XANES STUDY OF CE AND MO CONTAINING CONVERSION COATINGS ON ALUMINUM

Ce-Mo conversion coatings on superpure aluminium have been examined us ing XANES and analytical TEM to study the coating development over the electropolished surface. Ce species are predominantly in the Ce3+ sta te in the coating, resulting from the various steps of the process, an d Mo is in the Mo6+ state. After immersion in NaCl solution, Ce and Mo species leach from the coating. Conversion coating formation develops a hydrated film with cerium species incorporated; final anodic polari sation in MoO42- solution results in Mo species in the hydrated film. Corrosion inhibition is attributed to the coating acting as a barrier layer to environmental access to the aluminium substrate and reduced c athodic activity.