CNF-Enhanced SiC Matrix for Launch Vehicle Carbon/Carbon Composites

ASI proposes to develop ceramic matrix systems to replace the legacy fully micro-cracked morphology with a high strain, ligamentary, engineered foam structure producing a tough, high translation composite with available free volume for additives to further enhance performance. Historical toughening via uncontrolled shrinkage in thermal processing reduces interlaminar and in-plane properties without sealing out detrimental atmospheres. Disassembling Pyrograf III stacked cup carbon nano-fibers (CNFs) yields high strain, short Length/Diameter (L/D) 100 nm tubes with huge strain capabilities (>1000% transverse) which are small enough to infiltrate lamina filaments and, when subsequently fillet bonded, produce a 0.15 to 0.3 volume fraction foam with properties typical of a tough organic matrix system. Manipulating this porous skeletal framework, mechanical properties can be tailored for optimum composite performance and the free volume can be filled with protective and self-repairing agents to protect against environmental and physical damage via multi-temperature glass forming refractory chemistries. The proposed effort will feature modification of carbon nanofibers, dispersion into pre-ceramic polymers and conversion into ceramic matrix composites using conventional polymer processing techniques.The resulting composites will characterized for physical and mechanical properties and will be benchmarked against conventional ceramic matrix composites for both cost and performance.