Electrodeposition and Characterization of Ni-ZrO₂ Nanocomposites by Direct and Pulse Current Methods

Direct Current (DC) and Pulse current (PC) methods were used to get nanocrystalline Ni-ZrO₂ composites from tri-ammonium citrate bath. In the electrocomposite formation, the ZrO₂ particles were transported to the surface by mechanical action and got entrapped in the nickel matrix. Incorporation of ZrO₂ in the nickel matrix was found to increase with current densities when DC was employed. Beyond 2 A/dm², their incorporation became saturated when PC was used. PC method offered better electrocomposites than DC method producing finer grains and uniform surface. Scanning electron micrographs (SEM) reveals that smaller grains and uniform distribution of Zirconia particles in the nickel matrix. The increased hardness of Ni-ZrO₂ electrocomposite coatings is due to incorporation of ZrO₂ particles in the nickel matrix and also changes in grain size. Incorporation of ZrO₂ particles in Ni-matrix favoured the enhanced microhardness and corrosion resistance of the deposit.