Fabrication of complex-shaped alumina/nickel nanocomposites by gelcasting process

Complex-shaped Al₂O₃/Ni nanocomposites with preserved multifunctional magnetic properties are successfully fabricated by a gelcasting process. Based on an investigation of the effects of suspension composition on the drying, debinding, and reduction-pressureless sintering processes, a stable Al₂O₃/NiO binary oxide aqueous suspension with optimal monomer, dispersant, and solid composition is defined. Wet gelcast bodies produced using this suspension system shrink by 4.72% during humidity-controlled drying, with a bending strength of the fully dried green body of 3.84±0.84 MPa. The interconnected void structure of the debound green body provides hydrogen reduction of dispersed NiO without metamorphosis or shrinkage. Al₂O₃/Ni nanocomposites with complex shapes are successfully produced by pressureless sintering, and exhibit appropriate strength (586±50 MPa) after 21.5% shrinkage. Dispersed Ni particles exhibit typical ferromagnetic behavior in the Al₂O₃ matrix. This study confirms that gelcasting is a viable process for fabricating industrially applicable Al₂O₃/Ni nanocomposites with balanced mechanical and magnetic properties.