A novel preparation and properties of in-situ grown carbon nanotube reinforced carbon/carbon composites

In-situ grown carbon nanotube-reinforced carbon/carbon (C/CNT/C) composites were synthesized using a novel and eco-friendly method. The catalyst Ni was loaded onto carbon fiber surfaces through pre-oxidation fiber carbonization without reducing gas and then rapid chemical vapor infiltration (RCVI) for densification. The microstructure, morphology and properties of the C/CNT/C composites were studied. Results indicated that the existence of CNT on carbon fibers remarkably improved the microstructure, mechanical performances, thermal conductivity, and friction properties of the C/CNT/C composites compared with the carbon/carbon (C/C) composites. According to study of microstructure and failure mode of the C/CNT/C composites, the in situ growth of CNT location on the fiber surface can effectively create strong mechanical interlocking or local stiffening at the fiber/matrix interface. In addition, due to high specific surface area of modified fiber, the microstructure of carbon matrix has been improved. The flexural strength and storage modulus of the C/CNT/C composites increased by 34.9% and 19.5%, their internal friction and loss modulus decreased by 37.5% and 24.3%, respectively. C/CNT/C composites also demonstrated excellent frictional properties at different braking conditions. Thermal conductivities of the C/CNT/C composites in the X-Y and Z directions are remarkably improved for those of the C/C composites at 50-900 °C.