Initial stages of multi-phased aluminium alloys anodizing by MAO: micro-arc conditions and electrochemical behaviour

The electrochemical behaviour of AA1050 and AA2214 alloys was studied in a KOH/silicate in order to investigate the first stages of the coating formation during MAO process (by SEM and electrochemical measurements). Before the sparking initiation, occurring around 300 V for both alloys, a thin inner layer of aluminium oxide grows by a classical anodizing mechanism, and induces a great enhancement of the electrochemical resistance. Then, the...