One-step synthesis of asymmetric SiC foam ceramic membranes with in-situ growing mullite whiskers for environmental sustainability

Silicon carbide (SiC) ceramic membranes offer indispensable advantages for environmental applications particularly at extreme conditions, owing to their unique physical and chemical properties. However, their widespread application has been hindered by complex multistep fabrication processes, such as repeated coating–drying–sintering process, which are time-intensive and costly. To overcome these challenges, this study employed a novel foam–gel casting technique for the single-step fabrication of asymmetric SiC foam ceramic membranes (SiFCMs), integrating the foam support layer and the functional membrane layer simultaneously. Furthermore, in situ -grown mullite whiskers were incorporated to enhance membrane performance. The growth behavior of the mullite whiskers and the formation mechanism of the bilayer structure were thoroughly investigated. By adjusting the foaming agent content and sintering temperature, synchronous control over the microstructure and properties was achieved, enabling precise tuning of porosity (52.35%–75.61%), membrane layer thickness (98–325 μm), and support layer pore size (171–626 μm). The optimized SiFCMs (solid loading: 65–71 wt%) exhibited a remarkable combination of properties: bending strength of 7.1–7.4 MPa, average pore size of 4.98–8.92 μm, and high gas permeance of 332.5–368.7 m 3  m −2  h −1 ·kPa −1 . The membranes also demonstrated excellent interfacial bonding strength and outstanding chemical corrosion resistance. The separation performance of the resulting membrane was characterized by separating submicron particles at 300 °C, achieving 99.99% rejection rate for PM 0.3 . This study establishes an economically viable technical pathway for fabricating high-performance SiC ceramic membranes, thereby laying a solid foundation for meeting the application demands at extreme conditions.