柠檬酸钠对Ni-Sn-Mn合金电沉积行为及耐蚀性的影响

为了探索柠檬酸钠在Ni-Sn-Mn合金电沉积过程中的作用机制,采用扫描电子显微镜、阴极极化曲线、循环伏安曲线、电化学阻抗、恒电位阶跃及Tafel曲线等方法,研究了柠檬酸钠的浓度对Ni-Sn-Mn合金的表面形貌、电沉积行为及耐蚀性的影响。结果表明:随着柠檬酸钠浓度的增加,Ni-Sn-Mn合金电沉积的阴极极化增强,沉积电位负移,电荷转移电阻增大;不同柠檬酸钠浓度下的电沉积过程均不可逆,并且电结晶过程遵循由电荷传递过程和扩散过程共同控制的三维连续成核机制;当柠檬酸钠的浓度为0.5mol/L时,镀层最为均匀、细密,在质量分数为3.5%的NaCl溶液中具有最正的自腐蚀电位及最小的自腐蚀电流密度,耐蚀性最好。

Effect of Sodium Citrate on Electrodeposition Behavior and Corrosion Resistance of Ni-Sn-Mn Alloy

In order to explore the action mechanism of sodium citrate in the electrodeposition of Ni-Sn-Mn alloy,the effect of different concentrations of sodium citrate on the surface morphology,electrodeposition behavior and corrosion resistance of Ni-Sn-Mn alloy was investigated by scanning electron microscopy,cathodic polarization curve,cyclic voltammetry curve,electrochemical impedance spectroscopy,constant potential step and Tafel curve.The results showed that with the increasing of sodium citrate concentration,the cathodic polarization of Ni-Sn-Mn alloy electrodeposition enhanced,the deposition potential shifted negatively and charge transfer resistance value increased. The electrodeposition process under different concentrations of sodium citrate were all irreversible,and followed the mechanism of three dimensional continuous nucleation that controlled by the charge transfer process and diffusion process.The coating prepared with sodium citrate 0.5 mol/L was uniform and compact,and exhibited the best corrosion resistance in 3.5%(mass fraction)NaCl solution,it has the most positive self-corrosion potential and the smallest self-corrosion current density.