JP2013082987A - Method for manufacturing coated article superior in corrosion resistance and coated article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a coated article which has superior corrosion resistance by coating a hard film thereon and is suitable for formed parts such as plastic and rubber, and the coated article.SOLUTION: In the method for manufacturing the coated article superior in corrosion resistance, the hard film is coated on a substrate surface of the article by a physical vapor deposition method. The hard film consists of at least two or more layers comprising a first chromium-based hard film and a second chromium-based hard film located immediately above the first layer. Prior to coating the second chromium-based hard film, a surface of the first chromium-based hard film is polished. A bias voltage of negative pressure that is applied to the substrate is varied while the second chromium-based hard film is coated. It is preferable that while the second chromium-based hard film is coated, the bias voltage of negative pressure in the initial stage is different from that in the final stage.

Description

  The present invention relates to a method for producing a coated article and a coated article that require corrosion resistance, such as a mold, a tool, and an injection molding part used for molding plastics and rubber, for example.

  Conventionally, in the molding of plastics (resins) and rubbers, excellent corrosion resistance is required for articles such as molds and tools used for molding because of the corrosive environment caused by the molding material. For example, in the case of injection molding, various additives for improving heat resistance and strength are added to a material to be molded such as plastic. During injection molding, the plastic is decomposed by heating or heat generation, and corrosive gas is also generated from the above additives. Therefore, injection molding parts (for example, screw heads, seal rings, etc.) Exposed to severe corrosive environment and susceptible to damage such as pitting and gas seizure.

  As a technique for improving the corrosion resistance of various articles used in a corrosive environment, surface treatment on the component is generally used. For example, there is a technique for improving the corrosion resistance by coating a thick hard chrome plating. In addition, hard coatings such as TiN, CrN, TiCN, etc. coated by physical vapor deposition (hereinafter abbreviated as PVD) or chemical vapor deposition have high wear resistance in addition to their excellent corrosion resistance. Therefore, it is an effective method.

  For example, there is a technique for improving wear resistance and film adhesion by nitriding the surface of an injection molding part and then coating a CrN or TiN film by an arc ion plating method (Patent Document 1). Similarly, in the method of coating a CrN or TiN film, the CrN film having excellent adhesion and corrosion resistance to the base material is coated first, and then a high-hardness TiN film is coated in multiple layers, thereby improving the corrosion resistance. There is a method of giving (Patent Document 2).

  On the other hand, there is a technique for improving the film properties by improving the structure on the other hand by improving the film components. For example, in the field of cutting tools, when coating a hard film on the tool surface, intermediate ion etching (bombarding) is performed in the middle of the coating to remove droplets that cause crack fracture, and no voids or pores are generated. There is a technique for obtaining a smooth film (Patent Document 3). As a technique for removing the above-described droplets, there is a technique in which mechanical processing by sandblasting is applied (Patent Document 4).

JP 2001-150500 A JP 2005-144992 A JP 2009-078351 A European Patent No. 0756019

  Adopting PVD as the coating means for the hard coating is effective because the thermal load applied to the substrate is small. However, the droplets and particles described above are not a little present in the film coated with PVD. When voids, pores, or pinhole-like gap defects due to these penetrate into the base material in particular, the corrosion progresses violently at the site, which causes early pitting corrosion and gas seizure. Therefore, even if it is CrN which was excellent in corrosion resistance, the hard film of patent document 1 has the subject that original corrosion resistance cannot be obtained because the said defect exists in a film. Moreover, even if the hard film of patent document 2 coat | covers the TiN film | membrane on the CrN film | membrane, it is difficult to cover the defect once formed in the CrN film | membrane as it is.

  On the other hand, the application of Patent Document 3 or Patent Document 4 which is a technique for removing droplets is considered to be effective, but development of a new technique for imparting corrosion resistance for obtaining sufficient corrosion resistance is desired.

  In view of the above problems, an object of the present invention is to provide a method for producing a coated article and a coated article having improved corrosion resistance of a hard film.

  The present inventors examined a method for suppressing defects penetrating from the surface of the hard film coated with PVD toward the base material. As a result, it has been found that for this suppression, it is important to improve the corrosion resistance to polish smoothly during the coating process and to change the negative bias voltage applied to the substrate. In addition, it has been found that there is a structure form that improves the corrosion resistance.

  That is, the present invention is a method of manufacturing a coated article in which a hard film is coated on the surface of a base material of the article by a physical vapor deposition method. It consists of at least two layers of hard coating, the surface of the first chromium hard coating is polished before coating of the second chromium hard coating, and during the coating period of the second chromium hard coating This is a method for producing a coated article having excellent corrosion resistance by changing the negative bias voltage applied to the substrate.

Furthermore, it is preferable that the negative bias voltage applied to the substrate is different between the initial stage and the final stage during the coating period of the second chromium-based hard coating.
Further, before coating the second chrome hard film, the surface of the first chrome hard film is polished so that the arithmetic average roughness Ra is 0.05 μm or less and the maximum height Rz is 1.00 μm or less. It is preferable to do.

Furthermore, it is preferable that the negative bias voltage applied to the substrate is changed by 10 V or more during the coating period of the second chromium-based hard coating.
Further, it is preferable that the negative bias voltage applied to the base material is varied by 10 V or more between the initial stage and the final stage during the coating period of the second chromium-based hard coating.
Furthermore, it is preferable that the negative bias voltage applied to the base material is larger than 20 V during the coating period of the second chromium-based hard coating.

The first and / or second chromium-based hard coating preferably contains one or more elements selected from Mo, Nb, W, Si, and B.
In this case, the first and / or second chromium-based hard coating is one or two selected from Mo, Nb, W, Si, and B in atomic percent of only the metal component (including the semimetal). It is preferable to contain 1 to 20% of the above elements.

  Furthermore, it is preferable to polish the surface of the second chromium-based hard coating so that the arithmetic average roughness Ra is 0.05 μm or less and the maximum height Rz is 1.00 μm or less.

Further, the production method of the present invention is preferably coated by an arc ion plating method among physical vapor deposition methods.
Furthermore, the coated article is preferably an injection molding part and / or a mold.
Further, the injection molding part is preferably a screw and / or a tip part of the screw.

The present invention is also a coated article formed by any of the above manufacturing methods, wherein the hard coating is at least a first chromium-based hard coating and a second chromium-based hard coating coated directly thereon. It consists of two or more layers, and the surface of the first chromium-based hard coating is polished, and the second chromium-based hard coating is made of a corrosion resistance composed of particle layers having different particle sizes on the substrate side and the surface side. It is an excellent coated article. Furthermore, the hardness of the second chromium-based hard coating by the nanoindentation method is preferably 30 GPa or more.
Furthermore, the film thickness of the first chromium-based hard film is preferably 1.0 to 10.0 μm, and the film thickness of the second chromium-based hard film is preferably 1.0 to 10.0 μm.

  According to the manufacturing method of the present invention, the surface of the first chrome-based hard coating that is being coated with the hard coating is optimally polished, and further applied to the substrate during the coating period of the second chrome-based hard coating. By changing the negative bias voltage, the coated article has very few defects penetrating from the coating surface toward the substrate. Therefore, the present invention is useful for manufacturing injection molding parts, tools, and molds that are exposed to corrosive environments.

Sample No. which is an example of the present invention. 1 and sample No. 1 as a comparative example. 10 is a scanning electron micrograph showing a cross-section polisher (CP) processed fracture surface structure of No. 10. FIG. Sample No. which is an example of the present invention. 1 and sample No. 1 as a comparative example. 4 is a micrograph of a hard coating surface showing the results of corrosion test No. 4; Sample No. which is a conventional example. It is a microscope picture of the hard film surface which shows the result of a corrosion test of 6-11. Sample No. which is an example of the present invention. 12, 13, 15, 21 and a sample No. as a comparative example. It is a microscope picture of the hard film surface which shows the result of 22 corrosion tests. Sample No. which is an example of the present invention. 12 is a scanning electron micrograph showing a fracture surface structure of a hard coating of No. 12. Sample No. which is an example of the present invention. 12 is an observation photograph of a fractured surface structure processed by a focused ion beam method, using a scanning ion microscope. Sample No. which is an example of the present invention. 13 is an observation photograph of a fractured surface structure processed by a focused ion beam method, using a scanning ion microscope. Sample No. which is an example of the present invention. 25 and a sample No. as a comparative example. 27 is a photomicrograph of the hard coating surface showing the results of 27 corrosion tests. Sample No. which is an example of the present invention. 25 is an observation photograph of a fractured surface structure processed by the focused ion beam method, using a scanning ion microscope. It is the schematic of the film-forming apparatus used in the Example.

  The present inventors have found that it is important to improve the corrosion resistance to block the influence of impurities such as droplets on the surface of the film. In addition, it has been found that changing the negative bias voltage applied to the substrate during the coating period of the chromium hard coating on the surface side is extremely effective in improving the corrosion resistance. And the specific film structure and its manufacturing method which are extremely excellent in corrosion resistance were found, and the present invention was reached. Details will be described below.

The hard film of the present invention is a chromium-based hard film that is a film type having excellent corrosion resistance. In the present invention, the chromium-based hard coating means that the amount of chromium having excellent corrosion resistance is 50% or more in terms of atomic% of only the metal component (including metalloid). More preferably, it is 70% or more. Further, the chromium-based hard coating is preferably a nitride or carbonitride excellent in corrosion resistance and adhesion to the substrate.
The hard coating of the present invention can be coated at a temperature lower than the tempering temperature of the base material such as cold die steel, hot die steel, high speed steel, etc. by coating by physical vapor deposition. The fluctuation of the dimension of can be suppressed. In addition, a compressive residual stress can be imparted to the hard coating, and the mechanical properties of the hard coating can be improved. A surface hardening treatment using diffusion such as nitriding treatment or carburizing treatment may be applied in advance to the base material.

The surface of the first chromium-based hard coating coated by the production method of the present invention can improve the corrosion resistance not only by removing droplets and particles but also by smooth polishing the coating surface. And by polishing so that the arithmetic average roughness Ra in the surface roughness defined in JIS-B-0602-2001 is 0.05 μm or less and the maximum height Rz is 1.00 μm or less, there is very little unevenness. Since it becomes a smooth surface state, corrosion resistance improves and is preferable. In order to reliably remove droplets, particles and the like to obtain a smooth surface state, the following polishing method is preferable.
(1) A method of polishing the surface of a hard film with an abrasive cloth holding a polishing agent such as diamond paste (2) Using a polishing agent having diamond particles and humidity, and sliding at a high speed on a film coated on a substrate. Polishing by the generated friction force, so-called aero lapping (Aero lapping is a registered trademark of Yamashita Towers Co., Ltd.) etc. (3) Injecting an abrasive with elasticity and adhesion without using air Polishing method by so-called SMAP (mirror surface shot machine of Kamei Ironworks, Inc.) etc. Furthermore, after these treatments, diamond paste of 3 μm or less is polished to achieve more favorable smoothing it can.

In order to improve the corrosion resistance, it is preferable that the surface of the second chromium-based hard coating is also polished so that the arithmetic average roughness Ra is 0.05 μm or less and the maximum height Rz is 1.00 μm or less.
Further, it is preferable that the surface roughness of the base material before coating is polished so that the arithmetic average roughness Ra is 0.50 μm or less and the maximum height Rz is 1.00 μm or less.

Furthermore, in the production method of the present invention, it is important to change the negative bias voltage applied to the base material during the coating period of the second chromium-based hard coating.
When the negative bias voltage is low, the particle layer tends to be relatively fine, and when the negative pressure bias voltage is high, the particle layer tends to be relatively coarse. Further, by changing the bias voltage, not only the shape such as the grain size but also the crystal orientation changes.
Therefore, during the coating period of the second chromium-based hard film, by changing the bias voltage of the negative pressure applied to the base material, it continues from the inside of the existing film to the surface even if it is polished halfway. It is considered that voids, pores and pinhole-like gap defects due to droplets and particles are blocked in the middle, and the corrosion progress does not reach the inside of the base material, resulting in a coated article having extremely excellent corrosion resistance.
During the coating period of the second chromium-based hard coating, it is preferable to change the bias voltage between the initial stage and the final stage so that the corrosion path is easily interrupted in the middle of the coating.

If the change in the bias voltage is small, the effect of improving the corrosion resistance may not be sufficiently obtained. Therefore, in order to further improve the corrosion resistance, it is preferable to change the negative bias voltage applied to the base material by 10 V or more during the coating period of the second chromium-based hard coating. More preferably, it is 30 V or more. Furthermore, it is 50V or more.
More preferably, during the coating period of the second chromium-based hard coating, it is preferable to change the bias voltage of the negative pressure applied to the base material by 10 V or more in the initial stage and the final stage. More preferably, it is 30 V or more. Furthermore, it is 50V or more.
The finer structure on the surface side of the second chromium-based hard coating is preferable for improving corrosion resistance and wear resistance, and in the final stage, the negative bias voltage applied to the substrate is preferably 100 V or less. .

When the negative bias voltage applied to the substrate is 20 V or less, voids inside the film tend to increase. Therefore, it is preferable that the bias voltage of the negative pressure applied to the substrate is set to be larger than 20V during the coating period of the second chromium-based hard coating. More preferably, it is 30 V or more. If the negative bias voltage becomes too large, it is difficult to stabilize the film formation.
Even during the coating period of the first chromium-based hard coating, it is preferable that the negative bias voltage applied to the substrate is greater than 20V and not greater than 200V.

The first and / or second chromium-based hard coating contains one or more elements selected from Mo, Nb, W, Si, and B, thereby increasing the hardness and improving the wear resistance. Therefore, it is preferable.
In order to improve wear resistance, 1% to 20% of one or more elements selected from Mo, Nb, W, Si, and B are contained in atomic% of only metal components (including metalloids). It is preferable to add.
If it is less than this, the improvement in wear resistance is not sufficient. When it is more than this, the toughness of the film is lowered and the corrosion resistance may be lowered. More preferably, it is 3% or more and / or 15% or less.

  In order to impart sufficient wear resistance to the hard film, it is preferable to add the above elements to the second chromium-based hard film on the surface side. If the wear resistance of the second chromium-based hard coating is improved, even if the first chromium-based hard coating immediately below it is a simple compound containing no additive elements, the wear resistance of the entire coating will be sufficient. Is done. Furthermore, it is preferable to use an alloy target containing an additive element only for the second chromium-based hard coating because the manufacturing cost is reduced.

Further, it is preferable because Si and / or B is added to the chromium-based hard coating to increase the hardness, and the coating structure is refined to improve the corrosion resistance. In other words, by imparting high hardness to the film, it is possible to suppress wear corrosion in addition to improving wear resistance, so that even when a reinforcing material such as glass fiber is added to plastic, for example, the coating caused by wear It has a remarkable effect on preventing corrosion of articles.
In order to achieve both wear resistance and corrosion resistance at a higher level, the addition amount of Si and / or B is preferably 5 to 10% in terms of atomic% of only the metal composition (including metalloid). In particular, it is preferable to add both Si and B.

By adding Si and / or B to the second chromium-based hard coating, the average crystal grain width on each of the base material side and the surface side can be made 200 nm or less. Is finely divided, and the corrosion resistance can be further improved. Moreover, since the hardness of the film is increased, the wear resistance is also improved, which is preferable.
When the difference in crystal grain size is large at the interface between the first chromium-based hard coating and the second chromium-based hard coating, the adhesion strength may not be sufficient depending on the use environment. Therefore, when adding Si and / or B only to the second chromium-based hard coating, in order to make the crystal grain size of the first chromium-based hard coating as close as possible, the surface side is closer to the substrate side. It is preferable that the direction is coarse.

  The hard coating of the present invention is preferably coated by an arc ion plating method having a high film adhesion and a high film density among physical vapor deposition methods. It is preferable to coat each of the first chromium-based hard coating and the second chromium-based hard coating by an arc ion plating method having excellent adhesion.

The present inventor has intensively studied to improve the corrosion resistance. When coarse droplets are present in the film, internal defects such as voids are formed between the film and the film deposited on the upper surface, and corrosion proceeds through the defects. I found out. And it discovered that it was effective in interrupting | blocking the communication of the internal defect of the depth direction of a hard film | membrane by performing a polishing process in the middle of the formation process of a hard film | membrane.
Therefore, the coated article formed by the manufacturing method of the present invention polishes the first chrome-based hard film to remove droplets and particles and makes a smooth surface state. During the coating period of the system hard film, the surface is coated so that fine irregularities on the surface of the first chromium system hard film are filled. Therefore, the penetration defect etc. to a base material can be interrupted | blocked and the corrosion resistance of the whole membrane | film | coat can be improved significantly.
The polished surface can be confirmed from cross-sectional observation of the mirror-finished film. And by polishing smoothly, the interface between the first chromium-based hard coating and the second chromium-based hard coating of the present invention has less than two droplets having a major axis of 1 μm or more straddling the interface per 50 μm. be able to. Even if the major axis is a droplet having a major axis of less than 1 μm and the major axis is 1 μm or more, the presence of about two per 50 μm is preferable because it does not significantly affect the corrosion resistance.

  Further, in addition to smoothing the surface of the first chrome-based hard coating, the negative-voltage bias voltage applied to the base material is changed during the coating period of the second chrome-based hard coating. The two chromium-based hard coatings are easily composed of different particle layers. For this reason, the corrosion path from the surface is interrupted in the middle of the second chromium-based hard coating, so that corrosion does not easily reach the first chromium-based hard coating, and the corrosion resistance is likely to be improved. In this case, the substrate side may be finer than the surface side, and conversely, the surface side may be finer than the substrate side. Further, in order to change the particle size on the surface side and the substrate side, an inclined structure in which the particle size is gradually changed from the substrate side to the surface side may be used.

In order to compare the particle layer on the substrate side and the surface side of the second chromium-based hard coating, it is preferable to observe with a scanning ion microscope (hereinafter abbreviated as SIM) in which the crystal orientation contrast is strong.
Furthermore, the average particle width of the crystal grains in contact with each other when a straight line parallel to the substrate is drawn at a position of 0.3 μm to 0.5 μm from the interface with the first chromium-based hard coating and the surface of the coating, respectively. Thereby, the particle size difference between the base material side and the surface side of the second chromium-based hard coating can be more accurately compared. The difference in the average crystal grain width is preferably 50 nm or more.

If the hardness of the second chromium-based hard coating on the surface side measured by the nanoindentation method is 30 GPa or more, it is preferable because higher wear resistance can be obtained.
Furthermore, by adjusting the coating composition and the negative bias voltage applied to the substrate, it is possible to achieve a high hardness of 35 GPa or more, which is preferable.
In the present invention, in order to prevent the indentation hardness by the nanoindentation method from being affected by the base material, the test piece is tilted by 5 degrees and mirror-polished so that the maximum indentation depth becomes 1/10 or less of the film thickness. Control and add indentation load.

  The film thickness of the first chromium-based hard film of the present invention is 1.0 to 10.0 μm, and the film thickness of the second chromium-based hard film is 1.0 to 10.0 μm. It is preferable because it is sufficiently exerted. When the first and second chromium-based hard coatings are thinner than this, it is difficult to obtain a better corrosion resistance effect. If it is thicker than this, the adhesive strength of the whole film may be lowered. Moreover, it is preferable that the film thickness of a 1st chromium-type hard film and a 2nd chromium-type hard film is comparable.

The present invention is an injection-molded part used for the formation of plastics and rubbers that require particularly corrosion resistance among coated articles (for example, screws, screw heads, check rings, seal rings, cylinders, backflow prevention rings, spacers, etc.) And / or is preferably applied to a mold because the corrosion resistance is remarkably improved.
Among these, it is preferable to apply to screws and / or screw tip parts (for example, screw heads, backflow prevention rings, seal rings, spacers, etc.) that require excellent corrosion resistance and wear resistance. In this case, it is preferable to use tool steel containing 0.6 to 1.6% of C and 4 to 16% of Cr in atomic percent in the base material.

In Example 1, the effect of the present invention was demonstrated using CrN which is a basic composition.
An arc ion plating apparatus was used as the means for coating the hard film. A schematic diagram of the film forming apparatus is shown in FIG.
The film forming chamber 2 includes a plurality of arc discharge evaporation sources 3, 4, and 5 for mounting various targets (cathodes) 1, and a substrate holder 6 for mounting the substrate 7. A rotation mechanism 8 is provided below the substrate holder 6, and the substrate 7 rotates and revolves through the substrate holder 6. And when the base material 7 opposes various targets, the film | membrane by this target is coat | covered. Note that the target used in this example was manufactured by a powder metallurgy method.

Evaporation sources 3 to 5 were equipped with a target constituting a metal component (including a semimetal) of a hard film and a Ti target for metal ion etching. A JIS-SKD11 equivalent steel material tempered to 57-60 HRC was used as the base material, and the surface was polished to have an average roughness Ra of 0.01 μm and Rz of 0.07 μm.
The substrate whose surface was polished was degreased and washed and fixed to the substrate holder 7. Then, the substrate was heated to around 500 ° C. with a heater (not shown) installed in the chamber 2 and held for 50 minutes. Next, Ar gas was introduced, a bias voltage of −500 V was applied to the substrate, and a 20 minute plasma cleaning process (Ar ion etching) was performed. Subsequently, a bias voltage of −800 V was applied to the substrate, and Ti metal ion etching was performed for about 20 minutes (including cooling after metal ion etching). Details of the coating conditions for each sample will be described below.

<Invention Sample Sample No. 1>
After ion etching of the base material, nitrogen gas is introduced, a bias voltage of −120 V is applied to the base material, and the film thickness is about 3.0 μm under the conditions of the base material temperature of 500 ° C. and the reaction gas pressure of 3.0 Pa. CrN was coated so that Then, in order to grind | polish the surface of CrN smoothly, the base material was taken out from the chamber and surface treatment was performed using the Yamato towers company aero lapping apparatus (AERO LAP YT-300). Further polishing is then performed with a 1 μm diamond paste, followed by the use of a specular shot machine SMAP-II manufactured by Kamei Iron Works, with an arithmetic average roughness Ra of 0.05 μm or less and a maximum height The thickness Rz was 1.00 μm or less.
And after performing degreasing washing | cleaning, it returned in the chamber again and coat | covered the 2nd chromium type hard membrane | film | coat. First, Ar ion etching and Ti metal ion etching are performed, nitrogen gas is introduced, a bias voltage of −180 V is applied to the substrate at the initial stage of coating, the substrate temperature is 500 ° C., and the reaction gas pressure is 3.0 Pa. And coated for 5 minutes. Thereafter, the bias voltage was changed from −180 V to −60 V over 5 minutes, and the final stage was covered with −60 V for 5 minutes to cover about 3.0 μm of CrN.

<Invention Sample Sample No. 2>
Sample No. which is an example of the present invention. 2 shows that the process up to the coating of the second chromium-based hard coating is the same as the sample No. 2. Same as 1.
In the coating of the second chromium-based hard film, first, Ar ion etching and Ti metal ion etching are performed, nitrogen gas is introduced, and at the initial stage of coating, a bias voltage of −180 V is applied to the substrate, and a substrate temperature of 500 The coating was carried out for 5 minutes under the conditions of 0 ° C. and a reaction gas pressure of 3.0 Pa. Thereafter, the bias voltage was changed from −180 V to −90 V over 5 minutes, and the final stage was coated with −90 V for 5 minutes to coat approximately 3.0 μm of CrN.

<Comparative Example Sample No. 3-5>
Sample No. which is a comparative example. Nos. 3 to 5 are sample Nos. 1 to 2 before the coating of the second chromium-based hard coating. Same as 1.
During the coating period of the second chromium-based hard film, the bias voltage was kept constant and the CrN film of about 3.0 μm was coated.

<Conventional Example No. 6-8>
Sample No. which is a conventional example. In Nos. 6 to 8, the bias voltage was kept constant at −120 V, and polishing was not performed halfway, and two types of hard coatings were continuously coated in the same furnace by about 3 μm.

<Conventional Example No. 9-11>
Sample No. which is a conventional example. In Nos. 9 to 11, the bias voltage was kept constant at −120 V, and a single layer hard film was coated by about 6 μm.

  Finally, the outermost surface of each sample was smoothed by aero lapping, diamond paste polishing, and surface treatment using a specular shot machine SMAP-II manufactured by Kamei Iron Works.

  About these samples, the surface roughness measurement of the hard film, hardness, structure observation, and corrosion resistance evaluation were performed. Each evaluation test method is shown below.

(Surface roughness measurement)
According to JIS-B-0602-2001, the arithmetic average roughness Ra and the maximum height Rz were measured from the roughness curve. 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 test results.

(Hardness measurement)
The hardness of the hard coating was measured using an Elionix nanoindentation device. In order to measure the hardness of the film, the specimen was tilted by 5 degrees, and after mirror polishing, an area where the maximum indentation depth was 1/10 or less of each layer thickness within the polished surface of the film was selected. At this time, it was confirmed that there was no influence of the substrate even at about 1/5.
Ten points were measured under the measurement conditions of an indentation load of 49 mN, a maximum load holding time of 1 second, and a removal rate after loading of 0.49 mN / second, and the average value of 8 points excluding the maximum and minimum values was obtained.
The film hardness in this measurement method is easily influenced by the fine shape of the indenter, the temperature, humidity at the time of measurement, and the surface condition of the sample, and the obtained numerical values do not necessarily match the Vickers hardness. Therefore, the fused quartz which is a standard sample was measured. The film hardness of the fused quartz at that time is 11 GPa, and a relative comparison can be made based on this measurement result. Table 1 shows the test results.

(Tissue observation)
In FIG. 1, the sample No. 1 and sample No. 1 which is a comparative example which is not polished halfway. The cross-sectional observation photograph which processed 10 with the cross section polisher (CP) is shown. (In the figure, the spherical white portion is a droplet, and the black portion around the droplet is a void resulting from the droplet.)
In the chrome-based hard coating of the present invention, the interface between the first chrome-based hard coating and the second chrome-based hard coating is polished smoothly, and droplets at the interface are removed. It is confirmed that the second chromium-based hard coating is coated so as to fill the unevenness.
Sample No. polished halfway by the same polishing method. 2 to 5, sample No. Similar to 1, a smooth polished surface was confirmed. And sample no. In any of the samples 1 to 5, the number of droplets having a major axis of 1 μm or more straddling the interface between the first chromium hard coating and the second chromium hard coating was 1 or less per 50 μm.
Moreover, when the sample formed by the manufacturing method of the present invention was observed by SIM, the average width of the crystal particles was different between the base side and the surface side of the second chromium-based hard coating.

(Corrosion resistance evaluation test)
A test was performed in which a sample was immersed in a 10% aqueous sulfuric acid solution for 10, 20, and 30 hours, simulating a corrosive gas such as a halogen gas generated during actual injection molding.
The temperature of the aqueous solution was 50 ° C., and the surfaces other than the coated surface of the test piece were masked according to JIS-G-0591-2007. After immersion, the weight loss due to the corrosion was recorded, and pitting corrosion (pits) appearing on the surface was observed. The area ratio of corrosion on the test surface was evaluated by a micrograph (magnification: 8 times).
The number of pitting corrosion is determined by classifying the pitting corrosion (pits) appearing in the micrograph as a class A with a diameter of 0.8 mm or more and a class B with a size less than 0.2 to 0.8 mm. The number of meals was measured.
Moreover, the corrosion resistance was determined as follows.
◎: No pitting corrosion was observed. ○: Pitting corrosion with an area ratio of 1% or less was observed. Δ: Pitting corrosion with an area ratio exceeding 1 to 10% was observed. X: Area ratio exceeding 10%. Table 1 shows the test results.

  The surface of the film after the corrosion resistance evaluation test is shown in FIGS. 2 and 3 (in the figure, the light-colored portion confirmed to be spherical is pitting corrosion).

Sample No. which is a hard film of the present invention. 1 and 2 showed extremely excellent corrosion resistance even when the corrosion time was 30 hours.
During the coating period of the second chromium-based hard coating, the sample No. 1 with a constant negative bias voltage applied to the substrate was used. In Nos. 3 to 5, pitting corrosion was not confirmed when the corrosion time was 20 hours, and excellent corrosion resistance was shown. However, when the corrosion time was as long as 30 hours, the corrosion resistance was lowered as compared with the inventive examples.
In FIG. 2, the surface observation photograph after 30 hours of corrosion time of this invention example and a comparative example is shown. Sample No. which is an example of the present invention. 1 confirms that no pitting corrosion has occurred.
On the other hand, the conventional film No. In the case of Nos. 6 to 11, the occurrence of corrosion was extremely remarkable even when the corrosion time was 10 to 20 hours.

In Example 2, the second chromium-based hard coating was evaluated as (92Cr3Si5B) N (the numerical value is an atomic ratio).
No. of the example of the present invention. 12 to 21 and Comparative Example No. In both samples 22 and 23, the steps up to the coating of the second chromium-based hard coating were the same as the sample No. 1 in Example 1. Same as 1.
Comparative Example No. No. 24, the bias voltage applied to the substrate was kept constant at -90 V during the CrN coating period of the first chromium-based hard coating.
The surface of each sample and the first chromium-based hard coating was subjected to a surface treatment 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 the use of a specular shot machine SMAP-II manufactured by Kamei Iron Works, with an arithmetic average roughness Ra of 0.05 μm or less and a maximum height The thickness Rz was 1.00 μm or less.
No. 12-20, no. In Nos. 22 to 24, the coating conditions of the second chromium-based hard coating were the same as those in Example 1.
No. In No. 21, during the coating period of the second chromium-based hard film, the bias voltage applied to the base material was initially set to −90 V and the coating was performed for 5 minutes. Thereafter, in the middle stage, the voltage was changed to -180 V over 5 minutes, covered with -180 V for 5 minutes, and further changed to -90 V over 5 minutes. In the final stage, the film was coated at −90 V for 20 minutes, and coated at about 5 μm.
Finally, the outermost surface of each sample was smoothed by aero lapping, diamond paste polishing, and surface treatment using a specular shot machine SMAP-II manufactured by Kamei Iron Works. Table 2 shows the bias conditions and test results.

  In the coating period of the second chromium-based hard coating, sample No. of the present invention in which the negative bias voltage applied to the substrate was changed. Samples Nos. 12 to 21 are comparative sample Nos. Corrosion resistance superior to 22-24 was shown. In particular, when the negative pressure bias voltage applied to the substrate during the coating period of the second chromium-based hard coating was higher than 20 V, no pitting corrosion was confirmed even when the corrosion time was 30 hours. An observation photograph of the film surface after the corrosion resistance evaluation test is shown in FIG.

In FIG. The fracture | rupture cross-sectional observation photograph by 12 scanning electron microscopes is shown. It is confirmed that the particle layer of the second chromium-based hard coating containing Si and B is finer than that of the first chromium-based hard coating that is CrN.
And in the 2nd chromium system hard coat, since the bias voltage of the negative pressure applied to a substrate was changed during the covering period, it was confirmed that the particle layer on the surface side is finer than the substrate side. The
In FIG. 12 SIM images are shown. It is confirmed more clearly that the second chromium-based hard coating is a coarse particle layer on the base material side and a fine particle layer on the surface side compared to the fracture surface observation photograph of FIG.
Sample No. A crystal that comes into contact when a straight line parallel to the substrate is drawn at a position of 0.5 μm from the interface of the second chromium-based hard coating and the surface of the second chromium-based hard coating from the SIM image of 12 The particle width of the particles was measured. Two or more fields of view were measured. The average crystal grain width on the base material side was 148 nm, the average crystal grain width on the surface side was 77 nm, and the difference was 71 nm.
In all the samples formed by the production method of the present invention, the average width of the crystal particles was different between the base side and the surface side of the second chromium-based hard coating. In the cross-sectional observation photograph, sample No. Similar to 1, a smooth polished surface was confirmed. The number of droplets having a major axis of 1 μm or more straddling the interface between the first chromium hard coating and the second chromium hard coating was 1 or less per 50 μm.

  In FIG. 13 SIM images are shown. It is confirmed that the substrate side of the second chromium-based hard coating is fine and the surface side is a coarse particle layer.

In Example 3, the second chromium-based hard coating was evaluated as (85Cr10Mo5Si) N (the numerical value is an atomic ratio).
No. of the example of the present invention. 25, 26, and Comparative Example No. In any of the samples of No. 27, the steps up to the coating of the second chromium-based hard coating were the same as those of the sample No. 1 of Example 1. In the same manner as in No. 1, the surface of the first chromium-based hard coating was subjected to surface treatment 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 the use of a specular shot machine SMAP-II manufactured by Kamei Iron Works, with an arithmetic average roughness Ra of 0.05 μm or less and a maximum height The thickness Rz was 1.00 μm or less.
The coating conditions for the second chromium-based hard coating were the same as in Example 1.
Finally, the outermost surface of each sample was smoothed by aero lapping, diamond paste polishing, and surface treatment using a specular shot machine SMAP-II manufactured by Kamei Iron Works. Table 3 shows the bias conditions and test results.

  In the coating period of the second chromium-based hard coating, sample No. of the present invention in which the negative bias voltage applied to the substrate was changed. Nos. 25 and 26 are sample Nos. Of comparative examples in which bias voltage is not changed. Corrosion resistance superior to 27 was exhibited. An observation photograph of the film surface after the corrosion resistance evaluation test is shown in FIG.

In FIG. 25 SIM images are shown. It is confirmed that the substrate side of the second chromium-based hard coating is fine and the surface side is a coarse particle layer.
In all the samples formed by the production method of the present invention, the average width of the crystal particles was different between the base side and the surface side of the second chromium hard coating. In the cross-sectional observation photograph, sample No. Similar to 1, a smooth polished surface was confirmed. The number of droplets having a major axis of 1 μm or more straddling the interface between the first chromium hard coating and the second chromium hard coating was 1 or less per 50 μm.

  In the present invention, in addition to molds and tools for molding plastics and rubber, and injection molding parts, for example, a film component is adjusted to provide release properties from a molding material. It can be applied to metal injection molding dies and various machine parts.

1, target 2, film formation chamber 3, evaporation source 4, evaporation source 5, evaporation source 6, base material holder 7, base material 8, rotation mechanism

Claims (15)

A method of manufacturing a coated article in which a base film surface of an article is coated with a hard film by a physical vapor deposition method, wherein the hard film includes at least two of a first chromium-based hard film and a second chromium-based hard film directly thereon. Consisting of more layers,
Before coating the second chromium-based hard coating, the surface of the first chromium-based hard coating is polished, and during the coating period of the second chromium-based hard coating, a negative pressure applied to the substrate is applied. A method for producing a coated article excellent in corrosion resistance, characterized by changing a bias voltage.   The method for producing a coated article excellent in corrosion resistance according to claim 1, wherein the bias voltage of the negative pressure applied to the substrate is varied between the initial stage and the final stage during the coating period of the second chromium-based hard film.   Before coating with the second chromium-based hard coating, the surface of the first chromium-based hard coating is polished so that the arithmetic average roughness Ra is 0.05 μm or less and the maximum height Rz is 1.00 μm or less. The manufacturing method of the coated article of Claim 1 or 2 characterized by these.   The coated article with excellent corrosion resistance according to any one of claims 1 to 3, wherein the bias voltage of the negative pressure applied to the substrate is changed by 10 V or more during the coating period of the second chromium-based hard coating. Manufacturing method.   5. The coated article excellent in corrosion resistance according to claim 4, wherein during the coating period of the second chromium-based hard film, the negative bias voltage applied to the substrate is varied by 10 V or more between the initial stage and the final stage. Production method.   The coated article with excellent corrosion resistance according to any one of claims 1 to 5, wherein a negative bias voltage applied to the substrate is set to be larger than 20 V during the coating period of the second chromium-based hard coating. Manufacturing method.   The first and / or second chromium-based hard coating contains one or more elements selected from Mo, Nb, W, Si, and B, respectively. A method for producing a coated article having excellent corrosion resistance as described in 1.   The first and / or second chromium-based hard coating contains at least one element selected from Mo, Nb, W, Si, and B at an atomic percentage of only a metal component (including a semimetal). The method for producing a coated article excellent in corrosion resistance according to claim 7, comprising 1 to 20%.   The surface of the second chromium-based hard coating is polished so that the arithmetic average roughness Ra is 0.05 μm or less and the maximum height Rz is 1.00 μm or less. A method for producing a coated article having excellent corrosion resistance according to claim 1.   10. The method for producing a coated article having excellent corrosion resistance according to claim 1, wherein the physical vapor deposition method is an arc ion plating method.   The method for producing a coated article excellent in corrosion resistance according to any one of claims 1 to 10, wherein the coated article is an injection molding part and / or a mold.   The method for producing a coated article excellent in corrosion resistance according to claim 11, wherein the injection molding component is a screw and / or a tip component of the screw.   The coated article formed by the manufacturing method according to any one of claims 1 to 12, wherein the hard film is composed of a first chrome-based hard film and a second chrome-based hard film coated immediately thereon. It consists of at least two layers, and the surface of the first chromium-based hard coating is polished, and the second chromium-based hard coating is composed of particle layers having different particle sizes on the substrate side and the surface side. A coated article excellent in corrosion resistance characterized by the above.   14. The coated article having excellent corrosion resistance according to claim 13, wherein the hardness of the second chromium-based hard film by the nanoindentation method is 30 GPa or more.   The film thickness of the first chromium-based hard coating is 1.0 to 10.0 µm, and the thickness of the second chromium-based hard coating is 1.0 to 10.0 µm. 14. A coated article having excellent corrosion resistance according to 14.