SiC nanofiber reinforced porous ceramic hollow fiber membranes

Abstract

Brittleness is the main obstacle for commercial implementation of ceramic hollow fiber membranes. Here we report the reinforcement of porous alumina hollow fiber membranes by using commercial SiC nanofibers. The SiC reinforced alumina hollow fiber membranes were produced by the polymer-assisted phase inversion method and subsequent removal of the polymer and sintering at high temperatures. The effects of the amounts of SiC nanofibers (2.5–10.0 wt%) on the mechanical strength, microstructure and water flux of the hollow fiber membranes were investigated. The results showed that without addition of SiC nanofibers, the maximum bending strength was about 154 MPa for the porous alumina hollow fiber sintered at 1510 °C. However, the maximum bending strength of the reinforced membrane reached 218 MPa, in which 5 wt% SiC was incorporated and sintered at 1450 °C; in other words, a 40% improvement in bending strength was achieved. After being sintered at 1450 °C, the 5% SiC reinforced membrane exhibits a porosity of 41.7% and a peak pore size of 1.35 μm whereas the pure alumina membrane has a porosity of 37.5% and a peak pore size of 1.25 μm; the former shows a water permeability of 7.99 L m⁻² h⁻¹ kPa⁻¹, which is 3.3 times higher than that of the latter. Therefore, the ceramic nanofiber reinforcement is promising for the development of high-performance ceramic hollow fiber membranes for practical applications.