Influence of graphitization temperature on microstructure and mechanical property of C/C-SiC composites with highly textured pyrolytic carbon

• Highly textured pyrolytic carbon was introducted into C/C-SiC composites by isothermal chemical vapor infiltration. • The effect of graphitization treatment of highly textured pyrolytic carbon on C/C-SiC composites was studies. • The microstructure evolution of highly textured pyrolytic carbon affects the mechanical properties and fracture behavior. C/C-SiC composites with highly textured pyrolytic carbon (HT PyC) were prepared by a combining chemical vapor infiltration and liquid silicon infiltration. The effect of HT PyC graphitization before and after 2327 and 2723 K on C/C-SiC composites was investigated. The mechanical properties decreased with increasing graphitization temperature, but graphitization treatment changed the fracture behavior from brittle like to pseudo-ductile. The decrease in bending strength from 306.21 to 243.69 MPa resulted from the weak interfacial bonding between HT PyC and fiber, and the good orientation of graphite layers. The crack at border of fiber bundle and longitudinal crack in HT PyC shortened the path of crack propagation, resulting in fracture toughness decrease from 21.11 to 14.72 MPa·m 1/2 . A more pseudo-ductile behavior was due to the longer pull-out of fibers, the better orientation of graphite layers, the sliding of sublayers, and the deflection and propagation caused by the transverse cracks.