Swelling of SiC at intermediate and high irradiation temperatures

This paper presents results from a neutron irradiation campaign on CVD SiC carried out in the High Flux Isotope Reactor. Materials were irradiated in a range of temperature from 200 to 1500 degrees C and from a fraction of a dpa to similar to 6 dpa. Data on swelling and room temperature thermal conductivity are presented. The swelling behavior below similar to 800 degrees C agrees well with the literature values. Data in the range of 1000-1600 degrees C indicates that swelling increases as the dose is increased from 2 dpa to 6 dpa, at higher-swelling with increasing irradiation temperature. Any peak in void swelling apparently occurs at irradiation temperature > 1500 degrees C (> 0.6T(m)). In the 1100-1200 degrees C temperature range, volumetric swelling is apparently at a minimum though increases from similar to 0.2% to similar to 0.4% as dose increases from similar to 2 dpa to similar to 6 dpa. The maximum swelling was found to be similar to 1.5% at the maximum dose and temperature of this study, similar to 6 dpa and similar to 1500 degrees C. Room temperature thermal conductivity data over the entire temperature range are presented and a direct correlation between the thermal defect resistance and swelling is seen for materials irradiated at temperature less than 800 degrees C. Above 1000 'C the correlation between swelling and thermal defect resistance breaks down indicating a changing microstructure at high temperature to a microstructure less effective at scattering phonons on a swelling-normalized basis. (c) 2007 Elsevier B.V. All rights reserved.