Hybridized resin matrix approach applied for development of carbon/carbon composites—I

Abstract

Carbon/carbon (C/C) composites are known for their high heat of ablation, high thermal shock resistance and enhanced vibration damping. However, due to the numerous processing steps involved, C/C composites contain a high percentage of process related defects. The geometry created by the tows, variations in stacking sequence of lamina, flow characteristics of the precursor and formation of closed porosity are some of the factors that lead to these defects. In this work, a novel approach is taken to improve densification and mechanical properties of C/C composites by incorporating a laminaby-lamina curing scheme using a new polyimide resin, that exhibits much better thermal stability than conventional phenolic resins. The final consolidation of the precured laminae is done using conventional phenolic resin, thus, introducing a hybrid matrix of polyimide and phenolic resin. The use of polyimide resin enables development of an effective network of open cracks for densification of the composite. The hybridized composite was characterized for its thermal, mechanical, nondestructive and microstructural properties after each processing stage, that is, as-cured, carbonized and densified stage. These properties have been compared with C/C composites processed through the conventional route using commercial phenolic resin as precursor. The hybrid composite exhibits better densification mechanisms and improvement in toughness as compared to the composite processed from conventional phenolic resin.