Investigation of lubrication mechanism of phosphate ionic liquid by ReaxFF molecular dynamics simulations

The frictional characteristics of the interface between ionic liquid (IL) and metal can be significantly improved by the formation of a tribo-film, while the lubrication mechanism remains unclear. This study utilized reactive force field molecular dynamics (ReaxFF MD) simulation to investigate the tribological properties, interfacial tribochemical reactions, and formation mechanism of the tributyltetradecyl phosphonium di(2-ethylhexyl) phosphate ([P44414] [DEHP]) tribo-film. The findings indicate that the friction coefficients of ILs decrease as the normal pressure increases. The combination of normal pressure and shear force promotes the dissociation of ionic liquid chains and enhances the binding of free radicals to the end faces. The friction force is primarily influenced by the number of Fe-C bonds at the interface, which demonstrates a positive correlation with the normal pressure.