Effect of the addition of different sintering aids on the densification behavior of zirconia-toughened alumina nanocomposite powder

In the present study, Al2O3-5 wt.% ZrO2 nanocomposite powder was fabricated via the sol gel method, and then the sintering behavior was investigated using various sintering aids (MgO, TiO2 and MgO/TiO2) at different temperatures. In this regard, the size and structure of fabricated powder, and hardness, fracture toughness and density of sintered samples were studied. The results of X-ray diffraction indicated the presence of alpha-alumina and tetragonal zirconia. Scanning electron micrographs revealed agglomerated nanometer-sized spherical particles ranging in size from 60 to 150 nm. Energy-dispersive X-ray mapping micrographs also demonstrated the homogeneous dispersion of zirconia in alumina. Moreover, density results indicated that using 0.5 wt.% MgO/0.5 wt.% TiO2 produced the best results, as the relative density reached 95 % at 1 500 degrees C. Finally, it was observed that the presence of MgO and TiO2 induces higher hardness and lower fracture toughness.