从碱性NH4OH/NH4Cl缓冲溶液中电沉积镍

摘要

The electrodeposition of nickel on steel and copper from alkaline NH4OH/NH4Cl buffer solutions was investigated by cyclic voltammetry (CV),chronopotentiometry (CP),chronoamperometry (CA) as well as an opto-digital microscope,glow-discharge optical emission spectroscopy (GD-OES),XRF,and SEM-EDS techniques.The aim was to obtain Ni coatings from weak alkaline solutions and to optimize the process.The electrolyte composition,pH,temperature as well as current and potential parameters of the process were optimized using the quality of Ni deposit as a criterion.The role of hydrogen evolution in the process was discussed.An influence of Co as an additive was also investigated.It was found that a small amount of Co catalyzes Ni deposition process and improves the quality and color of the deposit.Therefore,in the possible application,the Ni/Co codeposition should be seriously considered.It was also shown that for constant current deposition mode,the width of self-established potential range,revealed at the very beginning of the process by the chronopotentiometric E=f(t) curves,is related to the quality of the coating.%采用循环伏安、计时电势、计时电流以及光学数码显微镜、辉光放电光谱(GD-OES)、X射线荧光光谱分析(XRF)、扫描电镜能谱(SEM-EDS)等技术,研究碱性NH4OH/NH4C1缓冲溶液中镍在钢和铜上的电沉积,目的是从弱碱性溶液中获得镍镀层,并优化工艺过程.以镍镀层质量为指标,对电解液组成、pH、温度、电流、电势等工艺参数进行优化.讨论析氢在电沉积过程中的作用,并研究Co作为添加剂的影响.发现少量的Co可以催化Ni沉积过程、改善镀层的质量和颜色.因此,在可能的应用中,应认真考虑Ni/Co共沉积.研究还表明,对于恒电流沉积模式,镀层的质量与极化电势区间的宽度有关,此电势区间宽度由计时电势曲线E=f(t)力在沉积过程刚开始时的部分确定.