Influence of Different Neutral Gas Irradiation in Low Earth Orbit on the Structure and Tribological Performance of WS2 Films

Pure WS2 film prepared by the radio frequency sputtering system exhibits a porous dendrite-like structure. The evolution in microstructure and tribological property of WS2 film were mainly investigated under different neutral gas irradiations using our self-made ground simulation device. After atomic nitrogen and atomic oxygen irradiation, the crystal structure and hardness of WS2 film were improved and wear life of film significantly prolong about 33% and 2 times, respectively. However, atomic hydrogen leads to a negative effect. The different results are found to be closely related to component change induced by irradiation on sliding contact area, further affecting formation of transfer film. Finally, lubricating mechanisms of WS2 film were revealed under different neutral gas irradiations in space environment.