Gas permeability of ice-templated, unidirectional porous ceramics

We investigate the gas flow behavior of unidirectional porous ceramics processed by ice-templating. The pore volume ranged between 54% and 72% and pore size between 2.9 mu m and 19.1 mu m. Themaximum permeability (k(1) = 1.39 x 10(-11) m(2)) was measured in samples with the highest total pore volume (72%) and pore size (19.1 mu m). However, we demonstrate that it is possible to achieve a similar permeability (k(1) = 1.09 x 10(-11) m(2)) at 54% pore volume by modification of the pore shape. These results were compared with those reported and measured for isotropic porous materials processed by conventional techniques. In unidirectional porous materials tortuosity (tau) is mainly controlled by pore size, unlike in isotropic porous structures where tau is linked to pore volume. Furthermore, we assessed the applicability of Ergun and capillary model in the prediction of permeability and we found that the capillary model accurately describes the gas flow behavior of unidirectional porous materials. Finally, we combined the permeability data obtained here with strength data for these materials to establish links between strength and permeability of ice-templated materials.