Effects of fabric architectures on the thermal expansion coefficient and the thermal diffusivity of carbon fiber reinforced silicon carbide composites

The thermal expansion coefficient and the thermal diffusivity of 2 dimensional (D), 2.5D and 3D carbon fiber reinforced silicon carbide (C/SiC) composites were tested from room temperature to 1400°C using a thermal dilatometer and laser flash apparatus. The microstructure was observed by scanning electron microscopy and light microscopy. The results show that at low temperature (below 700°C), the longitudinal and transversal thermal expansion coefficients of all these C/SiC composites increase slowly as the temperature increases, followed by fluctuations of different degrees after 700°C. At high temperature above 700°C, the longitudinal thermal expansion coefficients of all these materials and the transversal coefficient of the 2D C/SiC composite decrease as the temperature increases, but the transversal thermal expansion coefficients of the 2.5D and 3D C/SiC composites increase sharply as the temperature increases. The thermal diffusivity of all these composites decreases as the temperature increases, and the thermal diffusivity of the 3D C/SiC composite is the highest, it is 1-1.2 and 1.4-2 times higher than the 2.5D and 2D C/SiC composites respectively.