Composite surface treatment method for aluminum alloy die-casting part

Abstract

The invention provides a composite surface treatment method for an aluminum alloy die-casting part. The composite surface treatment method comprises the following steps: performing surface treatment on the surface of the aluminum alloy die-casting part to remove oil stains and dirt; performing sand-blasting treatment or wire-drawing treatment on the surface of the aluminum alloy die-casting part; cleaning and neutralizing the aluminum alloy die-casting part; performing anode oxidizing treatment on the surface of the aluminum alloy die-casting part, and performing dyeing and hole-sealing treatment on the surface of the treated aluminum alloy die-casting part; performing nano coating treatment on the surface of the aluminum alloy die-casting part with organic silicon modified paint which comprises nano silicon dioxide and a base material. According to the technical scheme adopted by the invention, the aluminum alloy die-casting part is even in surface color, and is as good as a common aluminum alloy machined part in appearance, and has better corrosion resistance.

Description

technical field [0001] The invention belongs to the technical field of metal surface treatment, and in particular relates to a composite surface treatment method for aluminum alloy die castings. Background technique [0002] The Si content of aluminum alloy die castings is generally 6.5% to 9.5%. High Si content makes the material have good fluidity in the die casting process and is easy to form. At the same time, the addition of Cu content can improve the tensile strength and hardness of the parts. However, due to the large proportion of Si and Cu in the die-casting alloy, it is very difficult to perform anodic oxidation treatment according to conventional methods, and after anodic oxidation treatment alone, there are many appearance defects such as mottling and "map-like lines" on the surface , can not meet the requirements of appearance decoration. [0003] At present, for die-casting parts, the surface decoration effect is improved by improving the silicon removal proce...

AI Technical Summary

Problems solved by technology

However, due to the large proportion of Si and Cu in the die-casting alloy, it is very difficult to perform anodizing treatment according to conventional methods, and after anodizing treatment alone, there are many appearance defects such as mottling and "map-like lines" on the surface , can not meet the requirements of appearance decoration

[0003] At present, for die-casting parts, the surface decoration effect is improved by improving the silicon removal process before anodic oxidation, and by improving the anodic oxidation process itself, but some silicon and other alloying elements will cause greater damage to the oxide film. Unevenness affects the appearance. At the same time, there are many alloy elements in the die casting, and the components involved in the film formation are complex. If the salt spray test is carried out according to ASTM B117, its corrosion resistance is far from the 336 hours required by MIL-A-8625F requirements

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