Electrochemical characterisation of anodic oxidation films formed in presence of corrosion inhibitors

Most oxide films provide extensive corrosion inhibitors by incorporation of chromium compounds (i.e. Cr(VI)) that provide such good protection. But, replacement of hexavalent chromium is also under active consideration because of its toxicity. This paper describes research, which has been carried out to find alternatives to chromic acid anodisation (H2CrO4), for 2024-aluminium alloy. Promising inhibitors: molybdate and permanganate anions have been identified. In this work, attempts have been made to incorporate these inhibitors into the anodic film during the anodising process. Corrosion performance has been studied and compared using anodic polarisation techniques and impedance spectrometry measurements.