Thermal properties of aligned carbon nanotube/carbon nanocomposites

Aligned carbon nanotube/carbon (Acnt/C) nanocomposites were fabricated with traditional chemical vapor infiltration (CVI) technology. Thermal conductivities of as-deposited and graphitized samples were tested by laser flash method. Results show that although only half the density and half the fraction of reinforcing element compared with carbon/carbon (C/C) composites in this work, the thermal diffusivity of Acnt/C is generally 3-5 times that of C/C composites, and the thermal conductivity of lower density Acnt/C (about 0.8 g/cm³) samples can reach 72.24 W/m K, about 12.31% higher than C/C composites with higher density (about 1.50 g/cm³). Heat transfer mechanism analyses show that the potential superiority of thermal conduction for Acnt/C can be ascribed to the long wrapped graphene layers of well-aligned carbon nanotubes, which can reduce phonon-phonon Umklapp scattering along the axial direction largely. The gap between predicted and measured thermal conductivity of Acnt/C suggests the demand for CNTs with virtually good thermal conducting capability and pyrocarbon with better properties by regulating CVI process.