OPEN PORE DESCRIPTION OF MECHANICAL-PROPERTIES OF CERAMICS

A dependence of Young s modulus of elasticity on open porosity in ceramics is derived from an open-porosity model, which in the literature, is applied to salinity conductivity and fluid permeability in rocks. A random distribution of grain and pore size is assumed. The relation developed, E(p) = E0(1 - p)m, where E is the modulus of elasticity of the porous ceramic, E0 is the theoretical elastic modulus, p is the porosity and m is an exponent dependent on the tortuosity of the structure of the ceramic, adequately describes the dependence of the modulus of elasticity on porosity. The model is applied to the experimental data from several ceramics such as alumina, silicon nitride, silicon carbide, uranium oxide, rare-earth oxides, and YBa2Cu3O7-delta superconductor, and the value of m is obtained for each case. We have shown that m has a value of nearly 2 for sintered ceramics, unless sintering aids or hot pressing have been used during fabrication of the ceramic. Such additional procedures approximately double the magnitude of m.