Abstract
A wet-chemical approach has been applied to derive fine powders with various ceria and yttria compositions in the CeO <sub>2</sub> -Y <sub>2</sub> O <sub>3</sub> ZrO <sub>2</sub> ceramic system by the co-precipitation method. The characteristics of the as-derived powders have been evaluated through differential thermal analysis, thermogravimetric analysis, BET surface-area analysis, and inductively coupled plasma technique. The hardness and fracture toughness of the as-sintered specimens were evaluated by the indentation method. A highly toughened ceramic with K <sub>IC</sub> >25 MPa m <sup>1/2</sup> was achieved with the composition 5.5 mol% CeO <sub>2</sub> -2 mol% YO <sub>1.5</sub> -ZrO <sub>2</sub> . The relationship between the mechanical properties and the compositions of stabilizers, CeO <sub>2</sub> and Y <sub>2</sub> O <sub>3</sub> is discussed with respect to the degree of tetragonal to monoclinic transformation as well as the grain size of the as-sintered ceramics. © 1992 Chapman & Hall.