High-Permeance Mullite/SiC Fiber Membranes for Gas/Solid Filtration at High Temperatures

SiC-based ceramic membranes are promising materials for gas/solid filtration in industrial applications, but they are limited by their low gas permeance. Herein, considering the similar thermal properties of SiC and mullite, mullite fibers were employed for fabricating a membrane layer on a SiC support to enhance gas mass transfer. However, the interfacial strength between the mullite fiber layer and the SiC support was not satisfactory. Therefore, TiO₂ nanocords were grown in situ on the SiC support to effectively enhance the bonding strength between the fiber layer and SiC support by increasing the number of contact points. In addition, processing parameters such as the sintering temperature and thickness of the mullite fiber membrane were investigated in detail. When the sintering temperature was 1200 °C and the membrane thickness was 200 μm, the resulting membrane exhibited a pore size of 21.9 μm and a gas permeance of 715 m³ m^-2 h^-1 kPa^-1. Furthermore, the membranes exhibited satisfactory thermal shock resistance and interfacial strength after the back pulse and ultrasonic treatments. Finally, the mullite/SiC-TiO₂ membrane was used to filter dust-laden gas containing fly ash particles as simulated dust, achieving 99.9% rejection of dust-laden gas after three filtration-cleaning cycles. This research provides guidance for the synthesis of ceramic membranes for gas/solid filtration at high temperatures.