Promoted high-temperature lubrication and surface activity of polyolester lubricant with added phosphonium ionic liquid

The effect of two types of additives, trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate and tricresyl phosphate on the tribological behavior of the polyolester based lubricant (POE) has been studied. Experiments revealed the lubricant equipped with both additives had friction reduction (up to 4 times) and a smaller wear rate (by almost 2 orders) of sliding steel surfaces in a wide range of temperature conditions in comparison to original POE and POE with each additive separately. Characterization revealed the formation of the phosphorous-rich film on the wear track that was responsible for observed friction and wear reduction. The rate of the film formation evaluated using Quartz Crystal Microbalance was found to increase with temperatures thus suggesting better efficiency of the steel surface protection during sliding.