Properties and microstructure of Nextel 720/SiC composites

Continuous Nextel 720 fibers reinforced SiC composites were fabricated by CVI at 1100 °C for 200 h using SiCH₃Cl₃ as precursor. The mechanical properties were measured by three-point bending. The microstructures of the interface and fracture surface were characterized by SEM. The values of the Nextel 720/SiC for mean strength and Yong's modulus were 316 MPa and 211 GPa, respectively. The composites had a high failure strain of 0.25%. The multi-layer PyC interface and the crevices between the fiber and the matrix resulted in a metal-like fracture behavior.