NOVEL OXIDATION-RESISTANT CARBON-SILICON ALLOY FIBERS

A novel silicon-containing carbon precursor was synthesised by reactin g a petroleum pitch fraction and polydimethylsilane. The precursor con taining about 26 wt% Si was melt spun into fibres and then oxidatively cured in air to render the fibres infusible. The cured fibres were py rolysed at 1200 degrees C under inert atmosphere to produce carbon-sil icon alloy (CSA) fibres. The oxidation behaviour is improved over that of pure carbon phase but at low temperature the carbon phase can be c ompletely removed. It was found that if during the pyrolysis process a t 1200 degrees C, the fibres are exposed to oxygen for a short period of time, they can form a protective silica surface which makes the fib res very oxidation resistant. These novel fibres have an average tensi le strength around 400-600 MPa similar to that of isotropic pitch base d carbon fibres but have the additional advantage of in situ oxidation protection at high temperatures. (C) 1997 Published by Elsevier Scien ce Ltd.