Mechanical properties and fracture behavior of CVI-iC/TaC modified C/C composite

Using needled carbon fiber felt as the preform，the fiber coating with multilayered (PyC/SiC/TaC) fabricating by chemical vapor infiltration was used to modify C/C composites. The novel C/C composites were fabricated by chemical vapor infiltration and impregnation of thermosetting resin and carbonization. The microstructures and mechanical properties of C/C composites were investigated. The results show that the multilayered (PyC/SiC/TaC) coating enwraps around the carbon fiber evenly and compactly and forms cannular microstructure in C/C composites; both the strength and toughness of modified composites increase apparently. The average flexural strength of the composites reaches 522MPa，the maximum fracture displacement reaches 1.19mm，and the fracture mode shows brittle fracture. After high temperature treating (HTT) at 2000℃，the flexural strength of the composites decreases，while the maximum fracture displacement increases，and the fracture mode of the composites shows "pseudo plastic"  fracture.