Aluminum itself is a very corrosion resistant material, but when exposed to oxygen it will form aluminum oxide oxidation on the surface of aluminum, which will slowly eliminate its corrosion resistance over a long period of time. In addition, aluminum is very sensitive to acidic substances. When acid is encountered, it will destroy the surface composition layer of aluminum. We then need to oxidize again and add another layer to the surface, improving the surface corrosion resistance of the protective film.
The anodic protection technology for aluminum oxidation is usually used on marine vessels because aluminum oxidizes more easily than steel in seawater. By attaching the aluminum block to the hull and immersing it in seawater, the aluminum oxidizes while the steel of the hull does not, so that the hull is protected. As the bottom layer of electroplating, the anodic oxide film is porous, and anodic oxidation treatment before electroplating treatment on the surface of aluminum profile can improve the quality of electroplating.Protecting the decorative material, chemical or electrochemical polishing before anodizing the aluminum profile, and anodizing afterwards can get an oxide film with higher transparency. If some organic or inorganic dyes are adsorbed before oxidation sealing, bright colors can be obtained. This colored oxide film is both a decorative and a protective layer.
The anodic oxide film and the electrochemical process used to produce it should be harmless to humans. Therefore, in order to reduce the weight of products, the convenience of machining, environmental protection and low toxicity requirements, some parts of some products are currently made of aluminum alloy hard oxide instead of stainless steel, electroplated hard chrome and other processes.