Abstract:The electrodeposition of black Ni-Co alloy film from Watts nickel solution and the effects of benzotriaozole and imidazole as the additives were studied. The electrolyte consists of NiSO₄, NiCl₂, H₃BO₃, CoSO₄ and KNO₃. The cathode current efficiency and the throwing power of the solution and the film adhesion to the mild steel metallic foil were determined by standard methods. The crystal structure, lattice parameter, crystal orientation and crystal size were analyzed by X-ray diffraction (XRD). Moreover, the surface morphology and elemental composition of the black Ni-Co alloy films were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) techniques. The darkness of the black films increases with increasing the incorporation of Co ion into the films. The XRD studies reveal that the black Ni-Co alloy films exhibit Ni (111) as the preferred orientation.

Key words: additive; electrodeposition; black Ni-Co alloy; adhesion