Combined Effect of Sodium Lauryl Sulphate and Saccharin on Microstructure and Corrosion Performance of Electrodeposited Nickel Prepared from Modified Watts Bath

dditives in Watts bath influence the surface properties of the electrodeposited nanocrystalline nickel. The changes in the properties are led by the alteration in the nucleation and plating over-potentials ( E_n E_p ). A galvanodynamic polarization technique was used to determine the E_n E_p in the modified Watts bath. From all the commercially available additives, sodium lauryl sulfate (SLS) was used as an anti-pitting agent, and saccharin (SAC) was added as a grain refiner. The concentration of SAC was varied in the range from 1.5 to 10 ml/l while keeping SLS concentration constant at 1.1 g/l in order to see its effect on polarization potentials, surface roughness, and corrosion behavior. Refinement of surface roughness and crystallite size, corresponding to steady values of E_n E_p was obtained for SAC at 3 ml/l and SLS at 1.1 g/l. The deposits with fine crystallite size showed minimal passivation current density and highest polarization resistance.