HYBRIDIZED RESIN MATRIX APPROACH APPLIED FOR DEVELOPMENT OF CARBON CARBON COMPOSITES - I/

Carbon/carbon (C/C) composites are known for their high heat of ablati on, high thermal shock resistance and enhanced vibration damping. Howe ver, due to the numerous processing steps involved, C/C composites con tain a high percentage of process related defects. The geometry create d by the tows, variations in stacking sequence of lamina, flow charact eristics of the precursor and formation of closed porosity are some of the factors that lead to these defects. In this work, a novel approac h is taken to improve densification and mechanical properties of C/C c omposites by incorporating a lamina-by-lamina curing scheme using a ne w polyimide resin, that exhibits much better thermal stability than co nventional phenolic resins. The final consolidation of the precured la minae is done using conventional phenolic resin, thus, introducing a h ybrid matrix of polyimide and phenolic resin. The use of polyimide res in enables development of an effective network of open cracks for dens ification of the composite. The hybridized composite was characterized for its thermal, mechanical, nondestructive and microstructural prope rties after each processing stage, that is, as-cured carbonized and de nsified stage. These properties have been compared with C/C composites processed through the conventional route using commercial phenolic re sin as precursor. The hybrid composite exhibits better densification m echanisms and improvement in toughness as compared to the composite pr ocessed from conventional phenolic resin. (C) 1998 Elsevier Science Lt d. All rights reserved.