The effect of the substrate surface roughness on tribological properties of MoS2/Ti films, and the friction and wear mechanism was studied. MoS2/Ti films were deposited on bearing steel with different surface roughness by magnetron sputtering. The adhesion strength between the film and substrate, phase composition, surface morphology and surface roughness of MoS2/Ti films were obtained respectively by scratch tester, X-ray diffractometer(XRD), scanning electron microscope (SEM) and roughness profiler. And the tribological properties of MoS2/Ti films under dry friction, solid-oil composite lubrication and solid-grease composite lubrication were studied by a ball-on-disk tribometer. The results show that with the increase of the substrate surface roughness, the surface roughness of MoS2/Ti films increases, the intensity of (002)MoS2 and (100)MoS2 diffraction peaks first decreases and then increases, and the adhesion strength between the film and substrate decreases. When the surface roughness of the substrate is 0.01 μm, the MoS2/Ti films have good lubrication characteristics under dry friction condition. The average friction coefficient is 0.101, and the wear scar is shallow and small. With the increase of substrate roughness, the average friction coefficient and the wear rate of the samples increase first and then decrease. Meanwhile, the main wear mechanism of the film changes from abrasive wear to chip formation and fragmentation. And the effect of intermolecular interaction is greater than that of mechanical engagement, when the substrate roughness of the samples is large (Ra=0.26 μm). Under the condition of solid-oil composite lubrication, there is no fragmentation phenomenon on the worn surface with large substrate roughness. The wear scar is shallow, and the average friction coefficient is reduced by about 19%. Under the condition of solid-grease composite lubrication, the tribological properties of the samples are poor, and the effect of the substrate surface roughness on the friction coefficient is not significant.
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