超薄膜润滑的分子动力学模拟

Research of ultra thin film lubrication by molecular dynamics simulation

超薄膜（膜厚趋于分子量级）的摩擦特性与宏观流体膜有很大的不同，与超薄膜的微观结构有密切的关系。本文应用可以同时模拟超薄膜宏观和微观特性的分子动力学模拟（ＭＤＳ）方法，研究了超薄膜的微观结构与摩擦学特性间的关系，发现了平行于壁面的层状类固态结构；固液作用强度及膜厚大小对类固态结构有着明显的影响；超薄膜的极限膜厚由类固态与液相的比例决定。这种微观结构的相变改变了超薄膜的摩擦学特性。模拟中还发现了剪切诱导的微观构型。

The properties of the ultra thin film are distinctly different from those of the macro fluid film. These phenomena are considered to relate to the microstructure of the film. The method of molecular dynamics simulation plays a key role in studying both the microstructure and macro properties of the ultra thin film. Special attention is paid to the fluid microstructures and its relations to the friction properties. The solid like structure of wall induced layering is much different from the bulk. The frictions profoundly depend on the phase transition, which is affected by the gap scale between two walls and the wall fluid interaction strength. The limitation thickness of the ultra thin film was defined by the ratio between solid like phase and liquid like phase. Shear induced configuration occurs in non Newtonian region in simulation.