Phase stability of (Y,NB)-TZP/Al2O3 composites under low temperature hydrothermal conditions

Abstract

Y2O3 and Nb2O5 co-doped tetragonal zirconia poly-crystals (TZP) containing 10 to 30 vol.% Al2O3 ((Y,Nb)-TZP/Al2O3) were sintered for 5 h at 1550 degrees C in air and hydrothermal stability of the composites was evaluated after aging for 5 h at 180 degrees C in 0.3 MPa H2O vapor pressure. (Y,Nb)-TZP/Al2O3 composites showed superior phase stability under the hydrothermal condition as compared with 3Y-TZP/Al2O3 composites due to the effects of Y-Nb ordering in t-ZrO2 and the Al2O3 addition. The optimized strength and fracture toughness were 670 MPa and 7.3 MPa m(1/2), respectively, when 20 vol.% of 3.8 mu m Al2O3 particles were added. (C) 1999 Elsevier Science B.V, All rights reserved.