Microstructure and tribological properties of GLC/MoS2 composite films deposited by magnetron sputtering

Abstract

Graphite-like carbon (denoted as GLC)/MoS2 composite films were deposited by closed field unbalanced magnetron sputtering system under different MoS2 target currents. The microstructure of the films was investigated by means of X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The tribological behavior of GLC/MoS2 composite films was evaluated using a ball-on-disk tribometer. The results revealed that with the increasing of MoS2 target currents, the existing state of Cr from nanocrystallite to amorphous, leading to the lower of hardness. The film deposited at 0.4A MoS2 target current exhibits the highest hardness (14.6 GPa) and elastic modulus (163.4 GPa) due to the structure of nanocrystallites embedded in amorphous matrix. Additionally, the film showed the lowest friction coefficient (about 0.1) and wear rate of 1.3 × 10−1633correct display 10-16 m3/N·m under 30% RH as the MoS2 target current increased to 1.6A. By contrast, the values of friction coefficient of other films were more than 0.2. On the other hand, the value of the friction coefficient of GLC/MoS2 film decreased to 0.15 as MoS2 target currents increased to 1.6A in the environment of much greater humidity (80% RH). These findings corroborate a thesis that the incorporation of GLC can improve the tribological properties of MoS2 films in humid air environment.