Anodization phenomena on aluminium and aluminium alloys

The formation of oxide layers on high purity aluminum and its alloys has been Investigated by means of the "transitometer'.' This apparatus comprises a constant current source and a switch which opens the circuit at certain preset tensions of the electric current and of an electronic timer working simultaneously. In this way, the time in which a tension is built up at the surface of the electrode is measured. The curves measured E versus t (tension-time) show sudden time peaks, which indicate that during the anodization process the oxide layer is broken up at certain places of the surface and new.