Hard anodic oxidation, electrochemical oxidation of metals and alloys. Aluminum and its alloys cause a layer of oxide film on aluminum products (anode) due to the effect of applied current under corresponding electrolyte and specific process conditions. Hard anodizing, if not specified, usually refers to sulfuric acid anodizing.

In order to overcome the shortcomings of aluminum alloy surface hardness and wear resistance, expand the application scale and service life, the surface treatment skills have become an indispensable part in the application of aluminum alloy, and the anodizing skills are the most widely used and successful.