Electrolyte Temperature Dependency of Electrodeposited Nickel in Sulfate Solution on the Hardness and Corrosion Behaviors

The hardness and corrosion resistance of nickel (Ni) deposit on a substrate could be reached by controlling electrolyte temperature during deposition. In this research, the electrodeposition of Ni at various temperatures of electrolytes was performed. Electrodeposited Ni films using an optical digital camera, X-ray diffraction (XRD), scanning electron microscope with energy-dispersive x-ray spectroscopy (SEM-EDS), microhardness test, and potentiostat were investigated. The bright deposit occurred at ۲۵ °C; an increase in the temperature to ۴۰ °C leads to a change of color into semi-bright. Shifting to a higher temperature would increase the deposition rate, cathodic current efficiency, grain size, and oxygen content. The X-ray reflections in the planes (۱۱۱), (۲۰۰), and (۲۲۰) correspond to as the Ni phase with a face center cubic (FCC) crystal structure. Decreasing crystallite size and micro-strain promoted to reach high hardness. Increasing the corrosion current density implies decreasing polarization resistance. The sample at the lowest electrolyte temperature has a better hardness, and the sample formed at ۲۵ °C sulfate solution had less corrosion rate.

Keywords:

Ni Films , Electrodeposition , Crystallite Size , Micro-strain