High Performance Thrusters for DACS Propulsion

Carbon-fiber reinforced silicon carbide matrix (SiC/Cf) composite was identified as the leading thruster construction material for SDACS for SM3-Block IIB. For SDACS propulsion applications, SiC/Cf composite surfaces must be hermetically sealed and SiC/Cf composite must be joined to each other and to refractory metal alloys for thruster construction. In Phase I we developed novel joining alloys and demonstrated joining techniques for SiC/Cf composites to each other and to C103, a refractory Nb alloy. The shear strengths of the SiC/Cf composite-C103 alloy joints (156 MPa) were almost 5 times higher than the highest value (34 MPa) reported in open literature. The Phase II project will expand on the success of Phase I work by (i) fine tuning braze alloy compositions, (ii) demonstrating the applicability of developed joining techniques to achieve high reliability SiC/Cf composite-(Mo-Re) alloy joints, (iii) designing joint geometries that are applicable for thruster construction by computer modeling, and (iv) providing a prototype SiC/Cf composite-C103 or Mo-Re alloy joint that is suitable for incorporating into an SDACS thruster for testing in collaboration with Aerojet-Sacramento.