The effects of nanoparticulate SiC upon the oxidation behavior of C-SiC-B4C composites

C-SiC-B4C composite materials were fabricated from pitch based needle coke, SiC and B4C with or without SiC nanoparticulate additive by grinding and then pressureless sintering. Anisothermal and isothermal oxidation tests of the composites obtained were carried out in oxygen Bow at temperature increasing continuously from 773 to 1573 K. Self-protection behavior of the composites with nanoscaled SiC additive was observed, in contrast to those without nanoscaled SiC additives. The morphology and constitution of the protective him that encapsulated the inner composites were investigated with scanning electron micrography and X-ray photon spectroscopy. A general model on the self-protection against oxidation was proposed. (C) 1998 Elsevier Science Ltd. All rights reserved.