Effect of TiO2 and Ta2O5 co-doping on phase stability, fracture toughness, and sintering behavior of ZrO2 stabilized by 10mol%(Y0.4Gd0.3Yb0.3)2O3

The effect of TiO2 and Ta2O5 co-doping on the phase structure, fracture toughness, and sintering behavior of 10mol%(Y0.4Gd0.3Yb0.3)2O3-stabilized zirconia was investigated using X-ray diffraction, scanning electron microscopy, microindentation, and pressureless sintering. The results showed that 10mol%(Y0.4Gd0.3Yb0.3)2O3–ZrO2 had a single cubic phase structure, and an increase in the Ta2O5 (≥6 mol%) and TiO2 doping concentrations resulted in a simultaneous increase in the content and stability of the tetragonal phase. The fracture toughness of TiO2 and Ta2O5 co-doping 10mol%(Y0.4Gd0.3Yb0.3)2O3–ZrO2 decreased with an increase in the Ta2O5 content. On the other hand, the TiO2 content had no significant effect on the fracture toughness of 10mol%(Y0.4Gd0.3Yb0.3)2O3–ZrO2. The sintering resistance of the specimens increased with an increasing in the Ta2O5 content; however, an increase in the TiO2 content accelerated the densification of the specimens. When the Ta2O5 content was 10 mol% and the TiO2 content was in the range of 4–8 mol%, a single non-transformable tetragonal phase structure with fracture toughness similar to that of 6–8 wt% Y2O3 stabilized ZrO2 and excellent anti-sintering properties could be obtained. This structure can be explored as a thermal barrier coating material for high-temperature applications.