The oxidation and erosion of atomic oxygen are considered to be the most dangerous environmental factors for materials exposed to the aerospace environment. In order to investigate the effect of atomic oxygen on the lubricating film and improve the tribological properties, MoS₂–WS₂ composite film was prepared by the sputtering technique. The film structure and mechanical behavior were characterized and their vacuum tribological properties were evaluated by a friction tester. The composite film possessed better atomic oxygen (AO) resistance than pure film because of the dense structure. The tribological performance of composite film was different under the conditions after AO-irradiation and sliding and during AO-irradiation. After AO-irradiation, the tribological properties of composite film were similar to those before AO-irradiation. However, high friction noise, wear rate, and reduced wear duration were observed for the composite film under the AO-irradiation/friction process because of the continuous damage of the lubricating film due to the AO-irradiation. The addition of 16 at.% WS₂ to the MoS₂-based film changed the composite film structure and improved the oxidation resistance of the film, making the composite film exhibit better tribological performance than pure MoS₂.

Due to their versatile and unique properties, tantalum-based thin films have been extensively studied. However, tantalum is susceptible to oxidation due to its higher chemical activity, which is crucial regardless of whether oxidations of Ta are beneficial or detrimental. Therefore, the oxidation of Ta during material processing, especially without conscious means, should be taken seriously. In this study, pure Ta films were fabricated by magnetron sputtering under set procedure parameters. The effects of base pressure and substrate temperature on the degree of oxidation of Ta films were investigated. The results revealed that the magnitude of the base pressure directly affects the oxidation state of the as-deposited Ta films. When preferably avoiding the oxidation of sputtered Ta films, the base pressure should be controlled below 4.4 × 10⁻⁴ Pa. The substrate temperature has little effect on the oxidation state of the as-deposited Ta films under a base pressure ranging from about 10⁻² Pa to 10⁻⁴. We hope that this study can provide some references for controlling the oxidation states of Ta involved in relevant film preparation.

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.