Fabrication of Porous Al₂O₃ Ceramics with Submicron-Sized Pores Using a Water-Based Gelcasting Method

The gelcasting method is usually employed to fabricate relatively dense ceramics. In this work, however, porous Al₂O₃ ceramics with submicron-sized pores were fabricated using the water-based gelcasting method by keeping the Al₂O₃ content at low levels. By controlling the water content in the ceramic slurries and the sintering temperature of the green samples, the volume fractions and the size characteristics of the pores in the porous Al₂O₃ can be readily obtained. For the porous Al₂O₃ ceramics prepared with 30 vol.% Al₂O₃ content in the slurries, their open porosities were from 38.3% to 47.2%, while their median pore sizes varied from 299.8 nm to 371.9 nm. When there was more Al₂O₃ content in the slurries (40 vol.% Al₂O₃), the porous Al₂O₃ ceramics had open porosities from 37.0% to 46.5%, and median pore sizes from 355.4 nm to 363.1 nm. It was found that a higher sintering temperature and Al₂O₃ content in the slurries increased the mechanical strength of the porous Al₂O₃ ceramics.