Comparison on Microstructure and Infrared Emissivity Properties of 3D Needled Composites

Three-dimensional (3D) needled composites, C/C, C/C-SiC, and C/SiC, were prepared and their infrared emissivity properties in 1000-1600°C were investigated. Results showed that the infrared emissivity of all composites increased almost linearly with temperatures. In comparison with C/C, C/C-SiC composites reduced by 10% in the total emissivity. Twenty-two vol% SiC in C/C-SiC composites caused a low zone in 10-14 μm, corresponding to the theoretical emissivity of SiC. For C/SiC composites prepared by CVI, 68 vol% SiC caused a "V" shape in the spectral emissivity. The high SiC content also endued the high infrared emissivity properties for C/SiC composites.