Tribological Characteristics of MoS2 and DLC Film in Sliding Contacts under Dry, Lubricant and Grease Lubrication Conditions

The objective of this study is to investigate the effect of solid and liquid lubrication on friction and wear performance of selected solid lubricating coatings, comparative experiments have been carried out on magnetron sputtered MoS2 coatings and chemical vapor deposited hydrogenated diamond-like carbon (DLC) films against Si3N4 ball using a ball-on-disk tribo-tester under the conditions of room temperature and different lubrication condition. Surface morphology of coatings was investigated by atom force microscope (AFM), and friction coefficient (COF) and, wear rate of solid films was also analyzed. It was shown that the friction was greatly reduced when the solid film which was lubricated with oil and grease was simultaneously compared and lubricated singly at the start-up or under boundary lubrication conditions. Liquid lubrication causes a dramatic decrease of the wear-ability to the MoS2 coatings, while the wear rate of DLC film was improved better. The effect of lubrication oil to the wear resistance property of MoS2 film was worse than lubrication grease, which was opposite to the DLC film.