Microstructure, mechanical and anti-ablation properties of SiCnw/PyC core-shell networks reinforced C/C–ZrC–SiC composites fabricated by a multistep method of chemical liquid-vapor deposition

Abstract C/C–ZrC–SiC composites reinforced by SiC nanowire (SiCnw)/pyrocarbon (PyC) core-shell networks were prepared by a multistep method of chemical liquid-vapor deposition (CLVD). The microstructure, mechanical property and ablation resistance were researched. The investigations presented that the PyC was deposited on the SiC nanowires, and the micro-scale core-shell structures were produced. Moreover, these micro-scale structures not only connected with the fibers and matrices, but also filled the pores in the composites. In contrast with C/C–ZrC–SiC composites, the flexural modulus and strength of SiCnw/PyC-C/C–ZrC–SiC composites increased by 36.91% and 44.53%, and the fracture mode was changed from the brittle to pseudo-plastic fracture. After the oxyacetylene torch ablation at two temperatures for 90s, the composites strengthened by SiCnw/PyC core-shell possessed a better resistant ablation. At ablation temperature of 2300 °C, the mass loss rate and linear reduction rate of the composites with core-shell networks decreased by 66.18% and 57.55% in contrast with the non-reinforced composites, and declined by 56.46% and 57.48% at ablation temperature of 3000 °C. The obvious decrease of ablation rates was ascribed to the dense microstructure, the small coefficient of thermal expansion (CTE), the good thermal conductivity, and the resistant ablation roles of SiCnw/PyC core-shell systems.