Oxygen evolution during the formation of barrier type anodic film on 2024-T3 aluminium alloy

In this paper oxygen evolution was investigated during the anodization of the 2024-T3 aluminium alloy in berate solution. It was observed that oxygen evolution starts at about 1.1 Vsce and this value of voltage does not depend on the thickness of the anodic coating or on the type of applied pretreatments. This oxidation reaction seems to take place at active sites related with the intermetallics of copper present at the specimen surface. Deterioration of the electrical characteristics of the anodic films formed at various constant voltages and increase of leakage current through these films during the anodic potentiodynamic polarization were observed. These phenomena appeared when a critical value of anodization voltage was exceeded. Their origin did not seem to affect the value of potential (1.1 Vsce) where the oxygen evolution started. (C) 1998 Elsevier Science Ltd. All rights reserved.