Strength and gas permeability of porous cordierite-mullite ceramics with different phase compositions and microstructures prepared by a pore-forming in-situ technique

Seven porous cordierite-mullite ceramics with different phase compositions and microstructures were fabricated by a pore-forming in-situ technique. The phase composition, pore characteristics, strength and thermal shock resistance were investigated through X-ray diffractometry (XRD), scanning electron microscopy (SEM), and a microscopical measured method, etc. It was found that the porous cordierite-mullite ceramics have an apparent and interconnected pore structure; and the strength, the thermal-shock resistance and the gas permeability of the porous cordierite-mullite ceramics with different phase compositions and microstructures are rather different. Additionally, for the porous cordierite-mullite ceramics with an apparent and interconnected pore structure, the gas permeability mainly depends on the median pore size. A porous cordierite-mullite ceramic consisting of 25 wt.% cordierite and 71 wt.% mullite gave the best performance, which had a high porosity of 42.4%, an appropriate median pore size of 42.3 mu m, a high compressive strength of 37.7 MPa, a high thermal-shock resistance and a high gas permeability of 4.68*10(-12) m(2).