Influence of solution pH on the structure formation and protection properties of ZnAlCe hydrotalcites layers on hot-dip galvanized steel

This study aims at investigating the influence of the solution pH and cerium cations on the formation and the anti-corrosion properties of hydrotalcite (HT) layers grown by the “in-situ” synthesis method on hot-dip galvanized steel substrate (HDG) in the pH range of 11–13. The anti-corrosion properties of all ZnAlCe HT layers were recorded by electrochemical tests and compared to bare HDG substrate during exposure to 0.1 M NaCl. The pH of precursor baths significantly impacted the orientation, chemical composition, microstructure of HT layers, and the intercalation of cerium cations inside HT with significant differences in their anti-corrosion performance. The ZnAlCe HT, prepared at pH 12, showed an obviously enhanced corrosion protection for HDG substrate compared to the other two HT layers. The anti-corrosion mechanism of HT layers as well as the role of cerium inside HT network was investigated and discussed in this research.