Black nickel electrodeposition from a modified Watts bath

摘要

Black nickel coatings were electrodeposited on to steel substrates from a Watts bath containing potassium nitrate. The best operating conditions necessary to produce smooth and highly adherent black nickel were found to be NiSO_4 center dot 6H_2O 0.63 M, NiCl_2 center dot 6H_2O 0.09 M, H_3BO_3 0.3 M and KNO_3 0.2 M at pH of 4.6, i = 0.5 A dm~(-2), 7=25 deg C and t = 10 min. The modified Watts bath has a throwing power (TP) of 61 percent, which is higher than that reported, not only for nickel, but also for many other metals electrodeposited from different baths. The potentiostatic current-time transients indicate instantaneous nucleation. X-ray diffraction (XRD) analysis shows that the black nickel deposit is pure metallic nickel with Ni(111) preferred orientation.