Abstract
A study was made on electrodeposition of nickel from nickel ethylene-diamine chelate solution for the purpose of determining the optimum condition of electrolysis.
The following results were obtained.
(1) Ethylene-diamine (En) and nickel ion formed chelate compound of Ni(En)2 in pH range of 6.0-7.8 and of Ni(En)3 in the range of above 7.8. The latter compound Ni(En)3 was found to give no nickel deposit on electrolysis.
(2) Bright nickel deposits were obtained from chelate solutions of pH 6.0-7.2 and the brightness was found to increase with the increase of the addition amount of En, but current efficiency decreased with the increase of En.
The optimum condition of the electrolysis was as follows.
NiCl2⋅6H2O(or NiSO4⋅7H2O)……0.4mol/l
En……0.8-1.0mol/l
pH……6.0-7.2
Temperature……room temperature
Current density 0.5-1.25amp./dm2
The current efficiency was about 80% at the density of 0.5amp./dm2 and about 60% at 1.25 amp./dm2.
(3) The nickel deposits obtained from Ni-En baths were fine grains in crystal structure with preferred orientation of (111).
