A three-dimensional nanostructure of graphite intercalated by carbon nanotubes with high cross-plane thermal conductivity and bending strength

A three-dimensional graphite consolidated composite (GCC) was prepared by the intercalation of carbon nanotubes (CNTs) at the interlayer of expanded graphite (EG) using chemical vapor deposition followed by hot-pressing. The intercalation of well-dispersed CNTs was attributed to the dispersion of catalysts at the interface of EG based on vacuum impregnation. The crystal orientation in the cross-plane direction of CNT/GCC blocks was remarkably improved by the intercalation of CNTs. The density of CNT/GCC was also increased by intercalating CNTs into the pore space of layered graphite. Thermal conductivity and bending strength of CNT/GCC were controlled by the growth time of CNTs and hot-pressing pressure. CNT/GCC showed a maximum cross-plane thermal conductivity (λ⊥) of 24.3 Wm−1K−1, which is threefold higher than that of GCC (6.2 W m−1K−1). A remarkable increase in λ⊥ was attributed to efficient heat flow of CNTs bridging graphite layers in the cross-plane direction and good contact between nanotubes and graphite layers. Furthermore, the cross-plane bending strength (σb⊥) of CNT/GCC up to 46 MPa is 48.4% higher than that of GCC at 31 MPa due to the combination of strong pull-out effect of high-density long nanotubes and the decreased open porosity.