纳米尺度下烷烃润滑薄膜分层现象和速度滑移机制的分子模拟研究

采用非平衡分子动力学模拟方法,研究了纳米尺度下十六烷润滑薄膜的分层现象和速度滑移现象,重点考察了剪切速度对速度滑移现象的影响规律,并对其中的微观机理作出了解释.研究结果表明:在铁壁面的限制情况下润滑薄膜出现了分层现象,当润滑薄膜厚度超过50?时,其中间区域呈现出体相均质流体的特征.润滑薄膜层间滑移和界面滑移的临界剪切速度分别为5.5和7.5?/ps,随着剪切速度增加,界面滑移程度增强,而层间滑移程度减弱.润滑薄膜第1和2层十六烷分子层间桥接分子数目决定层间滑移程度,随着剪切速度增加,桥接分子数目也相应增多,层间滑移程度随之减弱.

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.