Ionic liquids (ILs) have attracted considerable attention due to their unique characteristics and they have been applied widely in the field of lubrication. Though the ILs are widely used as neat lubricant and lubricant additives, few papers are reported on using ILs as base oil to synthesize lubricating greases.

Researchers at State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics (LICP), Chinese Academy of Sciences (CAS), have synthesized two kinds of new conductive lubricating greases using 1-octyl-3-methylimidazolium hexafluorophosphate and 1-octyl-3-methylimidazolium tetrafluoroborate as base oil and the polytetrafluoroethylene as thickener.

The photo images of the ILs lubricating greases and PAO grease: PAO 10 (a), L-P108 (b), and LB108 (c)

Compared with the PAO lubricating grease, the ILs lubricating greases are conductive. Thus, they can be used in the conductive parts of electrical equipment. In addition, the ILs lubricating greases showed better friction reducing and anti-wear properties at room temperature and high temperature (150℃). XPS analysis indicated that different friction mechanisms happened at room temperature and high temperature. At room temperature, the lubricating greases located stably and uniformly between two contact surfaces and various tribochemical products were formed during sliding process. However, at high temperature, the lubricating greases tended to agglomerate together and some base oil was exuded from the lubricating grease.

The work has received support from the National Program on Key Basic Research Project of China (973 Program). The findings have been published in Tribol Lett(Tribol Lett(2012) 46:33–42).