稀土铈对镀锌层三价铬彩色钝化膜的影响

Influence of Ce(SO_4)_2 on Cr(Ⅲ) Colorized Passivation Film of Zinc Galvanized Layer

为了提高镀锌层三价铬彩色钝化膜的性能,通过单因素试验和对比分析的方法研究了稀土铈盐对三价铬彩色钝化膜的影响。研究发现在三价铬彩色钝化液中添加硫酸铈1.5 g/L时,钝化膜的表面质量及耐腐蚀性能最好。对比三价铬钝化膜及含铈三价铬钝化膜的外观颜色,发现稀土铈盐的添加加深了彩色钝化膜的色泽,提高了钝化膜的亮度及均匀性。从金相显微镜和扫描电镜(SEM)分析可知,2种钝化膜膜层明显,且含铈钝化膜的表面致密度更高。通过能谱仪(EDS)分析可知,稀土铈元素参与了成膜过程。黏着力测试和电化学测试表明,含铈三价铬钝化膜有较好的耐磨性和耐蚀性。初步分析镀锌层三价铬彩色钝化膜的成膜过程可知,成膜反应和溶解膜反应形成了一个动态平衡过程,通过控制钝化浸渍时间和钝化液的p H值,控制钝化膜的溶解,可以提高钝化膜的致密性。

Abstract ： In order to improve the Cr（m） colorized passivation solution for zinc galvanized layer, the influence of Ce（ SO4 ） 2 on Cr（Ⅲ） eolor- ized passivation film was studied through single factor experiments and contrastive analysis methods. Results showed that when the dosage of Ce（ SO4 ） 2 additive in Cr（ Ⅲ ） eolorized passivation solution was 1.5 g/L, the obtained Cr（ Ⅲ ） passivation coating had the optimal appearance quality and corrosion resistance. Compared with the appearance of pure Cr（ Ⅲ ） passivation film and Ce-containing Cr（ Ⅲ） passivation film, the adding of Ce（ SO4 ）2 could increase the colors of colored passivation film and improve the brightness and uniformity. In addition, from the analysis of metallurgical microscope and scanning electron microscope （ SEM ） , the passivation coating containing cerium was more uniform. EDS analysis revealed that Ce element took part in film- formation process. Besides, the adhesion test and electrochemical test presented the Cr（ Ⅲ ） passivation film containing Ce possessed better abrasion resistance and corrosion resistance. Based on the preliminary analysis of the formation process of Cr（ Ⅲ ） eolorized passivation film of zinc galvanized layer, it was easily obtained that the formation and dissolution of film reached a dynamic balance process. By controlling the passivation immersed time and the pH value of passivation solution, the dissolution of passivation film could be regulated, which was beneficial to improving the compactness of passivation films.