氯盐氨性络合物体系电积镍的动力学研究

Kinetics Investigation of Nickel Electrodeposition in a Leaching Solution Containing Ammonia and Chloride

主要采用稳态极化曲线来初步探讨镍阴极电沉积的动力学规律。实验结果表明在NH_3·H_2O浓度为1.25～2.75mol·L^(-1)的范围之内,直接在电极上放电的络合离子形式为Ni(NH_3)^(2+)。拟合计算表明Tafel斜率为0.158V,表观传递系数为0.37,交换电流密度为1.57×10^(-7)A·cm^(-2),电极反应表观活化能为15.78kcal·mol^(-1)。在0.700～0.810V的电位范围内,第一电子传递反应为电极反应的速控步骤,而在较高的阴极化电位下,镍电沉积是混合步骤控制。

Kineties law of nickel electrodeposition from a leaching solutioncontaining ammomia and chloride was investigated by means of steady-state po-larization curves. The results indicate that Ni(NH_3)^(2+) is the direct dischargeion within ammonia concentration range from 1.25 to 2.75mol·L(-1).The ki-netics parameters were determined as follows: Tafel slope is 0.158 V, appar-ent transfer coefficien is 0.37, exchange current density is 1.57 ×10^(-7) A·cm^(-2), electrode reaction apparent activation energy is 15.78 kcal·mol^(-l).The first electron transfer reaction is the rate-determining step in the range ofvoltage from 0.700 to 0.810 V, however the electrode reaction is controlledby mixed step when the cathodic electrode polarization potential is made morenegative.