NSUF 18-1237: Kinetics of irradiation defect annealing and thermal conductivity recovery in silicon carbide at high temperature

The objective of this project is to enhance understanding of the annealing of irradiation induced defects in high purity and sintered SiC samples at high temperatures. Under neutron irradiation the thermal conductivity of SiC degrades significantly, and within a certain temperature range (<900 oC) saturates at a nearly constant temperature-dependent value. This phenomenon has been consistently observed for both high purity variants (e.g. chemical vapor deposition [CVD] SiC) and lower purity sintered variants, though to different extents. Although it is well known that the irradiation-induced defects anneal out at high temperatures, the kinetics of the defect annealing processes is not well known. No prior efforts in the literature focus on the kinetics of irradiation annealing due to neutron irradiation and the resulting thermal conductivity recovery under temperature ramps in environments and at temperatures relevant for fission systems. This effort will aim to irradiate both high purity CVD SiC and lower purity sintered NITE SiC. The existing irradiated samples identified both exhibit strong impact on the thermal conductivity, which saturates at doses greater than 1 DPA. The SiC samples that will be used in this work have already been irradiated.

Additional Info

Field	Value
Abstract	The objective of this project is to enhance understanding of the annealing of irradiation induced defects in high purity and sintered SiC samples at high temperatures. Under neutron irradiation the thermal conductivity of SiC degrades significantly, and within a certain temperature range (<900 oC) saturates at a nearly constant temperature-dependent value. This phenomenon has been consistently observed for both high purity variants (e.g. chemical vapor deposition [CVD] SiC) and lower purity sintered variants, though to different extents. Although it is well known that the irradiation-induced defects anneal out at high temperatures, the kinetics of the defect annealing processes is not well known. No prior efforts in the literature focus on the kinetics of irradiation annealing due to neutron irradiation and the resulting thermal conductivity recovery under temperature ramps in environments and at temperatures relevant for fission systems. This effort will aim to irradiate both high purity CVD SiC and lower purity sintered NITE SiC. The existing irradiated samples identified both exhibit strong impact on the thermal conductivity, which saturates at doses greater than 1 DPA. The SiC samples that will be used in this work have already been irradiated.
Award Announced Date	2018-02-01T14:17:04.997
Awarded Institution	Center for Advanced Energy Studies
Facility	Microscopy and Characterization Suite
Facility Tech Lead	Kory Linton, Yaqiao Wu
Irradiation Facility	None
PI	Nicholas Brown
PI Email	[email protected]
Project Type	RTE
RTE Number	1237