关键词: 化学镀, 极化, 电化学机理, 混合电势理论, 沉积速率

Abstract: Electrochemical behaviors of electroless nickel (EN) plating in three systems, namely, cathodic, anodic and complete bath solutions were investigated by polarization methods. The curves in the complete baths were not entirely consistent with those expected from a combination of the anodic and cathodic polarization curves, which implies that the anodic and cathodic reactions of the EN plating are interdependent. The effects of concentration of nickel ions, hypophosphite and pH on the polarization parameter and deposition rate in a complete bath were also discussed and compared by performing electrochemical and gravimetrical measurements. Based on these variations in the deposition potential and current density, a kinetic expression employing the Butler-Volmer equation is suggested and verified with the experimental findings. It was confirmed that the electroless nickel deposition processes in the present system was under a mixed control. The apparent activation energy determined by electrochemical methods was about 42.89 kJ·mol^-1.

Key words: electroless plating, polarization, electrochemical mechanism, mixed potential theory, deposition rate