Porosity and microstructure control of porous ceramics by partial hot pressing

Precise control of porosity and microstructure of porous ceramics is essential. This paper describes a method for the preparation of porous ceramics with porosity from 0.0 to 0.4. The ceramics were prepared via hot pressing a powder mixture to a definite dimension, and the porosity was easily adjusted by the powder amount. As examples, porous Si₃N₄ or SiC ceramics were produced by powder mixtures that contained Si₃N₄ or SiC and a sintering additive of oxide. It was demonstrated that the present method is advantageous for producing ceramics with controllable porosity and microstructure.