High porosity and robust strength silicon carbide ceramic membrane for water treatment

Abstract

Silicon carbide (SiC) ceramic membranes are renowned for their excellent properties, finding extensive applications across various fields. However, achieving a balance between porosity and strength poses a persistent challenge. This study uses a freeze-drying method to prepare a silica sol-starch composite xerogel as a pore-forming agent. The structural stability of the composite xerogel plays a critical role in supporting the pore structure during pressing, thus enhancing porosity and achieving a homogeneous microstructure. At approximately 1400 °C, carbon derived from the starch carbonizes and reacts with SiO₂ in the pore-forming agent via a carbothermal reduction, generating fine SiC particles. These particles further undergo recrystallization among the starting SiC particles, forming uniform pore structures to improve open porosity and robust sintering necks. With the pore-forming agent's dosage optimized to 15 %, the resulting high open porosity of 55.6 %, enhanced permeability, and improved mechanical strength of 54.9 MPa.