铝合金在铈盐溶液中成膜过程的电化学阻抗谱研究  

Cerium(Ⅲ) Film Formation Process for Aluminum Alloys Observed with Electrochemical Impedance Spectroscopy

作　　者：顾宝珊[1] 刘建华[1] 

机构地区：[1]北京航空航天大学材料科学与工程学院

出　　处：《中国稀土学报》2007年第2期210-216,共7页Journal of the Chinese Society of Rare Earths

摘　　要：应用电化学阻抗谱(EIS)研究B95铝合金在0.01 mol.L-1CeCl3溶液中铈盐转化膜的形成过程和机制。结果表明:EIS变化可以清楚地显示B95铝合金在铈盐溶液中成膜的动态过程,稀土转化膜的成膜过程可以分成形成、成长和稳定平衡3个阶段;形成阶段以Al合金的溶解为主;在成长阶段随着时间的增加,转化膜不断增厚,铝合金基体的溶解已经被抑制;稳定平衡阶段,膜的成长与溶解已经达到平衡,通过EIS解析表明自然条件下生成的转化膜不致密,该阶段阻抗谱图等效电路与成长阶段相同,但阻抗谱包含两个时间常数;在成膜三阶段基础上提出了稀土转化膜的成膜模型;同时给出各阶段阻抗谱图等效电路及其阻抗表达式。Electrochemical impedance spectroscopy （EIS） of B95 aluminum alloy in 0.01 mol·L^-1 CeCl3 solution was investigated to study the film formation and mechanism. Typical EIS spectrum changes were clearly observed during the film formation processes. EIS results indicated that Ce（ Ⅲ ） film can form on the aluminum surface by chemical treatment. EIS was used for in situ and continuously to observe the formation of cerium when aluminium alloy was immersed in 0.01 mol·L^-1 CeCl3 solution. Research was done on the process of film formation and mechanism of B95 aluminum alloy through the changes of EIS in the process. Followed was analysis on the tested EIS based on equivalent circuit. The result showed that the variation of EIS can clearly display the film change of B95 aluminum alloy in cerium solution. The film formation process of RE conversion film can be divided into three stages： formation stage, growth stage and stable equilibrium stage. The formation stage mainly involved the solution of aluminum alloy. In growth stage, the conversion film was gradually thickening with the lapse of time and the solution of aluminum alloy was inhibited. In stable equilibrium stage, the film growth and solution had reached a balance. The analysis of EIS showed that the conversion film developed in natural environment was not compact and EIS equivalent circuit in this stage was identical to that in growth stage, but the impedance spectrum contained two time constants. Based on the three stages the film formation model was proposed, meanwhile, the EIS equivalent circuit and the impedance expressions in different stages were also presented.

关 键 词：铝合金 交流阻抗谱 Ce转化膜模型 成膜过程 稀土 

分 类 号：O646.6[理学—物理化学] TG133.2[理学—化学]