Microstructure and mechanical properties of carbon fiber reinforced multilayered (PyC-SiC)_n matrix composites

Carbon fiber reinforced multilayered (PyC-SiC)_n matrix (C/(PyC-SiC)_n) composites were prepared by isothermal chemical vapor infiltration. The phase compositions, microstructures and mechanical properties of the composites were investigated. The results show that the multilayered matrix consists of alternate layers of PyC and β-SiC deposited on carbon fibers. The flexural strength and toughness of C/(PyC-SiC)_n composites with a density of 1.43g/cm³ are 204.4MPa and 3028kJ/m³ respectively, which are 63.4% and 133.3% higher than those of carbon/carbon composites with a density of 1.75g/cm³. The enhanced mechanical properties of C/(PyC-SiC)_n composites are attributed to the presence of multilayered (PyC-SiC)_n matrix. Cracks deflect and propagate at both fiber/matrix and PyC-SiC interfaces resulting in a step-like fracture mode, which is conducive to fracture energy dissipation. These results demonstrate that the C/(PyC-SiC)_n composite is a promising structural material with low density and high flexural strength and toughness.