The effects of nanoscaled amorphous Si and SiN _x protective layers on the atomic oxygen resistant and tribological properties of Ag film

The Ag film, and double layer films of Ag/Si and Ag/SiN _x were deposited by magnetron sputtering technique. The atomic oxygen (AO) irradiation tests were conducted using a ground AO simulation facility. The microstructure and composition of these films before and after AO irradiation tests were analyzed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), respectively, atomic force microscope (AFM) and scanning electron microscopy (SEM), respectively. Then the protective effects of nanoscaled amorphous Si and SiN _x layers on the atomic oxygen resistant property of Ag film were investigated. The results show that nanoscaled Si or SiN _x protective layer can provide better protection to Ag film against oxidation caused by AO irradiation. The silica layer formed on the surface of amorphous protective layers during AO exposure process plays the key role in protecting Ag film from oxidation. On the other hand, the tribological performance of Ag film and the multilayer films was comparatively studied using a ball-on-disc tribometer in vacuum condition. The tribotest results indicate that Ag/Si and Ag/SiN _x films show the better lubricating performance before and after AO irradiation than pure Ag film.