JP6274317B2 - Manufacturing method of die casting coating mold - Google Patents

Description

  The present invention coats a hard film by arc ion plating, which is used for casting of various ferrous and non-ferrous metals represented by steel, aluminum, magnesium, zinc and alloys thereof, and particularly for casting of aluminum and alloys thereof. The present invention relates to a method for manufacturing a die casting coating mold.

  In recent years, with the weight reduction, high performance, and diversification of applications of die-cast products, the accuracy of the mold for the product dimensions and the thermal stress conditions applied to the mold surface have become stricter year by year. The mold life tends to become unstable. Fatigue cracks due to thermal stress are generated on the surface of the die casting mold by repeatedly receiving heating by molten metal and cooling by spraying a release agent. At the same time, contact with the molten metal causes melting and seizure on the mold surface.

  Therefore, in order to prevent or suppress such problems, a die casting coating mold in which a hard film such as a nitride, carbonitride, oxynitride, or oxide is coated has been proposed. Among the coating means, the arc ion plating method is effective because the thermal load on the base material is small, so that the size of the mold is small and the adhesion of the hard film is excellent.

  For example, Patent Document 1 proposes to coat a single layer of Cr nitride by an arc ion plating method. Patent Document 2 proposes stacking a metal or alloy and a carbide, nitride, oxide, or carbonitride by an ion plating method. Further, in the cited document 3, it is disclosed that a chemically stable oxide film is applied. Specifically, an AlCr oxide is provided on a Cr oxide by an arc ion plating method. Proposed.

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

  The present inventor has confirmed that local melting damage and seizure occur even in a die casting coating die coated by an arc ion plating method having excellent coating adhesion. Then, when the cause of the occurrence of melting damage or seizure in the die casting coating mold was examined, local defects such as voids and voids starting from irregularities such as droplets and particles contained in the hard coating, It was confirmed that seizure occurred.

  In view of the above-described problems, an object of the present invention is to provide a method for manufacturing a die casting coating mold having excellent resistance to erosion and seizure against molten metal.

The present invention is a method of manufacturing a die casting coating mold in which a hard film is coated on the surface of a die casting mold base material by an arc ion plating method. Coating the hard film, smoothing the surface of the first hard film, and applying the second hard film by arc ion plating on the smoothed first hard film Is a method for manufacturing a die casting coating mold.
Here, the smoothing process is preferably a bombard process.
In the method for manufacturing a die casting coating mold according to the present invention, the first hard film or the second hard film is preferably a chromium nitride.
In the method for manufacturing a die casting coating mold according to the present invention, the second hard coating preferably has a multilayer structure of at least two layers.

  ADVANTAGE OF THE INVENTION According to this invention, the coating metal mold | die for die-casting which can exhibit the outstanding fusing resistance and seizure resistance with respect to molten metals, such as aluminum, can be provided.

It is the external appearance observation photograph by the optical microscope after the erosion test of this invention example 1-4. It is an external appearance observation photograph by the optical microscope after the melt-out test of Comparative Examples 1 and 2. It is the external appearance observation photograph by the optical microscope after the erosion test of this invention example 10-12. It is the external appearance observation photograph by the optical microscope after the melt-down test of this invention example 13-15. It is the external appearance observation photograph by the optical microscope after the erosion test of this invention example 16-18. It is an external appearance observation photograph by the optical microscope after the melt-out test of Comparative Examples 10-12. It is an external appearance observation photograph by the optical microscope after the erosion test of Comparative Examples 13 and 14.

  The present inventor has found that it is effective to provide a smoothing process in the middle of the coating process of the hard film by the arc ion plating method in order to reduce local melting damage and seizure of the coating mold for die casting. As a result, the present invention has been reached.

The present inventor has confirmed that local melting damage and seizure occur due to droplets and particles contained in the hard coating. And by simply smoothing the hard coating on the outermost surface, defects starting from droplets and particles contained in the coating cannot be removed, and melting and seizure of the die casting mold are suppressed. I confirmed that I can't. And in order to suppress the melting loss and seizure of the die-casting die, it has been found that it is effective to provide a smoothing treatment during the formation of the hard coating.
In the present invention, the first hard coating is coated by an arc ion plating method, and the surface thereof is smoothed. By smoothing the surface of the first hard film, the surface unevenness caused by droplets or particles on the surface of the film can be smoothed and smoothed. Then, after the surface of the first hard film is smoothed, it is important to coat the second hard film by the arc ion plating method. By coating the second hard film on the surface of the first hard film by the arc ion plating method on the first hard film that has been smoothed, fine irregularities caused by the smoothing process traces present on the surface of the first hard film As a result, the surface irregularities starting from the droplets and particles contained in the entire hard coating 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 value of the surface of the hard coating, such as mechanical polishing, bombardment treatment or the like. As the surface roughness parameter, arithmetic average roughness Ra and maximum height Rz based on JIS-B-0601-2001 can be used. And by said smoothing process, it is preferable to make arithmetic mean roughness Ra of the surface of a 1st hard film into 0.05 micrometer or less, maximum height Rz to 1.00 micrometers or less, and Rz to 0.50 micrometers or less. More preferably.

For the bombardment treatment, a bombardment treatment using a gas such as argon or a bombardment treatment using metal ions can be applied. If bombarding is applied, it can be continuously processed in the same furnace, which is preferable to mechanical polishing described later.
However, if the bombardment time is too long, the surface of the first hard coating becomes uneven, and the melt resistance tends to decrease. In order to exhibit better resistance to erosion, the bombardment treatment is preferably performed for 40 minutes or less. More preferably, it is 30 minutes or less. However, if the treatment time becomes too short, it is difficult to obtain the effect of improving the melt resistance. Therefore, it is preferable that the bombarding process has a processing time of 5 minutes or longer. Furthermore, it is preferable to set it as 10 minutes or more.
The gas bombardment treatment is preferably performed at a negative bias voltage applied to the substrate of −700 V or more and −400 V or less. When the negative bias voltage applied to the substrate is larger than −400 V (plus side from −400 V), the first hard coating is not sufficiently smoothed, so that the melt resistance and seizure resistance tend to decrease. In addition, when the negative bias voltage applied to the substrate is smaller than −700 V (minus side than −700 V), many irregularities are easily formed on the surface of the first hard film, and the resistance to fusing and seizure is lowered. Tend to.

On the other hand, the following mechanical polishing is effective in order to eliminate the surface irregularities caused by the droplets and to obtain a smooth surface state.
(1) A method of polishing the surface of a hard film with a polishing cloth holding an abrasive such as diamond paste (2) Using diamond particles and a water-containing abrasive, sliding the film coated on the substrate at a high speed to generate Polishing by so-called aero lapping (registered trademark), etc. (3) Polishing by spraying abrasives with elasticity and adhesion without using air, so-called SMAP (Kamei Iron Works) Further, a more preferable smoothing can be realized by polishing the diamond paste of 3 μm or less after the mechanical polishing.
In order to mechanically polish the surface of the first hard film, it is necessary to remove the sample from the furnace after coating the first hard film. After the first hard film is smoothed by mechanical polishing, the sample may be returned to the furnace to cover the second hard film.
Mechanical polishing can achieve a smoother surface state and is preferable for improving the resistance to erosion and seizure.

Nitride, carbide, carbonitride, carbonitride, oxynitride, and oxide can be applied to the first hard film and the second hard film of the present invention.
In the present invention, the first hard film and the second hard film may be a single layer, but preferably have a multilayer structure. By making the second hard film into a multilayer structure, excellent mechanical properties can be added to the second hard film. For example, high hardness is added to the second hard film by laminating chromium nitride with excellent adhesion and chromium nitride obtained by adding a third element such as Si or B to the chromium nitride. can do.

  The first hard film is preferably a nitride or carbonitride. If the first hard film on the substrate side is a nitride or carbonitride, it is preferable because the adhesion to the substrate tends to be more excellent. Further, a nitride is preferable. The first hard coating is more preferably a chromium-based nitride or carbonitride containing 50% or more of Cr in an atomic ratio (atomic%) of a metal (including metalloid) portion, and Cr It is more preferable to contain 70% or more.

  In order to improve the melt resistance and seizure resistance of the die casting coating mold, the second hard film on the surface side is preferably a nitride, carbonitride, oxynitride, or oxide. Further, nitride or oxynitride is preferable. In particular, a nitride is preferable. The second hard coating is more preferably a chromium-based nitride or carbonitride containing 50% or more of Cr in an atomic ratio (atomic%) of a metal (including metalloid) portion, and Cr It is more preferable to contain 70% or more.

  The second hard coating preferably contains at least one of Si and B. By containing at least one of Si and B, the film structure becomes finer, and the wear resistance and the erosion resistance are further improved. In order to fully exhibit these effects, it is more preferable that the second hard coating contains 3% or more of one or more of Si and B in the atomic ratio (atomic%) of the metal (including metalloid) portion. More preferably, it is 5% or more. However, when the contents of Si and B are excessive, the toughness of the film is lowered. Therefore, it is preferable that the second hard coating contains at least 15% of Si and B in an atomic ratio (atomic%) of a metal (including metalloid) portion, and at least 1 type of Si and B. It is more preferable to contain it at 10% or less.

  In the present invention, the surface of the second hard film is preferably smoothed. In this case, the surface of the second hard film is polished to have an arithmetic average roughness Ra (based on JIS-B-0601-2001) of 0.05 μm or less and a maximum height Rz (JIS-B-0601-2001). Is more preferably 1.00 μm or less, and further preferably Rz is 0.60 μm or less.

Although the base material of the present invention is not particularly defined, it is preferable to use hot tool steel represented by SKD61 of JIS-G-4404 (2006) and its improved material. Based on hot tool steel containing C and Cr, which determine the basic properties of tool steel, in the mass range of C: 0.35 to 0.45% and Cr: 4.0 to 6.0%. It is preferable to use it as a material.
The substrate may be preliminarily applied with a surface hardening treatment using diffusion such as nitriding treatment or carburizing treatment. It is preferable to use a base material that has been subjected to a nitriding treatment because melting resistance and seizure resistance tend to be further improved.

  In order to further improve the adhesion of the hard coating, the arithmetic average roughness Ra (based on JIS-B-0601-2001) is 0.05 μm or less, and the maximum height Rz (based on JIS-B-0601-2001). It is preferable to use a substrate having a surface roughness of 1.00 μm or less.

In order to adjust the surface roughness of the first hard coating or the second hard coating smoothly, it is preferable that the surface roughness of the substrate before coating is also polished smoothly. Specifically, the surface roughness of the base material before coating the hard film is A, the surface roughness of the first hard film before the smoothing process is B, and the surface of the first hard film after the smoothing process When the roughness is C, it is preferable that each arithmetic average roughness Ra and maximum height Rz satisfy the relationship of A <C <B.
In the present invention, in addition to smoothing the surface of the first hard film, it is preferable to smooth the second hard film. In this case, the second hard film is smoothed. More preferably, the relationship between Ra and Rz described above satisfies the relationship of A <C <D <B, where D is the subsequent surface roughness.
By smoothing the surface of the base material, film defects caused by unevenness on the surface of the base material can be suppressed. The film defects immediately above the base material directly corrode the base material itself, and it is more preferable that the film defects on the side close to the base material are small. Therefore, the surface roughness of the first hard coating is preferably smoother than the surface roughness of the second hard coating after polishing, and the surface roughness of the substrate before coating is the smoothest. It is preferable.
Furthermore, for the first hard film, when the droplets etc. on the surface at the time of coating are polished or etched away, the degree of removal, that is, the surface roughness C after the smoothing treatment, is the surface roughness before the smoothing treatment. It is preferable that the smoothing process is performed so that C / B is less than 1.0 for Ra and C / B is less than 0.5 for Rz. By satisfying these equations, defects in the hard coating can be further reduced.

  If the total thickness of the hard coating becomes too thin, the melt resistance and seizure resistance may not be sufficient. Therefore, the total film thickness of the hard coating is preferably 3 μm or more. Furthermore, the total film thickness of the hard coating is more preferably 5 μm or more, and further preferably 10 μm or more. On the other hand, if the total film thickness of the hard film becomes too thick, film peeling tends to occur. Therefore, the total film thickness of the hard coating is preferably 40 μm or less, and more preferably 30 μm or less.

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

A sample for evaluating the resistance to fusing required for a die casting die was prepared. As the base material, a steel material equivalent to SKD61 of JIS-G-4404 (2006), which has a hardness of 46 HRC and is generally used as hot tool steel, was used. The dimensions of the substrate for evaluation were a cylindrical shape having a diameter of 10 mm and a length of 120 mm, and the surface was polished so that the arithmetic average roughness Ra was 0.01 μm and the maximum height Rz was 0.07 μm. For all samples, a substrate that had been previously gas-nitrided was used.
And the hard film was coat | covered using the general arc ion plating apparatus. The surface-polished substrate was degreased and washed and fixed to the substrate holder. Then, the base material temperature was heated to about 500 ° C., and heat degassing was performed in a vacuum of 1 × 10 ⁻³ Pa. Next, Ar gas was introduced, a bias voltage of −500 V was applied to the substrate, and Ar bombardment treatment was performed for 20 minutes. Subsequently, a bias voltage of −800 V was applied to the substrate, and Ti bombardment was performed for about 5 minutes. The substrate was bombarded in the same manner for all samples.
For the coating, CrN was selected for the first hard coating and CrSiBN was selected for the second hard coating, and the substrate was coated. The contents of the smoothing treatment of the first hard film and the second hard film of Example 2 are shown in Tables 1 and 2. Detailed sample preparation conditions will be specifically described below.

<Invention Sample Sample No. 1>
Nitrogen gas is introduced into the furnace, a bias voltage of −120 V is applied to the base material, and the first hard film is about 5.0 μm of CrN under the conditions of the base material temperature of 500 ° C. and the reaction gas pressure of 3.0 Pa. Was coated. Next, for smoothing the first hard film, the base material is taken out from the chamber and polished using an aero lapping device (AERO LAP YT-300) manufactured by Yamashita Towers Co., Ltd. The film was smoothed. And the surface roughness of the 1st hard film was measured. And after performing degreasing washing | cleaning, it returned in the chamber again and coat | covered the 2nd hard film. First, in order to remove an oxide film and the like on the surface of the first hard film, the surface was cleaned by performing Ar bombardment treatment and Ti bombardment treatment. Thereafter, nitrogen gas is introduced, a bias voltage of −120 V is applied to the base material, and the second hard film made of CrSiBN of about 4.0 μm under the conditions of the base material temperature of 500 ° C. and the reaction gas pressure of 3.0 Pa. Was coated. The composition of the target was Cr ₉₂ Si ₃ B ₅ .
Then, the second hard film after coating was polished using an aero lapping apparatus, and then smoothed by polishing using a 3 μm diamond paste.

<Invention Sample Sample No. 2>
The process up to the first hard coating was the same as Example 1 of the present invention. For smoothing the first hard coating, the substrate is taken out of the chamber and polished using an aero lapping device (AERO LAP YT-300) manufactured by Yamashita Towers. And polished.
The process after the smoothing treatment of the first film was the same as Example 1 of the present invention.

<Invention Sample Sample No. 3>
The process up to the first hard coating was the same as Example 1 of the present invention.
After coating the first hard coating, in order to smooth the surface of the first hard coating by bombarding, the negative bias voltage applied to the substrate is set to -500 V, and bombarding using Ar gas is performed. Conducted for 30 minutes. And the base material after performing this smoothing process was taken out from the chamber, and the surface roughness of the 1st hard film was measured.
After measuring the surface roughness of the first hard coating, the substrate was returned to the chamber and the same surface cleaning as in Example 1 of the present invention was performed. Then, nitrogen gas was introduced, a bias voltage of −120 V was applied to the substrate, and the substrate was made of about 4.0 μm CrSiBN under the conditions of a substrate temperature of 500 ° C. and a reaction gas pressure of 3.0 Pa (the target composition was The same as Example 1 of the present invention) The second hard film was coated. The method for smoothing the second hard film is the same as in Example 1 of the present invention.

<Invention Sample Sample No. 4>
The process up to the first hard coating was the same as Example 1 of the present invention. For the smoothing treatment of the first hard film, the base material was taken out of the chamber, and a nylon nonwoven fabric (polishing pad # 400 manufactured by Bell Star Abrasives Industries Co., Ltd.) coated with an abrasive as the smoothing treatment was used. The process after the smoothing treatment of one film was the same as Example 1 of the present invention.

<Comparative Example Sample No. 1>
The process up to the first hard coating was the same as Example 1 of the present invention. For smoothing treatment of the first hard film, the base material is taken out from the chamber, and as a comparative example of the smoothing treatment, instead of the smoothing treatment of the present invention, shot blast treatment (projection material: steel grit 200 to 300 μm) )It was used. Shot blasting was performed for about 10 seconds. The process after the shot blasting treatment of the first film was the same as that of Example 1 of the present invention.

<Comparative Example Sample No. 2>
The process up to the first hard coating was the same as Example 1 of the present invention.
After the coating of the first hard film, no polishing treatment or the like was performed, and the second hard film was coated in the same process as in Invention Example 10 to prepare a sample. The method for smoothing the second hard film is the same as in Example 1 of the present invention.

<Surface roughness measurement>
The surface roughness of the base material and the hard coating is calculated using arithmetic contact roughness Ra and maximum height roughness Rz according to JIS-B-0601-2001 using a contact surface roughness measuring instrument SURFCOM 480A manufactured by Tokyo Seimitsu Co., Ltd. Was measured. The measurement conditions were as follows: evaluation length: 4.0 mm, measurement speed: 0.3 mm / s, cut-off value: 0.8 mm. Table 1 shows the surface roughness A of the base material before coating the hard coating, the surface roughness B before the smoothing treatment of the first hard coating, and the surface roughness C after the smoothing treatment of the first hard coating. And the measurement result of the surface roughness D after the smoothing process of a 2nd hard film is shown, respectively.

<Evaluation of erosion resistance>
The present invention example and the comparative example were immersed in a molten 720 ° C. aluminum for 30 hours, and the presence or absence of melting damage was confirmed by an optical microscope. In addition, the mass loss before and after the test was measured, and the melting rate (%) was confirmed. Table 2 summarizes sample preparation conditions and test results.

As shown in Table 2, the example of the present invention in which the surface of the first hard film was smoothed has a lower erosion rate (%) than the comparative example in which the smoothing treatment of the present invention is not performed. It was confirmed that the damage was excellent. Particularly, the present invention examples 2 and 4 in which the maximum height Rz after polishing of the first film is 0.5 μm or less and the maximum height Rz after polishing of the second film is 0.6 μm or less are excellent. It showed good resistance to erosion.
FIG. 1 shows a photograph of appearance observation with an optical microscope after evaluating the corrosion resistance of Examples 1 to 4 of the present invention. In Invention Examples 1 to 4 that showed excellent resistance to erosion, no erosion was confirmed at the tip and side portions.
FIG. 2 shows a photograph of appearance observation with an optical microscope after the evaluation of the corrosion resistance of Comparative Examples 1 and 2. In the comparative example, large melting damage was confirmed in both the tip portion and the side portion.
It was confirmed that through the process of smoothing the surface of the first hard film, and further the surface of the second hard film was also smoothed, thereby improving the resistance to melting.

  From Tables 1 and 2, it can be seen that the hard coating obtained by applying the production method of the present invention has a smooth surface roughness on the outermost surface of the coating and is excellent in resistance to erosion. As shown in FIG. 1, almost no erosion pitting corrosion was confirmed on the surface of the film after the molten aluminum corrosion resistance evaluation test.

  On the other hand, the hard coatings of Comparative Examples 1 and 2 subjected to shot blasting resulted in extremely poor melt resistance. The surface of the hard coating of Comparative Example 1 was roughened to increase the surface roughness value of the hard coating, and the surface of the hard coating of Comparative Example 2 was subjected to the smoothing treatment itself of the present invention on the first hard coating. As a result, the macro particles were not removed, and the surface roughness could not be reduced sufficiently.

  The base material used in Example 2, the base material polishing, and the base material bombarding conditions were the same as in Example 1. Some substrates were previously subjected to nitriding treatment. Table 3 shows the types of the first hard film and the second hard film of Example 2 and the contents of the smoothing treatment. Detailed sample preparation conditions will be specifically described below.

<Invention Sample Sample No. 10>
Nitrogen gas is introduced into the furnace, a bias voltage of −120 V is applied to the base material, and the first hard film is about 5.0 μm of CrN under the conditions of the base material temperature of 500 ° C. and the reaction gas pressure of 3.0 Pa. Was coated.
Thereafter, in order to smooth the surface of the first hard film by polishing, the base material was taken out of the chamber and polished using an aero lapping apparatus (AERO LAP YT-300) manufactured by Yamashita Towers. Further polishing is then performed with a 1 μm diamond paste, followed by Kamei Ironworks mirror shot machine SMAP-II, with an arithmetic average roughness Ra of 0.01 μm and a maximum height Rz of 0. .05 μm.
And after performing degreasing washing | cleaning, it returned in the chamber again and coat | covered the 2nd hard film. First, in order to remove the oxide film on the surface of the first hard film, the surface was cleaned by performing Ar bombardment treatment and Ti bombardment treatment. Thereafter, nitrogen gas is introduced, a bias voltage of −120 V is applied to the base material, and the second hard film made of CrSiBN of about 5.0 μm under the conditions of the base material temperature of 500 ° C. and the reaction gas pressure of 3.0 Pa. Was coated. A target having a composition of Cr ₉₂ Si ₃ B ₅ was used (numbers are atomic ratios, and so on). Then, the second hard film after coating was polished using an aero lapping apparatus, and then smoothed by polishing using a 3 μm diamond paste.

<Invention Sample Sample No. 11>
A base material on which a nitride layer of about 100 μm was formed by nitriding was used. Other than that, it was the same as Example 10 of the present invention.

<Invention Sample Sample No. 12>
A base material on which a nitride layer of about 100 μm was formed by nitriding was used. And it was the same as that of the example 10 of this invention until the coating of the 1st hard film.
After coating the first hard coating, in order to smooth the surface of the first hard coating by bombarding, the negative bias voltage applied to the substrate is set to -500 V, and bombarding using Ar gas is performed. Conducted for 30 minutes.
Thereafter, nitrogen gas is introduced, a bias voltage of −120 V is applied to the base material, and the second hard film made of CrSiBN of about 5.0 μm under the conditions of the base material temperature of 500 ° C. and the reaction gas pressure of 3.0 Pa. (The composition of the target was the same as in Example 10 of the present invention). Finally, the smoothing process described in Example 10 of the present invention was performed.

<Invention Sample Sample No. 13>
A base material on which a nitride layer of about 100 μm was formed by nitriding was used. The process up to the smoothing treatment of the first hard film was the same as Example 12 of the present invention.
After smoothing the first hard coating, nitrogen gas is introduced, a bias voltage of −120 V is applied to the substrate, and the substrate temperature is 500 ° C. and the reaction gas pressure is 3.0 Pa. The second hard film was coated with 0 μm CrN, followed by coating with about 4.0 μm CrSiBN (the target composition is the same as in Example 10 of the present invention). Finally, the smoothing process described in Example 10 of the present invention was performed.

<Invention Sample Sample No. 14>
A base material on which a nitride layer of about 50 μm was formed by nitriding was used. Otherwise, it was the same as Example 13 of the present invention.

<Invention Sample Sample No. 15>
The process up to the first hard coating was the same as Example 10 of the present invention.
After coating the first hard coating, in order to smooth the surface of the first hard coating by bombarding, the negative bias voltage applied to the substrate is set to -500 V, and bombarding using Ar gas is performed. Performed for 45 minutes.
After smoothing the first hard coating, nitrogen gas is introduced, a bias voltage of −120 V is applied to the substrate, and the substrate temperature is 500 ° C. and the reaction gas pressure is 3.0 Pa. The second hard film was coated with 0 μm CrN, followed by coating with about 4.0 μm CrSiBN (the target composition is the same as in Example 10 of the present invention). Finally, the smoothing process described in Example 10 of the present invention was performed.

<Invention Sample Sample No. 16>
The process up to the first hard coating was the same as Example 10 of the present invention.
After coating the first hard coating, in order to smooth the surface of the first hard coating by bombarding, the negative bias voltage applied to the substrate is set to -500 V, and bombarding using Ar gas is performed. Conducted for 60 minutes.
After smoothing the first hard film, nitrogen gas is introduced, a bias voltage of −120 V is applied to the substrate, and the substrate temperature is 500 ° C. and the reaction gas pressure is 3.0 Pa. A second hard film composed of 0 μm CrSiBN was coated (the composition of the target was the same as Example 10 of the present invention). Finally, the smoothing process described in Example 10 of the present invention was performed.

<Invention Sample Sample No. 17>
The process up to the first hard coating was the same as Example 1 of the present invention.
After coating the first hard coating, in order to smooth the surface of the first hard coating by bombarding, the negative bias voltage applied to the substrate is set to -500 V, and bombarding using Ar gas is performed. Conducted for 60 minutes.
After smoothing the first hard coating, nitrogen gas is introduced, a bias voltage of −120 V is applied to the substrate, and the substrate temperature is 500 ° C. and the reaction gas pressure is 3.0 Pa. A 0 μm CrN coating was applied, followed by a coating of about 4.0 μm CrSiBN (the composition of the target was the same as in Example 10 of the present invention), and a second hard coating was applied. Finally, the smoothing process described in Example 10 of the present invention was performed.

<Invention Sample Sample No. 18>
The process up to the first hard coating was the same as Example 1 of the present invention.
After coating the first hard film, in order to smooth the surface of the first hard film by bombarding, the negative bias voltage applied to the substrate is set to −700 V, and bombarding using Ar gas is performed. Conducted for 30 minutes.
After smoothing the first hard coating, nitrogen gas is introduced, a bias voltage of −120 V is applied to the substrate, and the substrate temperature is 500 ° C. and the reaction gas pressure is 3.0 Pa. A 0 μm CrN coating was applied, followed by a coating of about 4.0 μm CrSiBN (the composition of the target was the same as in Example 1 of the present invention), and a second hard coating was applied. Finally, the smoothing process described in Example 10 of the present invention was performed.

<Comparative Example Sample No. 10>
Nitrogen gas was introduced into the furnace, a bias voltage of −120 V was applied to the substrate, and about 5.0 μm of CrN was coated under the condition of a reaction gas pressure of 3.0 Pa, followed by about 5.0 μm of CrSiBN. Was coated. A target having a composition of Cr ₉₂ Si ₃ B ₅ was used (numbers are atomic ratios, and so on). Finally, the smoothing process described in Example 10 of the present invention was performed.

<Comparative Example Sample No. 11>
Nitrogen gas was introduced into the furnace, a bias voltage of −120 V was applied to the substrate, and TiAlN of about 13.0 μm was coated under the condition of a reaction gas pressure of 3.0 Pa. The composition of the target used was Ti ₅₀ Al ₅₀ . Finally, the smoothing process described in Example 10 of the present invention was performed.

<Comparative Example Sample No. 12>
A base material on which a nitride layer of about 100 μm was formed by nitriding was used.
Nitrogen gas was introduced into the furnace, a bias voltage of -120 V was applied to the base material, and each film thickness was 10 nm or less and VN and AlCrSiN were alternately laminated under the condition of a reaction gas pressure of 3.0 Pa. A 0.0 μm laminated film was coated. The composition of the target used for coating the AlCrSiN was Al ₆₀ Cr ₃₇ Si ₃ . Finally, the smoothing process described in Example 10 of the present invention was performed.

<Comparative Example Sample No. 13>
Nitrogen gas was introduced into the furnace, a bias voltage of -120 V was applied to the base material, and each film thickness was 10 nm or less and VN and AlCrSiN were alternately laminated under the condition of a reaction gas pressure of 3.0 Pa. A 5 μm laminated film was coated. The composition of the target used for coating AlCrSiN was Al ₆₀ Cr ₃₇ Si ₃ which was the same as that in Comparative Example 12. Finally, the smoothing process described in Example 10 of the present invention was performed.

<Comparative Example Sample No. 14>
A base material on which a nitride layer of about 100 μm was formed by nitriding was used. In Comparative Example 14, the base material was only nitrided and no hard coating was provided. Finally, the smoothing process described in Example 10 of the present invention was performed.

<Surface roughness evaluation>
In both the inventive examples and the comparative examples, the surface of the second hard film or the surface of the substrate was polished, and the arithmetic average roughness Ra was 0.04 μm and the maximum height Rz was 0.05 μm. The surface roughness of the base material and the hard coating is 4.0 mm and the measurement speed is 0 according to JIS-B-0601-2001 using a contact surface roughness measuring device SURFCOM 480A manufactured by Tokyo Seimitsu Co., Ltd. Measurement was performed under the conditions of 3 mm / s and a cutoff value of 0.8 mm.

<Evaluation of erosion resistance>
The present invention example and the comparative example were immersed in a molten aluminum at 720 ° C. for 20 hours, and the presence or absence of melting damage was confirmed with an optical microscope. In addition, the mass loss before and after the test was measured, and the melting rate (%) was confirmed. Table 3 summarizes sample preparation conditions and test results.

As shown in Table 1, the example of the present invention in which the surface of the first hard film was smoothed has a lower erosion rate (%) than that of the comparative example that has not been smoothed, resulting in resistance to erosion. It was confirmed that it was excellent. In particular, the inventive examples 10 and 11 polished and the bias voltage applied to the substrate at −500 V in the smoothing step and the inventive examples 12 to 14 treated with argon bombardment for 30 minutes have a loss rate (%). ) Was 0%, indicating excellent melt resistance. In addition, Examples 11 to 14 of the present invention in which the base material was subjected to nitriding treatment had a melting rate of 0% and exhibited excellent resistance to melting.
FIG. 3 shows a photograph of the appearance observed with an optical microscope after evaluating the corrosion resistance of Examples 10 to 12 of the present invention. FIG. 4 shows photographs of external appearance observation with an optical microscope after the evaluation of the corrosion resistance of Examples 13 to 15 of the present invention. FIG. 5 shows photographs of external appearance observation with an optical microscope after the evaluation of the corrosion resistance of Examples 16 to 18 of the present invention. In Examples 10 to 14 of the present invention that showed particularly excellent resistance to erosion, no erosion was confirmed at the tip and side portions.
FIG. 6 shows a photograph of external appearance observation with an optical microscope after the evaluation of the corrosion resistance of Comparative Examples 10-12. FIG. 7 shows photographs of external observation using an optical microscope after the evaluation of the resistance to melting of Comparative Examples 13 and 14. In the comparative example, large melting damage was confirmed in both the tip portion and the side portion.
It has been confirmed that the melt resistance is improved by performing a process of smoothing the surface of the first hard coating.

Claims (3)

A step of coating the surface of the base material of the die casting mold with the first hard film by an arc ion plating method;
Smoothing the surface of the first hard film, setting the arithmetic average roughness Ra of the surface of the first hard film to 0.05 μm or less and the maximum height Rz to 1.00 μm or less ;
Have a, a step of coating a second hard coating film by arc ion plating method on the first hard coating said treated smoothed,
The smoothing process is a gas bombardment process,
The gas bombardment treatment is performed at a negative bias voltage applied to the substrate of −700 V or more and −400 V or less,
The method of manufacturing a die casting coating mold , wherein the step of coating the first hard coating and the step of smoothing the surface of the first hard coating are performed in the same furnace . 2. The method for manufacturing a die casting coating mold according to claim 1, wherein the first hard coating or the second hard coating is a chromium nitride. 3. The method for producing a die casting coating mold according to claim 1 or 2 , wherein the second hard coating has a multilayer structure of at least two layers.

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