Mechanical Attachments for Advanced Thermal Protection Systems (TPS)

Two attachment designs for either carbide-based structural ceramic matrix composite TPS panels or oxide-based TPS based upon CMC-wrapped low density tiles have been identified as candidates for further development. Both designs require Nextel 720 fabric or braid faced flexible gap filler seals. The limited high temperature capability of Nextel 720 (approximately 2400°F for very short times) is currently a constraining factor. High temperature ceramic thermal barrier and emittance coating materials will continue to be investigated for their ability to limit the maximum temperature experienced by the Nextel fabric thereby improving the ultimate temperature capability, hot gas impermeability, erosion resistance, and long term durability of the seals based on encouraging preliminary results from the Phase I research. The Phase II research will optimize coating compositions and application techniques and develop an engineering design data base of coated fabric and braid material strength, permeability and emittance both in the as-fabricated and post-thermal exposure conditions. Phase II will also fabricate prototype coated flexible seals for thermoacoustic testing and arc jet testing of appropriate constituent materials and/or TPS components or subelements. Finally, Phase II will perform an initial feasibility demonstration of seal removal, replacement and re-test, another major objective of the overall effort.