WS2 Nanopowders as High-Temperature Lubricants: An Experimental and Theoretical Study

In view of the high-temperature operation conditions in lubrication, this work focused on the lubrication performances of WS2 nanopowders at high temperatures. A certainly low coefficient of friction (CoF) (about 0.05) of WS2 nanopowders is observed at 100-300 degrees C. High-temperature tribological experiments are performed, and first-principles simulations are applied to investigate the lubrication performances simultaneously. According to the XRD and XPS spectra, it should be noticed that WS2 lubricating films with (002) crystal plane preferred orientation are achieved at high temperature, and they have low shear strength and excellent lubrication performances. The simulation results reveal that strong interaction exists between the (002) crystal plane of WS2 and the high-speed steel (HSS) substrate. Benefiting from the essential low shear force of the (002) crystal plane of WS2, a high-temperature low friction was achieved. This discovery presented a description of the application of WS2 nanopowder tribology at high temperatures of 300 degrees C.