乙醇胺添加剂对AZ91D镁合金表面磷化膜耐蚀性能的影响研究

以磷酸盐化学转化膜为研究体系,采用动电位极化和交流阻抗分析方法及检测手段,研究乙醇胺添加剂及其浓度对AZ91D镁合金磷化膜耐蚀性能的影响.研究发现,(1)乙醇胺(MEA)作为添加剂可有效改善AZ91D镁合金表面磷化膜的耐蚀性能.在MEA添加量为1.2g/L时,磷化膜的耐蚀性最好.添加乙醇胺1.2g/L时制备的磷化膜,在3.5%(质量分数)NaCl溶液中的耐蚀性能比AZ91D镁合金基体提高了10倍;(2)MEA浓度在0.4～1.2g/L时,磷化膜的R_(ct)随MEA浓度增加成线性增长关系.MEA浓度1.2g/L时达到最大值.磷化膜的R_p在MEA浓度为1.2g/L时达到最高值.当MEA浓度继续增加时,R_p明显下降.MEA浓度控制在0.8＜C_(MEA)＜1.6g/L时获得的磷化膜的耐蚀性能最好.

Effect of ethanolamine on the anticorrosive properties of phosphate coating prepared on AZ91D magnesium alloy

In this paper,the effect of the concentration of ethanolamine additive on the anticorrosive properties of phosphate coating,which was prepared on AZ91D magnesium alloy,was investigated by potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS)techniques.The results showed that,(1)Ethanolamine(MEA)additive could improve the anticorrosive properties of phosphate coating.The corrosion resistance of phosphate coating is improved by 10 times that of the AZ91D magnesium alloy in 3.5wt% NaCl solution when the concentration of ethanolamine additive was 1.2g/L.(2) When the concentration of ethanolamine additive ranged from 0.4-1.2g/L,the anticorrosive properties of phosphate coating was in direct proportion to the concentration of ethanolamine additive; however,with the further increase in the concentration of ethanolamine additive,the anticorrosive properties of phosphate coating began to decrease.The phosphate coating with good anticorrosive properties could be obtained when the concentration of ethanolamine additive is between 0.8 and 1.6g/L.