Influence of Ce on Corrosion Resistance of Nanocrystalline Zinc Coating

By adding cerium salt in the acidic sulfate bath used for direct current electrodeposition of nanocrystalline zinc coating, a new nanocrystalline coating was deposited. The composition, morphology and structure of the coating were characterized by Atomic Emission Spectrometry, X-ray diffraction and scanning electron microscopy. The influence of Ce on corrosion resistance of nanocrystalline zinc coating was investigated by electrochemical methods. The results show that with Ce2 (SO4)3·8H2O in the bath, a small amount of Ce can be obtained in the coating and give rise to the grain refinement of zinc deposits. Compared with the pure zinc coating, the one containing Ce has the better corrosion resistance. The improvement of corrosion performance is due to the formation of a denser product layer consisting mainly of Zn5(OH)8Cl2·H2O and its preferred orientation different from that of pure zinc coating.