A Novel Oxidation Resistant SiC/B4 C/C Nanocomposite Derived from a Carborane-Containing Conjugated Polycarbosilane.

A novel oxidation resistant SiC/B₄ C/C nanocomposite was prepared by the pyrolysis of carborane-containing poly(silyleneethynylenephenyleneethynylene) ( CB- PSEPE) at 1450°C in argon. The phase composition and microstructure of the carbon-rich ceramic were investigated by X-ray diffraction, Raman spectroscopy and transmission electron microscopy. The β- SiC (~12 nm) and B₄ C (~20 nm) nanocrystalline phases were formed during the pyrolysis process of CB- PSEPE. The presence of boron in CB- PSEPE promotes the growth of β- SiC nanocrystals. The ceramic shows excellent thermooxidative stability based on thermogravimetric analysis in air. A borosilicate layer was formed on the surface of the ceramic after oxidation. This carborane-containing conjugated polycarbosilane could be a potential precursor for oxidation resistant carbon-based materials. [ABSTRACT FROM AUTHOR]