The effect of oxygen introduced by WO3 on the structure and tribological performance of W-S-O sputtered films

Oxygen-doped transition metal disulfides solid lubricating films have been less investigated due to the widespread viewpoint of the detrimental effect of oxidation on tribological properties. In this study, the introduction of oxygen into the deposited W-S-O film was achieved through sputtering WS2/WO3 composite targets. The hardness of W-S-O film has been found to increase threefold, accompanied by a 50% reduction in the friction coefficient and an order of magnitude increase in wear life. The compact structures and the embedded WO3 nanocrystals in the film contribute to the improved tribological property of the W-S-O film by improving the load-bearing capacity. Meanwhile, the presence of WO3 phase within the W-S-O film does not hinder the formation of the transfer film during friction. [Display omitted] •The presence of WO3 nanocrystals in the W-S-O film resulted in a substantially thick equiaxed crystal layer.•The W-S-O film exhibited lower friction coefficient and longer wear life compared to that for pure WS2 film.•The WO3 phase was expelled from the tribo-surface without hindering transfer film formation during friction.