Relationship between dimensional changes and the thermal conductivity of neutron-irradiated SiC

Three kinds of commercially available SiC ceramics, hot-pressed, pressureless-sintered and reaction-bonded SiC were neutron irradiated at temperatures of 300 and 650 °C and fluences 8.0 × 10 23 and 4.3 × 10 24 n/m 2 ( E>0.18 MeV), respectively. The thermal conductivity and dimensional change were measured by isochronal annealing experiment up to 1700 °C. The change in thermal conductivity was analyzed in terms of phonon scattering by point defects. The defect concentration calculated from the thermal conductivity agreed well with that calculated from the dimensional change of the same specimen. We obtained quite good agreement between changes of thermal conductivity and swelling. Therefore, it is confirmed that the same kind of irradiation induced defects are involved in the degradation of thermal conductivity and swelling of SiC.