Characterization of sol-gel derived zirconia with additions of yttria and ceria. Origin of high fracture toughness in ceria-stabilized samples

Abstract

Fine powders of ZrO₂ containing cubic or tetragonal phases in the systems Y₂O₃-ZrO₂ and CeO₂-ZrO₂ have been prepared using the sol-gel technique without the addition of any catalysts. The powders have been compacted and either sintered at 1823 K or hot isostatic pressed (HIPed) at 1723 K (1h) under a pressure of 140 MPa (argon atmosphere). The sintered and HIPed samples have been examined for the fracture toughness (K_IC) and biocompatibility. The K_IC values ranged from 7-12 MPa m^½ and all the samples have been found to exhibit a good biocompatibility. Formation of Ce₂Zr₂O₇ (pyrochlore) in the case of 15Ce-TZP/HIPed sample has been interpreted using a chemical reaction which is very likely to be a spinoidal decomposition. The high value of K_IC observed in 15Ce-TZP/HIPed has been rationalized by a probable decomposition of pyrochlore during crack propagation.