Magnetron Sputtering The Ws <sub> 2 </ Sub>-ag Nanocomposite Films Environmental Friction And Wear And Tear

Tungsten disulfide as a solid lubricant has the low friction coefficient and good wear resistance. But WS₂ film has poor tribological behavior in humid environment. To improve the tribological properties, WS₂-Ag nanocomposite films were deposited on medium carbon steel substrate by magnetron sputtering WS₂-Ag composite targets and magnetron co-sputtering method using a pure WS₂ target and a pure Ag target. The effects of Ag content and technological parameters on the microstructure and tribological properties of the films were investigated, and the influence of the tribological condition on the tribological properties of the films was also discussed.The WS₂-Ag nanocomposite films were deposited by sputtering the composite targets. The morphology and microstructure of the films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), atomic force microscope (AFM) and high-resolution transmission electron microscopy (HRTEM). The thickness of the films was measured by TENCOR instrument. The adhering force with the substrate was determined with the scratch tester. The tribological behavior was investigated using a ball-on-disk tribometer in vacuum and in humid air, and the morphology of the worn surfaces was characterized by scanning electron microscopy (SEM). WS2 and Ag were amorphous in the WS₂-Ag nanocomposite films. The microstructure and tribological properties of the films varied with the Ag content. At the content of 4.3 at.% Ag, the composite film had the most compact microstructure, the lowest friction coefficient and the smallest wear rate. The addition of Ag in the films increased obviously the environmental stability of tribological behavior compared to WS2 film.The WS₂-Ag nanocomposite films were deposited by sputtering the WS₂-Ag7.5% composite targets under different technological parameters. The effect of the technological parameters on microstructure and tribological properties of the films was studied by SEM, the scratch tester and the ball-on-disk tribometer. The surface morphology became coarser when the background argon pressure increased. The adhering force with the substrates increased with increasing the substrate bias and substrate temperature.The tribological properties of the WS₂-Ag nanocomposite films were investigated using the ball-on-disk tribometer under the different tribological conditions. The friction coefficient of the films decreased and the wear rate increased with increasing the load. The higher the rotate speed was, the lower the friction coefficient was. The films exhibited lower friction coefficient and smaller wear rate in vacuum than those in humid air.The WS2-Ag nanpcomposite films were also deposited by magnetron co-sputtering using a pure WS2 target and a pure Ag target. The morphology and microstructure of the films were characterized by XRD, SEM, EDS and HRTEM. The microhardness and elastic modulus measurements were determined with MTS Nano indenter XP using a load of 470 mN. The adhering force with the substrate was determined with the scratch tester and the tribological behavior was determined with the ball-on-disk tribometer. The crystalline Ag phase dispersed in amorphous WS2 and the size of the crystalline Ag increased with the Ag content in the films. At the content of 41 at.% Ag, the Ag phase dispersed uniformly, and the composite film had compact microstructure, the highest microhardness and elastic modulus. The tribological properties of WS2-Ag composite films varied with the Ag content. The amorphous WS2 in the WS2-Ag41% composite film made the main function during wear, so the film showed the lowest friction coefficient and the smallest wear rate. The adhering force with the substrate increased and the environmental sensitivity of tribological behavior decreased obviously due to the addition of Ag in the films.