Novel Fiber-Reinforced Polysiloxane Composites: Processing, Characterization, and Modeling for Hypersonic Applications

Fiber-reinforced polysiloxane composites (FRPCs) with glass, silica, carbon, graphite, car-bon/polybenzimidazole, alumina, and quartz fibers in different architectures, infiltrated with a high char yield polysiloxane resin, were developed for hypersonic applications. Techneglas manufactures the polysiloxane resin. FRPCs were manufactured by the Koo Research Group. Material characterization of thermal stability, flammability, ablation, thermophysical, and mechanical properties of these high-performance FRPCs was per-formed. Thermal stability properties were characterized using thermogravimetric analysis, and flammability properties using microscale combustion calorimetry for the FRPCs. Ablation properties using oxy-acetylene test bed with advanced diagnostics were performed at sev-eral heat flux test conditions, exposure times for recession rate, mass loss rate, front surface temperature, and back-face heat-soaked temperature to compare material performance. The microstructures of these FRPCs before and after ablation and mechanical testing were in-vestigated using scanning electron microscopy and micro-computed tomography. Thermophysical properties of the virgin and char FRPC were measured at elevated tem-peratures. Using these material properties and surface thermochemistry analysis, material response modeling was performed and validated with aerothermal test data. Mechanical properties, such as tensile, compression, and flexural were conducted via ASTM stand-ards. The above material properties of these FRPCs compared favorably with several commercial ablatives under similar extreme aerothermal environments.