Amino and polyamino acids as corrosion inhibitors for aluminium and zinc pigments

Abstract

A severe problem with water‐borne paints containing aluminium or zinc pigments is hydrogen corrosion of these metals in the aqueous alkaline paint media. The subject of the present study is the examination of corrosion inhibition of aluminium and zinc pigments in aqueous alkaline media by different amino and polyamino acids. Aspartic acid inhibits this corrosion reaction of aluminium pigment only at pH 8 (protection factor 96 per cent) whereas polyaspartic acids do not. In contrast, aspartic acid stimulates the corrosion reaction of zinc pigment whereas polyaspartic acids show a moderate corrosion inhibiting effect. So, corrosion inhibition by aspartic and polyaspartic acids is completely different on aluminium and zinc pigment.