镁锂合金的锰系磷化膜

Study on manganese phosphating film of Mg-Li alloy

为提高镁锂合金的耐蚀性,在镁锂合金表面制成了耐蚀性能较好的锰系磷化膜,采用极化曲线、电化学阻抗谱、时间电位曲线等电化学测试方法及SEM、EDS分析方法,研究了镁锂合金锰系磷化主盐浓度、磷化时间、金属离子、磷化助剂对磷化膜耐蚀性的影响,测试了试样在加入不同磷化助剂磷化时表面电极电位随时间的变化,观察了不同时间、温度条件下磷化膜的微观形貌,对比了锰系、锌系磷化膜的微观形貌,分析了膜层的组成.结果表明,随主盐高锰酸钾浓度的增加,膜层耐蚀性增加,适宜的磷化时间为20min,镍离子对磷化的促进作用大于铜离子,柠檬酸钠为较好的磷化助剂,锰系磷化膜较平整光滑,但膜层带有裂纹,随温度的增加裂纹加深,膜层的主要成分为磷酸锰.

In order to improve the corrosion resistance of Mg-Li alloy,manganese phosphate coating was prepared on the surface of Mg-Li alloy.The effects of concentration of phosphating main salt,phosphating time,metallic ion and phosphating accelerator on the corrosion resistance of Mg-Li alloy phosphating films were studied using SEM,EDS and some electrochemical test methods such as polarization curves,EIS and time potential curve.Changes of the surface electrode potential with time in different phosphating accelerators for the samples were tested.Micromorphologies of the phosphating films at different time and temperatures were observed and compared,and components of the films were also analyzed.The results indicate that the corrosion resistance is enhanced with the increasing concentration of main salt KMnO4,and the proper phosphating time is 20 min.Nickel ion is better than copper ion to accelerate the phosphating,and citric acid is a good kind of phosphating accelerator.Manganese phosphating film is even and smooth,but with crackles.With the temperature increased,the crackles become deeper;the main component of the phosphating film is phosphate.