Effect of pyrolysis temperatures on the performance of SiC_f/SiC composites

Continuous silicon carbide fiber reinforced silicon carbide matrix composites (SiC_f/SiC) are promising candidate materials for nuclear applications. In this paper, three–dimensional (3D) SiC_f/SiC composites were fabricated using the polymer infiltration and pyrolysis (PIP) process at different pyrolysis temperatures (i.e. 1100, 1300 and 1500 °C). The effect of the pyrolysis temperature on the thermal and mechanical properties of the SiC_f/SiC composites was investigated with a laser flash method, a three–point bending test and a single–edged notch beam method. The results indicated that the thermal diffusivity of the SiC_f/SiC composites improved considerably with increasing pyrolysis temperatures, due to a higher degree of crystallization in the matrix. Additionally, as the testing temperature increased, the thermal diffusivity of the SiC_f/SiC composites gradually decreased. With increasing pyrolysis temperatures, the mechanical properties of the SiC_f/SiC composites first increased and later decreased. The SiC_f/SiC composites fabricated at 1300 °C had the highest average flexural strength and fracture toughness, i.e. 535.6 MPa and 17.3 MPa m^1/2, respectively.