Study of the heterogenous reaction between iron lead oxides

Abstract

Different theories are proposed in the literature to explain passivation mechanisms of iron by means of the use of lead compounds. In some cases the protective action is related to the formation of lead soaps with vegetable oils or oleoresinous binders. These soaps are partially dissolved from the film, acting at the interface metallic substrate/paint film. In the case of inert binders (those corresponding to vinyl resins), red lead acts as a passivating agent. The protection of iron plates in the presence of suspensions of red lead, lead monoxide and lead dioxide in a 0.5~ sodium perchlorate solution as electrolyte is studied in this paper. Polarisation curves were traced and measurements of voltage at open circuits were made. Only two of the lead oxides tested (red lead and lead monoxide) have corrosion inhibiting action, both showing a similar behaviour