The space environment, particularly highly reactive atomic oxygen(AO), often causes performance degradation and accelerated wear of solid-lubricating materials used in aerospace applications. In this study, an in situ...The space environment, particularly highly reactive atomic oxygen(AO), often causes performance degradation and accelerated wear of solid-lubricating materials used in aerospace applications. In this study, an in situ oxygen-passivated WS_(2) lubricating film(W–S–Ti–O composite film) was deposited to withstand AO irradiation. The structural and tribological evolution of the film was examined after a six-month space exposure experiment conducted outside the Chinese Space Station. The results show that in situ oxygen passivation of sulfur vacancies in the WS_(2) film promoted the formation of a dominant WS_(x)O_(y) phase within the W–S–Ti–O composite film. This phase effectively suppressed excessive WO_(3) formation during prolonged AO exposure while maintaining a low friction coefficient. After space exposure, the film exhibited a low friction coefficient and a wear life exceeding 4.5 × 10^(5) cycles. This performance is attributed to two main factors:(1) the presence of friction-induced spherical WO_(3) nanoparticles(approximately 11 nm) embedded in the transfer film, which promoted a transition from pure sliding to a mixed rolling–sliding regime;and(2) the retention of oriented WS_(2)(002) crystalline layers in the tribofilm, which mitigated the plowing effect of nanoparticles and prevented a significant increase in the wear rate.展开更多
基金financially supported by the Space Utilization System of China Manned Space Engineering (Grant No.KJZ-YY-WCL05)。
文摘The space environment, particularly highly reactive atomic oxygen(AO), often causes performance degradation and accelerated wear of solid-lubricating materials used in aerospace applications. In this study, an in situ oxygen-passivated WS_(2) lubricating film(W–S–Ti–O composite film) was deposited to withstand AO irradiation. The structural and tribological evolution of the film was examined after a six-month space exposure experiment conducted outside the Chinese Space Station. The results show that in situ oxygen passivation of sulfur vacancies in the WS_(2) film promoted the formation of a dominant WS_(x)O_(y) phase within the W–S–Ti–O composite film. This phase effectively suppressed excessive WO_(3) formation during prolonged AO exposure while maintaining a low friction coefficient. After space exposure, the film exhibited a low friction coefficient and a wear life exceeding 4.5 × 10^(5) cycles. This performance is attributed to two main factors:(1) the presence of friction-induced spherical WO_(3) nanoparticles(approximately 11 nm) embedded in the transfer film, which promoted a transition from pure sliding to a mixed rolling–sliding regime;and(2) the retention of oriented WS_(2)(002) crystalline layers in the tribofilm, which mitigated the plowing effect of nanoparticles and prevented a significant increase in the wear rate.
