Preparation and characterization of near-stoichiometric silicon carbon fibres

Abstract

Near-stoichiometric SiC fibres (CVC-S fibres) were successfully prepared by pyrolysing chemical-vapour-cured polycarbosilane fibres under hydrogen and subsequent heat treatment in inert atmosphere at 1500 °C. The composition and properties of the obtained fibres were determined by Auger electron spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, tensile strength testing, and X-ray diffraction analysis. The results reveal that the CVC-S fibres with C/Si of 1.06 and O of 1.11 wt% have high tensile strength (2.6 GPa), high tensile modulus (321 GPa), and a highly crystalline structure (crystallite size, ∼14 nm.) In addition, the high-temperature behaviour of the CVC-S fibre was also investigated via heat treatment in argon and air at different temperatures. In particular, the fibres retain ∼2.2 GPa of their original strength after heating at 1600 °C for 1 h under argon. When argon was replaced by air, the tensile strength of the fibres could still be maintained at ∼1.1 GPa after annealing at 1400 °C. The more economical and practical approach along with the excellent performance of the obtained fibres render the CVC-S fibres promising materials for high-temperature applications.