Impact of Boron Nitride Nanoparticles on the Wear Property of Lithium Base Grease

In order to satisfy the requirement of lubrication under extreme working conditions (e.g., heavy load, high speed, and high temperature), a lubricating grease containing boron nitride (BN) nanoparticles was prepared by ultrasonic dispersion. And the effect of different content of nanoboron nitride on the tribological properties of lubricating grease was studied by means of a four-ball friction tester. The results showed that the grease containing 0.60 wt.% BN nanoparticles had the best anti-friction performance, as well as the smallest friction coefficient and wear scar radius. Additionally, a Raman spectrometer, scanning electron microscope, and three-dimensional profilometer were used to analyze the chemical composition, characterize the morphology of the wear scar in the steel balls after the friction tests, and the analysis results show that BN nanoparticles can not only produce lubricating film to protect friction pairs, but also its layered structure is easy to cause sliding of the friction pairs under the action of friction. Therefore, under the synergism of lubricating film and layered structure, the friction coefficient is obviously reduced and the friction reduction performance of grease is improved.