硫酸铈(Ⅳ)对镍沉积层晶粒细化和电结晶行为的影响

Effect of cerium(Ⅳ) sulfate on grain refinement and electrocrystallization behavior of nickel deposits

在工业电沉积镍的过程中,镍的晶粒尺寸将会直接影响其在工业生产中的使用情况。因此,细化沉积层晶粒就显得尤为重要。本文选用三电极体系,通过测试工业电解液中不同(0~1.5 g/L)硫酸铈(Ⅳ)浓度下阴极极化曲线、循环伏安曲线和计时电流曲线,探究硫酸铈(Ⅳ)对电沉积镍电结晶行为的影响规律;通过扫描电镜和X射线衍射对哈林槽实验获得的镍沉积层的晶粒尺寸和结构取向进行分析,探究硫酸铈(Ⅳ)对工业电解中镍沉积层晶粒细化及晶体生长取向的影响。结果表明:添加硫酸铈(Ⅳ)后,镍的起始沉积电位发生负移,阴极过电位增大,硫酸铈(Ⅳ)的加入对镍的电结晶起促进作用。未加入硫酸铈(Ⅳ)时,沉积层晶粒粗大不均匀;随着添加剂的加入,使镍沉积层晶粒明显细化;当硫酸铈(Ⅳ)的浓度为0.6 g/L时,峰值电流最大且形核弛豫时间最短,沉积层晶粒尺寸最小,细化效果最优,因此,0.6 g/L硫酸铈(Ⅳ)为硫酸铈(Ⅳ)的最优添加浓度。

In the process of industrial electrodeposition of nickel,the grain size of the nickel will directly affect its application in industrial production.Therefore,refinement of deposited layer grains is particularly important.In this paper,a three-electrode system was selected to investigate the influence of cerium( Ⅳ) sulfate on the electrocrystallization behavior of electrodeposited nickel by testing the cathodic polarization curve,cyclic voltammetry curve and timing current curve at different(0-1.5 g/L) cerium(Ⅳ) sulfate concentrations in industrial electrolytes.The grain size and structure orientation of nickel deposited layer were analyzed by SEM and XRD,and the effect of cerium(Ⅳ) sulfate on grain refinement and crystal growth orientation of nickel deposited layer in industrial electrolysis was investigated.The results show that the initial deposition potential of nickel is negatively shifted and the cathodic over potential increases after the addition of cerium(Ⅳ) sulfate,and the addition of cerium(Ⅳ) sulfate promots the electrocrystallization of nickel.When cerium(Ⅳ) sulfate is not added,the deposited layer has coarse and uneven grains.The nickel deposited layer grains are significantly refined with the addition of additives.When the addition concentration is 0.6 g/L,the peak current is the largest and the nucleation relaxation time is the shortest,the grain size of the deposited layer is the smallest and the refinement effect is the best,which is the optimal addition concentration of cerium(Ⅳ) sulfate.