Non-Eroding Sonic Throat (NEST)

Flame temperatures, and therefore motor performance, in non-Aluminized solid rocket motor (SRM) propulsion applications without Oxygen scavenging is limited to lower temperature propellants . Renewed efforts to increase SRM performance, by increasing flame temperature, without the use of Aluminum fuel, will inevitably cause current non-eroding materials for non-Aluminized propellants to fail as combustion chamber temperature and oxygen partial pressure rise. New solutions are needed to address current material shortcomings and move beyond the physics-based limitations facing all-metal solutions. Ceramic matrix composites (CMC) composed of carbide-based ceramics show promise in providing non-eroding performance with non-Aluminized propellants based on their high melting points, their oxidation resistance at elevated temperatures, and the high melting points / low vapor pressure of their respective oxides. In Phase I, Exo-Atmospheric Technologies, LLC, (EXO) working with our materials subcontractor, will develop a new throat insert and pintle material designed specifically to survive the highly oxidizing environment of high-performance non-Aluminized propellants . The Non-Eroding Sonic Throat (NEST) technology development effort will engineer a new CMC material solution and then perform a series of analytical and numerical investigations to investigate its performance culminating with a hot-fire test of a high performance non-Aluminized propellant to verify and validate the technical approach with the new throat insert. The NEST insert is a CMC material that will utilize the Reactive Melt Infiltration (RMI) process. Phase I thermomechanical studies will also utilize existing CMC data to construct a material model. Along with the material processing and fabrication effort, extensive numerical simulations and condensed phase kinetics modeling will be conducted to better understand the chemical compatibility and ablation resistance of the material. The Phase I hot-fire test will utilize a test motor burning a custom-cast propellant . . After testing, the inserts will be measured and inspected to examine material performance, this includes microscopy and micro-CT scans to examine microstructure and internal features with particular attention paid to throat shape and throat surfaces. Approved for Public Release | 24-MDA-11917 (27 Sep 24)