CARBON CERAMIC MICROCOMPOSITES, PREPARATION AND PROPERTIES/

Carbon-carbon and carbon-ceramic microcomposites were molded by using thermoplastic polyimide coated carbon and ceramic powders. The effect of particle size powders and different processes of hot pressing were examined. A 53 MPa flexural strength and a 10 Cpa flexural modulus wer e obtained for 2.15 g/cc density microcomposites. Thermo-oxidative sta bility of carbon microcomposites with three combinations of B4C/SiC ad ditives were compared with original carbon-carbon microcomposites. The oxidative stability of the carbon/B4C/SiC composites was extended up to 1000 degrees C. After exposure to flowing air at 700 degrees C for 100 h, the weight lost of the carbon-ceramic composites was only 4%, a ttributed to boron oxide evaporation. There is a degradation of the me chanical and physical properties of carbon-carbon and carbon-ceramic c omposites after carbonization and graphitization. This degradation is slowed down by B4C/SiC additives. (C) 1998 Elsevier Science B.V. All r ights reserved.