Effect of LaNbO4 addition on the mechanical properties of ceria-tetragonal zirconia polycrystal matrices

The formation of needle-like grains of LaNbO4 in CeO2-stabilized tetragonal zirconia (Ce-TZP) matrices was studied using powders produced by different methods. The amount as well as the aspect ratio of the elongated grains is a function of the sintering temperature and the way the powders have been produced. The formation of these needles is triggered by the presence of silica in the starting powders and, therefore, by the occurrence of a liquid phase. During sintering, also diffusion of Ce in LaNbO4 occurs. The matrices are therefore depleted in stabiliser's content affecting their transformability. Because of the elongated nature of the grains enhanced crack wake bridging occur, this bridging should be also accounted for the observed increase of strength and toughness. (C) 1998 Elsevier Science Limited. All rights reserved.