摘要
Application of a composite coating on AM60B magnesium alloy consisting of cerium-vanadium conversion coating and a hybrid sol-gel layer was investigated. Scanning electron microscopy and energy dispersive X-ray spectroscopy analyses revealed a cracked nodular structure for the cerium-vanadium conversion coating which was mainly composed of O, Ce, V, and Mg atoms. All the cracks in the conversion coating were completely sealed by a thin, compact and defect-free hybrid sol？gel film. Potentiodynamic polarization and electrochemical impedance spectroscopy experiments in Harrison’s solution showed that the cerium-vanadium conversion coating provides minimal protection against corrosion while the composite coating significantly increases the corrosion resistance of the magnesium alloy. Sol-gel film provides protection against corrosion by sealing cracks in the cerium-vanadium conversion coating and acting as a barrier. Scanning electron microscopy analyses after polarization tests confirmed the results obtained by the electrochemical tests.
研究AM60B镁合金表面复合涂层的应用,该涂层由铈-钒转化膜和混合溶胶-凝胶层组成。扫描电镜和X射线能谱分析显示铈-钒转化膜存在开裂结节结构,该转化膜由氧、铈、钒和镁原子组成。转化膜中的裂纹被致密无缺陷的混合溶胶-凝胶薄膜密封。在Harrison溶液中进行电位极化和电化学阻抗测试,结果表明铈-钒转化膜对镁合金提供了很小的防腐保护,然而复合涂层显著增大了镁合金的抗腐蚀性。通过密封铈-钒转化膜的裂缝,溶胶-凝胶膜对合金防护和阻碍腐蚀起到了很大的作用。极化测试后采用扫描电子显微镜验证了电化学测试结果。
