Abstract
SiC/SiC composites have gained significant attention as accident tolerant fuel cladding for their high temperature mechanical properties and superior oxidation kinetics in accident scenarios. However, operational LWR coolant and irradiation conditions cause issues regarding SiC matrix dissolution and fission product retention respectively. A potential solution is the application of a dual-purpose (environmental barrier and hermetic seal) coating. The goal of this research is to aid in the down-selection process in identifying the highest performance coating for LWR conditions. One of the most important selection criteria is the coating-substrate mechanical stability. This research presents an investigation of the relationship between fracture strength and microstructure through small scale mechanical testing and TEM analysis. Micro-cantilevers were fabricated across the SiC/coating interfaces on several candidates including PVD Cr and CrN. Testing was performed at ambient and 320°C. The lower-bound average ambient failure strength for the SiC/Cr and SiC/CrN interfaces were on the order of 3.2 GPa and 3-5 GPa respectively. High temperature tests revealed a dramatic reduction in strength, around 0.4GPa. Neutron irradiated SiC/Cr interfaces (~0.5dpa at 330°C) showed slightly reduced failure strength of 2.9 GPa at ambient temperature. A TEM investigation compared irradiated and pristine SiC/Cr interfaces.
| Original language | English |
|---|---|
| Pages | 1043-1051 |
| Number of pages | 9 |
| State | Published - 2019 |
| Event | 19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, EnvDeg 2019 - Boston, United States Duration: Aug 18 2019 → Aug 22 2019 |
Conference
| Conference | 19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, EnvDeg 2019 |
|---|---|
| Country/Territory | United States |
| City | Boston |
| Period | 08/18/19 → 08/22/19 |
Funding
The author would like to thank ORNL and the ORAU/ORISE program for enabling time and access to ORNL facilities. The coating and cantilever fabrication were supported by US DOE Office of Nuclear Energy (NE) for the Advanced Fuels Campaign under contact DE-AC05-00OR22725 with ORNL managed by UT Battelle, LLC. The testing was supported by U.S. DOE, Office of NE, Nuclear Science User Facilities program. This work was performed in part at the Analytical Instrumentation Facility (AIF) at North Carolina State University, which is supported by the State of North Carolina and the National Science Foundation (award number ECCS-1542015). The AIF is a member of the North Carolina Research Triangle Nanotechnology Network (RTNN), a site in the National Nanotechnology Coordinated Infrastructure (NNCI). Funding was provided by DOE-Nuclear Energy University Program DE-NE0008768.
| Funders | Funder number |
|---|---|
| DOE-Nuclear Energy University | DE-NE0008768 |
| National Science Foundation | ECCS-1542015 |
| U.S. Department of Energy | DE-AC05-00OR22725 |
| Oak Ridge National Laboratory | |
| North Carolina State University | |
| UT-Battelle |