Permeable carbon nanotube-reinforced silicon oxycarbide via freeze casting with enhanced mechanical stability

Reinforcement strategies were applied to solution-based freeze-casting systems to form porous ceramic composites. Multi-walled carbon nanotubes (MWCNT) were used as the reinforcing fillers in a polysiloxane preceramic polymer freeze cast with dimethyl carbonate to produce silicon oxycarbide-based lamellar pore structures. Using a carefully designed dispersion procedure, CNT agglomerates were reduced both in suspension and in pore walls. Electrical conductivity increased by ten orders of magnitude over pure silicon oxycarbide, indicating the preservation of CNTs after pyrolysis. Permeability, compression, and diametral compression (Brazilian disk) tests were performed to demonstrate the reinforcing effect of CNTs without sacrificing the permeability of the final porous structures.