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

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. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.