2Ceramics Technology Group, SIRIM Berhad,

The influence of small additions of Nb2O5 (up to 1 wt%) on the sintering behaviour of yttria-stabilized zirconia sintered over the temperature range from 1200 ºC to 1500 ºC was investigated. It was found that the mechanical properties of Yttria-tetragonal Zirconia Polycrystals ceramic (Y-TZP) were dependent on the dopant amount and sintering temperature. Fracture toughness increased as the Nb2O5 content increased, which indicated that the annihilation of oxygen vacancies in 3Y-TZP was responsible for the instability of the t-ZrO2 lattice. The results also revealed that there was no significant influence of the Nb2O5 doping on the sintered density of the Y-TZP. The relation between the measured mechanical properties is discussed with the emphasis on the role of the niobium oxide