2018 Volume 58 Issue 7 Pages 1316-1323
The corrosion resistance of electrogalvanized steels with trivalent chromate conversion coatings is investigated electrochemically to analyze the effect of organic additives on the corrosion resistance under wet-dry cyclic conditions. Three sets of polyamine additives, namely (i) imidazole and epihalohydrin, (ii) polyquaternary amine salt, and (iii) polyethyleneimine, are examined and compared. Electrochemical impedance spectroscopy and anodic stripping were employed to evaluate the corrosion resistance. Crystal-structure and compositional analyses were also applied to demonstrate the role of organic additives in controlling the structure of the zinc layer and the formation of the trivalent chromate conversion film.