Effects of TiO2 addition on the phase, mechanical properties, and microstructure of zirconia-toughened alumina ceramic composite

Ceramic composite made up of zirconia-toughened alumina (ZTA) with TiO2 as additive was constructed via a solid-state sintering route. The Vickers hardness of the obtained ZTA-TiO2 was evaluated at various levels of the TiO2 addition. Every sample was dry mixed, uniaxially pressed and sintered at 1600 °C for 1 h in a pressureless condition. The presence of TiO2 was observed to have greatly influenced the microstructure of the Al2O3. Grain growth of the Al2O3 particles was hindered with the addition of 3 wt% TiO2, but increased in size at an excess of 3 wt% TiO2. According to the results, tialite (Al2TiO5) begun appearing at a composition of ZTA-5 wt% TiO2 and this increased with the TiO2 content. The fracture toughness and hardness were enhanced from 5.93 MPa √m (0 wt% TiO2) to 6.56 MPa √m (3.0 wt% TiO2) and from 1516.13 HV (0 wt% TiO2) to 1615.8 HV (3.0 wt% TiO2), respectively. The improved bulk density from 3.9 g/cm3 (0 wt% TiO2) to 4.10 g/cm3 (3.0 wt% TiO2) resulted from the fine microstructure, thereby enhancing the mechanical properties.