Nanoscale triboactivity: The response of Mo–Se–C coatings to sliding

Mo–Se–C films were deposited by sputtering from a carbon target with pellets of MoSe2. In addition to the standard evaluation of their chemical composition, structure, morphology, hardness and cohesion/adhesion, the core objective of this paper was to analyze the tribological behavior of these films, particularly in the high-load regime. The carbon content varied from 29 to 68 at.% which led to a progressive increase of the Se/Mo ratio and the hardness. The friction coefficient of Mo–Se–C coatings clearly decreased with load from ∼0.15 to ∼0.05. The excellent friction properties were attributed to the formation of a thin molybdenum diselenide film on the top of the wear track of the coating and on the counterpart surface, while the role of the carbon in the sliding process is only secondary by increasing the coating hardness and thus its wear resistance.