The anodizing process of aluminum and aluminum alloys is widely used in industry. It can be used to prevent corrosion of products or achieve the dual purpose of protection and decoration, such as spray painting and electroplating.
1. Prevent corrosion of aluminum products
Since the film layer obtained by anodization itself has sufficient stability in the atmosphere, the oxide film on the aluminum surface can be used as a protective layer. The oxide film obtained by anodizing aluminum in a chromic acid solution is dense and has good corrosion resistance; the oxide film obtained from a sulfuric acid solution has larger pores than the former, but its film layer is thicker and has strong adsorption capacity. If it is With proper filling and sealing treatment, its corrosion resistance is also very good.
2. Protective decorative products
For most aluminum and its alloy products that require surface finishing, after chemical or electrochemical polishing and then anodizing with sulfuric acid solution, an oxide film with higher transparency can be obtained. This oxide film can adsorb many kinds of organic dyes and inorganic dyes, resulting in various bright colors. This colored film is both an anti-corrosion layer and a decorative layer. Under some special process conditions, a protective and decorative oxide film with a similar appearance to porcelain can also be obtained.
3.As a base layer for spray paint
Due to the porosity and good adsorption capacity of the anodized film, it can be used as the bottom layer of spray paint and other organic films to firmly combine the paint film and organic film with the product, thereby increasing its corrosion resistance.
4. As the bottom layer of electroplating
Before electroplating, aluminum and aluminum alloy products must be coated with a base layer before electroplating. There are many ways to apply a bottom layer on the surface of the substrate. In addition to electro-galvanizing, immersion zinc, and electroless nickel plating, anodizing is also one of the important methods.
