Alumite processing method

Abstract

To provide an alumite processing method that enables reproducible, stable gradient coloring.SOLUTION: An alumite processing method forms a first aluminum oxide film with multiple first holes on the surface of an aluminum member, adsorbs a first color into the first holes, irradiates the surface of the aluminum member with a pulse laser beam to remove the first aluminum oxide film in a first portion of the surface while leaving the first aluminum oxide film in a second portion of the surface, forms a second aluminum oxide film having multiple second holes on the surface of the aluminum member in the first portion where the first aluminum oxide film has been removed, and adsorbs a second color into the second holes. A gradation region is formed on the surface of the aluminum member, comprising multiple dot-like portions where the first aluminum oxide film has been removed and multiple dot-like portions where the first aluminum oxide film remains.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to an anodizing method. [Background technology]

[0002] The oxide film formed by electrolytic processing (anodizing) using aluminum as the anode has numerous pores measuring tens to hundreds of nanometers in size. Dyes are adsorbed into these pores to color aluminum products. However, a reproducible and stable gradation coloring technique has not yet been realized for this type of color anodizing process. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3568782 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-115901 Summary of the Invention [Problem to be solved by the invention]

[0004] Embodiments of the present invention provide an anodizing method that allows for reproducible and stable gradation coloring. [Means for solving the problem]

[0005] According to an embodiment of the present invention, an anodizing method includes a first oxidation treatment for forming a first aluminum oxide film having a plurality of first holes on a surface of an aluminum member by electrolysis; a first coloring treatment for causing the first holes to absorb a first color; a laser processing treatment for removing the first aluminum oxide film from a first portion on the surface of the aluminum member by irradiating a pulsed laser beam to expose the surface of the aluminum member at the first portion and leaving the first aluminum oxide film on a second portion on the surface of the aluminum member; and and a second coloring process for causing the second holes to absorb a second color, wherein in the laser processing, the first aluminum oxide film in the first portion is removed in the shape of a plurality of dots, and the first aluminum oxide film in the second portion is left in the shape of a plurality of dots, so that a gradation region including the plurality of dot-shaped portions where the first aluminum oxide film has been removed and the plurality of dot-shaped portions where the first aluminum oxide film has remained is formed on the surface of the aluminum member. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a flowchart of an anodizing method according to an embodiment. [Figure 2] 5(a) and 5(b) are schematic diagrams illustrating one step of the anodizing method according to the embodiment. [Figure 3] 5(a) and 5(b) are schematic diagrams illustrating one step of the anodizing method according to the embodiment. [Figure 4] FIG. 2 is a schematic diagram illustrating one step of the anodizing method according to the embodiment. [Figure 5] FIG. 3 is a waveform diagram of a pulse laser beam in a laser processing process of the anodizing method according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same elements are designated by the same reference numerals, and detailed description thereof will be omitted as appropriate. Note that the drawings are schematic, and the relationship between the thickness and width of each part, the size ratio between parts, etc., are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing.

[0008] 1, the anodizing method of the embodiment includes a first oxidation treatment S1, a first coloring treatment S2, a laser processing treatment S3, a second oxidation treatment S4, and a second coloring treatment S5. Each treatment will be described below.

[0009] <First oxidation treatment> As shown in FIG. 2(a), a first aluminum oxide film 21 is formed on the surface of an aluminum member 10 by electrolysis. Electrolysis is performed using the aluminum member 10, which is placed in an electrolytic solution (e.g., sulfuric acid or nitric acid), as an anode, to grow the first aluminum oxide film 21 on the surface of the aluminum member 10. The first aluminum oxide film 21 grows upward on the surface of the aluminum member 10 and also grows (erodes) downward on the surface of the aluminum member 10. In this anodization treatment (anodizing treatment) of the aluminum member 10, an oxidation reaction and a dissolution reaction of the oxide film in the minute recesses on the surface proceed simultaneously, forming a plurality of first holes 21a in the first aluminum oxide film 21. The thickness of the first aluminum oxide film 21 is, for example, 10 μm or more. The diameter of the first holes 21a is, for example, several tens to several hundreds of nanometers.

[0010] <First coloring process>

[0011] After the first oxidation treatment, a dye is allowed to penetrate into the first holes 21a of the first aluminum oxide film 21 to absorb the first color. Fig. 2(b) schematically shows the upper surface of the first aluminum oxide film 21 after being colored with the first color.

[0012] The dye of the first color does not easily penetrate deep into the first pores 21a and tends to be adsorbed in the area close to the opening of the first pores 21a. After the first color is adsorbed into the first pores 21a, a sealing treatment can be performed, for example, by forming a hydrate film on the opening of the first pores 21a, as needed. This can improve corrosion resistance and light resistance and make the material less susceptible to discoloration.

[0013] <Laser processing> After the first coloring treatment, a portion of the first aluminum oxide film 21 formed on the surface of the aluminum member 10 is removed by laser ablation. As shown in FIG. 3(a), a pulsed laser beam L is irradiated onto the first aluminum oxide film 21 from a laser processing device 50. The first aluminum oxide film 21 irradiated with the pulsed laser beam L is sublimated and removed from the surface of the aluminum member 10. The laser processing device 50 is, for example, a galvanometer scanner. The pulsed laser beam L is irradiated onto the first aluminum oxide film 21 multiple times while being scanned in a direction parallel to the surface of the aluminum member 10 by, for example, mirror control.

[0014] 3(b) schematically shows the surface of the aluminum member 10 after laser processing. The first aluminum oxide film 21 in the first portion 11 on the surface of the aluminum member 10 is removed, exposing the surface of the aluminum member 10 in the first portion 11. In the first portion 11, the first color applied to the first holes 21a of the first aluminum oxide film 21 is removed, exposing the surface (uncolored portion) of the aluminum member 10. The first aluminum oxide film 21 in the second portion 12 on the surface of the aluminum member 10 is left. In other words, the portion on the surface of the aluminum member 10 from which the first aluminum oxide film 21 has been removed is the first portion 11, and the portion where the first aluminum oxide film 21 remains is the second portion 12.

[0015] The first aluminum oxide film 21 in the first region 10A on the surface of the aluminum member 10 is entirely removed. The first aluminum oxide film 21 in the second region 10B on the surface of the aluminum member 10 is entirely left. Alternatively, the area of ​​the first portion 11 in the first region 10A is larger than the area of ​​the second portion 12, and the area of ​​the second portion 12 in the second region 10B is larger than the area of ​​the first portion 11.

[0016] A gradation region 10C is formed between the first region 10A and the second region 10B. In the gradation region 10C, the first portions 11 from which the first aluminum oxide film 21 has been removed are removed in the form of multiple dots, and the second portions 12 from which the first aluminum oxide film 21 remains are left in the form of multiple dots. In the gradation region 10C, the portions from which the first aluminum oxide film 21 has been removed in the form of dots (first portions 11) are mixed with the portions from which the first aluminum oxide film 21 remains in the form of dots (second portions 12). In the gradation region 10C, the first portions 11 and the second portions 12 are adjacent to each other. In the gradation region 10C, the multiple dot-shaped first portions 11 are spaced apart from each other, and the second portions 12 are located between the multiple first portions 11. In the gradation region 10C, the multiple dot-shaped second portions 12 are spaced apart from each other, and the first portions 11 are located between the multiple second portions 12. In the gradation region 10C, the first portions 11 may be in contact with each other, and the second portions 12 may be in contact with each other.

[0017] <Second oxidation treatment> After the laser processing, a second aluminum oxide film 22 is formed on the surface of the aluminum member 10 in the first portion 11 from which the first aluminum oxide film 21 has been removed, as shown in FIG. 4 . The second aluminum oxide film 22 is formed by the same electrolytic treatment as that for the first aluminum oxide film 21, and a plurality of second holes are formed in the second aluminum oxide film 22. In the second oxidation treatment, regrowth of an aluminum oxide film on the first aluminum oxide film 21 is suppressed. Therefore, the first color remains in the second portion 12, and the surface (uncolored portion) of the aluminum member 10 is exposed in the first portion 11.

[0018] <Second coloring process> After the second oxidation treatment, a second color is absorbed into the second holes of the second aluminum oxide film 22. As in the first coloring treatment, a dye is penetrated into the second holes of the second aluminum oxide film 22 to absorb the second color. The second color is a color different from the first color. The second portion 12 including the second region 10B becomes the first color, and the first portion 11 including the first region 10A becomes the second color.

[0019] In the gradation region 10C, the first color and the second color are mixed. In the gradation region 10C, the portion closer to the second region 10B has a stronger hue of the first color, and the portion closer to the first region 10A has a stronger hue of the second color. In the gradation region 10C, the hue of the first color gradually changes from the hue of the first color to the hue of the second color as it moves from the second region 10B to the first region 10A. In the laser processing described above, the difference in brightness and hue between the first color and the second color in the gradation region 10C is controlled by the removal density of the first aluminum oxide film 21 in the gradation region 10C (the density of the first portions 11). The higher the removal density of the first aluminum oxide film 21 (the density of the first portions 11), the stronger the hue of the second color.

[0020] According to this embodiment, by using the same operational settings for the laser processing device 50, it is possible to achieve a stable gradation coloring with reproducibility on the surface of the aluminum member 10.

[0021] FIG. 5 is a waveform diagram of the pulse laser light in one irradiation in the laser processing of this embodiment.

[0022] During a first period T1, the pulsed laser light rises to a maximum output and then decreases from the maximum output to a second output that is 10% to 50% of the maximum output. The second output continues during a second period T2 that follows the first period T1. The second period T2 is longer than the first period T1.

[0023] If the surface of aluminum member 10 (surface of first portion 11) after first aluminum oxide film 21 has been removed by laser processing is rough, second aluminum oxide film 22 does not grow by re-oxidation processing (second oxidation processing). By removing first aluminum oxide film 21 by irradiating it with waveform-controlled pulsed laser light as described above with reference to Figure 5, it is possible to reduce the roughness of the surface of aluminum member 10 after first aluminum oxide film 21 has been removed, and it is possible to grow second aluminum oxide film 22.

[0024] The total length of the first period T1 and the second period T2 is preferably 10 nanoseconds or more and 500 nanoseconds or less. The power density of the pulsed laser beam is 1.0 J / cm. 2 More than 200J / cm 2 The following conditions are preferable. The spot diameter of the pulsed laser light is preferably 10 μm or more and 300 μm or less. By setting these conditions, it was possible to reduce the roughness of the surface of the aluminum member 10 after removing the first aluminum oxide film 21, and to grow the second aluminum oxide film 22.

[0025] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0026] REFERENCE SIGNS LIST 10...aluminum member, 10A...first region, 10B...second region, 10C...gradation region, 11...first portion, 12...second portion, 21...first aluminum oxide film, 21a...first hole, 22...second aluminum oxide film, 50...laser processing device, L...pulse laser light

Claims

1. a first oxidation treatment for forming a first aluminum oxide film having a plurality of first holes on a surface of the aluminum member by electrolytic treatment; a first coloring process for causing the first holes to absorb a first color; a laser processing process in which the first aluminum oxide film is removed from a first portion on the surface of the aluminum member by irradiating a pulsed laser beam to expose the surface of the aluminum member at the first portion and to leave the first aluminum oxide film at a second portion on the surface of the aluminum member; a second oxidation treatment for forming, by electrolytic treatment, a second aluminum oxide film having a plurality of second holes on the surface of the aluminum member in the first portion from which the first aluminum oxide film has been removed; a second coloring process for causing the second holes to absorb a second color; Equipped with In the laser processing, the first aluminum oxide film of the first portion is removed in the form of a plurality of dots, and the first aluminum oxide film of the second portion is left in the form of a plurality of dots, so that a gradation area including a plurality of dot-shaped portions where the first aluminum oxide film has been removed and a plurality of dot-shaped portions where the first aluminum oxide film has remained is formed on the surface of the aluminum member.

2. 2. The anodizing method according to claim 1, wherein a difference in brightness and a difference in color tone between the first color and the second color are controlled by a removal density of the first aluminum oxide film in the first portion in the gradation region.

3. The pulsed laser light is In a first period, the output rises to a maximum output and then decreases from the maximum output to a second output that is 10% or more and 50% or less of the maximum output, 3. The anodizing method according to claim 1, wherein the second output continues for a second period longer than the first period.

4. The anodizing method according to claim 3 , wherein the sum of the first period and the second period is equal to or greater than 10 nanoseconds and equal to or less than 500 nanoseconds.

5. The power density of the pulsed laser light is 1.0 J / cm ２ More than 200J / cm ２ The anodizing method according to claim 3 or 4, wherein:

6. 3. The anodizing method according to claim 1, wherein the spot diameter of the pulsed laser beam is 10 μm or more and 300 μm or less.

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