Inhibition of corrosion of aluminium pigments by ortho-substituted phenol and aniline derivatives

Abstract

Aluminium pigments are found to corrode with the evolution of hydrogen when in contact with water-butyl glycol mixtures at pH 10. Stability tests showed that the corrosion reaction can be inhibited by the addition of chelate forming ortho-substituted phenol derivatives, and that ortho-substituted aniline derivatives are ineffective corrosion inhibitors. The results can be explained in terms of Pearson's principle of hard and soft acids and bases. The measurement of the evolution of hydrogen was used to study relative differences in behaviour between ortho-substituted phenol derivatives. It is concluded that the most effective corrosion inhibitor is salicyl alcohol.