Study on the C/SiC composites for hot gas valve of solid propellant ramjet

Carbon fiber reinforced silicon carbide matrix composites (3D C/SiC) for hot gas valve of solid propellant ramjet were prepared by using 'chemical vapor infiltration + precursor impregnation pyrolysis' (CVI + PIP) hybrid process. The mechanical properties and microstructure of 3D C/SiC composites were investigated. The density of 3D C/SiC composites can reach 2.1 g/cm³, and the shear strength and axial flexural strength are 55 MPa and 643 MPa respectively at room temperature. In the course of fracture, the composites present obvious nondestructive toughness fracture behaviour with many pulled-out fibers in the fracture cross-section. The composites possess superior insulation property with thermal conductivity of 14.5 W/(m · K) at Z-direction and 5.0 W/( m · K) at X-Y plane. The 3D C/SiC hot gas valves of solid propellant ramjet successfully pass the cool gas axial impact test and high-temperature gas test.