Novel oxidation resistant carbon-silicon alloy fibres Original Research Article

A novel silicon-containing carbon precursor was synthesised by reacting a petroleum pitch fraction and polydimethylsilane. The precursor containing about 26 wt% Si was melt spun into fibres and then oxidatively cured in air to render the fibres infusible. The cured fibres were pyrolysed at 1200 °C under inert atmosphere to produce carbon-silicon alloy (CSA) fibres. The oxidation behaviour is improved over that of pure carbon phase but at low temperature the carbon phase can be completely removed. It was found that if during the pyrolysis process at 1200 °C, the fibres are exposed to oxygen for a short period of time, they can form a protective silica surface which makes the fibres very oxidation resistant. These novel fibres have an average tensile strength around 400–600 MPa similar to that of isotropic pitch based carbon fibres but have the additional advantage of in situ oxidation protection at high temperatures.