Effect of organic additives on the hardness of ni electrodeposited from sulfamate and watt's solutions

Ni electrodeposition was galvanostatically conducted over the current density range of 1-5000 A/m² in unagitated sulfamate and Watt's solutions containing polyethylene glycol (PEG) or saccharin at 323 and 313 K, respectively, to examine the effect of the content of C and S in deposits and texture on the hardness of the deposited Ni. The content of C in Ni deposited from Watt's solutions containing PEG was significantly larger than that from the sulfamate solutions. There was little difference in S content in deposits between sulfamate and Watt's solutions containing saccharin except for 2000 A/m². The hardness of deposited Ni increased with C and S content in deposits, and the degree of increase in hardness decreased at S contents above 0.02 mass%. The texture of deposited Ni changed from the field-oriented texture type to the unoriented dispersed type when C and S were codeposited with Ni by addition of PEG and saccharin. The hardness of unoriented dispersed type of Ni was larger than that of the field-oriented texture type.