Oxidising type inhibitors for protection of aluminium and steel surfaces in sodium chloride solutions

Abstract

Photoelectron spectroscopy was used to study the composition of surface films formed on aluminium and steel when protected from corrosion in aqueous chloride media by inorganic inhibitors of the MeO²⁻ ₄ oxidising type and by mixtures of these and monoethanolamine (MEA). The surface condition plays a significant role in the protection of aluminium. In the adsorption of molybdate on to an etched surface reduction of Ma(VI) to Mo(IV) occurs whereas on an unetched surface, as also for a steel surface, no reduction occurs. In the case of chromate, reduction to Cr(III) took place on steel and on aluminium. Synergism was established in the inhibition of corrosion of steel by a combination of inorganic oxidisers and MEA and a study made of this phenomenon.