Tribological Properties of Polytetrafluoroethylene, Nano-Titanium Dioxide, and Nano-Silicon Dioxide as Additives in Mixed Oil-Based Titanium Complex Grease

Eight titanium complex greases (i.e., benzoic acid/stearic acid and sebacic acid/stearic acid titanium complex greases, and greases containing PTFE, or nano-titanium dioxide, or nano-silicon dioxide) were synthesized using 3-L reaction vessel. Their physical characteristics were characterized and their tribological properties were evaluated by using a four-ball tester. Chemical compositions of the boundary films generated on worn surfaces were analyzed with the use of scanning electron microscope and X-ray photoelectron spectrometer. Results show titanium complex greases containing PTFE, or nano-titanium dioxide, or nano-silicon dioxide exhibited excellent tribological performance. The mechanism for the friction-reduction and antiwear effect of all titanium complex greases was also proposed and discussed from a tribochemistry point of view.