INFLUENCE OF SOME ENVIRONMENTAL-CONDITIONS ON THE ELECTROCHEMICAL-BEHAVIOR OF ANODIC ZRO2 FILMS IN ACID-SOLUTIONS

Formation and dissolution behaviour of anodic ZrO2 films was studied k inetically in relation to the influence of two environmental condition s : concentration and temperature. The technique employed was galvanos tatic anodization of Zr metal, open circuit potential and impedance me asurements for the oxide covered electrode in acid solutions. The rate of oxide growth was found to increase by increasing the concentration of the anodizing bath concentration or by lowering its temperature. H igher concentration or temperature films are both more perfect (i.e. h ave less structural disorder) as they dissolve at a much slower rate c ompared to the other films which are grown at lower concentrations or at lower temperatures. The anodic oxide film has a duplex nature and t he dissolution rates for both layers of the film increase continuously as the dissolving acid concentration increases.