Preparation and properties of graphite-like carbon films fabricated by unbalanced magnetron sputtering

Abstract

A series of graphite-like carbon films is fabricated by the middle frequency magnetron sputtering technique. The microstructures and the morphologies of the resulting films are investigated by Raman spectroscopy, high resolution transmission electron microscopy and atomic force microscopy, respectively. The mechanical and the tribological properties of the films are studied by nanoindentation and CSM tribometer. The results show that the deposited carbon film is dominated by sp2 sites, and has an amorphous structure, a moderate hardness, low internal stress, high surface roughness and superior tribological properties. With the increase of the duty ratio, the intensity ratio between D and G peaks first decreases and then increases, while the film hardness first increases and then decreases. Tribological testing in humid atmosphere demonstrates that the present carbon film has a superior wear resistance (～10-11 cm3/N-1.m-1) and high load bearing capacity (～2.5 GPa). Although the duty ratio has no obvious influence on friction coefficient, the wear rate decreases obviously and then increases slightly with the increase of duty ratio. The superior tribological properties of the graphite-like carbon film are attributed mainly to its unique structure, low internal stress and high structure stability.