Research On Lubrication Mechnisms Of Titanium Grease With Solid Particle

Grease is widely used in all kinds of machinery, it plays a very important role in extending the service life of machinery. High and low temperature performance of the grease is required with the development of industrialization. Nano-sized solid particles as additives shows excellent tribological performance in lubrication, therefore researching nano-sized solid particles as additive to improve the wear performance of friction has important theoretical and practical meaning.In this paper, particle sizes are considered as the factor which influence tribological performance, the experiments were carried out on Four ball friction abrasion testing machine .Three kinds of solid particle as additive were studied, they are PTFE, the calcium carbonate and the graphite powder of different sides, 37 formulas were tested. The result indicated that different sizes has different lubricate mechanism, and the content of additive influence the tribological performance obviously: The nano-sized particles all has excellent anti-friction property and abrasion resistance, the submicron-sized and micron-sized particles performance differently because their lubricate mechanisms are different; the following formulas has well anti-rubs the anti-friction performance. Submicron-sized PTFE and micron-sized calcium carbonate have good tribological performance at high temperature, micron-sized graphite has excellent tribological performance at low temperature.SEM, EDAX and XPS were also used to observe and the analysis the surface appearance, the chemical composition and the chemical combination condition, in order to reveal the mechanisms of different sized material in titanium grease. The nano-sized PTFE particle generat metal fluoride, forms physical boundary film and repair the injured surface. Submicron-sized PTFE works as rolling element, micron-sized PTFE hinders relative motion of the friction surfaces due to the distortion from pressing. Calcium carbonate is transferred into the friction surface and has chemical reaction, finally forms self-repair layer with Ti oxide , in addition the different sized particle plays different synergism as well, so the surface is being protected. Micron-sized graphite forms sediments and relative sliding occurs during different layers of this sediments, so friction and wear are reduced. Nano-sized and submicron-sized particles of graphite have lost lamellar slip friction mechanism, but the nano-sized graphite can still forms physical boundary film and repair, however submicron-sized graphite can't reduce friction and wear.