稀土铈对热浸镀锌层耐蚀性能的影响

Effect of rare earth cerium on corrosion resistance of hot-dip galvanized coating

在锌浴中分别添加不同质量分数（0．00％～0．12％）的稀土Ce，获得了热浸镀Zn-Ce镀层。采用扫描电镜观察不同镀层的截面形貌，通过中性盐雾试验和测量电化学极化曲线及电化学阻抗谱，研究了Ce对锌镀层耐蚀性的影响。结果表明，稀土Ce对镀层结构无影响，但可在一定程度上控制Zn—Ce镀层的超厚生长。与纯锌镀层相比，Zn-Ce镀层经中性盐雾试验8h后的白锈面积较小，且出现红锈的时间也延后，在5％NaCl溶液中的自腐蚀电位更正，电化学阻抗也更高。因此锌浴中Ce的添加可提高镀层耐蚀性。Ce的添加量为0．08％时，Zn—Ce镀层的耐蚀性最佳。

Hot-dip galvanized Zn-Ce coatings were prepared by adding different mass fractions （0.00%-0.12%） of rare earth Ce to zinc bath. The cross-section morphologies of different coatings were observed by scanning electron microscope. The effect of Ce on the corrosion resistance of zinc coating was studied by neutral salt spray test, electrochemical polarization curve measurement, and electrochemical impedance spectroscopy. The results showed that rare earth Ce has no impact on the structure of galvanized zinc coating but can control its excessive thickness growth to some extent. Compared to pure zinc coating, the Zn-Ce coating has smaller white rust area after neutral salt spray test for 8 h, and a delayed formation of red rust; and it has more positive self-corrosion potential and higher electrochemical impedance in 5% NaCl solution. Accordingly, the corrosion resistance of galvanized Zn coating can be improved by adding Ce to zinc bath and the Zn-Ce coating obtained with 0.08% Ce has the best corrosion resistance.