Processing and properties of Al2O3 nanocomposites reinforced with sub-micron Ni and NiAl2O4

A new process has been developed to produce sintered α-Al2O3 reinforced with sub-micron Ni particles. The process is based on the infiltration of ceramic preforms with liquid salts, which are reduced during pressureless sintering to form metal particles. The reduction occurs within the open pores of the ceramic preform, after evaporation of the metal salts into the gas phase. By controlling the partial pressure of oxygen during the sintering process, a reaction between the Ni particles and the alumina matrix can be invoked to form Ni-spinel (NiAl2O4) particles. Three-point bending experiments show an increase in strength for the nickel-reinforced alumina and a significant increase for the spinel-reinforced alumina.