Hard Anodising
On exposure to air, Aluminium will immediately form a stable oxide layer. This natural oxide film is, however, very thin, approximately 1/100th of a micron and provides little corrosion resistance under normal atmospheric conditions.
Anodising is the controlled formation of an Aluminium oxide coating at the surface of items made from Aluminium and its alloys. The anodic coating is produced by passing an electric current through a dilute acid solution, using the component as the anode. The thickness, density, hardness and colour of the coating can be varied depending on the solution and the processing conditions.
By modifying the processing conditions, a wide range of properties and coatings can be achieved, making hard anodising an ideal surface engineering technique for a wide range of applications.