Gas permeability behavior of mullite-bonded porous silicon carbide ceramics

An apparatus was developed to evaluate the gas permeability behavior of mullite (3Al₂O₃·2SiO₂)-bonded porous silicon carbide (SiC) ceramics at room temperature. The permeability was calculated according to Forchheimer’s equation for the compressible gas. It was found that the sintering temperature and graphite (pore former) addition during the fabrication of the porous ceramics affect the permeability extremely by varying the texture of porous ceramics such as the open porosity, pore size distribution and tortuosity of pore channels. The increased sintering temperature results in a decreased Darcian (viscous) permeability but an increased non-Darcian (inertial) permeability. However, more graphite additions lead to the larger Darcian and non-Darcian permeability.