以三乙醇胺为辅助配位剂碱性电沉积锌镍合金的电化学行为

Electrochemical Behavior of Zinc-Nickel Alloy Coating Electroplated in Alkaline Bath Containing Triethanol Amine as Auxiliary Complexing Agent

碱性镀液中镍离子的配位剂对镀层影响很大,目前对其多种配位剂共同使用的研究较少。研究了以四乙烯五胺为镍离子的主配位剂,三乙醇胺(TEA)为镍离子辅助配位剂的锌镍合金碱性电沉积体系,在不同三乙醇胺含量和电流密度下在Q235低碳钢表面电沉积锌镍合金的电化学过程。结果表明:随着镀液中三乙醇胺含量增加,电流效率和沉积速率下降,溶液电阻、电荷传递电阻和电感先增加后降低,在n(TEA)∶n(Ni2+)=2.0时阴极极化最大;增加阴极电流密度使镀液的沉积电位变负,阴极极化增大,同时使电荷传递电阻和电感变小;该碱性电沉积锌镍合金的过程受电化学步骤和扩散步骤混合控制。

Zn-Ni alloy coating was electroplated on Q235 steel substrate while an alkaline bath containing tetraethylene pentamine as main complexing agent and triethanol amine(denoted as TEA) as the auxiliary complexing agent was adopted.The effect of content of TEA and current density on the electrochemical behavior of Zn-Ni alloy coating was examined.It was found that the current efficiency and deposition rate declined with increasing content of TEA,while the solution resistance,charge transfer resistance and inductance rose initially and then declined.Furthermore,the strongest cathodic polarization was obtained when the molar ratio of TEA to Ni + was adjusted as 2.0.In the meantime,increasing cathodic current density led to more negative deposition potential of the plating solution as well as enhanced cathodic polarization and reduced charge transfer resistance plus inductance.In one word,the electrodeposition process of Zn-Ni alloy coating in the title alkaline bath was jointly controlled by electrochemical procedure and diffusion procedure as well.