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采用化学转化法在镁锂合金表面制备了外观深灰色、结构均匀致密、耐蚀性能良好的锌锰磷酸盐转化膜,并研究了磷化温度对磷化膜性能的影响。采用扫描电子显微镜(SEM)、能谱(EDS)仪、X射线光电子能谱(XPS)和X射线衍射(XRD)仪对膜层的表面形貌、化学组成及结构进行了表征。采用动电位极化曲线、电化学交流阻抗(EIS)和腐蚀失重实验对磷化膜的耐蚀性进行了研究。结果表明,锌锰磷化膜主要由Zn、Zn3(PO4)2、MnHPO4、Mn3(PO4)2组成。锌锰磷酸化膜起到了保护镁锂合金的作用,提高了镁锂合金的耐蚀性,当磷化温度为45℃时,磷化膜的腐蚀电流密度最低,腐蚀速率最小,耐蚀性能最好。
The chemical conversion method was used to prepare zinc-manganese phosphate conversion coating with dark gray appearance, uniform structure and good corrosion resistance on the surface of Mg-Li alloy. The effect of phosphating temperature on the performance of the phosphate coating was also studied. The surface morphology, chemical composition and structure of the coatings were characterized by SEM, EDS, XPS and XRD. The corrosion resistance of the phosphate coating was investigated by potentiodynamic polarization curve, electrochemical impedance spectroscopy (EIS) and corrosion loss test. The results show that the zinc-manganese phosphate coating mainly consists of Zn, Zn3 (PO4) 2, MnHPO4 and Mn3 (PO4) 2. Zinc manganese phosphide film plays a role in protecting the magnesium-lithium alloy and improves the corrosion resistance of magnesium-lithium alloy. When the phosphating temperature is 45 ℃, the corrosion current density of phosphating film is the lowest, the corrosion rate is the smallest, and the corrosion resistance is the best it is good.