Preparation of porous SiC-Al2O3 ceramics with spherical shell structures of large surface area and high strength

The surface areas of porous ceramics can be enhanced by increasing their porosity but this improvement is at the expense of strength. To improve performance, it is necessary to fabricate porous ceramics with large surface areas and high strength. In this study, porous ceramics with spherical shell structures known as spherical-shell ceramics (SCs), characterised by a hollow ceramic sphere in each pore, were fabricated to address the above-mentioned problem. They were fabricated using soaked millet coated with slurries as the pore-forming agents. The compositions and particle sizes of the slurries as well as the sintering temperature were tuned to tailor the integrity, wall thicknesses and surface structures of the SCs. In addition, the formation mechanism of the SCs was proposed. Overall, the porous ceramics with SCs demonstrated large surface areas and high flexural strength. This study paves the way for the fabrication of high-performance porous ceramics.