Anodizing

Anodizing is an electrochemical process, most frequently used on aluminum, although it can be used with other metals, such as magnesium and titanium alloys. An electric current is passed through an electrolyte (usually chromic, phosphoric, or sulfuric acid) causing the surface of the anodic metal to form an oxide film. This film can be significantly thicker than the naturally occurring one, and thus can provide better corrosion protection. An advantage of anodizing over coating deposition methods is that the resultant coating is an integral part of the substrate rather than being a layer that is bonded to the substrate. Anodized coatings are, however, typically brittle and susceptible to strong acids and bases.