Improved thermal conductivity of silicon carbide fibers-reinforced silicon carbide matrix composites by chemical vapor infiltration method

A barrier for the application of silicon carbide fibers-reinforced silicon carbide matrix (SiC_f/SiC) composites fabricated by chemical vapor infiltration (CVI) as nuclear cladding materials is its low thermal conductivity, which is caused by high porosity. In this study, we reported new processing approach to fabricate SiC_f/SiC composites by introducing about 4 vol% SiC nanowires (NWs) in SiC_f preform, followed by CVI process. Microstructure, distribution of pore size, thermal conductivity, and bending strength of obtained SiC_f/SiC composites with and without NWs were studied. Results showed that densification of both intra-bundles and inter-bundles of SiC_f/SiC-NW composite was improved by introducing SiC NWs into the preform. With the decrease in the porosity, SiC_f/SiC-NW exhibited thermal conductivity of 26.7 W m⁻¹ K⁻¹ at room temperature. Moreover, bending strength of SiC_f/SiC-NW composite was up to 482 ± 36 MPa, which had an improvement of 19% compared to that of traditional SiC_f/SiC composite.