Tribological Properties of Novel Phosphate Ester Containing N and B as a Lubricating Additive

In order to explore high-performance lubricants suitable for titanium alloy systems and judge the feasibility of their application as lubricating additive for cutting fluids, the tribological properties of various water-based lubricating additives were researched in this study, revealing that phosphate esters containing N and B elements exhibited exceptional lubricating properties. The novel phosphate ester containing N and B was synthesized by phosphorylation reaction, and N and B elements were introduced into it, and the main functional groups in the compound were analyzed by Fourier transform infrared spectroscopy. The tribological properties at the different lubrication conditions were evaluated by a four-ball friction tester of levers. Optical microscope, scanning electron microscope and three-dimensional white light interferometric topography were used to analyze and characterize the wear surface. The tapping torque simulation evaluation tester simulated extreme cutting conditions and evaluated the lubrication performance of lubricants in harsh environments. Finally, X-ray photoelectron spectroscopy was used to characterize the chemical composition of the wear surface and analyze the lubrication mechanism. The results showed that novel phosphate ester containing nitrogen and boron had excellent anti-friction and wear-resistant properties at a mass fraction of 2%, the load-bearing capacity (P_B value) of the lubricating film was as high as 2 206N, and the average friction coefficient remained stable at 0.042 in an hour-long anti-wear performance test. The wear surface was relatively smooth without wide grooves and adhesive wear. The EDS analysis and test of wear surface showed that the active elements in the novel phosphate ester containing nitrogen could be evenly distributed on the metal surface, which significantly reduced the friction coefficient. Through the tapping torque test, it was found that the average torque after lubrication with the novel phosphate ester containing nitrogen and boron was reduced by more than 14% compared with the unlubricated state. Based on the analysis of wear surface, the lubrication mechanism proposed was as follows: the novel phosphate ester containing nitrogen and boron generated a composite boundary lubricating film on the metal surface by the chemical reaction film and synergistic action of adsorption film, which had high strength and stability, and significantly improved the anti-wear and friction effect.