Effects of environment on dry sliding wear behavior of silver-copper based composites containing tungsten disulfide

Silver based composites containing different amounts of WS2 were prepared by hot-pressing method and their tribological behaviors were investigated against coin silver under humid air, dry nitrogen and vacuum on a ball-on-disk tester with normal load of 5 N. The components of composites, microstructure of debris and worn surface were characterized using XRD SEM, EDS and XPS. It is demonstrated that environmental conditions significantly affect the tribological behavior of silver based composites. The friction coefficient is the highest in humid air, and the lowest in dry nitrogen. It is found that the friction and wear behavior of the composites are strongly depended on the characteristics of the lubrication film forming in different operating environments, such as thickness and composition. In addition, it is indicated that the dominant wear mechanisms of silver based composites are abrasive wear and delamination under different conditions.