关键词: 纳米结构, 复合材料, 热传导, 分子动力学, 振动态密度

Abstract:

The non-equilibrium molecular dynamics method was used to simulate the normal thermal conductivity of the three-dimensional graphene-carbon nanotube composite structure. The structure is based on multi-layer graphene, and the graphene layers are connected with each other through nanotubes. In this way, it is expected to have both low contact thermal resistance and high normal thermal conductivity. In this paper, the out-of-plane thermal conductivity of 3D GCHs is simulated by non-equilibrium molecular dynamics method. The results show that the out-of-plane thermal conductivity increases by one order of magnitude compared with that of multi-layer graphene, and the interface resistance decreases by one order of magnitude in comparison with thermal contact resistance of CNTs. However, the interface between graphene and CNT hinders the heat transfer of GCHs enhancing further. The heat transfer and phonon localization of the GCHs are further investigated through its phonon vibrational density of states and overlap energy. The results show that the addition of carbon nanotubes stimulates more medium and high frequency phonons to participate in heat transfer, but the low frequency phonons still dominate. It is verified that the deformation at the interface is the main factor to prevent the out-of-plane thermal conductivity from further increasing. This paper provides some directional guidance for the improvement and development of high thermal conductivity materials: in the three-dimensional structure of the same element, the fewer types of structural atoms, the better the coordination of inter-atomic vibration, the fewer phonon scattering, the lower the degree of energy localization, and the higher the thermal conductivity

Key words: nano structure, composite material, thermal conductivity, molecular dynamics, vibrational density of states