Molecular dynamics study of thermal transport properties across covalently bonded graphite-nanodiamond interfaces

The groundbreaking experiment [Luo et al. Nature 2022, 607 (7919) 486-491] recently led to the development of new ultrastrong Carbon/Carbon composites, in which graphene and nanodiamond are strongly connected via covalent bonding. This covalently bonded interface endows the composites with spectacular high strength and other exceptional properties. Herein, non-equilibrium molecular dynamic simulations are conducted to examine the interfacial thermal conductance of graphite-diamond structures by considering the effects of size, environmental temperature, interfacial atomic structures, and tensile strain. Further insight into the microscopic heat transport mechanism of various effects is obtained by analyzing the phonon vibration modes, structural deformation and atomic stress distribution. The variations of interfacial thermal conductance at various temperatures and interfacial configurations are explained qualitatively by the phonon coupling factor. Interestedly, our findings indicate that the interfacial thermal conductance is nearly independent of the graphene size, while it is dependent on the length of the diamond in the direction of heat transport. Furthermore, our study reveals that the interfacial structure retains its heat transport properties even subject to large tensile strain due to interface propagation. Our research provides valuable insights into the heat transport properties of these newly developed Carbon/Carbon composites.