TW201522710A - Method of surface-treating aluminum alloy - Google Patents

Abstract

Disclosed is a method of surface-treating an aluminum alloy, including pretreating an aluminum alloy; immersing the pretreated aluminum alloy in an etching solution having a predetermined composition so that the surface of the aluminum alloy is etched, thus forming a transparent glossy film; subjecting the aluminum alloy having the transparent glossy film to anodic oxidation, thus forming an oxide film on the surface of the aluminum alloy; and post-treating the aluminum alloy having the oxide film.

Description

Aluminum alloy surface treatment method

The present invention relates to a surface treatment method for an aluminum alloy, and more particularly to a surface treatment method for an aluminum alloy, wherein a target material comprising an aluminum alloy is immersed in an aqueous solution in which an acidic ammonium fluoride and a boric acid are mixed to remove mechanical grinding thereof. The resulting polishing pad marks and scratches are then anodized to obtain a high gloss surface of the aluminum alloy.

Typically, the surface of the aluminum alloy subjected to rolling or extrusion processes contains rough marks, and thus the rough surface of the aluminum alloy is removed by mechanical grinding and etching.

The anodizing process (which is a metal surface treatment method) is called an alumite process. Specifically, when aluminum or aluminum alloy is immersed in a sulfuric acid, oxalic acid or chromic acid solution to facilitate anodic electrolysis, anodization occurs to form an anodized film (Al ₂ O ₃ ᆞ x H ₂ O) on the surface of aluminum. Finally, the corrosion resistance and surface hardness of the aluminum alloy can be improved.

In addition to the above-described enhancement in corrosion resistance and surface hardness of the aluminum alloy, the anodizing method allows the anodized film to be colored by absorption of the dye. Therefore, metal surface treatment has a wide range of uses.

However, with respect to conventional anodization, the surface gloss of the aluminum alloy decreases as the anodization time increases. It is difficult to ensure a high-gloss surface of an aluminum alloy even if the surface of the aluminum alloy having a low gloss is polished after anodization.

The Korean Patent Application Publication No. 10-2005-0118918, entitled "A surface treatment method of aluminum and white-board product", contains an aluminum plate immersed in acidic ammonium fluoride and calcium gluconate. Pretreatment of the mixed aqueous solution.

Further, Korean Patent No. 10-0864316, entitled "Method of chemical treatment for surface of aluminum pipe for organic photo conductor," discloses an increase in the gloss of the aluminum tube, including immersing the aluminum tube in a content of 0.001 to 0.03 wt%. The 5-20% (w/v) ammonium fluoride solution of the hydrofluoric acid additive is subjected to acid etching for 1 to 5 minutes.

However, when the acidic ammonium fluoride is used alone or in combination with an aqueous solution of calcium gluconate or hydrofluoric acid, a white film layer can be obtained but may be both opaque and dull, making it difficult to ensure high gloss of the aluminum alloy. surface.

Accordingly, the present invention bears in mind the above-mentioned problems encountered in the related art, and an object of the present invention is to provide a surface treatment method for an aluminum alloy in which scratches and polishing pad traces on the surface of an aluminum alloy are effectively treated by mechanical grinding. It is removed and a high gloss surface of the aluminum alloy is obtained regardless of the anodization time.

The object of the present invention is not limited by the above description, and other objects that are not mentioned herein will be clearly understood by those skilled in the art from the following description.

In order to accomplish the above object, an embodiment of the present invention provides a surface treatment method for an aluminum alloy, comprising: pre-treating an aluminum alloy; immersing the pre-treated aluminum alloy in an etching solution having a predetermined composition, so that the aluminum alloy is The surface is etched to form a transparent, glossy film layer; the aluminum alloy having a transparent, glossy film layer is anodized to form an oxide film on the surface of the aluminum alloy; and then the aluminum alloy having the oxide film is post-treated.

The pretreatment of the aluminum alloy preferably includes: grinding the surface of the aluminum alloy; then immersing the ground aluminum alloy to a degreasing solution having a predetermined composition to remove impurities from the surface of the aluminum alloy.

The degreasing solution is preferably prepared by mixing 1 L of water with 3 to 10% of a hydrocarbon amine ethoxylate or an alcohol ethoxylate and 3 to 10% of sulfuric acid according to the total weight thereof, and the aluminum alloy is used at 50 to 60. °C immersed in the grease solution for 3 to 10 minutes and was degreased.

The etching solution is preferably prepared by thermally dissolving 45 to 475 g of acidic ammonium fluoride in a mixed solution of 1 L of water and 1 to 9% of boric acid mixed according to the total weight thereof, and the aluminum alloy is used in the chamber. The temperature immersion is not etched in the etching solution for 1 to 10 minutes.

The formation of the oxide film is preferably carried out by immersing the aluminum alloy in a sulfuric acid electrolytic solution at 20 ° C and then applying a voltage of 14 V for 50 minutes to form an oxide film having a thickness of 20 to 22 μm.

The post-treatment of the aluminum alloy having an oxide film preferably includes: coloring and polishing the surface of the aluminum alloy having the oxide film; and sealing the colored and polished aluminum alloy.

According to the present invention, scratches and polishing pad marks generated on the surface of the aluminum alloy by mechanical grinding can be effectively removed, and a high gloss surface of the aluminum alloy can be obtained regardless of the time of anodization.

The words used in the present invention may be selected from the most well-known words at present, and some of the words mentioned in the specification of the present invention are selected by the applicant, and the detailed meaning of the words should not be limited only by the actual words used. It is understood that the terms are to be understood in the meaning of the detailed description of the invention or the meaning

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description of the technical architecture of the present invention will be made with reference to the preferred embodiments of the drawings.

In view of this, FIG. 1 illustrates an aluminum alloy surface treatment procedure in accordance with an embodiment of the present invention, and FIG. 2 schematically illustrates an aluminum alloy surface before (a) and after (b) of the third step of FIG.

As illustrated in Figures 1 and 2, the aluminum alloy surface treatment method according to an embodiment of the present invention includes pretreatment of aluminum or aluminum alloy prepared by extrusion or rolling.

In this connection, the previous treatment includes grinding the prepared aluminum alloy surface (S100), and immersing the ground aluminum alloy in a degreasing solution having a predetermined composition, thereby removing the surface of the aluminum alloy to remove the oil from the surface. Impurities here (S200).

The following is a description of these pre-processing steps (S100 and S200).

The surface grinding of the aluminum alloy (S100) is a step (S100) of mechanically grinding the prepared aluminum or aluminum alloy using various grinding agents including an oil or grease grinding agent according to any grinder method, but the present invention is not particularly affected by the present invention. Limited to this.

After the surface grinding step (S100) of the aluminum alloy, impurities or grinding agents may remain on the surface of the aluminum or aluminum alloy due to mechanical grinding. These impurities must be removed.

In order to remove any impurities or residual grinding agents, the aluminum alloy surface treatment method according to an embodiment of the present invention comprises immersing the ground aluminum or aluminum alloy in a degreasing solution having a predetermined composition, thereby removing grease. To remove impurities or residual grinding reagent (S200) on the surface of the aluminum or aluminum alloy.

In this connection, by removing the oil stains (S200) to remove impurities or residual abrasive reagents, "using a degreasing solution containing various nonionic surfactants and sulfuric acid (H ₂ SO ₄ ) to surface from aluminum or aluminum alloys. This is done by removing the impurities or residual grinding reagent.

In a preferred embodiment of the invention, the degreasing solution is prepared by mixing 1 L of water with 3 to 10% of a hydrocarbon amine ethoxylate or alcohol ethoxylate and 3 to 10% sulfuric acid in total weight.

The aluminum or aluminum alloy is immersed in the degreasing solution under various temperature and time conditions to remove impurities or residual grinding reagents. In a preferred embodiment of the invention, the aluminum or aluminum alloy is immersed in the grease removal solution at 50 to 60 ° C for 3 to 10 minutes to remove any impurities or residual grinding reagent.

Further, removing the impurities or the residual grinding agent (S200) by degreasing can be effectively carried out by applying ultrasonic waves or vibration to the aluminum or aluminum alloy immersed in the degreasing solution, or by shaking the grease solution.

At the same time, aluminum or aluminum alloys prepared by rolling or extrusion have a rough surface due to the nature of the corresponding procedure. In this connection, this imposes limitations on the rough surface removal by the mechanical grinding step (S100) and the degreasing step (S200).

Specifically, the rough surface can be removed to some extent by the mechanical grinding step (S100) and the degreasing step (S200). However, as illustrated in Figure 2, subtle abrasive pad traces or scratches may be present after the degreasing step (S200).

The surface of the aluminum or aluminum alloy containing such fine polishing pad traces or scratches is difficult to obtain a high gloss surface even if it is further subjected to anodization and polishing.

After removing the oil staining step (S200), in order to remove fine polishing pad marks or scratches from the aluminum or aluminum alloy surface, the aluminum alloy surface treatment method according to an embodiment of the present invention includes immersing the aluminum or aluminum alloy in a predetermined composition. In the etching solution, the fine polishing pad traces or scratches existing on the surface of the aluminum or aluminum alloy can be removed by etching, and at the same time, a transparent, glossy film layer as shown in FIG. 2(b) is formed (S300) ).

According to an embodiment of the present invention, the etching solution is prepared by thermally dissolving 45 to 475 g of acidic ammonium fluoride in a mixed solution of 1 L of water and 1 to 9% of boric acid mixed according to the total weight thereof.

The acidic ammonium fluoride may be any one selected from the group consisting of NH ₄ F, NH ₄ HF and NH ₄ HF ₂ , and the boric acid is preferably an orthoboric acid represented by H ₃ BO ₃ and which is colorless, transparent or bright.

The reason why the above etching solution containing acidic ammonium fluoride and boric acid is used is as follows: when a conventional etching solution containing an aqueous solution of acidic ammonium fluoride or a mixed aqueous solution of acidic ammonium fluoride and calcium gluconate or hydrofluoric acid is used, Aluminum or aluminum alloy surfaces without fine abrasive pad marks or scratches.

However, when etching the surface of an aluminum or aluminum alloy using this conventional etching solution, the surface of the aluminum or aluminum alloy may become both opaque and dull, making it difficult to obtain a high gloss surface of the surface of the aluminum or aluminum alloy. Therefore, an etching solution containing acidic ammonium fluoride and boric acid will be helpful.

Furthermore, the formation of a transparent, glossy film layer (S300) can be carried out at different temperatures or times.

In a preferred embodiment of the invention, the formation of a clear, glossy film layer (S300) can be carried out by immersing the aluminum or aluminum alloy in the etching solution for 1 to 10 minutes at room temperature (about 25 ° C).

Further, the aluminum alloy surface treatment method according to an embodiment of the present invention comprises subjecting an aluminum or aluminum alloy having a transparent, lustrous film layer to anodization to form a predetermined thickness of oxidation on the surface of the aluminum or aluminum alloy. Membrane (S400).

The formation of the oxide film (S400) can be carried out using an electrolytic solution containing a mixture of any one or two or more selected from sulfuric acid, oxalic acid or chromic acid.

In a preferred embodiment of the invention, sulfuric acid (H ₂ SO ₄ ) is used as the electrolytic solution to increase the effectiveness, transparency of the oxide film, corrosion resistance, and wear resistance. The aluminum alloy was immersed in a sulfuric acid electrolytic solution at 20 ° C and then a voltage of 14 V was applied for 50 minutes to form an oxide film of 20 to 22 μm thick.

After the oxide film formation step (S400), the aluminum alloy surface treatment method according to an embodiment of the present invention includes post-treatment of aluminum or aluminum alloy.

In this connection, the post-treatment may include coloring and polishing the surface of the aluminum alloy having an oxide film (S500), and sealing the colored and polished aluminum alloy (S600).

The aluminum or aluminum alloy can be diversified in color by coloring and polishing (S500), and the polishing process can be performed using any mechanical means, but the invention is not limited thereto.

After the step of coloring and polishing (S500), the aluminum alloy surface treatment method according to an embodiment of the present invention may include sealing aluminum or aluminum alloy (S600).

The sealing step (S600) means a procedure of sealing micropores formed on the oxide film due to anodization, thereby improving properties including corrosion resistance and the like.

The sealing step (S600) according to an embodiment of the present invention can be carried out using various sealing procedures such as hydration, metal salt sealing, and organic compound sealing.

In a preferred embodiment of the invention, the sealing step (S600) is carried out by immersing the aluminum or aluminum alloy having an oxide film in an aqueous solution of the metal salt to seal through the metal salt.

In this connection, nickel is used as the metal salt, and aluminum or aluminum alloy is immersed in an aqueous solution of the nickel salt at 60 to 80 ° C for 10 minutes to ensure a high-gloss surface of the aluminum or aluminum alloy.

According to an embodiment or a preferred embodiment of the present invention, the surface treatment method of the aluminum alloy is such that scratches and polishing pad marks on the surface of the aluminum or aluminum alloy due to mechanical grinding can be effectively removed through the above steps.

Regardless of the time of anodization, a high gloss surface of the aluminum alloy can be obtained.

While the preferred embodiment of the present invention has been disclosed and described, it will be understood that various modifications, additions and substitutions may be made without departing from the scope and spirit of the invention. Invented version

The following is a detailed description of the embodiments of the present invention in conjunction with FIGS. 1 and 2.

Referring to Figures 1 and 2, an aluminum alloy surface treatment method in accordance with an embodiment of the present invention includes pre-treatment of aluminum or aluminum alloy prepared by extrusion or rolling.

In this connection, the pretreatment process includes grinding the prepared aluminum alloy surface (S100) and immersing the ground aluminum alloy in a degreasing solution having a predetermined composition to remove residual aluminum alloy by degreasing. Impurity (S200).

These pre-processing steps (S100 and S200) are explained in detail below.

Specifically, the grinding of the surface of the aluminum alloy (S100) is a step (S100) of mechanically grinding the prepared aluminum or aluminum alloy using various grinding agents including an oil or grease polishing agent.

After the surface grinding step (S100) of the aluminum alloy, impurities or grinding agents caused by mechanical grinding may remain on the surface of the aluminum or aluminum alloy. These residual impurities are required for removal.

For the purpose of removing these impurities or residual grinding reagents, "immers the ground aluminum or aluminum alloy in a degreasing solution with a predetermined composition" so that the surface of the aluminum or aluminum alloy is degreased to remove Impurities or residual grinding reagents there.

In this connection, the removal of impurities or residual grinding reagent (S200) by degreasing can remove impurities from the surface of aluminum or aluminum alloy by using a degreasing solution including a nonionic surfactant and sulfuric acid (H ₂ SO ₄ ). Or carry out the grinding reagent.

In the present invention, the degreasing solution can be prepared by mixing 1 L of water with 6.5% of a hydrocarbon amine ethoxylate or an alcohol ethoxylate and 6.5% of sulfuric acid according to the total weight thereof.

The aluminum or aluminum alloy was immersed in the grease removal solution at 55 ° C for 6 minutes to remove impurities or residual grinding reagent.

Further, the use of degreasing to remove impurities or residual abrasive reagent (S200) can be effectively carried out by applying ultrasonic waves or vibrations to aluminum or aluminum alloy immersed in the degreasing solution, or by shaking to remove the grease solution.

At the same time, aluminum or aluminum alloys prepared by rolling or extrusion have a rough surface resulting from the nature of the corresponding procedure. In this connection, the removal of the rough surface by the mechanical grinding step (S100) and the degreasing step (S200) is limited.

Specifically, the rough surface can be removed to some extent by the mechanical grinding step (S100) and the degreasing step (S200). However, as illustrated in Figure 2(a), fine polishing pad traces or scratches may be present after the degreasing step (S200).

Even if the aluminum or aluminum alloy surface containing such fine polishing pad traces or scratches is further subjected to anodization and polishing, it is difficult to obtain a high gloss surface.

Therefore, after the degreasing step (S200), "the aluminum or aluminum alloy is immersed in an etching solution having a predetermined composition to remove fine polishing pad marks or scratches from the surface of the aluminum or aluminum alloy", so that the presence Fine polishing pad marks or scratches on the surface of the aluminum or aluminum alloy are removed by etching, and at the same time a transparent, glossy film layer as illustrated in Figure 2(b) is formed.

According to an embodiment of the present invention, the etching solution can be prepared by thermally dissolving 260 g of acidic ammonium fluoride in a mixed solution obtained by mixing 1 L of water and 5% of boric acid according to the total weight thereof.

The acidic ammonium fluoride may include NH ₄ F, and the boric acid may be an ortho-boric acid represented by H ₃ BO ₃ and being colorless transparent or lustrous.

The reason why the above etching solution containing acidic ammonium fluoride and boric acid is used is as follows: when a conventional etching solution containing an aqueous solution of acidic ammonium fluoride or a mixed aqueous solution of acidic ammonium fluoride and calcium gluconate or hydrofluoric acid is used, An aluminum or aluminum alloy surface without traces or scratches of the fine polishing pad is obtained.

However, when etching the surface of an aluminum or aluminum alloy using this conventional etching solution etching, the surface of the aluminum or aluminum alloy may become both opaque and dull, making it difficult to provide a high gloss surface of aluminum or aluminum alloy. Therefore, an etching solution containing acidic ammonium fluoride and boric acid is advantageous.

Further, the formation of the transparent glossy film layer (S300) can be carried out by immersing the aluminum or aluminum alloy in the etching solution at room temperature (25 ° C) for 5 minutes.

Next, "the aluminum or aluminum alloy having a transparent glossy film is anodized to form an oxide film having a predetermined thickness on the surface of the aluminum or aluminum alloy" (S400).

In this connection, the formation of the oxide film (S400) can be carried out using an electrolytic solution containing sulfuric acid.

The aluminum alloy was immersed in an electrolytic solution of sulfuric acid at 20 ° C, and then a voltage of 14 V was applied for 50 minutes to form an oxide film of 20 μm thick.

After the oxide film forming step (S400), post treatment of aluminum or aluminum alloy is performed.

In this connection, the post-treatment may include coloring and polishing the aluminum alloy surface (S500) having an oxide film, and sealing the colored and polished aluminum alloy (S600).

After the coloring and polishing step (S500), sealing of aluminum or aluminum alloy is performed (S600).

The sealing step (S600) is performed by sealing the metal salt by "immersing the aluminum or aluminum alloy having an oxide film in the aqueous metal salt solution".

In this connection, nickel was used as the metal salt, and aluminum or aluminum alloy was immersed in the aqueous solution of the nickel salt at 70 ° C for 10 minutes to ensure a high-gloss surface of the aluminum or aluminum alloy.

Therefore, the steps of the above-described aluminum alloy surface treatment method according to the present invention are effective for removing scratches and polishing pad traces on the surface of aluminum or aluminum alloy due to mechanical grinding.

In addition, the aluminum alloy can have a high gloss surface regardless of the time of anodization. Industry implementation

According to the present invention, the surface treatment method of the aluminum alloy can effectively remove scratches and polishing pad marks generated by mechanical grinding.

Further, regardless of the anodization time, an aluminum alloy having high gloss can be produced, and therefore the present invention has industrial applicability.

Surface grinding of S100‧‧‧ aluminum alloy
S200‧‧‧Removing surface impurities of aluminum alloy by removing grease
Surface etching of S300‧‧‧ aluminum alloy and formation of transparent glossy film
S400‧‧‧Anodic oxidation and oxide film formation
S500‧‧‧Aluminum surface coloring and polishing
Surface seal of S600‧‧‧ aluminum alloy

Figure 1 illustrates a procedure for surface treatment of an aluminum alloy in accordance with an embodiment of the present invention;

Figure 2 schematically illustrates the aluminum or aluminum alloy surface before (a) and after (b) of the third step of Figure 1.

Surface grinding of S100‧‧‧ aluminum alloy

S200‧‧‧Removing surface impurities of aluminum alloy by removing grease

Surface etching of S300‧‧‧ aluminum alloy and formation of transparent glossy film

S400‧‧‧Anodic oxidation and oxide film formation

S500‧‧‧Aluminum surface coloring and polishing

Surface seal of S600‧‧‧ aluminum alloy

Claims (6)

An aluminum alloy surface treatment method comprising: pre-treating an aluminum alloy; immersing the pre-treated aluminum alloy in an etching solution having a predetermined composition, such that a surface of the aluminum alloy is etched to form a transparent, glossy film layer; the aluminum alloy having the transparent, glossy film layer is anodized to form an oxide film on the surface of the aluminum alloy; and the aluminum having the oxide film Alloy post treatment. The method for treating an aluminum alloy surface according to claim 1, wherein the pretreatment of the aluminum alloy comprises: grinding the surface of the aluminum alloy; and immersing the ground aluminum alloy in a predetermined composition Once in the grease solution, the impurities are removed from the surface of the aluminum alloy. The method for treating an aluminum alloy surface according to claim 2, wherein the degreasing solution comprises 1 L of water and 3 to 10% of a hydrocarbon amine ethoxylate or an alcohol ethoxylate and 3 to 10% of sulfuric acid according to the total thereof. The weight is prepared by mixing, and the aluminum alloy is degreased by immersing in the degreasing solution at 50 to 60 ° C for 3 to 10 minutes. The method for surface treatment of an aluminum alloy according to claim 1, wherein the etching solution is thermally dissolved in a mixed solution of 1 to 9% of water and 1 to 9% of boric acid according to the total weight thereof. The acid ammonium fluoride is prepared, and the aluminum alloy is etched by immersing the etching solution at room temperature for 1 to 10 minutes. . The method for treating an aluminum alloy surface according to claim 1, wherein the oxide film is formed by immersing the aluminum alloy in a sulfuric acid electrolytic solution at 20 ° C and then applying a voltage of 14 V for 50 minutes to form The oxide film has a thickness of 20 to 22 μm. The method for surface treatment of an aluminum alloy according to claim 1, wherein the post-treatment of the aluminum alloy having the oxide film comprises: coloring and polishing the surface of the aluminum alloy having the oxide film; and sealing The aluminum alloy that has been colored and polished.