Carbon, Hydrogen, and Silicon-containing Solid Lubricants

The development of micro-sized devices has prompted the need for protection of the surfaces of these devices. Amorphous carbon films (a-C and a-CH), doped carbon films, and self- assembled monolayers (SAMs) are all possible candidates for the passivation and lubrication of these devices. The fundamental problem associated with controlling friction and wear is a lack of understanding of the underlying atomic-scale chemical and physical processes that govern them. Extensive molecular dynamics (MD) simulations have been done that have examined the compression and friction of model hydrocarbon SAMs, amorphous carbon- and silicon-containing films both with and without hydrogen. We have examined the contact forces present at the interface between a tip and pure, or mixed-length, SAMs during sliding. Compression and shear-induced polymerization have also been modeled in unsaturated hydrocarbon films. In addition, we have also done simulations that analyze the mechanical and tribological properties of a-C, a-CH, a-C-Si, and a-C-Si-H films. Some of our recent results will be discussed.