Effect of Macropore Anisotropy on the Mechanical Response of Hierarchically Porous Ceramics

Abstract

Porous ceramics are commonly used in electrochemical, catalytic, biological, and filtration processes, but in many cases, improvements to their designed performance comes at the expense of their mechanical properties. By controlling the pore morphology and orientation, it is possible to mitigate some mechanical losses while maintaining adequately porous microstructures. Hierarchically, porous ceramics with similar porosities but differing macropore arrangements were synthesized using both freeze casting and slip casting, and then tested in compression to study the effects of macropore morphology and orientation on mechanical behavior. The mechanical properties of the anisotropic structures were a strong function of the orientation of the macropores relative to the applied stress. The properties of the isotropic hierarchical porous structures were in between the two orthotropic directions of the anisotropic porous ceramics. For the freeze‐cast samples, the compressive strength was a function of the macropore size. The experimental results are rationalized using detailed microstructural analysis.