Estimating thermal conductivities and elastic moduli of porous ceramics using a new microstructural parameter

Abstract

Porous ceramics are numerically constructed based on the convexity of the void phase: microstructures with convex pores are representative of isolated or randomly overlapping spherical pores, while particulate materials with non-convex pores are composed of randomly overlapping, partial overlapping or partially sintered solid spheres. Finite element simulations show that, given the porosity, thermal conductivities and elastic moduli for convex porosity are larger than the values for non-convex pores. These conditions are not well described by solely porosity. By contrast, this study proposes a new microstructural parameter, <lp2>/(<ls2>+<lp2>), to estimate thermal conductivities and elastic moduli for both convex and non-convex pores. <ls2> and <lp2> are respectively mean-square solid chord length and mean-square pore chord length of cross-sections, which can be conveniently extracted from SEM images combined with chord length distributions of solid and void.