ELASTIC PROPERTIES OF CERAMIC OXIDES USED IN SOLID OXIDE FUEL-CELLS (SOFC)

Measurements are presented for the effective Young's (E) and shear (G ) moduli and Poisson's ratio of some materials of interest for solid oxide fuel cells (SOFC), namely 10 and 20 mol% Gd2O3 doped CeO2 (GCO), 3 and 8 mol% Y2O3 stabilized ZrO2 (TZP and YSZ), and 75 mol% NiO-YSZ. The dependence of moduli on porosity was characterized by employing b oth theoretical (composite sphere method, CSM) and empirical (exponent ial, nonlinear, and linear) equations. The theoretical and empirical e quations were tested by determining the goodness of fit of the equatio ns to the experimental data and the standard error of estimation. All the equations described the modulus-porosity relationships equally wel l, except that, for NiO-YSZ, the empirical equations yield better fits than the CSM equations. This was attributed to the fact that the CSM equations, derived for two-phase composites, might not hold for calcul ating the effective moduli of three-phase composites, such as these Ni O-YSZ materials. (C) 1997 Elsevier Science Limited.