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 hybridizationcrosslinking approach associatedwith 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 kgm3, SSA of 444m2 g1, a micro-meso pore volume of 0.79 cm3 g1, total porosity above 90 vol%and ultimate compressive strength of 1.6MPa. The final product was compared to its cured gel and intermediates obtained during the pyrolysis process.