Friction Characteristics of Molybdenum Disulfide Thin Films Synthesized via Plasma Sulfurization

Herein, the tribological behavior of layered few nanometer-thick MoS2 thin films is evaluated to identify their applicability to an oil-free solid-lubrication coating layer. The MoS2 thin films are synthesized using a plasma sulfurization process with optimized steps and conditions derived from a previous study. MoS2 thin films with different thicknesses are heat treated at 400 degrees C to investigate the effect on their tribological properties. The ball-on-disk method is used to observe the friction and wear behavior of the MoS2 thin films, and this test is carried out under an applied load of 0.5 N in an ambient atmosphere (approximate to 23 degrees C). The coefficient of friction of the unheated MoS2 layers increases rapidly at 32-36 cycles regardless of the thickness. However, the heat-treated MoS2 films maintain a lower coefficient of friction for more cycles (60-86 cycles). The heat treatment effect effectively increases the wear life of the MoS2 thin film. Based on this result, it is believed that the heat-treated MoS2 thin films can be potential solid lubricant candidate for micro- and nanoelectromechanical systems.