Effect of Post-Oxidation Treatment on the Performance and Microstructure of Silicon Carbide Ceramic Membrane

Abstract

The post-oxidation treatment (POT) is an important step in the preparation of silicon carbide (SiC) ceramic membranes via recrystallization sintering, which is generally considered to remove any possible free carbon. It is found, however, that increasing the temperature of POT improves not only the hydrophilicity and flux of SiC ceramic membranes but also their mechanical properties, chemical stability, etc. Therefore, it is necessary to study the principle of POT in order to obtain SiC ceramic membranes with optimal properties. In this study, the principle of POT was characterized via scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, synchronous thermal analysis, and metallographic microscopy. According to the principle, the conditions, such as the temperature and air flow rate, of the post-oxidation process were optimized. Under the optimized conditions, POT improved the flux of SiC ceramic membranes from 1074 to 5118 L·m−2·h−1·bar−1, increased the bending strength from 26 to 35 MPa, and provided SiC ceramic membranes with high stability under acid and alkali conditions.