氯化铈对铝合金铬酸盐转化膜防护性能的影响

摘要

The corrosion resistance of the chromate conversion coatings (CCCs) formed on AA6061 in chromate solutions with cerium chloride (0 ～ 60 mg/L) as additive was investigated by electrochemical measurement technology. The results of potentiodynamic polarization curves showed that the values of the pitting corrosion potential (Epit) and corrosion potential (Eoorr) of the CCCs raised greatly by adding a small amount of CeCl3 (20～40 rng/L). The electrochemical impedance spectroscopy (EIS) showed that the values of normalized Rp also greatly increased. The two tests indicate that an appropriate amount of CeCl3 (20～40 mg/L) can improve effectively the corrosion resistance of the CCCs, whereas an excessive CeCl3 (e. g 60 mg/L) may deteriorate the property of the CCCs.%采用电化学方法研究了6061铝合金在以CeCl3(0～60 mg/L)为添加剂的铬酸盐处理液中所得转化膜的防护性能.极化曲线测试结果表明,加入适量的CeCl3(20～40 mg/L),使电极的腐蚀电位Ecorr和点蚀电位Epit提高很多;电化学阻抗(EIS)测试结果表明,加入CeCl3后,膜层的阻抗大幅度增加.研究表明,加入适量的CeCl3可以有效改善膜层的防护性能,而过量的CeCl3(60 mg/L)却使其性能变差.