Abstract: The tribological properties of a nitrogen phosphorus type extreme pressure anti-wear agent in lithium base grease were studied. Four ball test, SRV test and oscillating friction and wear test were carried out to compare the extreme pressure anti-wear and friction reduction properties of base grease and grease containing additives under extreme pressure. The results showed that P-N extreme pressure anti-wear additive with a mass fraction of 3.0% had outstanding anti-wear and antifriction properties and better extreme pressure properties. The anti-friction and anti-wear mechanism of extreme pressure was the formation of nitrogen and phosphorus-rich boundary lubrication film on the surface of the friction pair.

Key words: extreme pressure additive, friction test, three-dimensional topography, action mechanism