Introduction
Experimental procedure
Materials
Sample | SiC thickness (µm) | FBCVD deposition conditionsa
| Microstructural characteristics | Comment |
---|---|---|---|---|
UMAN TRISO | 35 | 1700 °C, MTS in hydrogen | Nano-sized grains along interface with the inner carbon coating, submicron grain size in the centre | Fabricated by UMAN |
CEA TRISO | 59 | 1550 °C, MTS in hydrogen | Nano-sized grains along the inner interface, elongated grains that can reach several microns in length in the centre of the coating | |
INET TRISO | 31 | 1560 °C | Uniform submicron grain size throughout the full coating, some porosity | Fabricated by INET |
Bulk CVD SiC | 2 mm disc | Static CVD | Large, randomly oriented grains with sizes in the range of 5 to 50 µm |
Microstructural characterization
High temperature nanoindentation measurements
Results
Microstructural characterisation
Grain diameter (µm) | Fraction of Σ3 (%) | Fraction of GB misorientation (%) | |||
---|---|---|---|---|---|
High (>15°) | Low (1.5° < θ < 15°) | Non-defined (<1.5°) | |||
UMAN | 0.86 ± 0.57 | 29 | 71 | 4 | 25 |
CEA | 1.38 ± 1.14 | 39 | 66 | 9 | 25 |
INET | 0.80 ± 0.46 | 37 | 71 | 4 | 25 |