Mechanical properties investigation of carbon/carbon composites fabricated by a fast densification process

Research highlights: → The flexural strength drops with increasing the heat treatment temperature. → The failure transfers from brittle to pseudoplastic as the preform changes. → The interlaminar shear strength increases significantly with the shift of preform. → The strength of interfacial bonding plays a key role to composite failure behavior. -- Abstract: Carbon/carbon (C/C) composites were prepared by thermal gradient chemical vapor infiltration with a fast densification rate. The fracture morphology and mechanical properties were examined by scanning electron microscopy and mechanical testing, respectively. The effects of preform type and heat treatment temperature (HTT) on the mechanical properties of C/C composites were analyzed. The results show that the average flexural strength drops from 47.8 MPa to 38.6 MPa as the HTT increases from 2100 oC to 2500 oC. C/C composites with felt as preform show brittle fracture and samples with needle-punched felt as reinforcement present obvious pseudoplastic property. The interlaminar shear strength of needle-punched felt reinforced composites is higher than that of sample with felt as preform by 44.26% owing to the needle-punched fiber in the thickness direction. The strength of interfacial bonding plays a key role to mechanical properties and failure behavior of C/C composites.