Novel 3D C-SiC Composites for Hot Structures

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.