镁锂合金表面高锰酸盐转化膜的研究

采用化学转化法在镁锂合金表面制得了结构致密、耐蚀性能较好的高锰酸盐转化膜,研究了转化液中高锰酸盐溶液浓度对成膜效果的影响.实验采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和X射线光电子能谱(XPS)对所制得转化膜的表面形貌、结构和组成进行了测试.同时,使用动电位极化曲线、电化学交流阻抗谱和腐蚀失重3种方法对镁锂合金及其转化膜的耐腐蚀性能进行了深入研究.结果表明:高锰酸盐转化膜较均匀、平整,间隙较小,转化膜主要由锰的氧化物组成.提高了镁锂合金的耐腐蚀性能,当高锰酸盐溶液浓度为4.0 g/L时,转化膜的腐蚀电流密度小、容抗弧大、腐蚀速率低,耐腐蚀性能佳.

Permanganate Conversion Coatings on Magnesium Lithium Alloy Surface

Compact conversion coatings with much better corrosion resistance for Mg-8.5Li alloy were obtained by immersing in a solution of permanganate. The concentration of potassium permanganate was discussed. The surface morphology of the conversion coatings was observed by scanning electron microscopy (SEM), and the chemical composition was characterized by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The corrosion resistance of Mg-8.5Li alloy and permanganate conversion coatings were investigated by means of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and mass loss measurement. The results show that the coatings with cracked morphology are homogeneous and uniform. The corrosion resistance of permanganate conversion coatings is improved greatly compared with that of Mg-8.5Li alloy. When the concentration of permanganate is 4.0 g/L, the corrosion current density is the smallest, capacitance arc is the biggest and corrosion rate reaches minimum and the conversion coating presents the best corrosion resistance behavior.