Low Deposition Temperature-Induced Changes of the Microstructure and Tribological Property of WS2 Film

Abstract

Pure WS2 films were prepared by the radio frequency sputtering of a WS2 target with the initial substrate temperature controlled to −40, −25, 0 °C and room temperature by cooling the holder with liquid nitrogen, respectively. The influence of the substrate temperature on the microstructures and the tribological properties of the prepared films have been evaluated and the wear mechanism of the films was explained. It revealed that with decreasing the substrate temperature, the prepared WS2 film changed from the loose and coarse columnar plate structure for film deposited at room temperature to a much more compact morphology for film deposited at −40 °C. The WS2 film deposited at low temperature of −40 or −25 °C exhibited a long wear life higher than 5.0 × 105 sliding cycles, while this was about 1.5 × 105 cycles for the WS2 deposited at room temperature. The improved tribological properties for the low temperature-deposited film were mainly attributed to the much lower wear rate resulted from the compact structure as well as the sustained and steadily formed transform layer on the counterpart ball.