Novel SiC/C Aerogels Through Pyrolysis of Polycarbosilane Precursors

A new approach for forming aerogels with various silicon‐based compositions and hybrids between ceramics and carbon has been developed by combining efficient hydrosilylation as the hybridization‐crosslinking approach associated with gelation in the presence of solvent and followed by supercritical drying techniques. Highly porous carbon‐enriched SiC/C aerogels with adequate mechanical durability have been synthesized, pyrolyzed, and characterized. The “wet” gels were obtained by crosslinking a commercial polycarbosilane with divinylbenzene via Pt‐catalyzed hydrosilylation reaction in highly diluted condition (90 vol% of solvent). A supercritical drying was performed after exchanging the solvent (cyclohexane) with liquid CO2 forming undamaged aerogels. A subsequent pyrolysis and heat treatment (up to 1500 °C) in argon flow converted the polymeric aerogel into a SiC/C‐based material with bulk density of 166 kg m−3, SSA of 444 m2 g−1, a micro‐meso pore volume of 0.79 cm3 g−1, total porosity above 90 vol% and ultimate compressive strength of 1.6 MPa. The final product was compared to its cured gel and intermediates obtained during the pyrolysis process. A new method to obtain SiC/C aerogels is proposed. Preceramic aerogels made of polycarbosilane crosslinked with divinylbenzene are obtained by means of Pt catalyzed hydrosilylation reaction in highly diluted condition. Supercritical drying is performed with liquid CO2 and after pyrolysis monolithic SiC/C aerogels are obtained.