Atomistic simulations of interfacial sliding in amorphous carbon nanocomposites

Nanocomposites with amorphous carbon matrix reinforced by hard crystalline nanoparticles are fast developing as next generation super-tough and wear resistant coatings. The frictional wear and toughness properties of these composites are determined by the properties of the interface between crystalline- and amorphous-phases. In this paper we use molecular dynamics and statics simulations to study the interfacial energetics, internal stresses, sliding and friction behavior of diamond- and amorphous-carbon interfaces. It is found that the orientation of crystalline phase has minor effect on sliding behavior. Sliding behavior is affected by two mechanisms (1) bond breaking and reattaching at the interface and (2) deformation of amorphous carbon in the region surrounding the interface. It is found that the deformation away from the interface reduces the resistance to sliding. In structures with higher SP3 content, bond breaking at the interface dominates and there is much lesser deformation in the amorphous phase. The frictional resistance is significantly less if the interfacial bonding is primarily due to the Van Der Waal’s interactions.