Enhancing Thermal Conductivity of SiC Matrix Pellets for Accident-Tolerant Fuel via Atomic Layer Deposition of Al 2 O 3 Coating

This study investigates the enhancement of thermal conductivity in silicon carbide (SiC) matrix pellets for accident-tolerant fuels via atomic layer deposition (ALD) of alumina (Al 2 O 3 ) coatings. Pressure-holding ALD protocols ensured precursor saturation, enabling precise coating control (0.09 nm/cycle). The ALD-coated Al 2 O 3 layers on SiC particles were found to be more uniform while minimizing surface oxidation compared to traditional mechanical mixing. Combined with yttria (Y 2 O 3 ) additives and spark plasma sintering (SPS), ALD-coated samples achieved satisfactory densification and thermal performance. Results demonstrated that 5~7 wt.% ALD-Al 2 O 3 + Y 2 O 3 achieved corrected thermal conductivity enhancements of 14~18% at 100 °C., even with reduced sintering aid content, while maintaining sintered densities above 92% T.D. (theoretical density). This work highlights ALD’s potential in fabricating high-performance, accident-tolerant SiC-based fuels for safer and more efficient nuclear reactors, with implications for future optimization of sintering processes and additive formulations.