双层镀镍体系的电化学行为

本文用极化曲线、双电层微分电容曲线、循环伏安法和恒电流暂态法研究了双层镀镍体系中,镍离子还原的电极过程和添加剂在电极表面的吸附作用。实验结果表明,镍离子在阴极的还原过程受电荷转移步骤控制。虽然有机添加剂的加入增大了镶离子还原的超电势,但不会改变电极过程的控制步骤。在所加入的添加剂中,糖精的吸附能力最强,糖精分子在电极表面吸附时,随着电极电势变负由直立吸附转变为平卧吸附,此时糖精分子中的硫容易进入光亮镍镀层中,从而增加了双层镍镀层间的电势差,恒电流暂态法结果表明,在阴极上还原的镍离子直接来自溶液,不存在前置吸附步骤。

THE ELECTROCHEMICAL BEHAVIOUR OF THE SYSTEM OF PLATING DUPLEX NICKEL LAYERS

In the system of plating duplex nickel layers, the electrode process of Ni2 reduction and the adsorption of additives on the electrode surface are studied dy means of polarization curves, differential capacity curves of electric double layer, cyclic voltammetry and transient galvanostatic method. Experimental results show that the reduction process of Ni2 on the cathode is controlled by the step of charge-transfer. Though the existence of organic additives increases the over potential of reduction of Ni2 , the rate-determining step of electrode process is not changed. The experimental result of transient galvanostatic method shows that Ni2 that reduce on the cathode comes directly from solution and there is no preceding adsorping step.