Modeling effects of gas adsorption and removal on friction during sliding along diamond-like carbon films

In this paper, the physical and tribochemical processes that occur in a sliding contact between two diamond-like-carbon (DLC)-coated counterparts are discussed. The applicability of some of the most cited of the adsorption kinetics equations for modeling the gas adsorption process when environment molecules form bonds to the surface are examined. The process modeling is also discussed when part of the adsorbate is removed due to rubbing the surface by a slider. A direct connection between a kind of molecular friction and gradual wear is established. The models are compared with some recent experimental results. The present computer simulations of the adsorption and mechanical desorption of oxygen help to explain how microscopic processes, such as the breaking and forming of interatomic bonds, may affect macroscopic phenomena such as friction. In particular, it is shown that the initial roughness of the DLC surface may have a considerable influence on the probability of breaking bonds during mechanical removal of adsorbate and on the process of the gradual tribochemical wear of DLC films.