Effect of Ta2O5 addition on the microstructure and mechanical properties of TiO2-added yttria-stabilized zirconia-toughened alumina (ZTA) composites

In this study, the effect of Ta2O5 addition on the phase evolution and mechanical properties of sintered (1600 degrees C, 4 h) TiO2-added yttria-stabilized zirconia-toughened alumina (ZTA) ceramic composites was investigated. The scanning electron microscopy and X-ray diffraction results revealed the formation of a new tantalum zirconium oxide, TaZr2 .75O8 , with a block-like morphology at Ta2O5 contents higher than 1 wt%. The grain sizes of both the Al2O3 and yttria-stabilized zirconia phases first increased and then decreased with an increase in the Ta2O5 content. The relative density, Vickers hardness, and fracture toughness of the composites were found to be strongly dependent on their grain sizes, relative densities, and the formation of the TaZr(2 .75)O(8 )secondary phases. The composite with 3 wt% Ta2O5 showed the highest relative density (99.3%), Vickers hardness (1932 HV), and fracture toughness (8.21 MPa m(1/)(2)).