Tribochemistry of glycerol-water mixtures confined between ferrous substrates: An atomic-scale concept by reactive molecular dynamics simulation

In this study, non-equilibrium molecular dynamics (NEMD) simulations with a reactive force field were used to investigate the tribochemical properties of glycerol, with and without water, confined between two ferrous surfaces. The results demonstrated that glycerol significantly reduced friction on α-Fe slabs more effectively than on functionalized amorphous magnetite. A numerical method was introduced to identify the interface region and evaluate the dissociated surface atoms. It was found that the dissociation rate of glycerol molecules increased with applied normal pressure and shear stress. Additionally, the production rate of water molecules from glycerol dissociation was consistently positive for all solutions above 80 % wt. The assumption of linear velocity distribution across the film thickness was validated for all systems studied. • Using MD with reactive force fields, this study explores the tribochemical properties of glycerol on ferrous surfaces. • Glycerol solutions show lower friction on α-Fe slabs versus amorphous magnetite, indicating varied lubrication performance. • A new method with normalized density profiles identifies interface regions and reveals Fe dissolution under high pressure. • Glycerol dissociates more on reactive α-Fe, producing more hydroxyl groups and forming oxides on the substrate. • Higher pressure and shear increase glycerol dissociation and water production, revealing mechanochemical effects.