MD studies of atomic-scale tribology in model SAMs and amorphous carbon films

COLL 317

Judith A. Harrison1, Ginger M. Chateauneuf1, G.T. Gao2, and Paul T. Mikulski3. (1) Chemistry Department, United States Naval Academy, 572 Holloway Road, MS 9B, Annapolis, MD 21402, (2) Chemistry Department, US Naval Academy, 572 Holloway Road, Annapolis, MD 21402, (3) Physics Department, United States Naval Academy, 527 Holloway Road, Annapolis, MD 21402
With the rapid development of MEMs and NEMs, protection of the surfaces of these devices has become an urgent issue. Amorphous carbon films (a-C and a-CH) and self-assembled monolayers (SAMs) are both possible candidates for the passivation and lubrication of MEMs. The fundamental problem associated with controlling friction and wear mechanisms is a lack of a complete understanding of the underlying chemical and physical processes at the atomic scale. We have done extensive molecular dynamics (MD) simulations examining the friction of model hydrocarbon SAMs and a-C (a-CH) films attached to diamond. Contact forces present at the interface between a tip and pure or mixed-length SAMs during sliding were examined. This analysis yielded insight into the difference in observed friction of pure and mixed-length SAMs. Compression and shear-induced polymerization has also been modeled in unsaturated hydrocarbon films. The structure and friction of a-C and a-CH films has also been examined.