KR101751377B1 - Preparing mehtod of anodizing film of alumium alloy having improved surface appearance - Google Patents

Abstract

The present invention relates to a method of manufacturing an anodized film of an aluminum alloy having improved surface appearance, and more particularly, to a method of manufacturing an anodized film of an aluminum alloy, Etching the degreased aluminum alloy surface with an etching solution containing sulfuric acid; Desmethylating the etched aluminum alloy surface with a desalting solution containing sulfuric acid; Anodizing the decomposed aluminum alloy surface by applying an electric voltage to an anodizing solution containing sulfuric acid; And sealing the anodized aluminum alloy surface with a sealing solution containing nickel acetate. The present invention also relates to a method for producing an anodized coating of an aluminum alloy with improved surface appearance.
The method of manufacturing an anodic oxidation film of an aluminum alloy improved in surface appearance according to the present invention is advantageous in that the etching of the etching solution containing sulfuric acid makes it possible to reduce the surface roughness of the aluminum alloy, The crystals can be efficiently removed or reduced, and an anodized film of a high quality aluminum alloy can be produced.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an anodized film of an aluminum alloy having improved surface appearance,

The present invention relates to a method for producing an anodized film of an aluminum alloy having an improved surface appearance by etching an aluminum alloy with an etching solution containing sulfuric acid (H ₂ SO ₄ ).

Since the specific gravity of aluminum (2.7) is about 1/3 of that of iron (7.8) or copper (8.9), effective alternatives are needed in the transportation sector such as automobile, railway, Especially, since the strength per unit weight is large, it is widely used as a structural material for precision machines and dry products.

The tensile strength of pure aluminum is not so high but when used as an aluminum alloy by adding magnesium, silicon, copper, zinc or manganese, .

Aluminum can be processed / formed into various shapes by easy plastic processing, and aluminum can form a dense and stable oxide film in the air to prevent corrosion of the aluminum alloy. The aluminum itself is not only beautiful in appearance, Surface hardness and color can be added by applying various surface treatment techniques such as anodic oxidation treatment.

In particular, when aluminum alloy is used as a material for a vacuum device, the gas release rate from the metal itself is very small and the vacuum reaching performance is very superior to other materials. Therefore, the aluminum alloy is used in various high vacuum pumps, piping, high vacuum semiconductor devices, Widely used.

Specifically, among the various aluminum alloys, the AL5000 series aluminum alloy is an attractive material that is difficult to find substitute materials in the display and semiconductor equipment industry because it has the characteristics of vacuum degree, appearance, corrosion prevention, and light weight, In the case of alloys, aluminum-magnesium (Al-Mg) series alloys show the highest strength among the non-heat treated alloys and excellent weldability.

In addition, AL5052 aluminum alloy is attracting attention in the equipment industry due to its moderate strength, excellent corrosion resistance and formability weldability. In particular, when an oxide film is formed, a homogeneous appearance quality can be obtained, Has been used.

However, the AL5052 aluminum alloy has the advantage of being able to realize a proper appearance by an appropriate strength and anodic oxidation, but functional improvement is demanded as the equipment becomes more sophisticated and larger as the generation passes.

In particular, in the case of laser-based equipment, the use of AL5083 aluminum alloy, which has the strongest strength among the 50 series of aluminum alloys among the non-heat treatment series, It is being tried.

However, in the case of AL5083 aluminum alloy, the properties such as strength are extremely excellent among the non-heat-treated alloys. However, since the rate and concentration of magnesium, which is the main component of the alloy, crystallize during casting, Batch) has a problem in that the surface pattern is varied.

Therefore, when the AL5083 aluminum alloy is treated with an anodic oxidation process of an alloy having a low magnesium content such as an existing AL5052 aluminum alloy or an aluminum alloy such as a 60 series, a cloudy surface or a stain-shaped surface quality defect may occur .

Therefore, AL5083 aluminum alloy is more resistant to bending due to stiffness and stress than AL5052 aluminum alloy, which can replace AL5052 aluminum alloy. Therefore, the anodic oxide coating of AL5083 aluminum alloy improved in surface appearance through anodization It is urgent to research and develop methods of manufacturing.

Korea Patent Publication No. 2015-0041357

An object of the present invention is to provide a method of manufacturing an anodic oxidation process of an aluminum alloy by using an etching solution containing sulfuric acid (H ₂ SO ₄ ) instead of a conventional sodium hydroxide (NaOH) solution used in an etching process, And an object of the present invention is to provide a method for manufacturing an anodic oxide film of an aluminum alloy improved in surface appearance that can reduce surface defects due to non-uniform crystallization and improve anodized appearance quality of aluminum alloy.

According to an aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: degreasing an aluminum alloy surface; Etching the degreased aluminum alloy surface with an etching solution containing sulfuric acid (H ₂ SO ₄ ); Desmethylating the etched aluminum alloy surface with a desalting solution containing sulfuric acid; Anodizing the decomposed aluminum alloy surface by applying an electric voltage to an anodizing solution containing sulfuric acid; And sealing the anodized aluminum alloy surface with a sealing solution containing nickel acetate. The present invention also provides a method for manufacturing an anodic oxide film of an aluminum alloy with improved surface appearance.

The method of manufacturing an anodic oxidation film of an aluminum alloy improved in surface appearance according to the present invention is advantageous in that the etching of the etching solution containing sulfuric acid makes it possible to reduce the surface roughness of the aluminum alloy, The crystals can be efficiently removed or reduced, and an anodized film of a high quality aluminum alloy can be produced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart showing a method for producing an anodized film of an aluminum alloy having improved surface appearance according to the present invention.
Fig. 2 is a view showing kinds of various aluminum alloys.
3 is a graph showing the characteristics of AL5083 aluminum alloy.
4 is a graph showing the characteristics of AL5083 aluminum alloy.
5 is a graph showing the characteristics of AL5083 aluminum alloy.
Fig. 6 is a graph showing the surface defects (b) after anodic oxidation of AL5083 aluminum alloy (a), AL5083 aluminum alloy, and the state after the anodic oxidation of AL5083 aluminum alloy (c).
7 is a graph showing the characteristics of AL5083 aluminum alloy.
8 is a view showing an etching principle of an aluminum alloy.
9 is a view showing the principle of formation of the aluminum anodized film.
10 is a view showing the surface of an anodized film obtained through an anodic oxidation process after AL5083 aluminum alloy is etched with an etching solution containing an aqueous solution of sodium hydroxide according to Comparative Example 1. FIG.
11 is a view showing a problem caused when AL5083 aluminum alloy is etched with an etching solution containing an aqueous solution of sodium hydroxide according to Comparative Example 1. FIG.
12 is a view showing the surface of an anodized film obtained through an anodic oxidation process after AL5083 aluminum alloy is etched with an etching solution containing an aqueous solution of sodium hydroxide according to Example 1 and Example 2. FIG.
FIG. 13 is a graph showing that the conventional problem can be solved when AL 5083 aluminum alloy is etched with an etching solution containing an aqueous solution of sodium hydroxide according to Example 1 and Example 2.

Hereinafter, the method for producing an anodized film of an aluminum alloy with improved surface appearance according to the present invention will be described in more detail.

The inventors of the present invention have conducted research and development on a method for suppressing the phenomenon that an anodic oxidation coating formed on the surface of an aluminum alloy becomes uneven in the anodic oxidation process of an aluminum alloy. However, instead of etching with an etching solution containing sodium hydroxide, The present inventors have found that an anodized film formed on the surface of an aluminum alloy can be uniformly formed to obtain a high quality anodized film surface.

The present invention relates to a method for manufacturing an aluminum alloy, comprising degreasing an aluminum alloy surface; Etching the degreased aluminum alloy surface with an etching solution containing sulfuric acid; Desmethylating the etched aluminum alloy surface with a desalting solution containing sulfuric acid; Anodizing the decomposed aluminum alloy surface by applying an electric voltage to an anodizing solution containing sulfuric acid; And sealing the anodized aluminum alloy surface with a sealing solution containing nickel acetate. The present invention also provides a method for manufacturing an anodic oxide film of an aluminum alloy with improved surface appearance.

Wherein the aluminum alloy contains 0.4 wt% of silicon (Si), 0.4 wt% of iron (Fe), 0.1 wt% of copper, 0.4 to 1.0 wt% of manganese (Mn), 4.0 to 4.9 wt% of magnesium (Ti): 0.15% by weight, and the remainder being aluminum and unavoidable impurities, and it is preferable that the aluminum alloy is used in an amount of 0.05 to 0.25% by weight of zinc (Zn), 0.25% But is not limited to.

[Table 1]

Specifically, the aluminum alloy is an AL5083 aluminum alloy (see Table 1 and FIG. 2) and can be anodized in the same manner as other aluminum alloys, but the alloy itself is not related to anodizing quality itself.

AL5005 aluminum alloy with a magnesium content of 0.5 wt% to 1.1 wt%, another 6xxx type aluminum alloy with a magnesium content of 1.2 wt% or less, or pure aluminum has a very high anodic oxidation quality (high-quality) It shows.

However, the magnesium content of the AL5083 aluminum alloy shows the inevitable fact that magnesium in the alloy structure is not perfectly homogenous in casting and solidification.

This is not due to the technical design of the casting but to the limited solubility of the magnesium in the solid solution (see FIG. 3).

Referring to FIG. 4, the far left shows a state in which magnesium is perfectly dissolved in the aluminum, and as a result, the solubility of magnesium is lowered as the temperature is lowered.

The red line is from a higher temperature pointing in the direction of the temperature, and you can see the line passing through P1 through P2 and past P3.

A value of at least 1 wt.% Of magnesium at the end of scale at 100 DEG C has already been achieved, and AL5083 aluminum alloy has a magnesium content of 4.0 wt.% To 4.9 wt.%.

Therefore, during the solidification process, it is not possible to prevent a part of the? -Phase from being excreted.

The AL5083 aluminum alloy shows a mixing zone in which both the perfect solution part and the β-phase conditional part are mixed together in all the structures.

These β-phases are individually invisible Al ₃ Mg ₂ These particles are clustered together during the solidification process, thereby continuously increasing the separation of the metal grain boundaries.

5, if it is assumed during run-up for anodization that such particle accumulations have a magnesium content of 33% by weight to 37% by weight, And shows different pickling behavior in comparison to structure surrounded.

Increased magnesium content causes stronger picking, which results in stronger picking attack and weaker pickling (brighter appearance). The result is a problem that leads to an optical error.

Also, referring to FIG. 6, the surface defective shape of AL5083 aluminum alloy is seen after alkaine etching.

Specifically, the magnesium content of the dark portion of the defective shape is slightly lower than that of the bright portion. When the surface of both areas is measured, it is recognized that the underneath portion of the anodizing layer at the lower part of the magnesium content is further increased by 1 to 2 μm can do. It can be seen that the lower magnesium content causes a weaker picking attack on the surface before anodizing.

Even though Al-Mg-based Al5083 aluminum alloy itself is cast in one batch, it is difficult to realize a uniform structure due to variations in aging time and distribution of additives in the alloy. Therefore, conventionally, aluminum alloy homogenization treatment induces grain boundary relaxation and re-precipitation through micro segregation. However, AL5083 aluminum alloy has a limit of material itself due to high magnesium content.

Therefore, the anodic oxidation quality of AL5083 aluminum alloy is effective by minimizing or eliminating the risk of badness by adjusting current anodization process and developing process process.

The anodic oxidation process improves the appearance quality of the aluminum alloy and artificially generates an oxide film to prevent corrosion by an intermetallic compound due to components that are necessarily added to the alloy, thereby forming a homogeneous oxide film.

In case of AL5083 aluminum alloy, magnesium content is higher than AL5052 aluminum alloy, which prevents homogeneous coating of the oxide film.

Therefore, in order to remove the crystalline and impurities contained in the AL5083 aluminum alloy such as magnesium and to homogenize the surface visual quality of the anodic oxidation, the chemical treatment agent and the concentration time in the etching process described below are adjusted to obtain the best result for the cost (See FIG. 7).

The etching may be performed by etching the degreased aluminum alloy surface with an etching solution containing 42 to 45 M (mol / l) sulfuric acid at 50 to 60 ° C for 10 to 20 minutes, but is not limited thereto.

Specifically, referring to Fig. 8, aluminum is an amphoteric metal that reacts with both acid and base. The etching process using the tendency of the metal atoms to be oxidized and become positive ions through an etching process which is a process of smoothing out the surface of aluminum using a chemical dissolution reaction is performed. Is performed in order to remove the oxides present on the surface of the aluminum alloy through an etching process and to produce a uniform surface to improve surface treatment performance and surface roughness.

The desermetting step may deselect the etched aluminum alloy surface at 18-22 ° C for 1 to 3 minutes with a desmeart solution containing 18-20 M (mol / l) sulfuric acid, But is not limited to.

The anodizing step may be performed by anodizing the decomposed aluminum alloy surface by an anodizing solution containing sulfuric acid of 18 to 20 M (mol / l) for 15 to 25 minutes by applying a voltage of 10 to 20 V But is not limited thereto.

Specifically, the anodized aluminum alloy surface is anodized for 15 to 25 minutes by applying a voltage of 10 to 20 V with an anodizing solution containing sulfuric acid of 18 to 20 M (mol / l) . The oxide formation process is shown in the following chemical formula 1.

[Chemical Formula 1]

2Al + 3H ₂ SO ₄ + 16H ₂ O ↔Al ₂ (SO ₄ ) ₃ 16H ₂ O + 3H ₂ ↑ Al ₂ O ₃ + 3H ₂ SO ₄ + 13H ₂ O

The physical properties of the anodized film produced through the above formula (1) exhibit a pore diameter of 10 to 20 nm, a microporous length of 9.4 μm, and a porosity of 15% The composition of the anodic oxide coating is composed of alumina (80 wt%), aluminum sulfate (18 wt%), and water (2 wt%) (see Fig.

The sealing may be performed by sealing the anodized aluminum alloy surface with a sealing solution containing 3 to 5 M (mol / l) of nickel acetate at 20 to 30 ° C for 15 to 25 minutes, but not limited thereto .

Hereinafter, the method for producing an anodized film of an aluminum alloy with improved surface appearance according to the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited by these examples.

< Example  1> Aluminum alloy with improved surface appearance Anodic oxidation coating  Produce

1. Degreasing Process

0.4 wt% of silicon, 0.4 wt% of iron, 0.1 wt% of copper, 0.4 to 1.0 wt% of manganese, 4.0 to 4.9 wt% of magnesium, (Product name DR-500) containing 0.25 wt% of chromium (Cr), 0.05 to 0.25 wt% of titanium (Ti) and 0.15 wt% of titanium and the balance of aluminum and inevitable impurities, (AL5083) was removed by degreasing at 25 to 30 ° C for 15 minutes, followed by washing with distilled water.

2. Etching process

The surface of the aluminum alloy (AL5083) degreased with an etching solution containing 45 M (mol / l) sulfuric acid (H ₂ SO ₄ , 98%) was etched at 55 ° C for 15 minutes and then rinsed with distilled water.

3. Decommert  fair

The aluminum alloy (AL5083) surface etched with a dissolution solution containing 18 M (mol / l) sulfuric acid (H ₂ SO ₄ , 98%) was demersatted at 20 ° C. for 2 minutes and then rinsed with distilled water .

4. Anodizing process

Aluminum alloy (AL5083), remove the daylight saving agent remaining on the surface 18 M (mol / ℓ) of sulfuric acid _{(H 2 SO 4, 98%} ) by applying a 15 V voltage to the anodizing solution containing 18 to 22 ℃ of For 20 minutes and then rinsed with distilled water.

5. Sealing process

The surface of the aluminum alloy (AL5083) was anodized and then subjected to a sealing treatment at 20 to 30 DEG C for 20 minutes with a sealing solution containing 5 M (mol / L) of nickel acetate to obtain an aluminum alloy having an oxide film of 18 to 22 mu m .

< Example  2> Aluminum alloy with improved surface appearance Anodic oxidation coating  Produce

45 M except that the cleaning sulfuric acid _{(H 2 SO 4, 98%} ) the degreased aluminum alloy with an etching solution comprising (AL5083) surface of the (mol / ℓ) to then at 60 ℃ etching for 15 minutes with distilled water, and , An aluminum alloy having an anodic oxide coating of 18 to 22 mu m was produced under the same conditions as in Example 1 above.

< Comparative Example  1>

1. Degreasing Process

0.4 wt% of silicon, 0.4 wt% of iron, 0.1 wt% of copper, 0.4 to 1.0 wt% of manganese, 4.0 to 4.9 wt% of magnesium, (Product name DR-500) containing 0.25 wt% of chromium (Cr), 0.05 to 0.25 wt% of titanium (Ti) and 0.15 wt% of titanium and the balance of aluminum and inevitable impurities, (AL5083) was removed from the aluminum alloy (AL5083) through a degreasing process at 25 to 30 DEG C for 5 to 10 minutes, followed by washing with distilled water.

2. Etching process

The surface of the aluminum alloy (AL5083) degreased with an etching solution containing 5 M (mol / l) of sodium hydroxide (NaOH, 98%) was etched at 40 to 50 ° C for 30 seconds to 3 minutes and then rinsed with distilled water .

3. Decommert  fair

35 M (mol / ℓ) of nitric acid (HNO _3, 98%) D. Sommer agent solution the aluminum alloy (AL5083) the surface at 18 to 20 ℃ for 30 seconds to 1 minute di After Summer bit distilled etched in containing the .

4. Anodizing process

Aluminum alloy (AL5083), remove the daylight saving agent remaining on the surface 18 M (mol / ℓ) of sulfuric acid _{(H 2 SO 4, 98%} ) in 18 ℃ 26 by applying a 15 V voltage to the anodizing solution containing For 30 minutes and then rinsed with distilled water.

5. Sealing process

The surface of the aluminum alloy (AL5083) was anodized and then subjected to a sealing treatment at 18 to 20 DEG C for 19 to 21 minutes in a sealing solution containing 5 M (mol / l) of nickel acetate to obtain an aluminum Alloy.

< Experimental Example 1> Aluminum  Alloy Anodic oxidation coating  Quality analysis

The quality of the surface of the anodized film of the aluminum alloy produced according to Examples 1 and 2 and Comparative Example 1 according to the present invention was analyzed.

Specifically, it was confirmed that the anodic oxide coating obtained through the anodic oxidation process after the AL5083 aluminum alloy was etched with the etching solution containing an aqueous solution of sodium hydroxide according to Comparative Example 1 was not improved in appearance defects due to the magnesium crystals (FIG. 10 Reference).

Specifically, the following chemical formula 2 represents the chemical reaction involved in the etching process of AL5083 aluminum alloy.

(2)

_{2Al + 2NaOH + H 2 O →} 2NaAlO 2 + 3H 2 or _{^{2Al + 2OH - + 6H 2 O}} → 2Al (OH) - 4 + 3H 2 → 2NaAlO 2 + 3H 2 O → 2Al (OH) 3 ↓ + 2NaOH

Referring to Formula 2, aluminum oxide and metal aluminum react with sodium hydroxide to produce sodium aluminate.

(3)

2NaOH + Al ₂ O ₃ = 2NaAlO ₂ + H ₂ O

Referring to Formula 3, aluminum is corroded while generating hydrogen gas to convert into a solution, thereby corroding the oxide film on the aluminum surface.

[Chemical Formula 4]

_{2NaOH + Al + 2H 2 O =} 2NaAlO 2 + 3H 2

Referring to the above formula (4), sodium aluminate is produced and water is produced.

[Chemical Formula 5]

2NaAlO ₂ + 3H ₂ O = 2Al (OH) ₃ ↓ + 2NaOH

Sodium hydroxide etching does not remove the phenomenon that only aluminum is melted and the alloy component remains on the surface.

Referring to FIG. 11, since an element such as magnesium is not removed in the sodium hydroxide etching process, unevenness of an oxide film is generated during anodic oxidation, thereby causing surface roughness and poor appearance. Therefore, an etching solution of AL5083 aluminum alloy having a high magnesium content It can be seen that sodium hydroxide is not suitable.

On the other hand, referring to FIG. 12, when the etching solution containing sulfuric acid was etched according to Example 1 and Example 2 according to the present invention, it was confirmed that the appearance of the anodized coating after AL5083 aluminum alloy etching was remarkably improved.

Specifically, magnesium tends to have a divalent cationization, and SO ₄ ^2- is a divalent anion, which acts to remove or reduce magnesium crystals that cause magnesium ions to bond with sulfate ions to cause surface unevenness of AL 5083 aluminum alloy It can be seen that sulfuric acid is more suitable as an etching solution of AL5083 aluminum alloy (see FIG. 13).

However, in the case of Example 2, the etching temperature was increased to higher than that in Example 1, and in this case, the etching power was improved. However, a temperature higher than a certain level caused difficulties in maintenance and deterioration of etching power. 1 and the etching solution containing sulfuric acid according to Example 2 (see FIG. 12).

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be possible to carry out various applications and modifications.

Claims (5)

Degreasing the aluminum alloy surface;
Etching the degreased aluminum alloy surface with an etching solution containing sulfuric acid;
Desmethylating the etched aluminum alloy surface with a desalting solution containing sulfuric acid;
Anodizing the decomposed aluminum alloy surface by applying an electric voltage to an anodizing solution containing sulfuric acid; And
Sealing the anodized aluminum alloy surface with a sealing solution comprising nickel acetate,
Wherein the etching comprises:
The degreased aluminum alloy surface was etched for 10 to 20 minutes at 50 to 60 DEG C with an etching solution containing 42 to 45 M (mol / l) sulfuric acid,
Wherein the deselecting comprises:
Desalting the etched aluminum alloy surface at 18-22 &lt; 0 &gt; C for 1 to 3 minutes with a desmeart solution containing 18-20 M (mol / l) sulfuric acid,
Wherein the anodizing comprises:
The depolymerized aluminum alloy surface is anodized for 15 to 25 minutes by applying a voltage of 10 to 20 V with an anodizing solution containing sulfuric acid of 18 to 20 M (mol / l)
Wherein the sealing comprises:
Characterized in that the anodized aluminum alloy surface is sealed with a sealing solution containing 3 to 5 M (mol / l) of nickel acetate at 20 to 30 DEG C for 15 to 25 minutes. A method for manufacturing an anodized film. delete delete delete delete

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