Description: Future NASA hypersonic vehicles offer a potential to incorporate advanced ceramic matrix composites (CMC). The key characteristics include excellent mechanical properties, excellent thermal shock resistance and ability to survive cyclic oxidation environments. Among the CMC composites carbon fiber-SiC matrix composites offer excellent high temperature capabilities. The highest specific strength C-SiC composites are fabricated via conventional Chemical Vapor Infiltration (CVI) SiC method. There are several limitations to SOTA CVI SiC technology. First, fixturing is required during the processing. Secondly, transverse mechanical properties are quite often design limiting criteria, thirdly manufacturing times are very long and fourth the fabrication of very large parts is limited due to huge capital investments required for very large equipment needed to operate at very low pressure. This proposal addresses all the above stated limitations of classical CVI. First it offers unique 3-D preform capable of increasing transverse properties with minimum degeneration of the in plane properties. Secondly the proposed processing eliminates the need of fixturing. Thirdly, modified CVI SiC significantly reduces processing time. And fourth, Phase II will extend to incorporate extremely novel atmospheric pressure CVI SiC, offering a paradigm shift in CVI SiC by allowing to utilize conventional, low cost atmospheric pressure furnaces routinely used in heat treating applications.

Benefits: This technology can be used as CMC exit cone, nozzle, nose tip, and many other high temperature components, including TPS,on future hypersonic vehicles. The hot structures in support of future NASA hypersonic vehicles can greatly benefit from low cost, very large, complex parts manufacturing. The future Thermal Protection System (TPS) can greatly benefit from the elimination of the cumbersome designs involving joining. The very large integrated TPS offers a new dimension in future NASA Reusable Airbreathing Launch Vehicles (RALV)., In addition research success of NASA X-43A and DoD X-51A opened a door to eventually commercial hypersonic vehicles. The significant manufacturing cost reduction combined with significantly improved transverse properties offers a paradigm shift in these future applications. Also the new preform extends the projected application to propulsion.

This technology can be used in many components for commercial space applications as well as DoD hypersonic vehicles. One of the current key limitations is the ability to manufacture large, complex CMC hot structures in support of DoD hypersonic weapon systems and surveillance vehicles. The technology addressed in this proposal offers a paradigm shift in the area of hot structures and propulsion systems for DoD advanced hypersonic applications.