Benefits and Impacts Obsolescence Reduction Risk Reduction Safety Improvement Cost Reduction

1. Silicon Carbide-Carbon Precursor Adhesives for Tile and Leading Edge Repairs Area(s) of Significant Benefit Safety Performance Sustainability Operations Infrastructure • Description • A new non-RTV adhesive system will be synthesized, tested and characterized for on-orbit tile and leading edge repairs • The adhesive formulation comprises a new SiC precursor(polyarylacetylenesilane) and a new high char yield phthalonitrile as a carbon precursor • During re-entry, these precursors will be converted into a SiC-C composite foam which is light weight, tough and strongly adheres to tile and RCC • The adhesives are room temperature, UV, addition cure with little or no volatiles released on-orbit • Easily proven solution to the problems of cracking, porosity, and poor adhesion observed in the current RTV adhesives • Technologies and Capabilities • New SiC-C composite materials are significantly tougher than currently used RTV • Dictated by the fundamental nature of the chemistry, the new non-RTV adhesives produce significantly less volatiles during cure resulting in higher quality products with less voids, compared to RTV based materials • The new adhesives can be used to bond a wide variety of surfaces including tiles, SIP, RCC, RCG, and aluminum • Cure with low out-gassing • Adhesive application techniques are EVA-friendly and gentle to the remaining TPS Benefits and Impacts Obsolescence Reduction Risk Reduction Safety Improvement Cost Reduction Process Improvement Other (Ultra-High Operations Improvement Reliability) Performance Enhancement • POC, Cost, Schedule and Maturity • TRL : 5 high temperature materials • POC: Ruth H. Pater, LaRC 757-864-4277 • Significant improvements in safety, performance, and operations • Multifunctional materials for title and RCC repairs , TPS bonding, and TPS /RCC precursors • Reduction in Category 1 Failure Rate of 5% For implementation, this technology will be combined and integrated with the RCC/Heat-Pipe-Cooled Leading Edges technology for TPS enhancements.

2. Silicon Carbide-Carbon Precursor Adhesives for Tile and Leading Edge Repairs • Total Project Costs: $ 20M • Obsolescence & Feasibility: $ 2.0M • Formulation: $8.5 M • Implementation: $ 9.5M • Project Submitted By: Ruth H. Pater LaRC 757-864-4277 • Note: Supplemental Information attached in MS Word document