Changes in the structure and tribological property of Ag film by LEO space environment exposure

LEO space environment exposure resistant behavior of Ag–Cu films

“…The average value was about 0.15 and almost equivalent to the one of non-exposed Ag-Cu film about 0.16 [16]. This behavior was different with the pure Ag film, whose friction coefficient became obviously high and instable after the SEE [20]. Namely, for the Ag film the deterioration of friction property resulted from the space exposure was declined by alloying with Cu element due to the improvement in the AO resistant capability.…”

“…Actually, the pure Ag film was also exposed in this space flight experiment and the results were reported elsewhere [20]. For the exposed Ag film, the Ag 2 O was also detected within the surface layer by XRD and XPS, and the cracking and flaking phenomena were clearly observed by FESEM.…”

“…Due to the oxidation, it was observed by visual inspection that after the SEE, the Ag-Cu film surface lost its metallic sheen and became color. As for the exposed Ag film [20], its surface became gray and showed significantly cracking and flaking phenomena. This difference was mainly attributed that the oxidation caused by the space exposure was slight for the Ag-Cu film compared to the Ag film.…”

“…The Ag 2 O was a common phase for the AO exposed Ag based films, such as the spaceexposed Ag film [20] and ground-exposed Ag-Cu film [16]. Fig.…”

“…Film deposition parameters were listed in Table 1. [20]. The AO flux was calculated from the spaceship altitude and attitude (~343 km and 42.4°, respectively) to be~1.19 × 10 18 atom·m −2 ·s −1 at the flight attack angle of 0°.…”