Effect of catalyst on microstructure and flexural properties of C/C composites

C/C composite was prepared by chemical liquid vapor deposition(CLVD) at different catalytic conditions and its density was about 1.65g/cm³. The microstructure and flexural properties of the composites were characterized. The results show that the use of catalyst has significant impact on the structure and flexural properties of C/C composites during CLVD. When there is no catalyst added in the precursor, smooth laminar(SL)pyrolytic carbon is formed and the fracture mode is brittle fracture. While Fe is used as catalyst, rough laminar (RL) and smooth laminar pyrolytic carbon structure is obtained. The flexural strength and flexurad modulas of the composites are improved and it shows pseudo plastic fracture. Rough laminar and isotropic (ISO) mixed structure is observed when Ni is added, and the composites show the pseudo plastic fracture behavior while the flexural strength is the same with the condition of nothing used as catalyst. The mixed Ni+Fe catalyst added in the precursor induces rough laminar pyrolytic carbon and the composites exhibit pseudo plastic fracture behavior, and their flexural strength and flexural modulus are improved significantly.