Abstract: Mixture of green petroleum coke, B₄C and SiC together with short carbon fiber were employed as starting materials, the mixture was press-formed without any binder after grinding, dense and homogeneous binderless SiC-B₄C-C(carbon/ceramic) composites were then obtained after sintering. Composites thus prepared possess excellent anti-oxidation property, that is, mass loss less than 1% within the temperature range from 900 to 1100℃ for 10h. Anti-oxidation mechanism was also discussed from the viewpoint of thermodynamics, excellent anti-oxidation property of materials thus prepared can be discribed to 1) solid SiO₂ formed from SiC, which restrains the filtering of oxygen and simultaneously, its volume expansion brought about by the reaction takes roles both walling up the original pores and making the material more compact; 2) liquid B₂O₃ from the reaction of B₄C not only makes the combination with C, B₄C and SiC tighter through forming solid solution, but also effect of reaction SiC(s)+2CO(g)=SiO₂(s)+3C(s) is an expansive process, which improves the microstructure of the material.

Key words:  SiC-B₄C-C composites; anti-oxidation; mechanism