Development of Novel High Interlaminar Strength Carbon-Carbon Composites for Advanced Rocket Propulsion Components: Nozzle Materials and Exit Cones

A program involving analysis and design, reinforcement materials research and development, composite fabrication, and composite property testing is proposed here to develop improved interlaminar properties of carbon-carbon composites used as the substrates for rocket propulsion components, such as exit cones and nozzle throats. The improved interlaminar properties must be obtained with minimal impact on the in-plane properties of the C-C composites. The most important technical objective that must be achieved to satisfy the primary objective of the proposed program is the successful further development of the concept of the discontinuous carbon fiber reinforcement interleaf material manufactured by Energy Sciences Laboratories, Inc. (ESLI) on San Diego, CA. The focus of the ESLI reinforcement interleaf material development is to achieve high interlaminar properties, low impact on in-plane properties, manufacturing scale-up to reasonable sizes, and cost affordability. A measure of success is the magnitude of interlaminar reinforcement properties improvement for similar impact on in-plane properties relative to competing technology such as stretch-broken fabric and needled fabric preforms. To provide the best assessment of the reinforcement interleaf technique to enhanced interlaminar properties, the proposed Phase II effort will procure stretch-broken and needled fabric reinforcement, along with continuous 2D carbon fabrics. C-C composites will be fabricated using no interlaminar reinforcement, two different types of reinforcement interleaf materials developed and fabricated by ESLI, stretch-broken fabric and needle-punched fabric. Mechanical property measurements, including both in-plane and interlaminar properties, will be performed to enable an assessment of the improved interlaminar properties and the reductions in in-plane properties associated with all of these composites. Finally, C-C exit cone designs will be developed for all of these reinforcement methods and their associated composite properties, to determine an analytical assessment of the minimum weight design achieved by the various reinforcement methods.