Gas permeation performance of porous silicon nitride ceramics with controllable pore structures

Abstract Porous Si3N4 ceramics with controllable pore structures were prepared by polymethyl methacrylate (PMMA) as the pore agent combined with cold isostatic pressing (CIP) method. The pore structures of specimens were tailored via the changes in the content and particle size of PMMA. The higher the addition and particle size of PMMA, the larger the open porosity and pore size respectively. The increased Darcian and non-Darcian permeability coefficients are obtained as the open porosity and pore size of pore structures increase. The ratio of Darcian and non-Darcian permeability coefficient representing the individual contribution of viscous and inertial resistance during permeation process, that is strongly dependent on the pore size and open porosity, but there is distinct relationship for small and larger pores. Moreover, the comparison of the theoretical permeability coefficients with the experimental permeability constants of porous materials is presented in this work.