高纯铝阳极氧化膜的电化学行为研究

The electrochemical behavior of anodic oxide film on high purity aluminum

为考察氧化膜状态对其电化学性能的影响,采用电化学方法研究了高纯铝阳极氧化膜在磷酸二氢钠缓冲溶液中的电化学性能.测试结果表明,高纯铝氧化膜的阴极极化过程分为3个阶段:1)电流密度变化较小而电位迅速负移,系克服氧化膜阻挡层电阻阶段;2)电流密度迅速增大而电位变化较小的析氢阶段;3)电流密度变化较小而电位迅速负移的氢离子扩散控制阶段.氧化膜具有单向导通性质,其阻抗大小由阻挡层决定,阻挡层愈厚,氧化膜的阻抗愈大.氧化电压与阻挡层的厚度成正比,在硫酸、草酸和磷酸溶液中阻挡层的成长率约为1 nm/V.

To investigate the effect of oxide film state on its electrochemical characteristic,the electrochemical performance of anodic aluminum oxide film on high purity aluminum was studied in the buffer solution of sodium dihydrogen phosphate by using electrochemical method.The results indicated that the cathodic polarization process of the oxide film could be divided into three stages.In the initial stage,the current density was small and the potential shifted to the negative quickly.In the second stage（hydrogen evolution stage）,the current density increased rapidly while its potential changed a little.In the last stage（diffusion-controlled stage）,the current density changed small and the potential shifted to negative rapidly.The anodic aluminum oxide film had single wizard-pass nature,and its impedance was controlled by the barrier layer.The thicker the barrier layer,the greater the impedance.The oxidation voltage was proportional to the thickness of barrier layer,and the growth rate of the barrier layer was about 1 nm in the sulfuric acid,oxalic acid and phosphoric acid solution.