Investigation on thermal radiation properties of C/SiC composites

The total hemisphere emissivity at 90°C and the normal spectral reflectance at room temperature of C/SiC composites were measured by using steady-state calorimeter method and Fourier infrared spectrometer (FTIR) respectively. The effect of fiber preform weaving mode, thickness of SiC coating and surface morphology on thermal radiation properties of C/SiC were investigated. The results show that thermal radiation properties of 3D C/SiC composites are superior to those of 2D C/SiC composites. Total emissivity of 2D C/SiC is 0.78, and total emissivity of 3D C/SiC is up to 0.82. The thickness of SiC coating has great effect on thermal radiation properties of C/SiC composites. With increase of SiC coating thickness, total emissivity of C/SiC firstly decrease, then increase, the largest emissivity may attain 0.85. Polished surface makes thermal radiation properties of C/SiC composites reduce with the result that total emissivity of 2D C/SiC and 3D C/SiC is 0.74 and 0.75 respectively.