Carbon fiber/SiC composites modified SiC nanowires with improved strength and toughness

In this study, Cf/SiC composite was modified with SiC nanowires (SiCnws) grown in-situ in SiC matrix. Effects of SiCnw on bending strength and fracture toughness were investigated by comparison with conventional Cf/SiC. Results showed that SiCnw significantly improved both strength and fracture toughness of Cf/SiC. Compared to Cf/SiC, flexural strengths of Cf/SiC-SiCnw/PyC and Cf/SiC-SiCnw composites increased from 363.1 MPa to 375 MPa and 466.9 MPa, respectively. Bending strength and fracture toughness were estimated to 565 MPa and 20.30 MPa m1/2 for Cf/SiC containing SiCnw at high temperature (1000 °C), respectively. These values were 13.2% and 16.1% higher than that of conventional Cf/SiC. The latter was attributed to deflection, bridging, and pull-out of SiC nanowires to cracks. Improvements in mechanical properties of modified C/SiC composites were mainly attributed to deflection and bridging of SiC nanowires on cracks and pulling out of SiC nanowires from the matrix.