Chelate Inhibitors for Zinc and Galvanized Products

White rust corrosion of zinc and galvanized products remains a serious commercial problem, in spite of almost 50 years of development of inorganic passivation techniques. Furthermore, such inhibitors compound the already difficult task of paint application to these materials. In a novel approach, the concept of surface chealtion has been taken as a starting point for the development of organic inhibitors for zinc which will act as monolayers strongly bonded to the metal substrate. Possible chelating groups were screened, resulting in identification of two particularly effective materials: (1) 2,5-dimercapto-1,3,4-thiadiazole, and (2) the esters of thioglycolic acid.