Studies On The Effect Of Additives On The Electrodeposition Of Nickel In Ammonia Complex

The advantages for electrodeposition of metal in ammonia complex is expected to solve the problems in the production and application of nickel industry.However,it was found that the nickel deposit obtained from the ammonia complex system is black and quite brittle,which makes it difficult to expand the application.In this thesis,we propose to improve the morphology and properties of the electrodeposited nickel layer obtained from ammonia complex system by adding additive,and the effect of the anode material on the electrodeposition of nickel was studied.The main results are as follows.In the third chapter,the effects of the single and multiple additives on the electrodeposition behavior of nickel in ammonia complex system were studied using insoluble electrode(Ti/RuO2)as the anode.Results show that nickel layer with metallic luster can be prepared by the addition of sodium benzenesulfinate.Further study about the mechanism of sodium benzenesulfinate on nickel electrodeposition showed that sodium benzenesulfinate can play a role in inhibiting the reduction of nickel and refining grain resulting in the nucleation changes from instantaneous nucleation to continuous nucleation.Moreover,sodium benzenesulfinate can increase the formation resistance of intermediate product,reduce the capacitance of sodium benzene sulfonate and(NiOH)ads,promote the preferred orientation of the grains in the(111)crystal plane,and inhibit(200)and(311)crystal plane.During the long-term electrodeposition test,it was found that the sodium benzenesulfinate could be oxidized at the anode with consumption of 911 g/KAH.In the fourth chapter,the effect of sodium benzenesulfinate on the electroplating behavior of nickel in ammonia complex system was studied using nickel containing sulfur as the anode.Results showed that the ammonia concentration has a significant effect on the consumption of sodium benzenesulfinate.When the ammonia concentration was 1-2 mol/L,the consumption of sodium benzenesulfinate has the lowest consumption rate with 14.88?15.75g/KAH.Under the optimal condition with 1 mol/L NiCl2,2 mol/L NH3,4 mol/L NH4Cl,100 mg/L sodium benzenesulfinate,current density of 200 A/m2,electrolyte temperature at 50?,the current efficiency can reach to 99.01%.The obtained nickel deposits show bright metallic luster and has high purity.In the fifth chapter,the effect of sodium benzenesulfinate on the electrolytic nickel ammonia complex system was studied using nickel matte as anode.Firstly,the anodic dissolution process of nickel matte was studied.The current efficiency of the anodic dissolution of Ni2+ reaches to 69%when the electrodeposition was conducted under the current density of 100 A/m2 at 50?60 ? with 3?4 mol/L NH4Cl.In addition,purified electrolyte can be obtained by removing the impurities such as copper and iron in the anode electrolyte using activated nickel sulfide and ammonia.High quality film can be obtained after the addition of sodium benzenesulfinate and ammonia into the purified nickel electrolyte.