高耐蚀性锌锰系磷化液的研究及磷化膜电化学分析

Investigation of the Zinc-Manganese Phosphating Solution and the Electrochemical Measurement of Phosphate Coatings with High Corrosion Resistance

应用正交实验优化碳钢磷化配方,制备的锌锰系磷化液沉渣少,性能稳定.磷化后的试片无需后处理,CuSO4点滴时间超过600 s,0.5 mol.L-1中性NaCl水溶液中浸渍时间超过24 h,膜层耐蚀性远优于国家标准,厚度(25μm)也符合要求.同时采用电化学阻抗(EIS)和塔菲尔曲线(Tafel)分析磷化膜耐蚀性,并与常规分析方法进行比较.结果表明,EIS和Tafel曲线分析能准确表征磷化膜的耐蚀性,且与盐水浸渍试验结果一致,可以减少使用常规方法引入的人为误差.

A steady phosphating bath for carbon steel was obtained with an orthogonal trial test. 25um phosphate coatings could be formed in this solution and the coatings could withstand over 600 s corrosion in CuSO4 test and more than 24 h corrosion in NaCl immersion test. Moreover, Electrochemical Impedance Spectroscopy and Tafel Polarization curves were used to evaluate the corrosion resistance of phosphate coatings. The results have shown that electrochemical techniques can accurately characterize the high corrosion resistance of phosphate coatings and the result obtained is in good agreement with 0.5 mol·L^-1 neutral NaCI immersion test. The electrochemical techniques are more reliable methods in the evaluation of phosphate coatings with lower artificial error.