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在硝酸铈(Ce(NO_3)_3)转化液中同时加入H_2O_2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CeO_2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?·cm~2;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。
In the cerium nitrate (Ce (NO_3) _3) conversion solution, H_2O_2 and citric acid were added simultaneously, and the dense cerium conversion coating was obtained on the surface of Mg-9.95Li alloy by chemical conversion. The composition and morphology of the dense cerium conversion coating were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The corrosion resistance of the conversion coating was tested by electrochemical impedance spectroscopy, polarization curves and open circuit potentials. The results showed that the conversion coating mainly consisted of CeO_2 and Ce (OH) _4 crosslinked by citric acid, and the formed conversion coating was denser and uniform. The resistance of the conversion coating could reach 104? Cm ~ 2 and the corrosion current density was 8.86 × 10 ~ (-6) A · cm ~ (-2), which is two orders of magnitude lower than that of Mg-9.95Li alloy. The conversion coating has good corrosion protection to Mg-9.95Li alloy.