Description: This SBIR Phase I program will identify the joining materials and demonstrate the processes that are suited for construction of advanced ceramic matrix composite (CMC) thrusters for advanced monopropellants and bipropellants for space propulsion. We will join CMCs to each other and to superalloys by brazing. In Phase I, we will experimentally evaluate and identify suitable active metal braze alloys through wetting experiments, brazing, microstructural examination, and shear strength measurements both at room temperature and 1100ºC. We will also demonstrate the feasibility of using stiff and compliant interlayers to increase the joint strength by reducing the thermal residual stresses in the joints. The Phase II project will demonstrate a working CMC HAN thruster using the joining technology developed in Phase I.

Benefits: CMC thrusters will also find applications in non-toxic propulsion systems to replace hydrazine-based systems for U.S. commercial satellite payloads, launch vehicle upper stages for launch service providers, and space vehicles for space tourism companies. The developed joining technology will also find applications in ceramic heat exchangers, pump components, and thermonuclear reactor components.

Availability of low-cost CMC thrusters will advance HAN-based propellant system development, and will provide significant cost savings as well as fast delivery to accelerate development of next generation chemical propulsion systems. CMC thrusters or combustion chambers are needed for non-toxic engine technologies, including HAN-based propulsion systems, for sample return missions under the Science Mission Directorate (SMD) and for replacement of operational NTO/MMH engines in other in space propulsion applications.