High performance C/SIC composites with multilayered interphase used for space rocket

Carbon fibers reinforced silicon carbide composite (C/SiC) offers excellent high temperature. However, high thermal conductivity precludes the C/SiC composite application in insulating structural components. A high strength, high roughness, and low thermal conductivity 2.5D C/SiC composite for space rocket component was manufactured by CVI+PIP combined process. In PIP process 10wt% SiO₂ nano-powders were filled in impregnant as low thermal conductivity filler. Before matrix densification, 2.5D carbon fibrous preform with the fiber volume content of 45% was coated with C/SiC/C multilayered interphase. SEM microstructure analysis indicated that there were many pulled-out fibers in cross-section of fracture composite specimen. The carbon fibers in the composite with C/SiC/C multilayered coating were not being eroded by SiO₂ fillers. The C/SiC composites exhibited excellent mechanical and insulation properties at room temperature with fracture toughness of 15.2MPa·m^1/2, flexural strength of 543MPa, and thermal conductivity of 3.45W/m·K. The high temperature (1300) properties of this material were also good with flexural strength of 527MPa.