Anodic Oxidation Principle of Aluminum

Anodic oxidation of aluminum is an electrolytic oxidation process in which the surfaces of aluminum and aluminum alloys are typically converted into an oxide film that is protective, decorative, and has other functional properties. The anodization of aluminum from this definition includes only the part of the process of forming an anodized film.

A metal or alloy article is used as an anode, and an oxide film is formed on the surface by electrolysis. Metal oxide films alter surface conditions and properties such as surface coloration, improved corrosion resistance, enhanced wear resistance and hardness, and protection of metal surfaces. For example, aluminum anodizing, aluminum and its alloys are placed in the corresponding electrolyte (such as sulfuric acid, chromic acid, oxalic acid, etc.) as an anode, and electrolysis is carried out under specific conditions and an applied current. The aluminum of the anode or its alloy is oxidized, and a thin layer of aluminum oxide is formed on the surface, the thickness of which is 5 to 30 micrometers, and the hard anodized film can reach 25 to 150 micrometers. Aluminized aluminum or its alloy improves its hardness and wear resistance up to 250~500kg/mm2, good heat resistance, hard anodized film with melting point up to 2320K, excellent insulation and resistance The wearing voltage is up to 2000V, which enhances the corrosion resistance and does not corrode in the salt fog of ω=0.03NaCl for several thousand hours. The oxide film has a large number of micropores in the thin layer, which can adsorb