The Use of ZrO2 Waste for the Electrolytic Production of Composite Ni–P–ZrO2 Powder

Ni–P–ZrO₂ composite powder was obtained from a galvanic nickel bath with ZrO₂ powder. Production was conducted under galvanostatic conditions. The Ni–P–ZrO₂ composite powder was characterized by the presence of ZrO₂ particles covered with electrolytical nanocrystalline Ni–P coating. The chemical composition (XRF method), phase structure (XRD method) and morphology (SEM) of Ni–P–ZrO₂ and the distribution of elements in the powder were all investigated. Based on the analyses, it was found that the obtained powder contained about 50 weight % Zr and 40 weight % Ni. Phase structure analysis showed that the basic crystalline component of the tested powder is a mixed oxide of zirconium and yttrium Zr_0.92Y_0.08O_1.96. In addition, the sample contains very large amounts of amorphous compounds (Ni–P). The mechanism to produce the composite powder particles is explained on the basis of Ni²⁺ ions adsorption process on the metal oxide particles. Current flow through the cell forces the movement of particles in the bath. Oxide grains with adsorbed nickel ions were transported to the cathode surface. Ni²⁺ ions were discharged. The oxide particles were covered with a Ni–P layer and the heavy composite grains of Ni–P–ZrO₂ flowed down to the bottom of the cell.