A Brief Review on Microstructure Control of Freeze-casted Porous Alumina during Sintering

Abstract

Freeze-cast ceramics provide a wide range of applications, including filters, catalyst supports, heat-resistant materials, and biomaterials. The unique porous structure of freeze-cast ceramics offers new perspectives in various fields. However, for the functionality and durability of freeze-cast ceramics, a sufficient mechanical strength of the porous architecture is essential. In the freeze-casting process, the final microstructure is determined during sintering at high temperature through densification and grain growth, highlighting the importance of sintering techniques, which can be originated from sintering strategies in the bulk system. In other words, enhancing densification while suppressing grain growth should be realized by tailoring processing variables and/or materials variables. In this review, we suggest an effective way to control the microstructure by addition of dopants in porous alumina prepared by freeze-casting. The results provide a facile method for microstructure control and provide insight into the selection of promising dopants for better mechanical strength of porous ceramics.