热水和硅酸钠封孔法对镁合金磷化膜耐蚀性的影响

Effects of Hot Water and Na_2SiO_3 Sealing on Corrosion Resistance of Phosphate Film for Magnesium Alloy

为了进一步提高镁合金磷化膜的耐蚀性,采用热水法和硅酸钠法对磷化膜进行了封孔处理。借助扫描电镜观察磷化膜的形貌并测试了其成分,通过动电位极化和交流阻抗等方法测试了磷化膜的耐蚀性。结果表明:两种封孔方法获得的磷化膜更加光滑,缺陷数量减少,且表现出更低的自腐蚀电流密度和更大的电荷转移电阻,特别是硅酸钠封孔后的磷化膜表现出更佳的耐蚀性。

To improve the corrosion resistance of phosphate film for magnesium alloy,pores＇of the film were sealed with hot water method and Na2SiO3 method.The morphology of the phosphate ＇film was observed and the composition analyzed by SEM,and its corrosion resistance was investigated using polarization curves and electrochemical impedance spectroscopy （EIS）.The results show that the film sealed by these two methods is smoother and less defective,and shows lower self-corrosion current density and higher charge transfer resistance,and the phosphate film sealed with sodium silicate solution exhibits abetter corrosion resistance.