present invention. For the smoothing treatment of the first hard coating, a nylon nonwoven fabric (Polishing Pad # 400 manufactured by Bellstar Abrasives Co., Ltd.) in which the base material was taken out of the chamber and coated with an abrasive as a smoothing treatment was used. After the smoothening treatment of the first coating, The same as in the case of the present invention.

<Comparative Example Sample No. 1>

Up to coating of the first hard coating was the same as in the first example of the present invention. For the smoothing treatment of the first hard coating film, a substrate was taken out of the chamber and a shot blasting treatment (projection material: steel grit 200 to 300 탆) was used as a comparative example of smoothing treatment instead of the smoothing treatment of the present invention. Shot blasting was performed for about 10 seconds in the short blast time. The steps after the shot blast treatment of the first coating film were the same as those of the first example of the present invention.

<Comparative Example Sample No. 2>

Up to coating of the first hard coating was the same as in the first example of the present invention.

After the coating of the first hard coating, the second hard coating was coated in the same process as in the case of the present invention 10 without performing any polishing treatment, and a sample was prepared. The smoothing processing method of the second hard coating is the same as that of the first embodiment.

&Lt; Surface roughness measurement &

The surface roughness of the substrate and the hard coating film was measured using a contact surface roughness tester SURFCOM480A manufactured by Tokyo Seimitsu Co., Ltd. according to JIS-B-0601-2001. The arithmetic average roughness Ra and the maximum height roughness Rz were measured. The measurement conditions were an evaluation length of 4.0 mm, a measurement speed of 0.3 mm / s, and a cut-off value of 0.8 mm. Table 1 shows the surface roughness A of the substrate before coating the hard coating, the surface roughness B of the first hard coating before smoothing treatment, the surface roughness C after smoothing treatment of the first hard coating, and the surface roughness after smoothing treatment of the second hard coating D, respectively.

<Evaluation of content dependency>

The present invention and the comparative example were immersed in a molten aluminum of 720 占 폚 for 30 hours, and the presence or absence of the spoilage was confirmed by an optical microscope. Also, the mass before and after the test was measured to determine the drag ratio (%). Table 2 summarizes sample preparation conditions and test results.

As shown in Table 2, the present invention in which the surface of the first hard coating was subjected to smoothing treatment had a lower drag ratio (%) than the comparative example without smoothing of the present invention, Respectively. In particular, Inventive Examples 2 and 4, in which the maximum height Rz after polishing of the first coating film was not more than 0.5 탆 and the maximum height Rz after polishing of the second coating film was not more than 0.6 탆 exhibited excellent content scratch resistance.

Fig. 1 shows photographs of appearance observations by an optical microscope after evaluating the content of hand in Examples 1 to 4 of the present invention. In Examples 1 to 4 of the present invention showing superior property handlability, no flaw was found in the tip portion and the side portion.

Fig. 2 shows photographs of appearance observations by an optical microscope after evaluation of the content rank of Comparative Examples 1 and 2. In the comparative example, both of the tip end portion and the side portion were found to have a large hand loss.

It was confirmed that the surface roughness of the surface of the first hard coating was interposed and the surface of the second hard coating was also smoothed to improve the content uniformity.

It can be seen from Tables 1 and 2 that the hard coating obtained by applying the production method of the present invention is smooth in surface roughness of the outermost surface of the coating film and excellent in content luck. As shown in Fig. 1, almost no formula for erosion was confirmed on the surface of the film after the evaluation of the content of the molten aluminum.

On the other hand, the hard coatings of Comparative Examples 1 and 2 subjected to the shot blast treatment had significantly poorer content loses. Since the surface roughness of the hard coating of Comparative Example 1 was adjusted, the surface roughness value of the hard coating became larger. In the hard coating of Comparative Example 2, since the first hard coating was not subjected to the smoothing treatment of the present invention, And the surface roughness could not be sufficiently reduced.

Example 2

The kind of the substrate used in Example 2, the polishing of the substrate, and the treatment conditions of the spring burdm treatment of the substrate were the same as those in Example 1. Some of the substrates were nitrided in advance. The types of the first hard coating and the second hard coating and the contents of the smoothing treatment in Example 2 are shown in Table 3. Details of sample preparation conditions will be described in detail below.

&Lt; Inventive Sample No. 10 &

Nitrogen gas was introduced into the furnace, and a bias voltage of -120 V was applied to the substrate to coat CrN of about 5.0 占 퐉 which is the first hard coating film at a substrate temperature of 500 占 폚 and a reaction gas pressure of 3.0 Pa.

Thereafter, in order to smooth the surface of the first hard coating film by polishing, the base material was taken out of the chamber and polished by using an aerowave apparatus (AERO LAP YT-300) manufactured by Yamashita Works Co., Ltd. Thereafter, polishing was performed with a diamond paste having a thickness of 1 탆, and subsequently, using a mirror-type shot machine SMAP-II type manufactured by Kamei Iron Works, the arithmetic mean roughness Ra was set to 0.01 탆 and the maximum height Rz was set to 0.05 탆.

After degreasing cleaning, the wafer was returned to the chamber and covered with the second hard coating. First, in order to remove the oxide film on the surface of the first hard coating film, an Ar spring pad treatment and a Ti spring pad treatment were performed to clean the surface. Thereafter, nitrogen gas was introduced and a bias voltage of -120 V was applied to the base material to coat a second hard film made of CrSiBN of about 5.0 占 퐉 at a base temperature of 500 占 폚 and a reaction gas pressure of 3.0 Pa. As the target, a composition of Cr ₉₂ Si ₃ B ₅ was used (numbers are atomic ratios, and so on). Then, the coated second hard coating was polished using an aerial apparatus, and then subjected to polishing treatment by polishing using a 3 μm diamond paste.

&Lt; Inventive Sample No. 11 &

A substrate having a nitrided layer of about 100 탆 formed thereon was used. Other than that, the same as in the case of the present invention.

&Lt; Inventive Sample No. 12 &

A substrate having a nitrided layer of about 100 탆 formed thereon was used. Up to the coating of the first hard coating film was performed in the same manner as in Example 10 of the present invention.

In order to smooth the surface of the first hard coating film by the spring pad treatment after the first hard film was coated, the negative bias voltage applied to the substrate was set to -500 V and the spring pad treatment using Ar gas was performed for 30 minutes Respectively.

Thereafter, nitrogen gas was introduced, and a bias voltage of -120 V was applied to the base material to coat a second hard film made of CrSiBN of about 5.0 탆 at a substrate temperature of 500 캜 and a reaction gas pressure of 3.0 Pa Is the same as that of the present invention. Finally, the smoothing process shown in the present invention 10 was performed.

&Lt; Inventive Sample No. 13 >

A substrate having a nitrided layer of about 100 탆 formed thereon was used. Until the smoothing process of the first hard coating film,

After the first hard film was subjected to smoothing treatment, nitrogen gas was introduced and a bias voltage of -120 V was applied to the substrate to coat CrN of about 3.0 占 퐉 at a substrate temperature of 500 占 폚 and a reaction gas pressure of 3.0 Pa, Subsequently, CrSiBN of about 4.0 占 퐉 was coated (the target composition was the same as in Inventive Example 10), and the second hard coating was coated. Finally, the smoothing process shown in the present invention 10 was performed.

&Lt; Inventive Sample No. 14 >

A substrate having a nitrided layer of about 50 탆 formed thereon was used. Other than that, the same as in the case of Inventive Example 13 was made.

&Lt; Inventive Sample No. 15 >

Up to coating of the first hard coating film was performed in the same manner as in Example 10 of the present invention.

After coating the first hard coating, the surface of the first hard coating was smoothened by the spring pad treatment, the negative bias voltage applied to the substrate was set to -500 V, and the spring pad treatment using Ar gas was performed for 45 minutes Respectively.

After the first hard film was subjected to smoothing treatment, nitrogen gas was introduced and a bias voltage of -120 V was applied to the substrate to coat CrN of about 3.0 占 퐉 at a substrate temperature of 500 占 폚 and a reaction gas pressure of 3.0 Pa, Subsequently, CrSiBN of about 4.0 占 퐉 was coated (the target composition was the same as in Inventive Example 10), and the second hard coating was coated. Finally, the smoothing process shown in the present invention 10 was performed.

&Lt; Inventive Sample No. 16 >

Up to coating of the first hard coating film was performed in the same manner as in Example 10 of the present invention.

In order to smooth the surface of the first hard coating film by the spring pad treatment after covering the first hard film, the negative bias voltage applied to the substrate was set to -500 V and the spring pad treatment using Ar gas was performed for 60 minutes Respectively.

After the first hard film was subjected to a smoothing treatment, nitrogen gas was introduced, and a bias voltage of -120 V was applied to the substrate. Under the conditions of the base temperature of 500 ° C and the reaction gas pressure of 3.0 Pa, the second hard film was made of CrSiBN (The composition of the target is the same as that of the present invention example 10). Finally, the smoothing process shown in the present invention 10 was performed.

&Lt; Inventive Sample No. 17 >

Up to coating of the first hard coating was the same as in the first example of the present invention.

In order to smooth the surface of the first hard coating film by the spring pad treatment after covering the first hard film, the negative bias voltage applied to the substrate was set to -500 V and the spring pad treatment using Ar gas was performed for 60 minutes Respectively.

After the first hard film was subjected to smoothing treatment, nitrogen gas was introduced and a bias voltage of -120 V was applied to the substrate to coat CrN of about 3.0 占 퐉 at a substrate temperature of 500 占 폚 and a reaction gas pressure of 3.0 Pa, Subsequently, CrSiBN of about 4.0 탆 was coated (the target composition was the same as in Example 10 of the present invention), and the second hard coating was coated. Finally, the smoothing process shown in the present invention 10 was performed.

&Lt; Inventive Sample No. 18 >

Up to coating of the first hard coating was the same as in the first example of the present invention.

After the first hard coating was coated, the surface of the first hard coating was smoothened by the spring pad treatment, the negative bias voltage applied to the substrate was set to -700 V, and the spring pad treatment using Ar gas was performed for 30 minutes Respectively.

After the first hard film was subjected to smoothing treatment, nitrogen gas was introduced and a bias voltage of -120 V was applied to the substrate to coat CrN of about 3.0 占 퐉 at a substrate temperature of 500 占 폚 and a reaction gas pressure of 3.0 Pa, Subsequently, CrSiBN of about 4.0 탆 was coated (the target composition was the same as in Inventive Example 1), and the second hard coating was coated. Finally, the smoothing process shown in the present invention 10 was performed.

&Lt; Comparative example Sample No. 10 &

Nitrogen gas was introduced into the furnace, a bias voltage of -120 V was applied to the substrate, CrN of about 5.0 mu m was coated at a reaction gas pressure of 3.0 Pa, and then CrNiN was coated to about 5.0 mu m. As the target, a composition of Cr ₉₂ Si ₃ B ₅ was used (numbers are atomic ratios, and so on). Finally, the smoothing process shown in the present invention 10 was performed.

<Comparative Example Sample No. 11>

Nitrogen gas was introduced into the furnace, and a bias voltage of -120 V was applied to the substrate, and TiAlN of about 13.0 탆 was coated at a reaction gas pressure of 3.0 Pa. The composition of the target used was Ti ₅₀ Al ₅₀ . Finally, the smoothing process shown in the present invention 10 was performed.

&Lt; Comparative example Sample No. 12 >

Nitrided to form a nitride layer having a thickness of about 100 탆 was used.

A nitrogen gas was introduced into the furnace, a bias voltage of -120 V was applied to the substrate, and a laminate film of about 12.0 mu m in which VN and AlCrSiN were alternately laminated with an individual film thickness of 10 nm or less under a reaction gas pressure of 3.0 Pa Lt; / RTI &gt; The composition of the target used for coating AlCrSiN was Al ₆₀ Cr ₃₇ Si ₃ . Finally, the smoothing process shown in the present invention 10 was performed.

<Comparative Example Sample No. 13>

A nitrogen gas was introduced into the furnace, a bias voltage of -120 V was applied to the substrate, and a laminate film of about 12.5 mu m in which VN and AlCrSiN were alternately laminated with an individual film thickness of 10 nm or less under a reaction gas pressure of 3.0 Pa Lt; / RTI &gt; The composition of the target used for covering AlCrSiN was Al ₆₀ Cr ₃₇ Si _{3, which} was the same as that of Comparative Example 12. Finally, the smoothing process shown in the present invention 10 was performed.

<Comparative Example Sample No. 14>

A substrate having a nitrided layer of about 100 탆 formed thereon was used. In Comparative Example 14, only the substrate was nitrided, and no hard coating was provided. Finally, the smoothing process shown in the present invention 10 was performed.

&Lt; Evaluation of surface roughness &

In both of the present invention and the comparative example, the surface of the second hard coating or the surface of the substrate was polished, and the arithmetic mean roughness Ra was 0.04 占 퐉 and the maximum height Rz was 0.05 占 퐉. The surface roughness of the substrate and the hard film was measured using a contact surface roughness meter SURFCOM480A manufactured by Tokyo Seimitsu Co., Ltd. according to JIS-B-0601-2001 with an evaluation length of 4.0 mm, a measurement speed of 0.3 mm / s, Was measured under the condition of 0.8 mm.

<Evaluation of content dependency>

The present invention and the comparative example were immersed in a molten aluminum of 720 占 폚 for 20 hours, and the presence or absence of the spallation loss was confirmed by an optical microscope. Also, the mass before and after the test was measured to determine the drag ratio (%). Table 3 summarizes sample preparation conditions and test results.

As shown in Table 1, the present invention in which the surface of the first hard coating was subjected to smoothing treatment showed a lower drag ratio (%) as compared with the comparative example without smoothing, confirming the superiority of the content luck . Particularly, in the step of smoothing treatment, the present invention examples 12 to 14, in which the bias voltage applied to the ground electrodes 10 and 11 and the base material polished, were -500 V and subjected to Ar spring pad treatment for 30 minutes, ) Was 0%. In Examples 11 to 14 obtained by subjecting the substrate to the nitriding treatment, the loss ratio was 0%, and excellent content luck was exhibited.

Fig. 3 shows a photograph of an appearance observation by an optical microscope after evaluating the content of hand damage in Inventive Examples 10 to 12. Fig. Fig. 4 shows photographs of appearance observations by an optical microscope after evaluating the content intentions of Inventive Examples 13 to 15. Fig. Fig. 5 shows photographs of appearance observations by an optical microscope after evaluating the content abilities of Examples 16 to 18 of the present invention. Especially, in Examples 10 to 14, which exhibited excellent content stability, no flaws were found in the tip portion and the side portion.

Fig. 6 shows photographs of appearance observations by an optical microscope after evaluation of the content abuse of Comparative Examples 10 to 12. Fig. Fig. 7 shows photographs of appearance of Comparative Examples 13 and 14 by optical microscopy after evaluation of the content appearance. In the comparative example, both of the tip end portion and the side portion were found to have a large hand loss.

It was confirmed that the content of the hard coat was improved by interposing a step of smoothing the surface of the first hard coat.

Claims (4)

A step of coating a surface of a substrate of a die casting mold with a first hard coating by an arc ion plating method,
A step of smoothening the surface of the first hard coating to set the arithmetic average roughness Ra of the surface of the first hard coating to 0.05 m or less and the maximum height Rz to 1.00 m or less,
And a step of coating the second hard coating on the smoothed first hard coating by an arc ion plating method,
The smoothing process is a gas sparging process,
The gas plasma treatment is carried out at a negative bias voltage of -700 V to -400 V,
Wherein the step of coating the first hard coating and the step of smoothing the surface of the first hard coating are treated in the same furnace. The method according to claim 1,
Wherein the first hard coating or the second hard coating is a chromium-based nitride. 3. The method according to claim 1 or 2,
Wherein the second hard coating has a multilayer structure of at least two layers. delete

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