Electrodeposition of ceria-based layers on zinc electroplated steel

CeO2 layers were electrodeposited on a Zn-electroplated steel from relatively high concentrations of cerium nitrate. Increasing the current density resulted in a better coverage of the surface but cracks also appeared. Partial dissolution of the substrate occurred, but no defined conversion layer was observed by SEM. XRD, Raman and FT-IR indicated however the formation of zinc hydroxides and hydrozincite as corrosion products. The addition of polyethylene glycol (PEG) limited such dissolution. DSC results showed that PEG was trapped in the coating. This limited the reduction of water, hence to decrease the number of cracks. The coatings microstructure remained however similar.