铝-锌合金在氯化物-醋酸介质中的电化学活化机理

目的 研究商用Al-Zn(Zn 4%)合金在氯化物-乙酸介质中的电化学行为.方法 用传统电化学方法获得其电化学数据.通过利用扫描电镜(SEM)和定量能量色散X-射线分析(EDX),测试了金电极的表面特征.结果 研究发现,在氯化物溶液中,活性分解发生在一个非常负的电位上(-1.5V).这显著增加了该合金的电化学行为.其目的在于解释该合金给出的工作电位(-1.1V)、高效率、观察到的准均衡侵蚀和增强的电化学行为(-1.5V)之间的关系.提出了一个用来解释这一发现和利用铟离子来活化纯铝的标准模型.结论 研究发现铝的活化机制有2个:(ⅰ)当在表面上有足够的以准液体状态存在铟时,In-Al汞合金是造成活化作用过程(-1.5 V)的原因.这一过程是通过置换反应促进了Zn的表面富集.(ⅱ)在更高阳极电位处(接近-1.2 V),表面上铟的存在促进了氯化物的吸附过程,该过程使阳极反应去极化.

Electrochemical activation mechanism of aluminum zinc alloy in chloride and acetic medias

Aim The electrochemical behaviour of a commercial Al-Zn(Zn 4%) ally was studied in the presence of indium(III)(In3+) in chloride and acetic medias.Methods Obtaining its electrochemistry data with conventional electrochemical means.The surface characteristics of goldmetallized electrodes were examined by using canning electronmicroscopy(SEM) and quantitative energy dispersive X-ray(EDX) analysis.Results It was found that in chloride solutions,active dissolution takes place at very negative potentials(-1.5 VSCE).This significative enhancement in the electrochemical activity of the alloy was discussed.Our aim is to explain the relationship between the operating potential(-1.1 VSCE) given by the alloy,its high efficiency,its quasiuniform attack observed and the enhanced activity found(-1.5 VSCE).An unified model that explains this findings and the activation process of pure Al using In3+ is proposed.Conclusion It was found that two activation mechanism are operative on aluminum:(i) When sufficient amounts of In at the interface in quasi-liquid state are present,an In-Al amalgam is responsible for the activation process(-1.5 VSCE).This process is favoured by Zn reach zones that favours In enrichment at the interface by displacement reaction.(ii) At higher anodic potentials(near-1.2 VSCE),the presence of In at the interface facilitates a chloride adsorption process which depolarised the anodic reaction.