Effective modulus and coefficient of thermal expansion of Ni-YSZ porous cermets

Nickel zirconia, Ni-YSZ, porous cermets used in solid oxide fuel cells can be considered as composite materials consisting of three phases, namely nickel (Ni), ytrria-stabilized zirconia (YSZ), and voids. Based on Ni-YSZ's microstructural features, such as the volume fractions, average particle sizes and their correlations of a physical sample, a three-dimensional stochastic reconstruction method is used to recreate the three-phase composite. The digitally reconstructed microstructure is then transferred into finite element models to obtain the material's corresponding effective elastic modulus and effective coefficient of thermal expansion at various temperatures. Predictions from such a numerical methodology agree well with experimental results. (C) 2008 Elsevier B.V. All rights reserved.