Abstract: To investigate the relationship between molecular structure parameters of phosphate ester extreme pressure antiwear agents and their extreme pressure antiwear performance at the molecular level, triethyl phosphate was selected as model compound, and the interaction mechanism between phosphate ester molecules and the Fe(110) surface was studied by molecular simulation method. It was revealed that phosphate ester molecules mainly adsorbed onto the Fe surface by providing electrons through O atom in the P=O group. Then the molecular simulation method was used to calculate various structural parameters of different phosphate ester extreme pressure antiwear agents. A genetic function approximation was used to establish the relationship equation between the molecular structure parameters of phosphate ester extreme pressure antiwear agents and extreme pressure antiwear performance. The results of the internal and external tests show that the equation has good predictive effect. According to the equation, the key structural parameters that affect the extreme pressure antiwear performance of phosphate ester molecules include the charge of the O or S atom in the P=O or P=S group, the chemical bond energy of the C—O or C—S bond, and the content of S atom.

Key words: phosphate ester, thiophosphite ester, extreme pressure antiwear agent, molecular simulation, structure-performance relationship