Anodizing, the electrochemical oxidation of a metal or alloy.  The process by which an oxide film is formed on aluminium products (anodes) by the action of an applied current under the appropriate electrolyte and under specific process conditions for aluminium and its alloys. Anodising usually refers to sulphuric acid anodising if not specifically specified.
In order to overcome the defects in the surface hardness and wear resistance of aluminium alloys, to extend the range of applications and to prolong the service life, surface treatment technology has become an indispensable part of the use of aluminium alloys, and anodising technology is the most widely used and most successful.