Description:
OBJECTIVE: For future solid propulsion applications, develop and evaluate refractory coatings for carbon-based substrates that will survive an oxidizing environment of 1) greater than 3200 deg F for 10 minutes and 2) greater than 5,000 deg F for 1 minute. Evaluate the mechanical properties of the coating-substrate technologies and establish proof of concept in a laboratory environment and then subscale solid rocket motor firings. DESCRIPTION: The current state-of-the-art for strategic solid rocket motor and gas generator components is to use expensive, monolithic refractory metals, such as tantalum tin tungsten, or ablative carbon materials that require long-lead procurement times. A less expensive, less time consuming, and non-eroding material-design solution is desired. The technical challenge is to develop a coating that bonds well to a carbon-based substrate while having the necessary high-temperature mechanical and chemical properties to survive a solid rocket motor firing. Potential applications include solid rocket motor nozzle flame-side liners, and manifolds and valve components for hot-gas control systems. PHASE I: The contractor shall deliver a report that provides 1) details on the fabrication approach for high-temperature coating technologies for carbon-carbon and/or carbon phenolic, 2) microscopy/metallographic evaluation of the fabricated coating-substrate bond line, and 3) mechanical property evaluation of the coating-substrate bondline. Multiple candidates for high-temperature coating technologies shall be investigated for further evaluation and down selection in Phase 2 and Phase 3. PHASE II: The contractor shall deliver a report on the evaluation of multiple candidates for coating technologies in laboratory evaluations of high-temperature compatibility. The laboratory evaluations shall be conducted at temperatures greater than 3,000 deg F using a gaseous environment that mimics the oxidizing potential of solid rocket motor propellant and gas-generator propellant combustion products to investigate gas-solid interactions. The report shall include pre- and post-test microscopy/metallographic evaluation of the fabricated coating-substrate bond line. The report shall include performance evaluations and down-selection to two coating candidate technologies. PHASE III: The contractor shall deliver a report on the evaluation of coating-substrate samples that have been subjected to subscale solid rocket motor firings having a burn duration of greater than 30 seconds. The report shall include pre- and post-test microscopy/metallographic evaluation of the fabricated coating-substrate bond line. The report shall include performance evaluations and down-selection to one coating technology candidate for future evaluation and demonstration in an RDT & E Strategic Propulsion Applications Programs. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: High temperature coatings are applicable throughout aerospace including commercial launch vehicles and air-breathing propulsion. REFERENCES: 1. NASA SP-8115, Solid Rocket Motor Nozzles (June 1975) 2. AIAA-2000-3559, Economical Erosion-Resistant Rhenium Coating on Carbon Substrates
