Low Conductivity SiC-Based Ceramic Composites for Fusion Blanket Flow Channel Inserts

Dual-coolant blanket designs, needed for magnetic fusion systems, require low electrical conductivity and low thermal conductivity inserts that are compatible with the lead-lithium breeder/coolant. Silicon carbide fiber-reinforced silicon carbide composites have been shown to be compatible with liquid Pb-Li at elevated temperatures and to have good stability in high neutron flux environments. However, these SiC/SiC composites are believed to have an unacceptably high electrical and thermal conductivity for use as flow channel inserts. The development of a silicon carbide fiber-reinforced insulating silicon carbide matrix composite, or a SiC/SiC composite with an irradiation-stable insulating fiber coating, would significantly reduce the through-thickness electrical and thermal conductivity. This project will investigate several approaches to incorporating an insulative composite constituent ¿ namely, matrix modification and fiber coating ¿ with an emphasis on manufacturability. Commercial Applications and other Benefits as described by the awardee: The technology would address a critical component of the long-term path to the deployment of fusion energy systems. In the near term, a high-temperature radiation-compatible material could be utilized in fission reactors currently under development. The modification of SiC/SiC to a nonconductive form also would enable further utilization as a high temperature insulator. Finally, an insulating ceramic composite could have application to the aerospace industry for structural thermal protection systems.