Mechanical Attachments for Advanced Thermal Protection Systems (TPS)

In the proposed program, MSNW, Inc. will address critical materials problems associated with the hot gas seals required with two novel designs for the mechanical attachment of reusable space access vehicle thermal protection systems (TPS). The Boeing Company (Boeing Phantom Works), in conjunction with the Air Force Research Laboratory (AFRL), has selected for near-term development two attachment designs for either carbide-based structural ceramic matrix composite TPS panels or oxide-based TPS based upon CMC-wrapped low density tiles. Both designs use Nextel 720 fabric faced gap filler seals and the limited high temperature capability of Nextel 720 (approximately 2400°F) used in the seals is currently a constraining factor. High temperature ceramic coatings and/or infiltrant materials will be investigated for their ability to limit the maximum temperature experienced by the Nextel fabric to improve the ultimate temperature capability, hot gas impermeability, erosion resistance, and long term durability of the seals. Two primary approaches will be examined: a refractory, reasonably compliant thermal barrier layer, and a high emittance treatment. Representative proof-of-concept physical and mechanical property test coupons will be prepared and tested for comparison of as-produced and post-thermal exposure properties. Testing will include limited permeability, mechanical strength, resilience and, where appropriate, emittance measurements.