KR0171679B1 - Surface coating method of metal products - Google Patents

Abstract

The present invention relates to a method for producing a decorative color development of a metal product to create a variety of colors by using the interference effect of the transparent coating layer coated after various treatments on the metal product.

The present invention provides a transparent metal oxide interference thin film of 50-1000 nm by physical dry plating after various treatments on the surface by performing polishing, mechanical polishing, sand blasting, chemical etching, electropolishing, etc. on the surface of the metallic product having a gloss. It is characterized by various colors by evaporation. In addition, the gloss and strength are enhanced by coating a metal thin film made of the same metal under the metal oxide coating layer as a base layer.

Description

Surface coating method of metal products

The present invention relates to a method for coating a surface of a metal product having a decorative effect by coating a transparent oxide after various treatments on the metal surface, in particular, to create a variety of colors using the interference effect of the transparent metal oxide coating layer. It relates to a surface coating method of a metal product.

Even when light is incident on an apparently transparent material, part of the light is reflected by the difference in refraction before and after the interface. Therefore, when a thin and transparent film of several μm or more is coated on a highly reflective surface, the thin film becomes color due to interference, which causes mutual interference with the thin film of light reflected at the interface of the thin film and air and the light reflected at the interface of the substrate. Appears. In general, when a single layer of oxide thin film is coated on a metal surface, the light reflected at each interface is reflected with the same phase change. At this time, the two lights have different phases due to the thickness of the thin film, thereby causing interference. In actual sunlight, light in all wavelength ranges is incident simultaneously. At this time, if the thickness of the thin film corresponds to an odd multiple of 1/4 of a specific wavelength, such light disappears due to destructive interference between the two reflected waves. Therefore, the light corresponding to the complementary color of this extinguished light appears to dominate. This phenomenon is the basic principle of color development by interference.

As mentioned above, the light we deal with in everyday life comes from the sun, and it includes all light in all wavelength ranges. Therefore, if the thickness of the thin film is gradually changed, the wavelength causing the disappearance interference is changed, and thus the complementary color is also changed.

Theoretically, all seven colors that make up light are possible, but in practice, yellow, red, blue, and green are the dominant reasons for the narrow wavelength range of each light. Get up. Also, since the extinction interference of light occurs at a thickness corresponding to an odd multiple of 1/4 of the wavelength, the interference color repeatedly occurs as the thickness increases, and when the thickness becomes thicker than several μm, the interference color is overlapped by each wavelength region. Will lose. Thus, the thickness of the interfering thin film is in the range of tens to thousands of nm.

There are a wide variety of materials in conventional color coatings applied to metal products. The easiest method is to apply an organic coating film such as paint, which can easily obtain various colors, but has a disadvantage of being weak to heat and easily scratched. Especially in aquaculture machines, the use is restricted due to the harmful properties to the human body. The most widely used for aquaculture machines or other decorative coatings include precious metals such as gold and silver, or alloy coatings thereof, or titanium nitride, zirconium nitride, titanium nitride, zirconium carbide, titanium zirconium nitride, or the like to replace them. Titanium nitride, titanium carbide, hafnium nitride, chromium nitride, tungsten nitride, diamond-like carbon, and various other alloys have also been tried to develop various colors. However, these coatings have only one color in one composition and have a limit in expressing clear and bright colors. On the other hand, the color development using interference of the transparent coating layer of the metal oxide is possible to various colors of yellow, red, blue, green, and the middle tone of these tones depending on the thickness of the layer.

The coating of such an interference film can be mainly applied by a wet oxidation method, a thermal oxidation method at a high temperature after a wet treatment, or a vacuum evaporation method using heating in a vacuum.

In the case of a wet oxide film, oxidation by a reaction between a metal plate and a solution such as sulfuric acid is used. In the case of thermal oxidation, the metal is pretreated in a solution such as chromic acid and heated to a temperature of about 450-500 ° C. in air to obtain an oxide film. This method is advantageous in treating a large area steel sheet, but it uses a pollution solution and has a problem in that it is impossible to precisely or automatically control the thickness, which is an important element of the interference film. In the vacuum deposition method, a metal material is evaporated in a vacuum by resistance heating or electron beam heating, and then oxygen is injected to generate an oxide film on the steel sheet.

While this method has the advantage of forming an oxide film in a relatively short time, it is difficult to precisely control the thickness and has a rough and coarse surface of the film. On the contrary, the physical dry and plating methods represented by the magnetron sputtering, the double ion beam method, the ion beam assisted deposition method, and the like used in the present invention may be a method capable of precisely and automatically controlling the thickness of the film while having a relatively fast film forming speed.

In addition, due to the impact effect of the ions, it is characterized by obtaining a coating that is compact and hard even in a thin thickness and has excellent adhesion.

The above-described interference film can be applied to both a flat surface, a surface having a slight curvature, or a surface with a specific pattern. However, since the film is basically coated on a flat metal surface, its color is simple and it is noticeable when fingerprints are easily stained or scratched. The present invention has been devised to solve the above problems and at the same time to obtain ancillary decoration effect, the outline of which is to apply an interference coating film after various treatments to the base material. The term "treatment" refers to a frost pattern treatment (Satin treatment) such as sand blasting, chemical etching and electropolishing treatment of a desired part of a metal product. The interference film is deposited on the surface where the same pattern is formed, so that it has an effect similar to that of a pearl or mother-of-pearl. This shows the effect of two or more colors being projected at the same time by using the characteristics of the interfering film and the shape of the fine curved surface that changes color depending on the angle. The diffuse reflection of the light gives a bright and subtle color like a jewel. Meanwhile, another pretreatment process was devised and applied in order to increase the adhesion of the thin film to the base material and to obtain more beautiful color. That is, a method of specularly polishing the surface with a high temperature abrasive of 3 μm or less or coating a base layer corresponding to the raw metal of the oxide between the metal surface and the metal oxide to be coated. For example, thin layer of aluminum is applied before coating aluminum oxide on the metal surface. This method improves the adhesion of the coating layer by removing the surface microdefects or the affinity between the metal and the metal, and the affinity between the metal and the oxide thereof, while using the excellent roughness and gloss of the coated surface to obtain a glossy surface. It is characterized by obtaining the color. Since the coating layer obtained by this method basically uses the interference effect of light, it is possible to obtain a special effect of changing the color depending on the viewing angle with a clear and bright color like the color of a jewel.

In order to achieve the above-described present invention, various physical dry plating methods are possible, but in the present embodiment, magnetron sputtering, ion beam assisted deposition, and dual ion beam methods are used to manufacture metal articles such as flatware for the production of interference thin films. Partially coated decorative thin film. In more detail,

Metal products made of stainless STS 304 or 410,420 are cleaned and dried with detergent and alcohol. Either use the product as it is, or mask the specific area to expose only the part you want to decorate and install it on the product holder in the chamber. At this time, even if the base material is not heated during the deposition, a certain temperature rise occurs due to the collision of ions, so it is important to use the masking agent as having heat resistance. Such masking agents are known to include phenylated polysiloxanes. In addition, the present embodiment has devised a method using a heat resistant tape for easy masking. As a heat resistant tape for this use, a silicone type tape is suitable, and a commercially available 3M Kapton tape was obtained as this heat resistant tape. The tape was cut and removed in the same shape as the part of the product to be exposed and immediately attached to the product for use. It has been shown that there is a limit in the temperature at which the heat resistant tape withstands this method. Therefore, the product holder was used for cooling water so that the reaction occurred at 200 ° C or lower. As the target, a metal having a purity of 99% or more or an oxide thereof is used.

Preparation Example 1

The present invention is a method using magnetron sputtering so that the product holder and the target are placed facing each other and the distance is placed as close as possible to obtain a film of uniform thickness. When the base pressure of the chamber reaches 10 ^-6 Torr by operating the vacuum pump, argon gas is injected and RF bias is applied to the product holder for several minutes while maintaining the chamber pressure between 10 ^{-3 and} 10 ^-1 Torr. Ion wash the product. At the same time, a DC bias is applied to the target to remove foreign substances. At this time, close the shutter between the product holder and the target to prevent contamination of the target.

After cleaning, oxygen is injected into the chamber to create an oxidizing atmosphere. At this time, if the oxygen is too small, the transparent oxide is not formed properly, if there is too much oxygen there is a problem that the sputtering efficiency is lowered. However, in the case of aluminum oxide, Al ₂ O ₃ is the most stable compound in a wide range, and since there are few compounds having an aluminum / oxygen ratio, there is a characteristic that it is not necessary to pay much attention to the composition of the deposit. Here, stable aluminum oxide is formed when the ratio of argon to oxygen is about 20 to 1 or more. When DC power of ² to 10 W / cm ² is applied to the target in such an atmosphere, an oxide film is formed on the surface of the product by the sputtering action of argon plasma. At this time, the thickness of the deposited oxide film is substantially linearly proportional to the process time under the same conditions, and thus the process time can be adjusted to obtain an interference film having a desired color.

Example 1

The flatware made of stainless STS 304 is polished well and finally polished with alumina abrasive of 0.1 μm. Wash it with a mild detergent, rinse it with distilled water, wipe off with alcohol and dry again. Mask the machine with heat-resistant tape to expose only the part you want to decorate and mount it on the product holder in the chamber. 99.5% aluminum is used as the target.

When the base pressure of the chamber reaches 10 ^-6 Torr by injecting the vacuum pump, 110 sccm of argon gas is injected to maintain the pressure of the chamber at 10 ^-2 Torr for 5 minutes at 13.56MHz 2W / cm ² . Ion wash the product by applying power. At the same time, foreign material is removed by applying DC power of 3W / cm ^{2 to} the target. At this time, close the shutter between the product holder and the target to prevent contamination of the target.

After cleaning, 10 sccm of oxygen is injected into the chamber and magnetron sputtering is performed for a desired time by applying DC power of ⁵ W / cm ² to the target. At this time, the target serves as a negative electrode. At the end of the deposition the masking tape is removed.

As a result, various colors were obtained in the range of 150 to 800 nm in thickness of the thin film. When the thickness of the film reached a few μm or more, the interference color did not appear. The time at which each thickness was obtained varied with the working conditions, but there was no difference in the interference colors obtained for the same thickness. Representative interference colors are as follows.

When the thickness of the thin film was in the range of several μm, the color due to the interference disappeared and a transparent thin film reflecting the unique color of stainless was obtained.

The aluminum oxide thin film as described above is changed in color depending on the viewing angle due to its low refractive index. The above colors show the colors when viewed from the front. This characteristic is applied to the surface with a slight curvature or the surface with the uneven pattern, thereby giving a special pattern by the harmony of the two colors.

Example 2

Made of stainless STS 410, a well polished flatware is masked with the masking agent on the remaining parts except the desired area, followed by sand blasting and chemical etching to form frosty patterns. It is washed with a mild detergent and rinsed with distilled water, then wiped with alcohol and dried, and then mounted on the product holder in the chamber. 99.5% of aluminum oxide is used as the target.

Start the vacuum pump so that the chamber's base pressure is 10 When Torr is reached, 110 sccm of argon gas is injected to increase the pressure in the chamber. 13.56MHz 2W / cm in product holder for 5 minutes with Torr Ion wash the product by applying RF power. At the same time, the target is 3W / cm Remove foreign substances by applying DC power. At this time, close the shutter between the product holder and the target to prevent contamination of the target.

After cleaning, 10 sccm of oxygen is injected into the chamber and 5 W / cm at the target. Magnetron sputtering is performed for the desired time by applying negative DC power of. At the same time, the -100V RF bias is applied to the holder to increase the film adhesion. After the deposition is complete, the solvent is used to remove the masking agent.

The aluminum oxide film obtained by this method has a very high transparency, exhibits a refractive index of 1.6 to 1.65, and has a subtle but jewel-like color, and has a value as a decorative coating due to its relatively high strength. In addition, the color varies depending on the viewing angle due to the refractive index.

Production Example 2

This method uses dual ion beam sputtering so that the product holders are placed facing each other with the target. The main ion gun is then placed at a 45 ° angle to the plane towards the target. The auxiliary ion gun is placed at a 45 ° angle to the face towards the product holder. In this state, the target and the product holder can be rotated respectively so that the angle can be changed as needed. On the other hand, each ion gun was equipped with a neutralizer to prevent accumulation of overcharge. Start the vacuum pump so that the base pressure of the When Torr is reached, 300 ~ 1000 eV argon ion beam is applied to the product holder for several minutes to ion clean the product. In the method using the ion gun, the base material can be cleaned very effectively by using the high energy of the argon ion beam before deposition. At this time, the state of the cleaned surface is changed by adjusting the angle of 45 ~ 90 ° with respect to the ion beam. By the control thereof, the adhesion of the coating layer can be improved.

After the cleaning, argon plasma is generated on the ion gun and the target is sputtered with an ion beam of 1000 to 3000 eV. Oxygen plasma is generated in the auxiliary ion gun and applied to the holder at an energy of 60 to 500 eV. When this action reaches the stable region, the shutter is opened to begin dual ion beam deposition. In this case, the thickness of the deposited oxide film is linearly proportional to the process time under the same conditions, and thus, the interference film having a desired color can be obtained by adjusting the process time.

Example 1

A well polished cooker made of stainless STS 304 is thoroughly cleaned with a mild detergent, rinsed with distilled water, then wiped with alcohol and dried. Mask the machine with heat-resistant tape to expose only the part you want to decorate and mount it on the product holder in the chamber. 99.5% zirconium is used as the target.

Start the vacuum pump so that the chamber's base pressure is 10 When Torr is reached, 500 eV argon ion beam is applied to the product holder for 5 minutes to ion clean the product. At this time, by attaching a shutter between the product holder and the evaporation source to prevent contamination of the evaporation source.

After cleaning, the target is sputtered at 1500 eV for 5 minutes with an argon main ion gun to form a zirconium coating layer. After 5 minutes, the shutter is closed and oxygen plasma is generated with the auxiliary ion gun to irradiate the product holder with energy of 300 eV. When this action reaches the stable region, the shutter is opened to start deposition. At the end of the deposition the masking tape is removed.

As a result, various colors were obtained in the range of 150 to 800 nm in thickness of the thin film. When the thickness of the film reached a few μm or more, the interference color did not appear. The time at which each thickness was obtained varied with the working conditions, but there was no difference in the interference colors obtained for the same thickness. Representative interference colors are as follows.

When the thickness of the thin film was in the range of several μm, the color due to the interference disappeared and a transparent thin film reflecting the unique color of stainless was obtained.

Example 2

Made of stainless STS 410, the well polished flatware is masked with the masking agent on the remaining parts except the desired area, then sandblasted and the electropolishing is etched to form frosty patterns. It is washed with a mild detergent and rinsed with distilled water, then wiped with alcohol and dried, and then mounted on the product holder in the chamber. 99.5% of zirconium oxide is used as the target.

Start the vacuum pump so that the chamber's base pressure is 10 When Torr is reached, 500 eV argon ion beam is applied to the product holder for 5 minutes to ion clean the product. At this time, the shutter is closed between the product holder and the evaporation source to prevent contamination of the evaporation source.

After cleaning, the target is sputtered at 1500 eV with an argon main ion gun, and an oxygen plasma is generated with an auxiliary ion gun to irradiate the product holder with 300 eV of energy. When this action reaches a stable region, the shutter is opened to start deposition. After the deposition is complete, the solvent is used to remove the masking agent.

Preparation Example 3

This method uses ion beam assisted deposition and the product holders are placed facing each other with the evaporation source and the distance is as close as possible to obtain a film of uniform thickness. And the ion gun is placed toward the holder at an angle of 30 to 90 degrees on the line of the evaporation source and the holder. Start the vacuum pump so that the chamber's base pressure is 10 When Torr is reached, 300 ~ 1000 eV argon ion beam is applied to the product holder for several minutes to ion clean the product. In the method using the ion gun, the base material can be cleaned very effectively by using the high energy of the argon ion beam before deposition. At this time, the state of the cleaned surface is changed by adjusting the angle of 45 ~ 90 ° with respect to the ion beam. By the control thereof, the adhesion of the coating layer can be improved.

After cleaning, evaporation source is evaporated by generating electron beam using voltage of several KV to evaporation source, oxygen plasma is generated by auxiliary ion gun and irradiated toward product holder with energy of 60 ~ 500eV. Open and start secondary deposition with an ion beam. In this case, the thickness of the deposited oxide film is almost directly proportional to the process time under the same conditions, and thus the interference film having a desired color can be obtained by adjusting the process time.

Example 1

The flatware made of stainless STS 304 is well polished and then mirror polished with 0.1 μm of alumina abrasive. Wash the flatware with a mild detergent and rinse it with distilled water, then wipe off with alcohol and dry. Mask the machine with heat-resistant tape to expose only the part you want to decorate and mount it on the product holder in the chamber. 99.9% titanium is used as the evaporation source.

Start the vacuum pump so that the chamber's base pressure is 10 When Torr is reached, 500 eV argon ion beam is applied to the product holder for 5 minutes to ion clean the product. At this time, the shutter is closed between the product holder and the evaporation source to prevent contamination of the evaporation source.

After cleaning, the evaporation source generates an electron beam using a voltage of 5 kV and evaporates titanium, generates an oxygen plasma with an auxiliary ion gun and irradiates the product holder with 300 eV of energy. To start. At the end of the deposition the masking tape is removed.

As a result, various colors were obtained in the range of 150 to 800 nm in thickness of the thin film. When the thickness of the film reached a few μm or more, the interference color did not appear. The time at which each thickness was obtained varied with the working conditions, but there was no difference in the interference colors obtained for the same thickness. Representative interference colors are as follows.

When the thickness of the thin film was in the range of several μm, the color due to the interference disappeared and a transparent thin film reflecting the unique color of stainless was obtained. The titanium oxide thin film has a refractive index of about 2.6, which is very high, and due to this characteristic, there is little change in color depending on the angle at which the thin film is viewed. Therefore, such a thin film can be used when you want to exclude the color according to the angle.

Example 2

Made of stainless SUS 304, the well polished flatware is masked with the masking agent on the remaining parts except the desired area, and then sandblasted and electropolished to form frost pattern. It is washed with a mild detergent, rinsed with distilled water, then wiped with alcohol and dried again, and then mounted in the product holder in the chamber. 99.9% titanium oxide is used as the evaporation source.

Start the vacuum pump so that the chamber's base pressure is 10 When Torr is reached, 500 eV argon ion beam is applied to the product holder for 5 minutes to ion clean the product. At this time, the shutter is closed between the product holder and the evaporation source to prevent contamination of the evaporation source.

After cleaning, the evaporation source generates an electron beam using a voltage of 5 kV to evaporate titanium oxide, generates an oxygen plasma with an auxiliary ion gun, and irradiates the product holder with 300 eV of energy. To start. After the deposition is complete, the solvent is used to remove the masking agent.

Such a coating film can be applied to both a flat surface, a surface having a slight curvature, or a surface having a specific pattern. However, in order to produce a more special effect, a method of coating a film after electrolytic polishing on the base material was invented. If the desired part of the product is subjected to electropolishing treatment such as sand blasting, chemical etching, etc., and the aluminum oxide film is coated on it by the method described above, an interference film is deposited on the fine bends of the etched surface to have an effect similar to that of a mother-of-pearl. . The effect is that two or more colors are projected at the same time by using the specific shape of the interference film and the shape of the minute curved surface that changes color depending on the angle, and the diffuse reflection of the light gives a bright and subtle color like a jewel.

Claims (4)

A surface coating method of a metal product, characterized by coating a transparent oxide coating layer after the surface treatment using sand blasting, chemical etching, electrolytic polishing sequentially or repeatedly to the metal surface to be coated. The metal surface to be coated is coated with a transparent oxide coating layer consisting of a metal of the same component as the oxide under the metal oxide thin film layer. The surface coating method for a metal product according to any one of claims 1 to 3, wherein the coating layer has a thickness of 50 to 1000 nm and exhibits a decorative effect due to an interference effect of light. 4. The surface coating method of claim 3, wherein the transparent thin film is an oxide of various metals and exhibits a transmittance of 50% or more in the visible light region.