Tribology of fluorinated diamond-like carbon coatings: First principles calculations and sliding experiments

Sliding contact experiments and first principles calculations were conducted to study tribological properties of aluminium and fluorinated diamond-like carbon (F-DLC) surfaces. Sliding tests between Al and an F-DLC coating generated a low coefficient of friction (COF) of 0.09-0.14 and led to the formation of carbonaceous transfer layers containing AlF₃ on the Al surfaces as determined by X-ray photoelectron spectroscopy. An interface model that examined the interactions between Al (111) and F-terminated diamond (111) surfaces revealed that F atoms would transfer to the Al surface in increasing quantities with an increase in the contact pressure and the F transfer would lead to the formation of a stable AlF₃ compound at the Al surface. The generation of repulsive forces between two F-passivated surfaces as a result of the F transfer to the Al surface was shown to be responsible for the low COF between Al and F-DLC. © 2012 John Wiley & Sons, Ltd.