Ni-Fe合金共沉积的电化学行为

Electrochemical behaviors of Ni-Fe alloy codeposition

通过线性扫描、循环伏安、交流阻抗方法,研究了柠檬酸溶液中Ni-Fe合金共沉积的电化学行为。结果表明,Ni-Fe合金的共沉积为异常共沉积,Fe发生了欠电位沉积;增大FeSO4浓度,阴极极化增大,镀层中Fe含量升高,镀层的耐蚀性降低;柠檬酸起增大电流密度、减小阴极极化、促进Ni-Fe合金共沉积的作用;光亮剂增大阴极极化,对Fe2+离子的阻碍作用大于对Ni2+离子的阻碍作用;陈化作用有利于阴极极化的增大和镀层光亮度的提高;Ni-Fe合金的共沉积过程为电化学步骤控制。XRD表明Ni-Fe合金为面心立方固溶体晶体结构,SEM表明镀层表面光亮平滑。

Electrochemical behaviors of Ni-Fe alloy codeposition in citric acid solutions were studied by the methods of linear potential sweep, cyclic voltammetry and A. C. impedance. From the results it can be concluded that Ni-Fe alloy codeposition is anomalous codeposition and Fe shows underpotential deposition. With increasing the concentration of FeSO4, both the cathodic polarization and the Fe content in the deposits increased, and the cor- rosion resistance of the deposits decreased. Citric acid played a role of increasing current density, decreasing cathodic polarization and promoting the Ni-Fe alloy codeposition. The brightener increased the cathodic polarization and its baffling to the deposition of Fe^2＋ ions was larger than that of Ni^2＋ ions. The aging of the electrolyte was favor of increase cathodic polarization and the improvement of the deposit＇s brightness. The codeposition process of Ni-Fe alloy was an electrochemical determinative step. The XRD pattern showed that Ni-Fe alloy was a FCC solid solution with a crystal structure, the SEM pattern indicated that its appearance was smooth and bright.