考虑双电层力时微纳间隙动压润滑边界滑移研究

Research on Boundary Slip of Hydrodynamic Lubrication in Micro-nano Scale System with Considering Double-layer Force

采用原子力显微镜对微纳米间隙下硅基片与纯角鲨烷液体固-液接触面的边界滑移进行试验研究,同时考虑固-液接触面处双电层力,拟合Si O2小球与固体试样的表面电荷密度以及角鲨烷流体动压力。结果表明,在不考虑小球重力、惯性力及分子间作用力的情况下,小球在垂直趋近固体试样的过程中主要受力为双电层力及流体动压力,在低速时,双电层力占主导地位;在角鲨烷液体环境中,探针趋近硅基片的过程中,双电层力表现为引力,且其大小与趋近速度无关;在试验的趋近速度范围内,Si(100)表面与角鲨烷的接触面均会产生边界滑移,且滑移长度随着速度的增大而升高。

The atomic force microscope was used to research experimentally the boundary slip of the silicon substrate and pure squalane on solid-liquid interface in micro-nano gap.By taking the effect of double-layer electronic force between the solid-liquid interfaces into account, the surface charge densities of sphere of silicon dioxide and solid surface specimen were analyzed, and a measurement of hydrodynamic force of squalane was made.Results indicate that at the conditions of without considering the gravity and inertia force of the small ball and inter-molecular force, the ball is mainly exerted double-layer force and hydrodynamic force during the process when the sphere approaches the solid specimen vertically.At low speeds, the double-layer force is dominant.In squalane liquid environment, in the process of a probe approaching the silicon substrate, the double-layer force is showed the gravitational force, and its size is independent of the approaching velocity,In the range of approaching velocity of experiment, the boundary slip occurs on the interface of the surface of Si（100） and squalane,and the degree of slip is increased with the increasing of the velocity.