Thermal-diffusivity measurement of 3D-stitched C–SiC composites

Effect of siliconization conditions on thermal diffusivity of 3D-stitched fiber architecture-based C–SiC composites was investigated to select desired conditions. Several 3D-stitched C–SiC composite blocks were prepared using coal–tar pitch as a carbon precursor and siliconization was carried out at 1450 and 1650 °C for 10 and 120 min. Thermal diffusivity of blocks was investigated using laser-flash equipment in in-plane and through-thickness directions. It varies from 77 mm2/s at room-temperature to 14.7 mm2/s at 1500 °C in in-plane and 36–6.1 mm2/s in through-thickness direction. A model was developed to estimate thermal diffusivity in in-plane and through-thickness directions based on the volume fraction of the constituents and porosity of the composite blocks. The estimated thermal-diffusivity values were compared with the measured values. The values were found to be close to the experimental values in entire testing temperature range at all the siliconization conditions.