Effects of annealing treatment on tribological behavior of tungsten-doped diamond-like carbon film under lubrication (Part 2): Tribological behavior under MoDTC lubrication

Molybdenum dialkyldithiocarbamate (MoDTC) is widely used as a friction modifier in engine lubricating oil. Under MoDTC lubrication, the friction and wear behaviors of tungsten-doped diamond-like carbon (W-DLC) films annealed at 100–400 °C were discussed and evaluated using scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy. Under (polymerized alpha olefin) PAO + MoDTC lubrication, the coefficient of friction of all samples decreased, but the wear rates of the W-DLC films annealed at 300 °C increased significantly. By interacting with zinc dialkyldithiophosphate (ZDDP), the wear rates of W-DLC films annealed at different temperatures declined significantly owing to the formation of dense phosphate tribofilms on the worn surfaces.