Effect Of Impurity Ions On The Electrocrystallization Behavior Of Nickel In Industrial Electrolyte

The composition of the industrial electrolyte of the nickel sulfide soluble anode / sulfate system is complex.Due to its production process,it will inevitably contain various impurity ions,which complicates the already complicated electrocrystallization process.Therefore,the effect of impurity ions on the electrocrystallization behavior of nickel in the industrial electrolyte was studied.In this paper,the traditional three-electrode system is used,and the nickel electrode is used as the working electrode.Through the cathodic polarization method,cyclic voltammetry,and chronoamperometry,the copper ion,ferrous ion,and zinc ion of different mass concentrations are analyzed for the initial behavior of nickel electrocrystallization.The effect of electrodeposition experiments was performed using Hall grooves.The microstructure morphology,grain size,and growth mode were observed by scanning electron microscope(SEM),and the grain orientation was analyzed by XRD.The results show:(1)The growth of nickel in the industrial electrolyte is performed through the nucleation / growth process.The nucleation mode of nickel basically follows the Scharifker-Hills model.The growth mode is the spiral dislocation growth mode.(200)surface growth;(2)The addition of copper ions of different mass concentrations reduces the nickel electrocrystallization overpotential and the initial deposition potential of nickel shifts positively,which does not change the process of nickel passing through nucleation / growth;the addition of copper ions causes it to nucleate The relaxation time tm gradually decreases,the peak current Im gradually increases,and the copper ion mass concentration is 0.5g / L,1g / L,and the step potential is-0.85 V.It is in a three-dimensional continuous nucleation and a three-dimensional instant nucleation.In between,when the step potential is-0.90 V ~-1.00 V,it is close to instantaneous nucleation.As the copper ion concentration increased to 1.5 g / L and 2 g / L,it changed from a three-dimensional continuous nucleation / growth mechanism to a three-dimensional instant nucleation.Nickel-copper electrolyte is more suitable for three-dimensional instantaneous nucleation / growth mechanism during electrodeposition.With the introduction of different mass concentrations of copper ions,nickel and copper are evenly distributed on the surface of the substrate.The size of the crystal grains becomes larger.The morphology of the sedimentary layer gradually changed from the original small spherical particles to a pyramid shape,and the growth mode was still dominated by spiral dislocation growth.The grain orientation of changed from(111)planes to(111),(220)plane growth.(3)During the electrocrystallization of nickel,the introduction of different mass concentrations of ferrous ions reduces the nickel elect rocrystallization overpotential,and the initial deposition potential of nickel shifts positively,which does not change the process of nickel passing through nucleation / growth..Compared with industrial electrolytes,when 0.5g / L and 1g / L ferrous ions are added,it conforms to three-dimensional continuous nucleation at low potential and three-dimensional instant nucleation at high potential.When 1.5g / L and 2g / L ferrous ions are added,it is more consistent with the three-dimensional instant nucleation.After adding ferrous ions to the industrial electrolyte,the growth mode of nickel does not change.With the addition of ferrous ions,the grain orientation is still dominated by(111)plane growth,and the intensity of the diffraction peaks changes with the change of the ferrous ion mass concentration.(4)In the nickel electrocrystallization process,the addition of zinc ions of different mass concentrations causes the initial deposition potential of nickel to shift positively,and the nickel electrocrystallization overpotential decreases;it does not change the process of nickel passing through nucleation / growth.Compared with industrial electrolytes,the addition of zinc ions conforms to the three-dimensional continuous nucleation / growth mechanism at low potentials and the three-dimensional instant nucleation / growth mechanism at high potentials;the addition of zinc ions at different concentrations does not change its spiral The dislocation growth method,with the increase of zinc ion concen tration,anomalous co-deposition of nickel and zinc occurred,and the grain size gradually increased.the grain orientation is still dominated by(111)plane growth,The diffraction intensity changes with the change of zinc ion mass concentration.