Preparation and characterization of tubular porous silicon carbide membrane supports

Starting from a submicron β-SiC powder doped with 3 wt% of Al2O3 additive, SiC tubes with an outer diameter of 6 mm, an inner diameter of 4 mm and lengths over 500 mm were formed by extrusion and sintered at temperatures ranging from 1800 to 1900 °C. All the sintered tubes had homogeneous and defect-free microstructures. The tubes sintered at 1800, 1850 and 1900 °C had porosities of 45.7%, 42.1% and 40.4%, pore sizes of 0.19, 0.22 and 1.70 μm, radial crushing strengths of 47, 62 and 110 MPa, respectively. Their gas (N2, He and H2) permeance values were around 10−6 to 10−5 mol m−2 s−1 Pa−1. The tubes showed no strength degradation and limited oxidation during the water vapor corrosion test at 800 °C for 100 h. The defect-free structure, high porosity, high strength, high gas permeance and good water vapor corrosion resistance make these porous SiC tubes promising supports for hydrogen separation membranes.