Phosphonium-based ionic liquids as grease additives in rolling bearing tests

Two phosphonium-derived ionic liquids: trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate (IL1) and trihexyltetradecylphosphonium tricyanomethanide (IL2) were used as additives in lithium complex-(G1) and anhydrous calcium-based (G2) greases at 5 wt%. Friction torque and wear tests were performed using a modified four-ball machine for testing rolling bearings in order to determine the friction and wear reducing properties of these grease samples in a real component. The IL2 improved the friction reduction performance of both greases, especially G1. Both ILs improved the antiwear behaviour of grease G2. Grease G2 showed higher oxidation and thermal ageing levels than G1, but the addition of the ILs, IL2 in particular, improved this issue.

Automated summary

Two phosphonium-derived ionic liquids (IL1 and IL2) were added to lithium complex (G1) and anhydrous calcium-based (G2) greases at a concentration of 5 wt%. Friction torque and wear tests were performed to evaluate the effects of the ILs on the friction and wear properties of the greases. IL2 showed improved friction reduction performance for both greases, especially G1. Both ILs improved the antiwear behavior of G2 and IL2 also helped alleviate the oxidation and thermal aging issues in G2.