Preparation of Al2O3-ZrO2-Ni nanocomposite by pulse electric current and pressureless sintering

Dense Al2O3/(ZrO2 + Ni) nanocomposites were prepared by pulse electric current sintering (PECS) at 1350 C for 5 min or by pressureless sintering (PLS) at 1600 C for 1 h. Nanometre-sized Ni particles (about 10 nm) were first introduced into the (Al2O3 + ZrO2) powder mixtures by using a coating technique. The presence of the Ni particles prohibited the coarsening of the composite prepared by PLS, but enhanced the grain growth of the composites prepared by PECS. The sub-micron-sized ZrO2 particle acted as a microstructural stabiliser that slowed down the coarsening of matrix grains in the composites prepared by both processes. Due to microstructural refinement, the strength of the Al2O3/(5% ZrO2 + 1% Ni) nanocomposite was about 40% higher than that of Al2O3 alone. 25 refs.