On the Structure–Activity Relationship of Glyceryl oleate Friction Modifiers and Its Synergistic Mechanism on Phosphate ester Antiwear Additives

Abstract

The structure-activity relationship of glyceryl oleate organic friction modi ers and the difference in interaction with antiwear additives signi cantly affect the friction and wear characteristics of the lubrication system. This paper comprehensively considers the differences between polar functional groups and hydrocarbon tail chains, a combination of experiments and simulations were used to investigate the structure-activity relationships of three glyceryl oleate friction modi ers and the synergistic antiwear mechanisms with phosphate ester additives. The results indicate that the reduction of hydroxyl groups in glyceryl oleate weakens the electrostatic interaction with the metal interface and hydrogen bonding interaction, and the increase in hydrocarbon tail chains leads to the enhancement of the steric hindrance effect. Resulting in the substitution of polar functional groups and the increase in hydrocarbon tail chains deteriorating tribological properties. In addition, the binary additive system of glyceryl monooleate and phosphate ester exhibits a signi cant synergistic antiwear effect. It is attributed to the chemisorption of additive O(C = O/P-O/P = O) active sites and the Fe 2 O 3 metal interface, GMO hydrogen bond interactions, the deprotonation of phosphate ester, as well as the carbonate and phosphate protective lm generated by tribochemical reaction.

Ionic Liquid/Functionalized Graphene Oxide as a Nano Additive for Corrosion Protection and Lubrication

“…Figure a,b shows the adsorption energy at the solid–liquid interface. We found that the adsorption energy of the lubrication system is generated by van der Waals energy and electrostatic energy, where electrostatic energy dominates the system because water and ethylene glycol are polar molecules and the positive and negative charge centers of the molecules do not coincide . Interestingly, after adding additives, the adsorption energy at the solid–liquid interface decreases, with an increase in van der Waals energy and a decrease in electrostatic energy.…”

“…The lubricant WP comprises H 2 O and PEG, and therefore, to represent it, H 2 O and ethylene glycol are used. , A mixed system model was created with one additive molecule, 150 H 2 O molecules, and 150 ethylene glycol molecules to explore how the dynamic behavior of functionalized GO in WP lubricants is influenced by structural differences. In addition, to simulate actual bearing steel friction pair materials, the α-Fe 2 O 3 (0001) crystal surface establishes an adsorption surface, as shown in Figure S2g. A 20 Å vacuum layer was created on the Z -axis to eliminate the impact of periodic boundary conditions on the system interaction.…”