Controlling friction and wear of nc-WC/a-C(Al) nanocomposite coating by lubricant/additive synergies

► The nc-WC/a-C(Al) coating shows nanocrystallite/amorphous microstructure. ► The nc-WC/a-C(Al) coating has good mechanical properties. ► Tribofilm can be formed for the boundary-lubricated nc-WC/a-C(Al) coating. ► Superior tribological performance of nc-WC/a-C(Al) coating is achieved by lubricant/additive synergies.