Effect of pyridine and picolines on the electrocrystallisation of nickel from sulphate solutions

The effect of pyridine, 2-picoline and 4-picoline on current efficiency (CE), deposit morphology, crystallographic orientation and polarization of the cathode during electrodeposition of nickel from acidic sulphate solutions containing boric acid were investigated. These additives were found to have no significant effect on current efficiency. However, the nickel deposits obtained were smoother, more compact and more leveled in case of picolines than with pyridine. The (200) plane was the most preferred plane and was not affected by the presence of these additives in the electrolyte. Each of the additives polarized the cathode with the order of polarization being 4-picoline>2-picoline>pyridine. The quality of the deposit was improved by these additives in the order 4-methyl pyridine>2-methyl pyridine>pyridine.