Solid lubricating film/oil or grease complex system I: Tribological properties of MoS₂ film at dry sliding and coated with trifluorinated-butyl with methyl terminated silicon oil or the related grease formulated with powder of PTFE

The use of space satellites for communication and navigation is ever increasing in both military and commercial applications. High costs for both constructing and launching satellites are driving the need to extend the useful lifetime of these satellites. Improving lubrication of the mechanical systems is one of the key issues for prolonged service lifetime of satellite or spacecraft. MoS₂-based film was prepared by rf-sputtering. Lubricants, i.e. trifluorinated-butyl with methyl terminated silicon oil (code as 115^# oil) and the related grease formulated by PTFE powders (code as KK-5 grease) were synthesized at laboratory. Friction and wear properties of the MoS₂ film, MoS₂ film coated with 115^# oil or KK-5 were investigated on a UMT-2MT tribo-meter. The effects of load and speed on friction and wear were also investigated. The worn surfaces of the MoS₂ and its counterpart AISI 52100 steel balls were observed by scanning electron microscopy (SEM). It was found that the friction coefficient and wear lifetime of MoS₂ dry-film were about 0.11 and 1.0 × 10⁵ revolution, respectively. The friction and wear properties of solid lubricating film/oil or grease complex lubrication system were much better than that of MoS₂ dry-film. The friction coefficient and wear lifetime of the MoS₂ film lubricated with KK-5 grease were about 0.09 and 2.1 × 10⁵ revolution, respectively. The complex lubrication system, MoS₂+115^# oil, exhibited excellent friction and wear properties. Its friction coefficient was about 0.07 and its wear lifetime exceeded 8.0 × 10⁵ revolution.