Porous Si3N4 ceramics by a gel casting preparation route have received considerable attention because of their excellent performance. In this paper, orthogonal experimental design L16(45) was used to investigate the preparation of porous Si3N4 ceramics by a gelcasting technique. Three variables including solid loading, monomer content and the ratio of monomers were studied. Through range analysis and variance analysis, the results suggest that the ratio of monomers has a significant influence on both the flexural strength and porosity of Si3N4 sintered bodies. For the flexural strength of a Si3N4 sintered body, the order of significance levels was as follows: the ratio of monomers, solid loading and monomer content. For the porosity of a Si3N4 sintered body, the order of significance levels was as follows: the ratio of monomers, monomer content and solid loading. The experimental results suggest also that solid loading has an optimum value where the flexural strength can achieve a maximum value.

Keywords: Si3N4 ceramics, Orthogonal experimental design, Flexural strength, Porosity, Gel casting.