Effect of co-doping NiO and Nb2O5 on phase stability and mechanical properties of Y2O3-stabilized ZrO2/Al2O3 composites

Abstract

Previous study demonstrates that the strength of yttria-stabilized zirconia (YSZ) can be enhanced through the addition of alumina (Al2O3). In the present study, the toughness of YSZ/Al2O3 composite is further enhanced by 100% through the addition of a small amount of two aliovalent additives, NiO and Nb2O5. Though the addition of these two additives affects little on oxygen vacancy concentration, the electrical conductivity and thermal conductivity of YSZ/Al2O3 composites are reduced. It suggests that other defects and/or structural distortion are formed due to the addition of NiO and Nb2O5. The amount of monoclinic phase increases with increasing additive content; the toughness enhancement shows strong dependence on the amount of monoclinic phase.