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104Q·cm2;腐蚀电流密度为8.86×10-6 A.cm-2,较Mg-9.95Li合金降低了2个数量级,转化膜对Mg-9.95Li合金具有良好的耐蚀防护性能.
Dense cerium conversion coating was prepared on the surface of Mg-9.95Li alloy by immersing Mg-9.95Li alloy in cerium nitrate solution with H2O2 and citric acid addition.The chemical composition and morphologies of conversion coatings were characterized by X-ray photoelectron spectroscopy(XPS) and scanning electron microscopy(SEM),respectively.Electrochemical measurements (electrochemical impedance spectroscopy,polarization curves,open circuit potential) were used to analyze the corrosion resistance of the conversion coating.The results indicate that the conversion coating is mainly composed of CeO2 and Ce(OH)4 cross-linked by citric acid,which becomes denser and more uniform.The dense cerium conversion coating has better corrosion resistance to Mg-9.95Li alloy.The electrochemical impedance reaches 104 Ω·cm2,and the corrosion current density is only 8.86× 10-6 A·cm-2,which is reduced by two orders than that of Mg-9.95Li alloy.
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