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 degrees C. (C) 2016 Elsevier Ltd. All rights reserved.