Atomistic simulations of tribochemical reactions at carbon surfaces

Tribochemical reactions occurring at carbon surfaces have a strong influence on the friction and wear properties of diamond and diamond-like carbon (DLC) surfaces [1]. Molecules that are in contact with a surface can undergo dissociative chemisorption before or during tribological load and passivate dangling bonds. This prevents the formation of strong covalent bonds between sliding surfaces, resulting in a lower friction coefficient. Furthermore, molecules can physisorb at passivated carbon surfaces by means of hydrogen bonds and van-der-Waals interactions. This can lead to the formation of adsorbed layers that in turn modify the friction properties of the surface. These mechanisms are believed to play a crucial role in the superlubricity that tetrahedral-amorphous carbon (ta-C) surfaces exhibit when in contact with certain OH-containing molecules (e.g. Hydrogen peroxide, glycerol or glycerol monooleate (GMO)) [2,3].