锌-铁合金异常共沉积中锌沉积机理的研究(Ⅲ)——Zn阴极沉积的动力学研究

Deposition Mechanism of Zn in Anomalous Electro Codeposition of Zn Fe Alloy (III)——Dynamic Study on Cathodic Deposition of Zn

为了从动力学角度论证电极反应机理的正确与否 ,采用稳态极化曲线法 ,测得电极反应的动力学参数分别为 :阴极过程Tafel斜率为 - 0 .114V ,表观传递系数α→ =0 .5 19,阳极过程Tafel斜率为 - 0 .0 4 1V ,表观传递系数α→ =1.4 35 ,控制步骤化学计量数ν =1。从电极反应速度的理论动力学方程中求得各动力学参数 ,阴、阳极Tafel斜率分别为 - 0 .118V和 - 0 .0 39V ,与实验值非常吻合。最后根据多电子反应的电化学动力学方程 ,运用表观传递系数进一步论证了Zn阴极沉积电极反应机理的正确性。

The electrode reaction mechanisms during the anomalous electro codeposition of Zn Fe alloy coating were validated in the point of view on dynamic, with the dynamic behavior of the Zn cathode deposition to be emphasized. Thus the steady state polarized curve method was used to determine the kinetic parameters of the electrode reactions. As the results, the Tafel slopes of the cathodic and anodic processes were measured to -0.114 V and (-0.041 V), respectively. The corresponding apparent transfer coefficients were determined to be α→=0.519 and α→=1.435, respectively, while the chemical measurement number for the rate controlling step,ν, was determined to be 1. The cathodic and anodic Tafel slopes were calculated to be -0.118 V and -0.039 V, respectively, in accordance with the theoretical kinetics equation, which agreed well with the experimentally measured ones. Accordingly, the electrode reaction mechanism for the electrodeposition of the Zn cathode was further verified using apparent transfer coefficient, in the light of the electrochemical kinetics equation of multi electron reaction.