Impermeable SiC Composites

Next generation nuclear plants will operate with helium as the working fluid and, for highest efficiency, at temperatures approaching 1000°C. However, the steel alloys used in reactor construction lose their strength at temperatures above 850°C. SiC/SiC composite systems might be suitable candidates, but these systems generally have helium permeabilities that are too high for duct components. This project will develop a carbon-fiber-reinforced, silicon-carbide-matrix composite system that retains its strength above 1000°C and has helium permeability less than 10-9 m2/s. Nanophase materials used in the matrix will minimize porosity without sacrificing strength or high temperature performance. Commercial Applications and other Benefits as described by the awardee: The development of high temperature composite systems that are impermeable to gas flow should facilitate the incorporation of high temperature ceramic composites into next generation gas turbines. The impermeable composites also could be integrated into engine nozzle structures, enabling higher engine operation temperatures.