High Temperature Treatment of Carbon Fiber / Ceramics Composites Prepared from Borosiloxane with High Boron Content

Abstract

This work was aimed at preparing carbon fiber (CF) / ceramics composites with oxidation resistance. Matrix material, diphenylborosiloxane (PBS) was prepared from diphenylsilanediol and boric acid, their mole ratio (Si/B) being 3/2. PBS with high boron content was combined with CF, and calcined at 100°C to form a composite (UD, 3mm in diameter).
The surface of the composite was covered with a compact glassy film. According to X-ray diffractometry ingredients of the composite were carbon, β-SiC and B₂O₃. Thermogravimetry on this composite up to 1000°C in the air gave a weight reduction of 24%. The composite coated by a compact oxidation resistant film containing B₂O₃ showed a greater oxidation resistivity than that from PBS with low boron content.
The composite was heat-treated up to the temperature of 2000°C, and its crystal structure were examined.