Formation of vanadium-containing anodic films on an aluminum alloy

The data are given on the features of formation of vanadium-containing anodic films in the polyphosphate-metavanadate electrolyte during microplasma discharge. It is shown that spots enriched with vanadium and phosphorus are formed as nuclei at defects in the initial anodic film. Under conditions of the spark discharge, the nuclei of the new phase expand and merge, covering the whole surface of anode with time. The effect of the content of sodium polyphosphate and metavanadate in the electrolyte on the changes in the electrode voltage during the anodic process and the elemental composition of the films obtained are studied. It is shown that, in order to form the films with high concentration of vanadium, a certain salt ratio in the solution is necessary. Assumption is made that the complex formation in solution affects the formation and elemental composition of the anodic films.