Effects of TiO₂ on the microstructure and mechanical properties of Al₂O₃/ZrO₂ composites

The microstructure and mechanical properties of hot-pressed zirconia-toughened alumina (ZTA), fabricated from the ZTA powders containing (Zr, Ti)O₂ in Ar gas were investigated. In hot-pressed ZTA, the presence of Ti concentration in the grains of Al2O3 or (Zr, Ti)O₂ was analyzed by the energy dispersive spectroscopy (EDS) attached to the analytical electron microscope (AEM) apparatus. Experimental results showed that some Ti ions diffused to the grain boundary and into the Al₂O₃ grains, thereby enhancing the densification of hot-pressed ZTA. It was possible to retain tetragonal ZrO₂ at room temperature in the ZTA specimens containing ≥5.5 mol% TiO₂ and hot pressed at 1350 °C for 1 h. The bending strength and toughness of hot-pressed ZTA were enhanced by the addition of TiO₂.