研究目的
To experimentally quantify the stored energy release upon thermal annealing of previously irradiated high-purity silicon carbide (SiC) and correlate the release to the observed microscopic swelling, lattice dilation, and microstructure.
研究成果
The study found comparable stored energy in SiC to that of nuclear graphite, with a stored energy release in excess of its speci?c heat in some irradiation conditions. The maximum measured stored energy was ~1390 J/g, extrapolated to ~2500 J/g at the assumed amorphization dose. The findings are consistent with existing theory, though the amount of stored energy given the large observed crystalline strain is remarkable.
研究不足
The irradiation temperature of this campaign, ~60 (cid:1)C, is very low with respect to currently proposed nuclear applications of SiC, requiring care when extrapolating results to relevant temperature regimes.
1：Experimental Design and Method Selection:
Samples of highly-faulted poly-crystalline CVD b-SiC and single crystal 6HeSiC were irradiated in a mixed spectrum ?ssion reactor near 60 (cid:1)C in a ?uence range from 5 (cid:3) 1023 to 2 (cid:3) 1026 n/m2 (E > 0.1 MeV). The stored energy release was quantified and correlated to the observed microscopic swelling, lattice dilation, and microstructure as observed through TEM.
2：1 MeV). The stored energy release was quantified and correlated to the observed microscopic swelling, lattice dilation, and microstructure as observed through TEM.
Sample Selection and Data Sources:
2. Sample Selection and Data Sources: Ultra-high purity highly-faulted polycrystalline CVD SiC produced by Rohm & Haas Advanced Materials and electronic grade 6HeSiC procured from Cree were used.
3：List of Experimental Equipment and Materials:
High Flux Isotope Reactor (HFIR) for irradiation, Netzsch DSC 404C Thermal Analyzer for stored energy measurements, Bruker D2 Phaser for x-ray analysis, FEI-Versa 3D Dual Beam for TEM sample preparation, JEM2100F for TEM imaging.
4：Experimental Procedures and Operational Workflow:
Samples were irradiated, cleaned, and analyzed for density through density gradient column and x-ray diffraction. Stored energy measurements were carried out using a Netzsch DSC 404C Thermal Analyzer.
5：Data Analysis Methods:
Lattice parameters were determined by least-squares re?nement of angles calculated using Bragg's law to measured Bragg angles. Stored energy release was determined by comparison with known heat capacity.
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