Abstract
Lead and lead alloys were subjected to anodic oxidation in sulfuric acid solution under potentiostatic conditions. The current‐time transients reveal that, as a result of inhibited ionic diffusion across the corrosion film, a secondary corrosion reaction takes place below the lead sulfate layer built up in the primary phase. The experimental findings are explained in terms of a high local pH in the interior of the corrosion film. This hypothesis is shown to be in accord with self‐depassivation phenomena and cathodic constant‐current stripping experiments. The potential‐determining reactions in the corrosion film are discussed in the light of new pH‐potential diagrams, constructed under consideration of the formation of basic lead sulfates. A model for the composition of the corrosion film is developed which conforms to all experimental findings, including the phenomena relating to the ohmic resistance of the film.