Effect of Versenium Hydrogensulfate on Properties of Nickel Coatings.

The salt of formula [H 2 EDTA 2+ ][HSO 4 - ] 2 (dihydrogen ethylenediaminetetraacetate di(hydrogen sulfate(VI)) was used to examine the physicochemical properties of the resulting Ni layer and evaluate the applicability of the salt as a new additive for Watts-type baths. The Ni coatings deposited from baths containing [H 2 EDTA 2+ ][HSO 4 - ] 2 were compared with those obtained from other baths. The nucleation of nickel on the electrode was proven to occur the slowest in the bath that contained the mixture of [H 2 EDTA 2+ ][HSO 4 - ] 2 and saccharin compared with other baths. The addition of [H 2 EDTA 2+ ][HSO 4 - ] 2 alone (bath III) generated a coating with a morphology similar to that obtained from bath I (without additives). Despite the similar morphology and wettability of the Ni-coated surfaces plated from various baths (all Ni coatings were hydrophilic with contact angles in the range of 68 to 77°), some differences in electrochemical properties were noted. The corrosion resistance for the coatings plated from baths II and IV containing saccharin (I corr = 1.1 and 1.5 µA/cm 2 , respectively) and the mixture of saccharin and [H 2 EDTA 2+ ][HSO 4 - ] 2 (I corr = 0.88 µA/cm 2 ), respectively, was similar or even better than the coating obtained from baths without [H 2 EDTA 2+ ][HSO 4 - ] 2 (I corr = 9.02 µA/cm 2 ).