FORMATION AND DISSOLUTION OF THE ANODIC OXIDE FILM ON ZIRCONIUM IN ALCOHOLIC AQUEOUS-SOLUTIONS

The dissolution behavior of the anodic oxide film formed in alcoholic aqueous solutions was studied. Results indicated the dissolution mecha nism of the duplex oxide film followed a zero-order rate equation. The increase in methanol concentration in the formation medium (phosphori c acid [H3PO4]) resulted information of an oxide film that incorporate d little phosphate ion and that dissolved at a low rate. The dissoluti on rate of the oxide film decreased with increasing methanol concentra tion in the dissolution medium. This was attributed to the increase in the viscosity of the medium which led to a decrease in the diffusion coefficient of the dissolution product of the zirconium oxide film. Di ssolution of the anodic oxide film also was investigated as a function of the chain length of alcohols.