Aluminum alloy anodizing process, aluminum alloy article, and aluminum alloy anodizing solution

Abstract

The embodiment of the present application provides an aluminum alloy anodic oxidation process, an aluminum alloy product and an aluminum alloy anodic oxidation solution. The aluminum alloy anodic oxidation process comprises the following steps: providing a first oxidation solution, wherein the first oxidation solution comprises oxalic acid, sulfuric acid, hydroxyacetic acid, citric acid and water, the concentration of the oxalic acid is 30g / L-40g / L, the concentration of the sulfuric acid is 3g / L-10g / L, the concentration of the hydroxyacetic acid is 5g / L-30g / L, and the concentration of the citric acid is 10g / L-40g / L; and placing the aluminum alloy workpiece in the first oxidation solution to perform anodic oxidation. The anodic oxidation process can form a dense oxide film on the surface of the aluminum alloy workpiece, and has little influence on the brightness and luster of the high-brightness surface on the aluminum alloy workpiece.

Description

Technical Field

[0001] This application relates to the field of aluminum alloy surface treatment technology, and in particular to an aluminum alloy anodizing process, aluminum alloy products, and aluminum alloy anodizing solution. Background Technology

[0002] Aluminum alloys are widely used in industries such as electronics, building materials, transportation, and aerospace due to their lightweight, good ductility, excellent formability, and strong machinability.

[0003] In actual production, CNC drilling or mechanical polishing processes are used to process some or all areas of the surface of aluminum alloy workpieces into a high-gloss finish to improve the appearance of the aluminum alloy workpieces. After the high-gloss finish is formed, anodizing treatment is usually required to form an oxide film on the outer surface of the aluminum alloy workpiece, thereby improving the wear resistance and corrosion resistance of the aluminum alloy workpiece. However, the existing anodizing process often leads to a significant decrease in the brightness of the high-gloss finish of the aluminum alloy workpiece, resulting in a large loss of gloss. Summary of the Invention

[0004] This application provides an aluminum alloy anodizing process, aluminum alloy products, and aluminum alloy anodizing solution. The anodizing process can form a dense oxide film on the surface of aluminum alloy workpieces and has little impact on the brightness and gloss of high-gloss surfaces on aluminum alloy workpieces.

[0005] In a first aspect, embodiments of this application provide an aluminum alloy anodizing process, including:

[0006] A first oxidizing solution is provided, comprising oxalic acid, sulfuric acid, glycolic acid, citric acid, and water, wherein the concentration of oxalic acid is 30 g / L to 40 g / L, the concentration of sulfuric acid is 3 g / L to 10 g / L, the concentration of glycolic acid is 5 g / L to 30 g / L, and the concentration of citric acid is 10 g / L to 40 g / L.

[0007] The aluminum alloy workpiece is placed in the first oxidizing solution for anodizing.

[0008] In some embodiments, when the aluminum alloy workpiece is placed in the first oxidizing solution for anodizing, the temperature of the first oxidizing solution is controlled to be 25°C to 30°C, and the oxidation treatment time is 15 minutes to 40 minutes.

[0009] In some embodiments, after the aluminum alloy workpiece is placed in the first oxidizing solution for anodizing, the aluminum alloy anodizing process further includes:

[0010] A second oxidizing solution is provided, the second oxidizing solution comprising sulfuric acid, glycolic acid, adipic acid and water, wherein the concentration of sulfuric acid is 50 g / L to 100 g / L, the concentration of glycolic acid is 5 g / L to 30 g / L, and the concentration of adipic acid is 5 g / L to 20 g / L;

[0011] The aluminum alloy workpiece is placed in the second oxidizing solution for anodizing.

[0012] In some embodiments, when the aluminum alloy workpiece is placed in the second oxidizing solution for anodizing, the temperature of the second oxidizing solution is controlled to be 18°C ​​to 22°C, and the oxidation treatment time is 15 minutes to 40 minutes.

[0013] In some embodiments, after the aluminum alloy workpiece is placed in the second oxidizing solution for anodizing, the aluminum alloy anodizing process further includes: placing the aluminum alloy workpiece in a sealing solution for sealing treatment;

[0014] The sealing solution has a pH of 5.5 to 6.5, a temperature of 85°C to 95°C, and a sealing time of 20 to 50 minutes.

[0015] In some embodiments, before placing the aluminum alloy workpiece in the first oxidizing solution for anodizing, the aluminum alloy anodizing process further includes:

[0016] The aluminum alloy workpiece is mechanically polished to form a high-gloss surface;

[0017] The aluminum alloy workpiece that has undergone mechanical polishing is placed in a degreasing solution for degreasing treatment;

[0018] The degreased aluminum alloy workpiece is immersed in an acidic solution to remove impurities from its surface.

[0019] In some embodiments, before placing the aluminum alloy workpiece in the first oxidizing solution for anodizing, the aluminum alloy anodizing process further includes:

[0020] The aluminum alloy workpiece is placed in a degreasing solution for degreasing treatment;

[0021] The aluminum alloy workpiece that has undergone degreasing treatment is then subjected to chemical polishing.

[0022] The aluminum alloy workpiece that has undergone chemical polishing is immersed in an acidic solution to remove impurities from the surface of the aluminum alloy workpiece.

[0023] A third oxidizing solution is provided, wherein the concentration of sulfuric acid in the sulfuric acid aqueous solution is 180 g / L to 220 g / L; the aluminum alloy workpiece is placed in the third oxidizing solution for anodizing;

[0024] The aluminum alloy workpiece is placed in a sealing solution for sealing treatment;

[0025] A localized area of ​​the aluminum alloy workpiece is treated to remove the oxide film formed by the third oxidizing liquid on the surface of the localized area, thereby forming a high-gloss surface.

[0026] Secondly, embodiments of this application provide an aluminum alloy product, including an aluminum alloy workpiece and an oxide film disposed on the outer surface of the aluminum alloy workpiece, wherein the oxide film is obtained by anodizing the aluminum alloy workpiece using the aluminum alloy anodizing process described above.

[0027] Thirdly, embodiments of this application provide an aluminum alloy anodizing solution, comprising oxalic acid, sulfuric acid, glycolic acid, citric acid, and water, wherein the concentration of oxalic acid is 30 g / L to 40 g / L, the concentration of sulfuric acid is 3 g / L to 10 g / L, the concentration of glycolic acid is 5 g / L to 30 g / L, and the concentration of citric acid is 10 g / L to 40 g / L.

[0028] Fourthly, embodiments of this application provide an aluminum alloy anodizing solution, comprising sulfuric acid, glycolic acid, adipic acid, and water, wherein the concentration of the sulfuric acid is 50 g / L to 100 g / L, the concentration of the glycolic acid is 5 g / L to 30 g / L, and the concentration of the adipic acid is 5 g / L to 20 g / L.

[0029] The aluminum alloy anodizing process provided in this application uses a first oxidizing solution to anodize the aluminum alloy workpiece. The first oxidizing solution includes oxalic acid, sulfuric acid, glycolic acid, citric acid, and water. Oxalic acid is the main electrolyte in the first oxidizing solution. Since oxalic acid is a weak acid, its corrosive effect on the metal surface is weak, which can promote the formation of a dense oxide film on the surface of the aluminum alloy workpiece and has little impact on the brightness and gloss of the high-gloss surface of the aluminum alloy workpiece. In addition, by adding a small amount of sulfuric acid to the first oxidizing solution, on the one hand, it can help the oxalic acid enhance the conductivity of the first oxidizing solution and accelerate the formation rate of the oxide film. On the other hand, the amount of sulfuric acid added is small and will not have a strong corrosive effect on the high-gloss surface. By adding a small amount of citric acid to the first oxidizing solution, it can also enhance the conductivity of the first oxidizing solution, thereby accelerating the formation rate of the oxide film. By adding glycolic acid to the first oxidizing solution, glycolic acid can act as a corrosion inhibitor, effectively reducing the corrosive effect of sulfuric acid on the high-gloss surface and ensuring that the gloss of the high-gloss surface is not lost during the oxidation process. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a first flowchart of an aluminum alloy anodizing process provided in an embodiment of this application.

[0032] Figure 2 This is a second flowchart of the aluminum alloy anodizing process provided in an embodiment of this application. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0034] Please see Figure 1 , Figure 1 This is a first flowchart of an aluminum alloy anodizing process provided in an embodiment of this application. An embodiment of this application provides an aluminum alloy anodizing process, including:

[0035] S100 provides a first oxidizing solution, which includes oxalic acid, sulfuric acid, glycolic acid, citric acid, and water, wherein the concentration of oxalic acid is 30 g / L to 40 g / L, the concentration of sulfuric acid is 3 g / L to 10 g / L, the concentration of glycolic acid is 5 g / L to 30 g / L, and the concentration of citric acid is 10 g / L to 40 g / L.

[0036] It should be noted that since the main electrolyte in the first oxidation solution is oxalic acid, which is a weak acid, its corrosive effect on metal surfaces is relatively weak. This promotes the formation of a dense oxide film on the surface of aluminum alloy workpieces and has minimal impact on the brightness and gloss of the high-gloss surface. Furthermore, adding a small amount of sulfuric acid to the first oxidation solution can, on the one hand, assist oxalic acid in enhancing the conductivity of the solution and accelerating the oxide film formation rate; on the other hand, the small amount of sulfuric acid added will not have a strong corrosive effect on the high-gloss surface. Similarly, adding a small amount of citric acid to the first oxidation solution can also enhance its conductivity, thereby accelerating the oxide film formation rate. Finally, adding glycolic acid to the first oxidation solution acts as a corrosion inhibitor, effectively reducing the corrosive effect of sulfuric acid on the high-gloss surface and ensuring that the gloss of the high-gloss surface is not lost during the oxidation process.

[0037] S200 involves placing the aluminum alloy workpiece in the first oxidizing solution for anodizing.

[0038] For example, when an aluminum alloy workpiece is placed in a first oxidizing solution for anodizing, the temperature of the first oxidizing solution is controlled at 25℃~30℃ (e.g., 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, etc.), and the current density is 0.5A / dm³. 2 ~2.0A / dm 2 (e.g., 0.5A / dm) 2 1.0A / dm 2 1.5A / dm 2 2.0A / dm 2 The oxidation treatment time is 15 to 40 minutes (e.g., 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, etc.).

[0039] It should be noted that when anodizing aluminum alloy workpieces in the first oxidation solution, the Al content in the first oxidation solution needs to be controlled. 3+ The concentration is less than 5 g / L because when too many aluminum ions accumulate in the oxide solution, the conductivity of the oxide solution will decrease, affecting the growth of the oxide film. Furthermore, the transparency of the oxide film will decrease, and even local white spots or streaks and other appearance defects may appear.

[0040] For example, when placing an aluminum alloy workpiece in the first oxidizing solution for anodizing, the aluminum alloy workpiece can be clamped on a titanium alloy fixture and placed together in an anodizing tank containing the first oxidizing solution. The middle part of the copper rod (or copper bar) is connected to the titanium alloy fixture, and both ends are connected to the positive terminal of the power supply. The cathode plate is connected to the negative terminal of the power supply. Under the action of direct current, an electrochemical reaction occurs on the surface of the aluminum alloy workpiece, forming an oxide film.

[0041] For example, aluminum alloy workpieces can be structural components made from aluminum alloy materials of grade 5XXX or 6XXX (including but not limited to aluminum extrusions, coils, sheets, etc.) through processes such as stamping, CNC (Computer Numerical Control) machining, or rolling.

[0042] Please see Figure 2 , Figure 2 This is a second flowchart of an aluminum alloy anodizing process provided in an embodiment of this application. After step S200 (placing the aluminum alloy workpiece in the first oxidizing solution for anodizing), the aluminum alloy anodizing process in this embodiment of the application may further include:

[0043] S300 provides a second oxidizing solution, which includes sulfuric acid, glycolic acid, adipic acid, and water, wherein the concentration of sulfuric acid is 50 g / L to 100 g / L, the concentration of glycolic acid is 5 g / L to 30 g / L, and the concentration of adipic acid is 5 g / L to 20 g / L.

[0044] It should be noted that, in this embodiment, by placing the aluminum alloy workpiece in a first anodizing solution for anodizing and then placing it in a second anodizing solution for anodizing, the thickness of the oxide film on the surface of the aluminum alloy workpiece can be further increased, and the color of the oxide film on the surface of the aluminum alloy workpiece can be gradually changed from light golden yellow (first anodizing) to silver (second anodizing). The second anodizing solution uses sulfuric acid as the main electrolyte and adipic acid as the auxiliary electrolyte. During the oxidation process of the aluminum alloy workpiece using the second anodizing solution, the strong conductivity of sulfuric acid further increases the thickness of the oxide film on the surface of the aluminum alloy workpiece; and because adipic acid is a weak acid, it can react with aluminum ions (Al2O3) on the surface of the oxide film. 3+ The generation of weak acid salts effectively inhibits the strong dissolving effect of sulfuric acid on the oxide film and aluminum alloy, avoids a significant increase in the porosity and defects on the oxide film surface, and ensures the smoothness and mirror effect of the oxide film surface. By adding glycolic acid to the second oxidation solution, glycolic acid can act as a corrosion inhibitor, effectively weakening the corrosive effect of sulfuric acid on the high-gloss surface and ensuring that the gloss of the high-gloss surface is not lost during the oxidation process.

[0045] S400 involves placing the aluminum alloy workpiece in a second oxidizing solution for anodizing.

[0046] For example, when an aluminum alloy workpiece is placed in a second oxidizing solution for anodizing, the temperature of the second oxidizing solution is controlled at 18℃~22℃ (e.g., 18℃, 19℃, 20℃, 21℃, 22℃, etc.), and the current density is 0.5A / dm³. 2 ~2.0A / dm 2 (e.g., 0.5A / dm) 2 1.0A / dm 2 1.5A / dm 2 2.0A / dm 2 The oxidation treatment time is 15 to 40 minutes (e.g., 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, etc.).

[0047] It should be noted that when anodizing aluminum alloy workpieces in a second oxide solution, the Al content in the second oxide solution needs to be controlled. 3+The concentration is less than 5 g / L because when too many aluminum ions accumulate in the oxide solution, the conductivity of the oxide solution will decrease, affecting the growth of the oxide film. Furthermore, the transparency of the oxide film will decrease, and even local white spots or streaks and other appearance defects may appear.

[0048] For example, when placing an aluminum alloy workpiece in a second oxidizing solution for anodizing, the aluminum alloy workpiece can be clamped on a titanium alloy fixture and placed together in an anodizing tank containing the second oxidizing solution. The middle part of the copper rod (or copper bar) is connected to the titanium alloy fixture, and both ends are connected to the positive terminal of the power supply. The cathode plate is connected to the negative terminal of the power supply. Under the action of direct current, an electrochemical reaction occurs on the surface of the aluminum alloy workpiece, forming an oxide film.

[0049] For example, after the aluminum alloy workpiece has undergone anodizing treatment, the aluminum alloy anodizing process of this application embodiment may further include:

[0050] S500 involves placing aluminum alloy workpieces in a sealing solution for sealing treatment.

[0051] It is understandable that after the anodizing process is completed, the oxide film formed on the surface of the aluminum alloy workpiece has a porous structure. By sealing the porous structure of the oxide film, the corrosion resistance and dirt resistance of the oxide film can be improved. When dye molecules are adsorbed in the porous structure, sealing the pores can also prevent the dye molecules from escaping from the porous structure.

[0052] For example, the sealing solution can be a sealing solution obtained by diluting commercially available R500 sealing agent (Yongbao Chemical Co., Ltd.) with water, wherein the concentration of R500 sealing agent in the sealing solution is 7g / L-12g / L, and the pH value of the sealing solution is 5.5-6.5.

[0053] For example, when an aluminum alloy workpiece is placed in a sealing solution for sealing treatment, the temperature of the sealing solution can be controlled at 85°C to 95°C, and the sealing treatment time can be 20 minutes to 50 minutes.

[0054] It should be noted that "after the aluminum alloy workpiece has undergone anodizing treatment" can refer to "after the aluminum alloy workpiece has been placed in the first anodizing solution for anodizing". In other words, it is not necessary to place the aluminum alloy workpiece in the second anodizing solution for anodizing. After the aluminum alloy workpiece has been placed in the first anodizing solution for anodizing, the sealing treatment can be carried out directly.

[0055] Alternatively, "after the aluminum alloy workpiece has undergone anodizing treatment" can also refer to "after the aluminum alloy workpiece has been placed in the first oxidizing solution and the second oxidizing solution for anodizing treatment in sequence". That is to say, the aluminum alloy workpiece first undergoes a first anodizing treatment in the first oxidizing solution, then undergoes a second anodizing treatment in the second oxidizing solution, and after the second anodizing treatment is completed, the hole is sealed.

[0056] In some embodiments, after the "anodization treatment of aluminum alloy workpiece" is completed and before the "sealing treatment of aluminum alloy workpiece in sealing solution", the oxide film on the surface of aluminum alloy workpiece can be dyed as needed. Specifically, after cleaning the anodized aluminum alloy workpiece with pure water, the aluminum alloy workpiece can be immersed in a water-soluble dye solution for dyeing. The dye molecules diffuse into the oxide film through the adsorption of the porous structure of the oxide film to complete the coloring.

[0057] It should be noted that after the aluminum alloy workpiece is placed in the first oxidizing solution for anodizing, the oxide film formed on the surface of the aluminum alloy workpiece is light golden yellow. If the aluminum alloy workpiece does not need to be placed in the second oxidizing solution for anodizing, and the light golden yellow color meets the product requirements, the sealing process can be performed directly. If the light golden yellow color does not meet the product requirements, the oxide film needs to be dyed to make the surface color of the aluminum alloy workpiece meet the product requirements before the sealing process is performed.

[0058] It should be noted that after the aluminum alloy workpiece undergoes anodizing treatment in the first and second anodizing solutions in sequence, the oxide film formed on the surface of the aluminum alloy workpiece is its natural color, that is, the surface of the aluminum alloy workpiece exhibits the color of the aluminum alloy material itself (silver). If the silver color meets the product requirements, the sealing treatment can be performed directly. If the silver color does not meet the product requirements, the oxide film needs to be dyed to make the surface color of the aluminum alloy workpiece meet the product requirements before the sealing treatment is performed.

[0059] For example, before placing the aluminum alloy workpiece in the first oxidizing solution for anodizing (i.e., before step S100), the aluminum alloy anodizing process of this application embodiment may further include:

[0060] S010 is used to mechanically polish aluminum alloy workpieces to create a high-gloss surface.

[0061] Mechanical polishing of aluminum alloy workpieces can create a high-gloss finish on all or part of its outer surface. For example, the surface roughness Ra of the high-gloss finish formed after mechanical polishing is less than 800 nm.

[0062] It should be noted that mechanical polishing generally refers to a surface treatment process that uses automatic, semi-automatic, or manual methods to press the workpiece against a continuously rotating polishing cloth or polishing wheel to achieve a smooth finish. Typically, the polishing cloth or wheel is pre-coated with polishing wax, or polishing wax or polishing liquid is evenly sprayed onto the polishing wheel during the process to cool and lubricate it. Mechanical polishing can create a bright, smooth mirror-like effect (i.e., a high-gloss finish) on the surface of metal workpieces.

[0063] S020 involves placing mechanically polished aluminum alloy workpieces in a degreasing solution for degreasing treatment.

[0064] Degreasing treatment of aluminum alloy workpieces can remove oil and wax stains from their surface.

[0065] For example, the degreasing solution can be a degreasing solution obtained by diluting commercially available R105 degreasing agent (Yongbao Chemical Co., Ltd.) with water, wherein the concentration of R105 degreasing agent in the degreasing solution is 30g / L-50g / L, and the pH value of the degreasing solution is 8.0-9.5.

[0066] For example, when aluminum alloy workpieces are placed in a degreasing solution for degreasing treatment, the temperature of the degreasing solution can be controlled at 40℃~50℃ (e.g., 40℃, 42℃, 44℃, 46℃, 48℃, 50℃, etc.), and the degreasing treatment time can be 3 minutes~5 minutes (e.g., 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, 5 minutes, etc.).

[0067] S030 involves immersing degreased aluminum alloy workpieces in an acidic solution to remove impurities from their surface.

[0068] For example, the acidic solution can be an aqueous solution of HNO3 with a volume concentration of 20% (v / v) to 30% (v / v); when the aluminum alloy workpiece is immersed in the acidic solution, the temperature of the acidic solution can be controlled at 15°C to 25°C (e.g., 15°C, 20°C, 25°C, etc.), and the immersion time can be controlled at 30s to 90s (e.g., 30s, 40s, 50s, 60s, 70s, 80s, 90s, etc.).

[0069] Before immersing aluminum alloy workpieces in an acidic solution, they can first be cleaned with water to remove the degreasing solution from their surface. Then, by immersing the workpieces in the acidic solution, impurities such as suspended black oxides on the surface of the workpieces can be removed, and the residual degreasing solution on the surface of the workpieces can be neutralized.

[0070] Understandably, after step S030, the aluminum alloy workpiece needs to be placed in the first oxidizing solution for anodizing treatment (i.e., performing step S100 + step S200), or the aluminum alloy workpiece needs to be anodized sequentially in the first and second oxidizing solutions (i.e., performing step S100 + step S200 + step S300 + step S400) to form an oxide film on the high-gloss surface of the aluminum alloy workpiece (i.e., the mechanically polished area), thereby improving the corrosion resistance and dirt resistance of the high-gloss surface. Since the first and second oxidizing solutions have a weak dissolving effect on the surface of the aluminum alloy workpiece, the oxide film formed on the high-gloss surface can be guaranteed to have good flatness and good mirror effect. That is to say, after the anodizing treatment with the first oxidizing solution or after the anodizing treatment with the first and second oxidizing solutions, the light loss of the high-gloss surface of the aluminum alloy workpiece is small, and it can still maintain a high brightness.

[0071] For example, before placing the aluminum alloy workpiece in the first oxidizing solution for anodizing (i.e., before step S100), the aluminum alloy anodizing process of this application embodiment may further include:

[0072] S001, the aluminum alloy workpiece is placed in a degreasing solution for degreasing treatment.

[0073] For example, when the appearance of an aluminum alloy workpiece needs to have a textured effect, a textured pattern can be formed on the outer surface of the aluminum alloy workpiece before "the aluminum alloy workpiece is placed in a degreasing solution for degreasing treatment". For example, the textured pattern can be formed on the outer surface of the aluminum alloy workpiece by wire drawing or sandblasting.

[0074] Degreasing treatment of aluminum alloy workpieces can remove oil and wax stains from their surface.

[0075] For example, the degreasing solution can be a degreasing solution obtained by diluting commercially available R105 degreasing agent (Yongbao Chemical Co., Ltd.) with water, wherein the concentration of R105 degreasing agent in the degreasing solution is 30g / L-50g / L, and the pH value of the degreasing solution is 8.0-9.5.

[0076] For example, when aluminum alloy workpieces are placed in a degreasing solution for degreasing treatment, the temperature of the degreasing solution can be controlled at 40℃~50℃ (e.g., 40℃, 42℃, 44℃, 46℃, 48℃, 50℃, etc.), and the degreasing treatment time can be 3 minutes~5 minutes (e.g., 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, 5 minutes, etc.).

[0077] S002, chemical polishing treatment is performed on aluminum alloy workpieces that have undergone degreasing.

[0078] For example, "chemical polishing of degreased aluminum alloy workpieces" may specifically include immersing the aluminum alloy workpiece in a chemical polishing solution, wherein the chemical polishing solution is an 85wt% phosphoric acid aqueous solution with a specific gravity of 1.68 g / cm³. 3 -1.72g / cm 3 During the chemical polishing process, the temperature of the chemical polishing solution needs to be controlled at 75℃-90℃, and the chemical polishing time should be 30s-120s.

[0079] It should be noted that when performing chemical polishing on aluminum alloy workpieces, the Al content in the chemical polishing solution needs to be controlled. 3+ The concentration is less than 15 g / L because when the concentration of aluminum ions in the chemical polishing solution is too high, it will reduce the polishing reaction rate of the aluminum alloy workpiece surface and prolong the chemical polishing reaction time.

[0080] It is understandable that chemical polishing of aluminum alloy workpieces can improve the overall gloss of all areas on the outer surface of the workpiece.

[0081] S003 involves immersing chemically polished aluminum alloy workpieces in an acidic solution to remove impurities from the surface of the workpieces.

[0082] For example, the acidic solution can be an aqueous solution of HNO3 with a volume concentration of 20% (v / v) to 30% (v / v). By immersing the aluminum alloy workpiece in the acidic solution, impurities such as black oxides suspended on the surface of the aluminum alloy workpiece can be removed. When immersing the aluminum alloy workpiece in the acidic solution, the temperature of the acidic solution can be controlled at 15°C to 25°C (e.g., 15°C, 20°C, 25°C, etc.), and the immersion time can be controlled at 30s to 90s (e.g., 30s, 40s, 50s, 60s, 70s, 80s, 90s, etc.).

[0083] S004, providing a third oxidizing solution, which is an aqueous solution of sulfuric acid, wherein the concentration of sulfuric acid in the aqueous solution is 180g / L to 220g / L (e.g., 180g / L, 190g / L, 200g / L, 210g / L, 220g / L, etc.); the aluminum alloy workpiece is placed in the third oxidizing solution for anodizing.

[0084] It should be noted that the third oxidizing solution is a traditional aluminum alloy anodizing solution. By placing the aluminum alloy workpiece in the third oxidizing solution for anodizing, an oxide film can be formed on the glossy surface of the aluminum alloy workpiece after chemical polishing, thereby protecting the glossy surface formed by chemical polishing.

[0085] For example, when anodizing an aluminum alloy workpiece in a third oxidizing solution, the temperature of the third oxidizing solution is controlled at 18℃~22℃ (e.g., 18℃, 19℃, 20℃, 21℃, 22℃, etc.), and the current density is 1.0A / dm³. 2 ~3.0A / dm 2 (e.g., 1.0A / dm) 2 1.5A / dm 2 2.0A / dm 2 2.5A / dm 2 3.0A / dm 2 The oxidation treatment time is 30 to 60 minutes (e.g., 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, etc.).

[0086] It should be noted that when anodizing aluminum alloy workpieces in a third oxidation solution, the Al content in the third oxidation solution needs to be controlled. 3+ The concentration is less than 10 g / L because when too many aluminum ions accumulate in the oxide solution, the conductivity of the oxide solution will decrease, affecting the growth of the oxide film. Furthermore, the transparency of the oxide film will decrease, and even local white spots or streaks and other appearance defects may appear.

[0087] For example, when placing an aluminum alloy workpiece in a third oxidizing solution for anodizing, the aluminum alloy workpiece can be clamped on a titanium alloy fixture and placed together in an anodizing tank containing the third oxidizing solution. The middle part of the copper rod (or copper bar) is connected to the titanium alloy fixture, and both ends are connected to the positive terminal of the power supply. The cathode plate is connected to the negative terminal of the power supply. Under the action of direct current, an electrochemical reaction occurs on the surface of the aluminum alloy workpiece, forming an oxide film.

[0088] S005, The aluminum alloy workpiece is placed in a sealing solution for sealing treatment.

[0089] For example, between steps S004 and S005, the oxide film on the surface of the aluminum alloy workpiece can be dyed according to the appearance color requirements of the product. Specifically, after cleaning the anodized aluminum alloy workpiece with pure water, the aluminum alloy workpiece can be immersed in a water-soluble dye solution for dyeing. The dye molecules diffuse into the oxide film through the adsorption of the porous structure of the oxide film to complete the coloring.

[0090] It is understandable that by sealing the holes of aluminum alloy workpieces, the corrosion resistance and dirt resistance of the oxide film formed on the surface of the aluminum alloy workpieces in the third oxidation solution can be improved. When dye molecules are adsorbed in the porous structure of the oxide film, the dye molecules can also be prevented from escaping from the porous structure.

[0091] For example, the sealing solution can be a sealing solution obtained by diluting commercially available R500 sealing agent (Yongbao Chemical Co., Ltd.) with water, wherein the concentration of R500 sealing agent in the sealing solution is 7g / L-12g / L, and the pH value of the sealing solution is 5.5-6.5.

[0092] For example, when an aluminum alloy workpiece is placed in a sealing solution for sealing treatment, the temperature of the sealing solution can be controlled to be 85°C to 95°C, and the sealing treatment time can be 30 minutes to 50 minutes.

[0093] S006, a localized treatment is performed on an aluminum alloy workpiece to remove the oxide film formed by the third oxidizing liquid on the surface of the localized area, resulting in a high-gloss finish.

[0094] For example, CNC drilling and cutting can be used to process localized areas such as the side edges and corners of an aluminum alloy workpiece, removing the oxide film in these areas to obtain a high-gloss surface with a mirror effect. At this point, most of the surface of the aluminum alloy workpiece is a glossy surface formed by chemical polishing, and this glossy surface undergoes anodizing treatment with a third oxide solution. The localized areas of the aluminum alloy workpiece surface (i.e., the CNC-cut areas) exhibit a high-gloss surface with a mirror effect, thus allowing different areas of the aluminum alloy workpiece to exhibit different brightness and gloss, thereby enhancing the aesthetics and appearance of the aluminum alloy workpiece. For example, the surface roughness Ra of the high-gloss surface formed after CNC drilling and cutting is less than 800 nm.

[0095] Understandably, after step S006, the aluminum alloy workpiece needs to be placed in the first oxidizing solution for anodizing treatment (i.e., performing step S100 + step S200), or the aluminum alloy workpiece needs to be anodized sequentially in the first and second oxidizing solutions (i.e., performing step S100 + step S200 + step S300 + step S400) to form an oxide film on the high-gloss surface of the aluminum alloy workpiece (i.e., the CNC drilling area), thereby improving the corrosion resistance and dirt resistance of the high-gloss surface. Since the first and second oxidizing solutions have a weak dissolving effect on the surface of the aluminum alloy workpiece, the oxide film formed on the high-gloss surface can be guaranteed to have good flatness and good mirror effect. That is to say, after anodizing treatment with the first or second oxidizing solution, the high-gloss surface of the aluminum alloy workpiece has less gloss loss and can still maintain a high brightness and gloss effect. During the anodizing process in the first or second oxidizing solution, since the oxide film formed on the surface of the aluminum alloy workpiece in step S004 has been sealed (step S005), it has strong corrosion resistance and will not be further oxidized or stained.

[0096] This application provides an aluminum alloy product, including an aluminum alloy workpiece and an oxide film disposed on the outer surface of the aluminum alloy workpiece. The oxide film is obtained by anodizing the aluminum alloy workpiece using the aluminum alloy anodizing process in any of the above embodiments.

[0097] This application also provides an aluminum alloy anodizing solution, comprising oxalic acid, sulfuric acid, glycolic acid, citric acid, and water, wherein the concentration of oxalic acid is 30 g / L to 40 g / L (e.g., 30 g / L, 32 g / L, 34 g / L, 35 g / L, 36 g / L, 38 g / L, 40 g / L, etc.), and the concentration of sulfuric acid is 3 g / L to 10 g / L (e.g., 3 g / L, 5 g / L, 7 g / L, etc.). The concentrations of acetic acid are 5 g / L to 30 g / L (e.g., 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, etc.), and the concentrations of citric acid are 10 g / L to 40 g / L (e.g., 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, etc.). It should be noted that this aluminum alloy anodizing solution is the first anodizing solution used in the aluminum alloy anodizing process described above.

[0098] This application embodiment also provides an aluminum alloy anodizing solution, comprising sulfuric acid, glycolic acid, adipic acid, and water, wherein the concentration of sulfuric acid is 50 g / L to 100 g / L (e.g., 50 g / L, 55 g / L, 60 g / L, 65 g / L, 70 g / L, 75 g / L, 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, etc.), the concentration of glycolic acid is 5 g / L to 30 g / L (e.g., 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, etc.), and the concentration of adipic acid is 5 g / L to 20 g / L (e.g., 5 g / L, 7 g / L, 10 g / L, 12 g / L, 15 g / L, 17 g / L, 20 g / L, etc.). It should be noted that the aluminum alloy anodizing solution is the second anodizing solution used in the aluminum alloy anodizing process described above.

[0099] The aluminum alloy anodizing process, aluminum alloy products, and aluminum alloy anodizing solution provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An anodizing process for aluminum alloys, characterized in that, include: A first oxidizing solution is provided, comprising oxalic acid, sulfuric acid, glycolic acid, citric acid, and water, wherein the concentration of oxalic acid is 30 g / L to 40 g / L, the concentration of sulfuric acid is 3 g / L to 10 g / L, the concentration of glycolic acid is 5 g / L to 30 g / L, and the concentration of citric acid is 10 g / L to 40 g / L. The aluminum alloy workpiece with a high gloss surface is placed in the first oxidation solution for anodizing.

2. The aluminum alloy anodizing process according to claim 1, characterized in that, When the aluminum alloy workpiece is placed in the first oxidizing solution for anodizing, the temperature of the first oxidizing solution is controlled at 25℃~30℃, and the oxidation treatment time is 15 minutes~40 minutes.

3. The aluminum alloy anodizing process according to claim 1, characterized in that, After the aluminum alloy workpiece is placed in the first oxidizing solution for anodizing, the aluminum alloy anodizing process further includes: A second oxidizing solution is provided, comprising sulfuric acid, glycolic acid, adipic acid, and water, wherein the concentration of sulfuric acid is 50 g / L to 100 g / L, the concentration of glycolic acid is 5 g / L to 30 g / L, and the concentration of adipic acid is 5 g / L to 20 g / L. The aluminum alloy workpiece is placed in the second oxidizing solution for anodizing.

4. The aluminum alloy anodizing process according to claim 3, characterized in that, When the aluminum alloy workpiece is placed in the second oxidizing solution for anodizing, the temperature of the second oxidizing solution is controlled at 18℃~22℃, and the oxidation treatment time is 15 minutes~40 minutes.

5. The aluminum alloy anodizing process according to claim 3, characterized in that, After the aluminum alloy workpiece is placed in the second oxidizing solution for anodizing, the aluminum alloy anodizing process further includes: placing the aluminum alloy workpiece in a sealing solution for sealing treatment; The sealing solution has a pH value of 5.5~6.5, the temperature of the sealing solution is controlled at 85℃~95℃, and the sealing treatment time is 20 minutes~50 minutes.

6. The aluminum alloy anodizing process according to claim 1, characterized in that, Before placing the aluminum alloy workpiece in the first oxidizing solution for anodizing, the aluminum alloy anodizing process further includes: The aluminum alloy workpiece is mechanically polished to form a high-gloss surface; The aluminum alloy workpiece that has undergone mechanical polishing is placed in a degreasing solution for degreasing treatment; The degreased aluminum alloy workpiece is immersed in an acidic solution to remove impurities from its surface.

7. The aluminum alloy anodizing process according to claim 1, characterized in that, Before placing the aluminum alloy workpiece in the first oxidizing solution for anodizing, the aluminum alloy anodizing process further includes: The aluminum alloy workpiece is placed in a degreasing solution for degreasing treatment; The aluminum alloy workpiece that has undergone degreasing treatment is then subjected to chemical polishing. The aluminum alloy workpiece that has undergone chemical polishing is immersed in an acidic solution to remove impurities from the surface of the aluminum alloy workpiece. A third oxidizing solution is provided, wherein the concentration of sulfuric acid in the sulfuric acid aqueous solution is 180 g / L to 220 g / L; the aluminum alloy workpiece is placed in the third oxidizing solution for anodizing; The aluminum alloy workpiece is placed in a sealing solution for sealing treatment; A localized area of ​​the aluminum alloy workpiece is treated to remove the oxide film formed by the third oxidizing liquid on the surface of the localized area, thereby forming a high-gloss surface.

8. An aluminum alloy product, characterized in that, It includes an aluminum alloy workpiece and an oxide film disposed on the outer surface of the aluminum alloy workpiece, wherein the oxide film is obtained by anodizing the aluminum alloy workpiece using the aluminum alloy anodizing process as described in any one of claims 1-7.

9. An aluminum alloy anodizing solution, characterized in that, The mixture includes oxalic acid, sulfuric acid, glycolic acid, citric acid, and water, wherein the concentration of oxalic acid is 30 g / L to 40 g / L, the concentration of sulfuric acid is 3 g / L to 10 g / L, the concentration of glycolic acid is 5 g / L to 30 g / L, and the concentration of citric acid is 10 g / L to 40 g / L.

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