Mg-9.95Li合金表面致密铈转化膜制备及耐蚀性研究

Preparation and Corrosion Resistance of Dense Cerium Conversion Coatings on Mg-9.95Li Alloy

摘要:

在硝酸铈(Ce(NO3)3)转化液中同时加入H2O2和柠檬酸，利用化学转化法在 Mg-9.95Li合金表面获得致密铈转化膜。采用X-射线光电子能谱(XPS)和扫描电子显微镜(SEM)表征了致密铈转化膜的成分与形貌，采用电化学阻抗谱、极化曲线和开路电位测试了转化膜的防腐蚀性能。结果表明，转化膜主要由柠檬酸交联的CeO2和Ce(OH)4组成，形成的转化膜更加致密均匀，转化膜的阻抗可以达到104 Ω?cm2；腐蚀电流密度为8.86×10-6 A?cm-2，较Mg-9.95Li合金降低了两个数量级，转化膜对Mg-9.95Li合金具有良好的耐蚀性能。

Abstract:

Dense cerium conversion coating was prepared on the surface of Mg-9.95Li alloy by immersing Mg-9.95Li alloy in cerium nitrate solution which added H2O2 and citric acid. The chemical composition and morphologies of conversion coatings were characterized by X-ray photoelectron spectroscopy(XPS) and scanning electron microscopy(SEM). Electrochemical measurements(electrochemical impedance spectroscopy, polarization curves, open circuit potential) were used to analyze the anticorrosion properties of the conversion coatings. The results indicate that the conversion coating mainly composed of CeO2 and Ce(OH)4 cross-linked by citric acid, then make the conversion coating more dense and uniform. The dense cerium conversion coatings have better anticorrosion properties to Mg-9.95Li alloy. The electrochemical impedance was reached 104 Ω?cm2, and the corrosion current density was only 8.86×10-6 A?cm-2, which reduce two orders than that of Mg-9.95Li alloy.