KR101558286B1 - Surface treating method for internal/external material by anodizing multilayer metal film, and internal/external material treated by the same - Google Patents

Abstract

The present invention relates to a surface treatment technique for an inner and outer material, and more particularly to a surface treatment method of an inner and outer material through anodization of a metal film of a multi-layered structure in which two or more multi-layered metal films are coated on the surface of an inner / And an interior and exterior material surface-treated thereby.
According to the present invention, by applying the anodic oxidation treatment technique to the surface of general aluminum and aluminum, zinc, stainless steel, magnesium, plastic and other interior and exterior materials, uniform and beautiful colors can be realized regardless of viewing angles or three- .

Description

TECHNICAL FIELD [0001] The present invention relates to a surface treatment method of an inner and outer metal material by anodizing a metal film of a multi-layer structure, and to an inner and outer surface material treated by the method.

The present invention relates to a surface treatment technique for an inner and outer material, and more particularly to a surface treatment method of an inner and outer material through anodization of a metal film of a multi-layered structure in which two or more multi-layered metal films are coated on the surface of an inner / And an interior and exterior material surface-treated thereby.

The surfaces of various products including mobile phones are required to implement various colors in terms of design. At present, color is implemented by paint painting or PVD method. However, there is a problem of scratching due to insufficient surface hardness in paint painting, and there is a problem of color difference due to thickness irregularity due to three dimensional shape in PVD method Yellow, rose gold, or black. Currently, a method of making various interference colors by applying anodic oxidation to metal materials such as titanium is widely used in the decorative industry.

Anodizing is an electrochemical film forming method, in which an anodic oxidation film is formed on the surface of a metal such as aluminum by using a solution of sulfuric acid, anhydrous acid, chromic acid, or the like as an electrolytic solution to form a film having mechanical, electrical, Means a technique for forming an excellent coating film. The film formed by such anodizing treatment is extremely hard, has high corrosion resistance and can be dyed in various colors. Accordingly, it is used in various industrial fields. Especially, in the field of product related industries such as a mobile phone case, Technology.

However, in the case of aluminum materials, only an aluminum alloy sheet is machined and then subjected to anodic oxidation. In the case of pure aluminum, the strength is insufficient. On the other hand, aluminum alloy, So that a uniform anodic oxide film can not be formed.

In addition, the machining method can be applied only in the case of simple form considering the productivity, and it is difficult to apply it to the complicated form due to the economical efficiency according to the manufacturing cost, and also a lot of efforts and cost are required for the subsequent assembling process. Accordingly, a method of vacuum-depositing aluminum on an aluminum die-casting product which is easy to mass-produce complicated shapes and anodizing the deposited aluminum has recently been developed, but there is a problem such as adhesion to a thin film of a vacuum evaporation method.

Accordingly, the present inventor has solved the adhesion problem of the vacuum evaporation method by a combination of a vacuum deposition method and an arc method through Korean Patent Laid-Open Publication No. 10-2012-0116558 (high-speed deposition apparatus and deposition method using the same, published October 22, 2012) And disclosed in Korean Patent Laid-Open Publication No. 10-2012-0116557 (a method of surface treatment of a die casting alloy and a die casting alloy material having a surface structure thereby prepared, disclosed in Oct. 23, 2012) Oxide, nitride or oxynitride has been proposed.

On the other hand, there is no problem in the method of coloring and sealing the aluminum after the anodic oxidation as described above. However, in the case of the anodic oxidation method of titanium or niobium which expresses the interference color using the refractive index of the oxide film itself, There is a problem that the colors are different depending on the angle or the colors are different depending on the shape of the product.

1, a metal layer 2 is formed on the surface of an internal and external material 1 and then anodized to form an anodized layer 3. After the light passes through these thin films, ), And depending on the thickness of the anodic oxide layer (3), which is a high-refractive-index thin film, light of a specific wavelength causes destructive interference with each other and exhibits a unique interference color. By tilting the surface of the product or adjusting the viewing angle, When the angle of incidence is changed, the effective thickness of the anodic oxide layer 3 changes, and the wavelength of the light causing the destructive interference changes. Therefore, the color of the interference is different depending on the viewing angle.

Also, since most products have a three-dimensional shape, there is a problem that different colors are expressed even if they are the same product.

Korean Patent Laid-Open Publication No. 10-2012-0116558 (High Speed Film Deposition Device and Film Deposition Method Using Same, Published on October 23, 2012) Korean Patent Laid-Open Publication No. 10-2012-0116557 (Diecasting alloy surface treatment method of die casting alloy and die casting alloy material having the surface structure thus produced, published on October 23, 2012)

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a multi-layered metal film anodizing method capable of realizing a uniform and beautiful surface color irrespective of viewing angle or three- And to provide an internal and external material surface-treated by the method.

According to an embodiment of the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of: a) forming a first metal layer (10) of a low melting point metal having a melting point of 700K or less on a surface of an inner / ; b) forming a second metal layer (30) on the first metal layer (10) with a valve metal; And c) anodizing the surface of the second metal layer (30) to form an anodized layer (31) to develop an interference color.

In the step a), the first metal layer 10 may be formed within the range of 2/3 to 2/3 of the melting point of the starting metal based on Kelvin temperature, and zinc (Zn), indium In, tin (Sn) and bismuth (Bi), or more preferably two or more alloys.

 The valve metal of the second metal layer 30 may be at least one selected from the group consisting of titanium (Ti), niobium (Nb), tantalum (Ta), zirconium (Zr), vanadium (V), tungsten Hf), aluminum (Al) and yttrium (Y), or may be two or more alloys, preferably titanium-aluminum alloy, more preferably titanium and 5 to 55 (Ti6Al4V) of titanium and 6 wt% aluminum and 4 wt% vanadium, or an alloy (Ti6Al7Nb) of titanium and 6 wt% aluminum and 7 wt% niobium.

Washing the surface of the inside / outside material (1) using an organic solvent and an ultrasonic cleaning device before the step a); Removing impurities or oxides on the surface of the inner and outer material (1) through an argon gas ion collision or a metal ion collision in a vacuum chamber; Polishing the surface of the inside / outside material (1) by performing chemical polishing, electrolytic polishing or mechanical polishing; And a step of sanding or hair-line-treating the surface of the internal and external material (1).

The barrier metal layer 20 may further include a barrier metal layer 20 between the step a) and the step b), wherein the barrier metal layer 20 is formed of a valve metal on the first metal layer 10, The valve metal is made up of a group consisting of titanium (Ti), niobium (Nb), tantalum (Ta), zirconium (Zr), vanadium (V), tungsten (W), hafnium (Hf) More preferably titanium and 5 to 55 wt% aluminum alloy, an alloy of titanium and 6 wt% aluminum and 4 wt% vanadium (Ti6Al4V) or titanium and 6 wt% aluminum (Ti6Al7Nb) of 7 wt% niobium, but is preferably made of a material different from the valve metal of the second metal layer (30).

The first metal layer 10, the barrier metal layer 20, and the second metal layer 30 may have a thickness of 0.3 to 5 탆. The first metal layer 10, the barrier metal layer 20, May be formed by physical vapor deposition (PVD), more preferably sputtering.

In order to achieve the above object, according to another embodiment of the present invention, a first metal layer 10 is formed on a surface of an inner and outer cover material 1 using a low melting point metal having a melting point of 700 K or less as a raw material metal A second metal layer 30 made of a valve metal is formed on the first metal layer 10 and the surface of the second metal layer 30 is anodized to form an anodic oxidation layer 31, The present invention provides an internal and external material surface-treated through a formed, multi-layered metal film anodization.

The method of surface treatment of an internal and external surface material through the metal film anodization of the multi-layered structure of the present invention as described above and the internal and external surface material treated by the anodic oxidation method are applied to the surface of general aluminum and aluminum, It is possible to realize various uniform and beautiful colors regardless of the viewing angle or the three-dimensional shape of the surface.

FIG. 1 is a schematic diagram showing the principle of coloring the surface by the anodic oxidation method and the problem of the prior art in which the colors are changed according to the angle of incidence of light.
FIG. 2 is a schematic diagram showing a thin film crystal structure depending on the formation temperature of a metal layer. FIG.
FIGS. 3 and 4 are schematic views showing a laminated structure of a surface treated internal and external material according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and should be construed in a sense and concept consistent with the technical idea of the present invention.

(B) forming a second metal layer (30) on the first metal layer (10); c) forming a first metal layer (10) on the surface of the inner and outer material ) Anodizing the surface of the second metal layer (30) to form an anodized layer (31). Hereinafter, the time-series steps of the present invention will be described in detail.

First, step a) is a step of forming a first metal layer 10 on the surface of the inner and outer cover material 1. The inside / outside material 1 refers to materials that can be used as an inside / outside material of a product. Examples of the material include press materials such as zinc, stainless steel, magnesium and aluminum, and die casting alloys (silicon, iron, copper, manganese, , Titanium, lead, tin, and chromium may be added), injection molded plastic, and plated plastic.

The role of the first metal layer 10 will be specifically described below. As described above, there is a problem in that when the interference color is realized through the anodization, the effective thickness of the oxide film having a high refractive index varies depending on the angle of incidence of light, i.e., the angle of view with the naked eye or the three-dimensional shape of the product, . In order to solve such a problem, a first metal layer 10 is formed between the second metal layer 30 subjected to the anodic oxidation treatment and the internal / external material 1. [

Referring to FIG. 2, when the metal thin film is formed at a temperature lower than 1/3 of the melting point of the metal to be a raw material based on the Kelvin temperature, Grows and forms an acicular shape, and many pores are formed. On the other hand, when forming at a temperature of 1/3 to 2/3 of the melting point, the thin film grows in a dense columnar form as shown in FIG. 2 (b) and has a smooth surface and is formed at a temperature of 2/3 or more of the melting point The thin film grows in an equilibrium shape as shown in FIG. 2 (c), and the surface has a uniform roughness.

As described above, when the metal film is grown in the temperature range of 2/3 to the melting point of the metal melting point of the starting material as shown in FIG. 2 (c), the surface has a uniform concavo-convex structure and a constant roughness is generated. The averaged color of the interference is expressed regardless of the dimensional shape, and uniform color can be implemented as a whole. In order to utilize this principle, the first metal layer 10 is grown on the surface of the internal and external member 1 at a temperature in the range of 2/3 to the melting point of the raw material metal melting point.

The first metal layer 10 is preferably a low melting point metal having a melting point of 700 K or less and harmless to the human body and a metal having a melting point exceeding 700 K such as aluminum (melting point: 933 K) There is a problem in that it can not be applied to a material which can not withstand such a high temperature because the forming temperature is relatively high at 622 to 933 K.

The first metal layer 10 may be formed using various low melting point metals but preferably a single metal such as zinc (melting point 629.5K), bismuth (544.5K), tin (504.9K), indium (429.6K) Or two or more of these alloys may be used. When these metals are used, the first metal layer 10 can be formed in a concavo-convex form at a temperature of 200 ° C or more in the case of zinc, at 100 ° C or more in the case of bismuth or tin, and at 25 ° C at the room temperature of indium.

When the CVD (Chemical Vapor Deposition) method is applied to form the first metal layer 10, the process temperature is usually not less than 500 ° C., which may cause problems such as deformation of the material. (Physical Vapor Deposition) method. More specifically, it is preferable to employ at least one method selected from the group consisting of vacuum evaporation, sputtering, and cathodic vacuum arc method, It is most preferable to use a sputtering method.

More preferably, before the formation of the first metal layer 10, 1) the surface of the internal / external material 1 is cleaned by using an organic solvent and an ultrasonic cleaning device to remove oil components and foreign substances remaining on the surface, 2) performing an argon gas ion collision or a metal ion collision inside the vacuum chamber to remove surface impurities or oxides, 3) performing a surface polishing operation such as chemical polishing, mechanical polishing, electrolytic polishing, or 4) The surface can be sanded or hairline treated.

In the case of manufacturing a glossy product, when the thickness of the thin film is increased, the gloss of the thin film is decreased. Therefore, before the step a), the polishing step, more specifically, chemical polishing, electrolytic polishing Or performing mechanical polishing is further preferably added. Chemical polishing refers to a process of chemically smoothing the surface of a metal by performing polish polishing without using an external current. Typically, the main raw material for chemical polishing is phosphoric acid, which forms a phosphate film. Electrolytic polishing refers to a polishing method that overcomes the limit of surface gloss formation caused by chemical polishing and electrolyzes under a predetermined condition to make a smooth surface when a higher gloss is required.

In order to achieve the required surface treatment object, the sanding is a process of polishing the surface of the undercoat with a prescribed sand paper, which is used for removing surface defects and improving smoothness and adhesion Work. A hair line is a work that is used for the purpose of improving the quality of a product by giving a hair-like line to the surface.

Next, step b) is a step of forming a second metal layer 30 on the first metal layer 10. The second metal layer 30 is a metal layer for anisotropically oxidizing the surface to develop an interference color. The raw metal of the second metal layer 30 is preferably a valve metal.

Valve metal is a metal that exhibits a valve effect. A valve effect is a phenomenon in which a current in a solution flows in a direction from a solution to a metal, whereas a flow in a solution does not flow in a direction from a metal to a solution .

Among the valve metals, titanium and niobium are used to produce various colors through the anodizing process in the decorative industry that deals with jewelry. More specifically, when these valve metals are anodized, an interference color such as blue, yellow, pink or green is developed according to an applied voltage, and an anodizing depth is controlled according to the magnitude of the applied voltage, Various colors are displayed.

According to an embodiment of the present invention, the valve metal as a raw material of the second metal layer 30 may be titanium, Ti, ), Hafnium (Hf), aluminum (Al), and yttrium (Y), or two or more alloys, and more preferably titanium-aluminum alloy.

However, in the case of zirconium, hafnium, yttrium, tungsten, vanadium, etc., the refractive index thereof is near 2.0, and since the color is not clear and the raw material price is high, it is not easy to widely use. (Ti 6 Al 4 V) of titanium and 6 wt% aluminum and 4 wt% vanadium (Ti 6 Al 4 V), or an alloy of titanium and 6 wt% aluminum and 7 wt% niobium (Ti 6 Al 7 Nb) Most preferred.

As used herein, the term "Ti6Al4V" or "Ti6Al7Nb" does not denote the stoichiometric ratio of the compound but refers to the weight ratio in the alloy. More specifically, the term " Ti6Al4N "means a titanium-aluminum-vanadium alloy containing 6 wt% of aluminum (Al) and 4 wt% of vanadium (V) based on the total weight, Refers to a titanium-aluminum-niobium alloy containing 6 wt% of aluminum (Al) and 7 wt% of niobium (Nb) based on weight.

The second metal layer 30 as described above is an outermost metal layer for forming an interference color by anodic oxidation. The formation method thereof is the same as that of the first metal layer 10 in the PVD (Physical Vapor Deposition) It is preferable to employ at least one method selected from the group consisting of vacuum evaporation, sputtering, and cathodic vacuum arc. When the adhesion of the formed product is taken into account, It is most preferable to use the method.

Next, step c) is a step of anodizing the surface of the second metal layer 30 formed in step b) to form the anodization layer 31.

The anodizing treatment, that is, the anodizing treatment, is a process of forming a film of aluminum oxide (Al ₂ O ₃ ) or the like by polarizing a metal product such as aluminum as an anode under a suitable electrolytic solution under appropriate conditions. This coating is very resistant to corrosion and has a porous layer and can be dyed with various colors. Therefore, it is possible to increase the commercial value by imparting a beautiful, heavy color to the surface as well as practicality such as corrosion resistance and abrasion resistance to be.

As the anodic oxidation, any one of sulfuric acid, hydroxycarboxylic acid, chromic acid, and mixed acid thereof can be used. The anodic oxidation can be performed by controlling the thickness of the film, the kind of the anodic oxidation solution, the kind of the starting metal, And the depth of anodization is usually in the range of 300 to 400 nm.

A surface-treated inner and outer cover material 1 in which a first metal layer 10 and a second metal layer 30 are sequentially coated on the surface of the inner and outer casing 1 and an anodized layer 31 is formed by anodizing the second metal layer 30, Is shown in Fig.

The present invention may also be embodied as a method of forming a first metal layer 10 on a first metal layer 10, prior to forming a second metal layer 30 after forming a first metal layer 10, And forming a barrier metal layer 20 from the valve metal. The cross-sectional structure of the surface treated inner and outer material 1 composed of the inner and outer material 1 - first metal layer 10 - barrier metal layer 20 - second metal layer 30 - anodization layer 31 is shown in FIG. 4 have.

The role of the barrier metal layer 20 will be described in detail below. When the surface of the second metal layer 30 is anodized to realize an interference color, a plurality of pores are formed in the second metal layer 30. As a result, the anodic oxidation electrolyte comes into contact with the first metal layer 10 through the pores, and the current may be excessively flowed to melt or fuse the portion. In order to prevent this, it is difficult to avoid generation of pores even if the second metal layer 30 is coated with a dense and thick coating.

A barrier metal layer 20 made of a valve metal is formed between the first metal layer 10 and the second metal layer 30 in the same manner as the second metal layer 30 for adhesion and anodizing, Even if pores are formed up to the barrier metal layer 20 due to the difference in the reaction mechanism, the pores of the second metal layer 30 are not connected to each other, Stable anodic oxidation can be achieved without causing a phenomenon of explosion or melting due to excessive use.

In the case of the barrier metal layer 20, as in the case of the first metal layer 10 and the second metal layer 30, a PVD (Physical Vapor Deposition) method, more specifically a vacuum evaporation method, a sputtering method, Cathodic Vacuum Arc, and it is most preferable to use a sputtering method in consideration of the adhesion of the formed product.

The thickness of the first metal layer 10, the barrier metal layer 20, and the second metal layer 30 is preferably in the range of 0.3 to 5 μm. In the case of the first metal layer 10, a thickness of at least 0.3 탆 is required in order to obtain an arbitrary surface roughness of the equiaxed crystal, and if the thickness is excessively larger than 5 탆, the productivity is deteriorated. The barrier metal layer 20 or the second metal layer 30 may have a thickness of at least 0.3 탆 or more in order to realize various desired colors or to serve as the barrier metal layer 20 including a typical anodic oxidation depth (300 to 400 nm) It is preferable that the thickness is not more than 5 占 퐉 in terms of economical efficiency and productivity.

Hereinafter, embodiments of the surface treatment method of an internal and external surface material through the metal film anodization of the multilayered structure of the present invention and the inner and outer surface materials treated by the method will be described. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. shall.

The surfaces of metal interior and exterior materials such as zinc, stainless steel, magnesium and aluminum alloy are polished by buffing and then sanded or hairline is formed to eliminate gloss. After that, the surface of the workpiece was cleaned by using an organic solvent and an ultrasonic cleaning device, and an argon gas ion collision was performed by mounting the workpiece in a vacuum furnace.

A negative DC voltage and a pulsed DC voltage were applied to the material for several to several tens of volts at a few to several tens of minutes while the argon gas was introduced or the surface was cleaned while maintaining the cathodic arc discharge to remove the surface impurities and the oxide film.

The first metal layer 10 was coated with 1 탆 of zinc through sputtering at a temperature of 200 캜 or higher. Thereafter, the barrier metal layer 20 was coated with 1 m of Ti6Al4V alloy, and then the second metal layer 30 was coated with 1 m of niobium.

The anodic oxidation was carried out using an electrolyte such as citric acid or ammonium sulfate.

Depending on the applied voltage, various colors such as blue, yellow, pink, and green were developed, and there was no color variation according to the part, and the color did not change according to the viewing angle.

A Ti6Al7Nb alloy was coated on the first metal layer 10 with a thickness of 2 mu m as the second metal layer 30 without the barrier metal layer 20. [ The same anodic oxidation was applied and various colors such as blue, yellow, pink, and green were developed depending on the applied voltage. There was no color variation according to the part, and the color did not change according to the viewing angle.

The surface of the plated plastic inner and outer material (1) was washed with an alcohol and an ultrasonic cleaner. After attaching the material to the vacuum furnace, the first metal layer 10 was coated with 1 μm of bismuth through sputtering at 100 ° C. or higher.

Thereafter, 1 μm of titanium was coated on the second metal layer 30, and the surface of the second metal layer 30 was anodized using citric acid or ammonium sulfate.

Depending on the applied voltage, various colors such as blue, yellow, pink, and green were developed, and there was no color variation according to the part, and the color did not change according to the viewing angle.

The present invention is not limited to the above-described specific embodiments and descriptions, and various modifications can be made to the present invention without departing from the gist of the present invention claimed in the claims. And such modifications are within the scope of protection of the present invention.

1: interior and exterior material
2: metal layer
3: Anodized layer
10: first metal layer
20: barrier metal layer
30: second metal layer
31: Anodizing layer formed by anodizing the surface of the second metal layer

Claims (25)

a) forming a first metal layer (10) with a low melting point metal having a melting point of 700 K or less on the surface of the inner and outer cover material (1) as a raw material metal;
b) forming a second metal layer (30) on the first metal layer (10) with a valve metal; And
c) anodizing the surface of the second metal layer 30 to form an anodized layer 31 to form an interference color;
/ RTI >
Wherein the first metal layer (10) and the second metal layer (30) are formed by physical vapor deposition (PVD). The method according to claim 1,
In the step (a), the first metal layer (10) is formed within the range of 2/3 to 2/3 of the melting point of the starting metal based on Kelvin temperature. To < / RTI > The method according to claim 1,
Wherein the low melting point metal is a single metal selected from the group consisting of zinc (Zn), indium (In), tin (Sn) and bismuth (Bi) To < / RTI > The method according to claim 1,
Wherein the first metal layer (10) has a thickness of 0.3 to 5 占 퐉. The method according to claim 1,
The valve metal of the second metal layer 30 may be at least one selected from the group consisting of Ti, niobium, tantalum, zirconium, vanadium, tungsten, hafnium, ), Aluminum (Al), and yttrium (Y), or a combination of two or more alloys. 6. The method of claim 5,
Wherein the valve metal of the second metal layer (30) is a titanium-aluminum alloy. The method according to claim 6,
The valve metal of the second metal layer 30 is made of an alloy of titanium and 5 to 55 wt% aluminum, an alloy of titanium and 6 wt% aluminum and 4 wt% vanadium (Ti6Al4V) or titanium, 6 wt% aluminum and 7 wt% (Ti6Al7Nb). ≪ / RTI > A method for surface treatment of an internal and external material through anodization of a metal film of a multi-layer structure. The method according to claim 1,
Prior to step a)
Cleaning the surface of the inside / outside material (1) using an organic solvent and an ultrasonic cleaning device;
Removing impurities or oxides on the surface of the inner and outer material (1) through an argon gas ion collision or a metal ion collision inside the vacuum chamber;
Polishing the surface of the inside / outside material (1) by performing chemical polishing, electrolytic polishing or mechanical polishing; And
Sanding or hair-line processing the surface of the internal and external material (1);
Wherein at least one step selected from the group consisting of anodic oxidation and oxidation is performed. The method according to claim 1,
Between the steps a) and b)
Forming a barrier metal layer (20) on the first metal layer (10) with a valve metal;
Further comprising:
Wherein the barrier metal layer (20) is formed by physical vapor deposition (PVD). 10. The method of claim 9,
The valve metal of the barrier metal layer 20 may be selected from the group consisting of titanium, niobium, tantalum, zirconium, vanadium, tungsten, hafnium, aluminum, Yttrium (Y), or two or more alloys,
Wherein the second metal layer (30) is made of a material different from the valve metal of the second metal layer (30). 11. The method of claim 10,
The valve metal of the barrier metal layer 20 is made of an alloy of titanium and 5 to 55 wt% aluminum, an alloy of titanium and 6 wt% aluminum and 4 wt% vanadium (Ti6Al4V), titanium, 6 wt% aluminum and 7 wt% niobium Alloy (Ti6Al7Nb)
Wherein the second metal layer (30) is made of a material different from the valve metal of the second metal layer (30). 10. The method of claim 9,
Wherein the barrier metal layer (20) has a thickness of 0.3 to 5 占 퐉. delete 10. The method of claim 1 or 9,
Wherein the physical vapor deposition method is a sputtering method. ≪ RTI ID = 0.0 > 11. < / RTI > A first metal layer (10) is formed on the surface of the inner and outer casing (1) with a low melting point metal having a melting point of 700 K or less as a raw material metal,
A second metal layer 30 made of a valve metal is formed on the first metal layer 10,
Wherein the surface of the second metal layer (30) is anodically oxidized to form an anodic oxidation layer (31) in which an interference color is developed. 16. The method of claim 15,
Wherein the first metal layer (10) is formed within a range of 2/3 to 2/3 of the melting point of the starting metal based on Kelvin temperature, and the inner metal material . 16. The method of claim 15,
Wherein the low melting point metal is a single metal selected from the group consisting of zinc (Zn), indium (In), tin (Sn) and bismuth (Bi) The inside and the outside of which the surface is treated. 16. The method of claim 15,
Wherein the first metal layer (10) has a thickness of 0.3 to 5 占 퐉. 16. The method of claim 15,
The valve metal of the second metal layer 30 may be at least one selected from the group consisting of titanium, niobium, tantalum, zirconium, vanadium, tungsten, hafnium, aluminum, And yttrium (Y), or two or more alloys selected from the group consisting of yttrium (Y) and zirconium (Y). 20. The method of claim 19,
Wherein the valve metal of the second metal layer (30) is a titanium-aluminum alloy. 21. The method of claim 20,
The valve metal of the second metal layer 30 is made of an alloy of titanium and 5 to 55 wt% aluminum, an alloy of titanium and 6 wt% aluminum and 4 wt% vanadium (Ti6Al4V) or titanium, 6 wt% aluminum and 7 wt% (Ti6Al7Nb). The inner and outer surfaces of the inner and outer surfaces are subjected to surface treatment through metal film anodization. 16. The method of claim 15,
Between the first metal layer 10 and the second metal layer 30,
And a barrier metal layer (20) made of a valve metal is formed on the surface of the metal film. 23. The method of claim 22,
The valve metal of the barrier metal layer 20 may be selected from the group consisting of titanium, niobium, tantalum, zirconium, vanadium, tungsten, hafnium, aluminum, Yttrium (Y), or two or more alloys,
Wherein the second metal layer (30) is made of a material different from the valve metal of the second metal layer (30). 24. The method of claim 23,
The valve metal of the barrier metal layer 20 is made of an alloy of titanium and 5 to 55 wt% aluminum, an alloy of titanium and 6 wt% aluminum and 4 wt% vanadium (Ti6Al4V), titanium, 6 wt% aluminum and 7 wt% niobium Alloy (Ti6Al7Nb)
Wherein the second metal layer (30) is made of a material different from the valve metal of the second metal layer (30). 23. The method of claim 22,
Wherein the barrier metal layer (20) has a thickness of 0.3 to 5 占 퐉.

Images