铝合金阳极化膜上铈转化膜沉积的电化学研究

Electrochemical Investigation of Cerium Conversion Coatings Deposited on Porous Film of Anodized Aluminum

阳极氧化膜在含 1g/LCeCl3和 2 .7g/LH2 O2 的水溶液中阴极电解可以在其表面沉积富铈转化膜 .用循环伏安、φ t和j t曲线等电化学测试方法对转化膜成膜反应进行了研究 ,以期获得对成膜机理的深入了解和证实根据其它工作提出的成膜机理 .研究结果表明铈转化膜的生成包括阳极氧化膜的化学溶解和 4价铈化合物的电化学还原两个过程 ;在阴极电位达到析氢电位之前 ,这两个过程主要是由H2 O2 在阴极的电还原改变了阴极表面附近溶液的局部pH值引起的 ,而O2 的还原通常不能引起这两个过程的发生 .

Cerium-rich conversion coatings was deposited on porous film of anodized aluminum by cathodic electrolysis in a solution containing 1 g/L CeCl3&middot7H2O and 2.7 g/L H2O2. Electrochemical and chemical reactions related with coating formation were studied using electrochemical methods such as cyclic voltammetry, ψ-t curve and j-t curve tests. It was revealed that the formation of cerium conversion coatings involves a chemical dissolution process of anodized film and an electroreduction process of 4-valent-state cerium compound. Reduction of H2O2 was considered to be the major factor responsible for the occurrence of the two processes, by changing the local pH at surface of anodized film before cathodic potential reached up to hydrogen evolution potential. While the reduction of O2 was unable to trigger the occurrence of the above processes.