Abstract: Based on density functional theory (DFT), parathion-based extreme pressure anti-wear agent (EP) and ester oil agent were geometrically optimized, and their global and local reactive sites and quantum chemical parameters of the structure were calculated; these two kinds of additives were added into the emulsion, and the tribological properties were investigated by four-ball test; the morphology and element distribution on the surface of four-ball test steel balls were characterized by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The results showed that the reactive sites of EP molecules were mainly distributed on S、Zn and other polar atoms. The emulsion containing zinc dialkyl dithiophosphate (ZDDP), oil agent ethyloleate (EO), compound emulsifier and rust-preventing agent benzotriazole (BTA) had excellent extreme pressure anti-wear performance, its maximum no-bite load was 1 403 N, the friction coefficient was 0.029, the wear spot diameter was only 0.69 mm, and the extreme pressure anti-wear lubrication coefficient was 11.16.

Key words: emulsion, density functional theory, reactivity, tribological property