有机添加剂对AZ91D镁合金锡酸盐转化膜性能的影响

Influences of Organic Additives on Stannate Conversion Coating Prepared on the AZ91D Magnesium Alloy Surface

摘要:

采用化学转化法在镁合金表面制备锡酸盐转化膜。采用硫酸铜点滴实验、电化学交流阻抗(EIS)测试和Tafel曲线、扫描电子显微镜(SEM)测试和X射线衍射分析(XRD)等方法检测膜层的性能。研究了几种有机添加剂（Tartaric?acid、Citric?acid、Phytic?acid、EDTA、Sodium?dodecyl?sulfate）对膜层耐蚀性的影响，结果表明溶液中添加SDS后，转化膜的硫酸铜点滴时间由35 s提高到了86 s，明显提高转化膜的耐腐蚀性能，膜层的形貌为呈“颗粒”状紧凑的连接到一起，该膜层的主要成分为MgSn(OH)6、Mg(OH)2

Abstract:

A stannate conversion coating was prepared on the AZ91D magnesium alloy surface by a chemical conversion process. The coating performances were tested by CuSO4 drip experiment, EIS, Tafel, SEM and XRD. The effects of some organic additives including tartaric?acid, citric?acid, phytic?acid, EDTA, and sodium?dodecyl?sulfate on the coating corrosion resistance were studied. The results show that the drip time is increased from 35 to 86 s by adding sodium?dodecyl?sulfate and it could improve the corrosion resistance of the film to a large extent. The morphology of the membrane layer mainly contains MgSn(OH)6 and Mg(OH)2 which is granular-bonded