Ice-templated porous alumina structures

The formation of regular patterns is a common feature of many solidification processes involving cast materials. We describe here how regular patterns can be obtained in porous alumina by controlling the freezing of ceramic slurries followed by subsequent ice sublimation and sintering, leading to multilayered porous alumina structures with homogeneous and well-defined architecture. We discuss the relationships between the experimental results, the physics of ice, and the interaction between inert particles and the solidification front during directional freezing. The anisotropic interface kinetics of ice leads to numerous specific morphological features in the structure. The structures obtained here could have numerous applications, including ceramic filters and biomaterials, and could be the basis for dense multilayered composites after infiltration with a selected second phase. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.