View article

In an effort to provide improved protection against inside-out perforation corrosion for automotive body panels, organic/metallic composite coatings, such as Durasteel (thin organic coated ZnNi) and Zincroplex, have been developed for sheet steels. In the present study, evaluated were two thin organic coatings, one solvent-borne and one water-borne, in combination with three metallic coated sheet steels of electroplated pure Zn, hot-dipped galvanneal and electroplated ZnNi. Perforation corrosion resistance was evaluated by measuring the weight loss and thickness reduction of flat panels in two long-duration cyclic corrosion tests. The results showed that the organic coatings improved corrosion resistance through their barrier protection, supplementing the sacrificial protection of the Zn-base metallic coatings; while all composite coatings outperformed their respective metallic-only coated steels, ZnNi performed the …