Developments in highly toughened CeO2-Y2O3-ZrO2 ceramic system

A wet-chemical approach has been applied to derive fine powders with various ceria and yttria compositions in the CeO₂-Y₂O₃ ZrO₂ 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 withK_IC>25 MPa m^1/2 was achieved with the composition 5.5 mol% CeO₂-2 mol% YO_1.5-ZrO₂. The relationship between the mechanical properties and the compositions of stabilizers, CeO₂ and Y₂O₃ is discussed with respect to the degree of tetragonal to monoclinic transformation as well as the grain size of the as-sintered ceramics.