Coarse-Grained Molecular Dynamics Simulations of Nanoscale Roughness Effects on Oil Film Delamination

In boundary lubrication, the detachment of lubricant molecules from a solid surface is likely to occur due to the presence of high compressive normal stress combined with shear stress exerted on the solid–liquid interface. This phenomenon often results in a delamination behavior at the interface. We aim to investigate the nanoscale roughness effect on the oil film delamination from sliding iron surfaces with grain boundaries by coarse-grained molecular dynamics simulations. As a result, the oil film delamination was effectively suppressed in higher roughness. Two distinct mechanisms of delamination were found depending on surface roughness when the critical normal stress is exceeded. High roughness enhanced the ability to prevent complete slip but had negligible influence on partial slip. Graphical Abstract