Graded Porous Silicon Carbide for High Temperature Membrane Applications

Abstract

Due to its excellent thermal shock resistance, mechanical and chemical stability at both room and elevated temperatures, silicon carbide (SiC) is an attractive material for environmental protection and energy production applications such as catalyst supports, molten metal filters and gas separation membranes. Precise pore size control and high porosity are the key deciding factors for such applications. In this study, we demonstrated the fabrication of bi-layered SiC membranes with a graded porosity, consisting of porous nano-SiC layer on the surface of a porous coarse-grained SiC support layer. Nano-SiC powders utilized for this study were synthesized using a novel process based on mechanical activation of silica fume and graphite mixtures, resulting in particle sizes as small as 30 nm. The effects of sintering temperature were investigated to control the pore size, particle size and overall density of the bi-layered membrane.