Molecular Simulation Studies on Delamination Phenomenon and Velocity Slippage Mechanism of Alkanes Lubricating Film at Nanoscale

Non-equilibrium molecular dynamics simulation was carried out to study the delamination and velocity slippage phenomenon of the hexadecane lubricating film at nanoscale. In this work, the effect of shear velocity on the velocity slippage phenomenon was studied, and the microscopic mechanism of the phenomenon was explored. Results show that delamination occurred in the lubricating film under the shear action of the iron walls. The middle region of the lubricating film exhibited the features of bulk fluid when the film thickness reached 50 Å. The critical shear rates of the interlamination slippage and interfacial slippage were 5.5 and 7.5 Å/ps, respectively. With increasing shear velocity, the interfacial slippage was strengthened and the interfacial slippage was weakened. The degree of the interlamination slippage was determined by the number of bridging molecules between the first and second layers of the lubricating film. The increasing shear velocity reduced the number of the bridging molecules, which therefore weakened the interlamination slippage.