电极电位解释阳极氧化物的生长

Electrode Potential Explaining the Growth of Anodic Oxides

摘要:

多孔阳极氧化物的形成机理至今仍不清楚。研究者倾向于用物理模型来解释它们的生长机理，很少报道电极电位对阳极氧化的影响，因为阳极氧化电压远远高于电极电位。创新性地引入电极电位理论、氧气气泡模型以及离子电流和电子电流理论来解释3种金属（Ti、Zr和Fe）在低电压下多孔阳极氧化物的生长机理。以Ti在0.5%（质量分数）NH₄F水溶液中的阳极氧化为例，计算了电极电位，解释了在低电压下多孔阳极氧化物的形貌。结果表明，多孔阳极氧化物的生长由离子电流和电子电流的比值决定。阳极氧化过程中的金属分为2类：一类是容易形成致密氧化层的金属，另一类是容易导致氧气析出的金属。相应的，电解液也被分为2类：容易形成致密氧化层的电解液和容易导致氧气析出的电解液。

Abstract:

The formation mechanism of porous anodic oxides remains unclear till now. The classical field-assisted dissolution (FAD) theory cannot explain the relationship between the current curve and FAD reaction, and the influence of the electrode potential on anodization is rarely reported. The electrode potential theory, oxygen bubble model and the ionic current and electronic current theories were introduced to explain the growth of porous anodic oxides of three metals (Ti, Zr and Fe). Taking the anodization of Ti in aqueous solution containing 0.5wt% NH₄F as an example, the electrode potential was calculated, and the morphology of porous anodic oxides was investigated at low voltages. Results show that the growth of porous anodic oxides is determined by the ratio of the ionic current to the electronic current. During the anodization, metals are classified into two groups: one is easy to form the compact oxide layer, and the other is easy to induce oxygen releasing, thus forming oxygen bubbles. The electrolyte is also classified into two groups correspondingly: compact oxide layer-assisted electrolyte and releasing oxygen-assisted electrolyte.