Preparation and characterization of pure SiC filters with an asymmetric structure

Abstract

In this work, SiC filters with an asymmetric structure were successfully constructed, consisting of solid-state-sintered SiC (S–SiC) supports and in-situ synthesized SiC membranes. The S–SiC supports were prepared by a pressureless sintering technique. Following the preparation of the supports, SiC membranes ~30 μm in thickness were formed in-situ on their surfaces through a dip-coating process combined with carbothermal reduction. Using X-ray diffraction, only the peaks of the SiC phase were detected for both the S–SiC supports and the SiC membranes, indicating the high purity of the asymmetric SiC filters. The distribution of the pore throat size in the SiC membranes was narrow with an average value of ~130 nm, suggesting a high filtration precision. The flexural strengths of the S–SiC supports at room temperature and 1000 °C were 123.6 ± 18.1 MPa and 114.0 ± 4.5 MPa, respectively, enabling the asymmetric SiC filters to withstand high temperatures and high pressures during service. Moreover, asymmetric SiC filters presented excellent acid and alkali corrosion resistance, indicating their great potential for applications in corrosive environments.