Direct visualization of sliding-induced tribofilm on Au/MoS2 nanocomposite coatings by c-AFM

The nanoscale lubrication mechanism of nanocomposite Au/MoS2 solid lubricant coatings has been studied by conductive atomic force microscopy (c-AFM). A direct visualization of the lubricating process suggests tribomechanical formation of a MoS2 tribofilm to be a key mechanism. The sliding-induced tribofilm formation was visualized by a reduction in local friction and conductivity in nanoscale AFM images. The tribofilm was found to possess considerable crystallinity and orientation, which was not observed in the as-deposited coatings. The observed mechanism is broadly applicable to a range of nanocomposite metal/MoS2 coatings.