Tribology dependence on both structures of bulk a-C:H:Si films and transfer layer via adjustable Si content

Abstract

Si doped hydrogenated amorphous carbon (a-C:H:Si) films were fabricated in mixed atmosphere of SiH4 and Ar by magnetron sputtering methods, with different SiH4 flow rates. The microstructures and tribological performances were measured by Atomic Force Microscopy (AFM), Scanning Electron Microscope (SEM), X-ray Photoelectron Spectroscopy (XPS), Raman Spectroscopy and Tribo-tests. The results showed that the as-fabricated a-C:H:Si films exhibited good tribological performances with low friction and wear. The -OH termination which was deduced by SiO structure inside the a-C:H:Si film reacted with water molecules in atmosphere could passivate the film and counterpart surface, leading to the low friction of a-C:H:Si film. The wear rate increased with the increase of SiH4 gas flow rate, which could be attributed to the formation and increase of SiC phase with high hardness. The SiC phase enhanced the three-body abrasion between the contact surfaces, which increase the wear of the a-C:H:Si film at high SiH4 flow rate.