Improving thermal conductivity in the through-thickness direction of carbon fibre/SiC composites by growing vertically aligned carbon nanotubes

Combining heat transfer and high-temperature heat resistance is very important for realising thermal management in harsh environments. Achieving high heat conduction in the through-thickness direction (k⊥) is challenging for carbon fibre (CF) reinforced SiC matrix composite (CF/SiC) based heat resistant materials due to their anisotropic structures and weak bonding between the CF and the matrix. We present a three-dimensional (3-D) hierarchical vertically aligned carbon nanotubes (VACNTs)-CF hybrid by growing VACNTs on the surface of CF fabric. The SiO2 coating enables the strong deposition of the catalyst, facilitating high-density growth of VACNT. The VACNT-CF reinforced SiC composite is prepared by stacking VACNT-CF following by precursor infiltration and pyrolysis process. The VACNT forest not only enables strong interfacial bonding between the CF and the matrix but also greatly improve the k⊥ due to the good interfacial compatibility. The VACNT-CF/SiC composite exhibits k⊥ of 16.80 W/(m K), which is higher than that of the CF/SiC (7.94 W/(m K)), due to highly thermally conductive pathways in the dense structure. The VACNT-CF/SiC composite also conducts heat rapidly in the through-thickness direction. The VACNT-CF/SiC composite with high thermal conductivity, high strength and high oxidation resistance can be used for heat dissipation and resistance by optimising the microstructure.

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