Tuning the interfacial thermal conductance via the anisotropic elastic properties of graphite

Abstract

The effects of interatomic bonding strengths of graphite itself, in the in-plane (IP) and cross-plane (CP) direction, on the interfacial thermal conductance between graphite and substrate copper (Cu), are investigated by molecular dynamics simulations. It is found that the interfacial thermal conductance at the graphite/Cu interface monotonically decreases with respect to the increase of the IP bonding strength of graphite. However, the interfacial thermal conductance has a maximum with respect to the increase of the CP bonding strength of graphite. By extracting the acoustic iso-energy surfaces and phonon density of states of graphite under various bonding strength parameters, it is found that increasing the IP bonding strength decreases both the incident phonon group velocity component and average interfacial transmission coefficient. Increasing the CP bonding strength also decreases the incident phonon transmission coefficient. However, increasing the CP bonding strength increases the phonon group velocity component. To provide a practical method to enhance the interfacial thermal conductance, we compared the interfacial thermal conductance of porous graphite/Cu interface, which is higher than the graphite/Cu interface mainly due to the large reduction of the in-plane elasticity. This study provides important guidance in the active regulation of the interfacial thermal conductance between anisotropic materials and substrate.