Gelcasting process of Al₂O₃/Ni nanocomposites

Al₂O₃/Ni nanocomposites were fabricated by gelcasting an Al₂O₃/NiO mixture, followed by reduction-sintering process. Dispersant quantity was optimized at 1.75 wt.% with measurement of rheological behaviors to determine the best dispersion state of binary oxides colloidal suspension for casting. Hydrogen reduction of NiO in the shaped body was accomplished successfully through pore channels of debinded organic chemical volume. The reduced Al₂O₃/NiO green body comprised Al₂O₃ and Ni phases without a reacted phase. One-dimensional diametric shrinkage reached 21% after pressureless sintering treatment, while fairly high strength of 586 MPa was maintained. Dispersed Ni particles revealed typical ferromagnetic behavior in the Al₂O₃ matrix. Near-net shaping and sintering for the Al₂O₃/Ni nanocomposite were also achieved by present gelcasting, indicating applicability of this process for industrial use.