THE ANODIC BEHAVIOR OF NIOBIUM .3. KINETICS OF ANODIC FILM GROWTH BY POTENTIODYNAMIC AND GALVANOSTATIC TECHNIQUES - GENERAL-MODELS, EQUATIONS AND THEIR APPLICATIONS

A general quantitative treatment for the growth of continuous anodic films on metals, under potentiodynamic and galvanostatic conditions, is proposed and applied to the case of niobium in Na2CO3 solutions. The general equations include different overpotentials, across the film and the metal/film and the film/solution interfaces, and take into account, for transport through the film, the different existing models. Special regions of the experimental results are analysed, showing that at these regions it is possible (through the application of the general equations) to deduce special equations which permit one to obtain the parameters of the different models.