Influence of ethanol on the electrocodeposition of Ni/Al2O3 nanocomposite films

The effect of ethanol on the electrocodeposition of nickel alumina nanocomposites was investigated using an acidic nickel sulfamate electrolyte. The surface charge and sedimentation behaviour of the 13 nm alumina particles in the nickel plating bath were characterized as a function of the ethanol concentration and the pH of the electrolyte. High ethanol contents cause a decrease in the surface charge and dispersion stability of the alumina particles in the plating electrolyte. The effects of the deposition conditions, i.e. ethanol content, current density, and particle content of the electrolyte on the codeposition of nickel alumina composites were investigated systematically. Low values of current density and high amounts of ethanol in the plating bath were found to be beneficial for the particle entrapment. The structure as well as the microhardness of the nickel films were investigated as a function of the electrolyte composition and the particle incorporation. A textural modification combined with a distinct grain refinement was found with increasing ethanol content of the electrolyte and due to the alumina incorporation. The microhardness of the layers increased with decreasing ethanol content of the electrolyte and increasing nanoparticle incorporation.