Method for anodizing aluminum or aluminum alloy and metal workpiece

Abstract

A method for anodizing aluminum or aluminum alloys and a metal workpiece are disclosed. The anodizing method includes: anodizing an aluminum or aluminum alloy metal substrate to form an anodized film with a porous structure on the surface of the metal substrate, obtaining a first intermediate; activating the first intermediate with an activator containing copper sulfate and a desiccant, allowing copper sulfate to enter the porous structure, obtaining a second intermediate; and sealing the second intermediate with a sealing agent containing nickel acetate, whereby nickel acetate and copper sulfate form a blue complex within the porous structure, and the complex is sealed within the porous structure. This method utilizes a desiccant to ensure that copper sulfate fully enters the porous structure, and then seals the copper sulfate within the porous structure, effectively reducing the yellowing and darkening of the anodized film and improving the surface treatment effect of the anodized film.

Claims

1. A method for anodizing aluminum or aluminum alloys, wherein, include: Anodizing an aluminum or aluminum alloy metal substrate to form a porous anodic oxide film on the surface of the metal substrate yields a first intermediate. The first intermediate is activated with an activator containing copper sulfate and a desiccant, allowing copper sulfate to enter the pore structure to obtain a second intermediate. The desiccant comprises: 8 wt% to 10 wt% tartaric acid, 4 wt% to 6 wt% acetic acid, 20 wt% to 28 wt% sodium sulfonate, 8 wt% to 12 wt% citric acid, and the balance being water. In the activator, the mass ratio of copper sulfate to sodium sulfonate is 1:(12 to 72). The second intermediate is then sealed with a sealing agent containing nickel acetate, whereby nickel acetate and copper sulfate form a blue complex in the pore structure, and the complex is sealed within the pore structure.

2. The method for anodizing aluminum or aluminum alloys as described in claim 1, wherein, The concentration of copper sulfate in the activator is 1 g / L to 4 g / L.

3. The method for anodizing aluminum or aluminum alloys as described in claim 1, wherein, The activation time is 1 min to 4 min.

4. The method for anodizing aluminum or aluminum alloys as described in claim 1, wherein, Prior to the step of anodizing the metal substrate, the method further includes: chemically polishing the metal substrate and removing the black film using the descaling agent.

5. The method for anodizing aluminum or aluminum alloys as described in claim 4, wherein, The time for peeling off the black film is 1 min to 4 min.

6. The method for anodizing aluminum or aluminum alloys as described in claim 1, wherein, The electrolyte for anodic oxidation includes oxalic acid and sulfuric acid, wherein the concentration of oxalic acid is 20 g / L to 25 g / L, the concentration of sulfuric acid is 100 g / L to 110 g / L, and the mass concentration ratio of oxalic acid to sulfuric acid is sulfuric acid: oxalic acid = 1: (4 to 5.5).

7. The method for anodizing aluminum or aluminum alloys as described in claim 1, wherein, The thickness of the anodic oxide film is 10μm~16μm; the voltage of the anodic oxidation is 12V~17V; the temperature of the anodic oxidation is 25℃~29℃; and the time of the anodic oxidation is 40min~50min.

8. A metal workpiece, wherein, It includes a metal substrate and an anodic oxide film formed on the metal substrate, the anodic oxide film being prepared by anodizing as described in any one of claims 1 to 7.

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