RESEARCH ON LIQUID FILM SURFACE FORCE CONFINED WITHIN NANO-METER SPACING AND ITS EFFECT ON SURFACE CONTACT

本文分析了拉普拉斯压力引起的固体表面变形，讨论了它对表面力仪测量弯月面力的影响。理论分析表明，当弯月面曲率半径较小时，变形量可达几个纳米量级，并使弯月面力大大减小。结果表明，纳米弯月面力与F=4πγRcosθ方程的偏差既不是由于氢键作用，也不是由于短程固-固相互作用。其主要原因在于固体表面由于拉普拉斯压力而变形。拉普拉斯压力引起的固体表面的纳米级变形是测量弯月面力的重要因素，除了表面变形外，货车德瓦尔斯力也被认为是拉脱力的一个贡献。结果表明，拉脱力在很大程度上取决于 关于我们 为了减小固体表面变形对拉脱力测量的影响，提出了一种直接测量拉普拉斯压力的新方法，设计了测量装置，并在该装置上进行了测量。在上述基础研究的基础上，从滑动雪崩的角度分析了表面力对磁头滑动气浮性能的影响。数值结果表明，表面力降低了滑动空气轴承的刚度和承载能力，以及。值得注意的是，尽管承载能力的降低可能不显著，但刚度的降低对于许多情况可能是关键的。滑动空气轴承刚度的下降，由于表面力可能是最重要的机制之一的滑移雪崩。预测的起飞高度，以克服表面力约为几纳米。增大俯仰角往往会减小起飞高度。1 nm左右的润滑膜在一定程度上降低了滑移雪崩的风险，但增加润滑膜厚度的影响不大。少

The deformation of solid surfaces caused by the Laplace pressure is analyzed and its effect on the ^meniscus force measurement on a surface force apparatus is discussed. It is found theoretically that the deformation reaches several nano meter orders and reduces greatly the meniscus force when the meniscus curvature radius is small. It is concluded that the deviation of the measured meniscus force with the surface force apparatus from equation F=4πγRcosθ for nano meter meniscus may be neither due to the hydrogen bonding interaction, nor the short range solid-solid interaction. The main reason lies in the deformation of the solid surface due to the Laplace pressure. The nano meter deformation of solid surfaces caused by the Laplace pressure is of great importance in measurement of the meniscus force.In addition to the surface deformation, van der Waals force is also considered as a contribution to the pull-off force. As a result, it is found that the pull-off force will depend greatly o … More n the vapor pressure around the solid surfaces.As a solution to reduce the effects of solid surface deformation on the measurement of the pull-off force, a new method of direct measurement of the Laplace pressure was proposed, measuring device was designed, and measurement was conducted on the new device. Satisfactory agreement between the Experimental and theoretical results was obtained.In addition to the basic studies mentioned above, the effect of surface force on the performance of slider air bearing of magnetic head in hard disc systems was analyzed with respect to the glide avalanche. The numerical results show that surface force reduces the stiffness of the slider air bearing and the load carrying capacity as well. It is worth noting that, although the decrease in the load carrying capacity may not be significant, the reduction in the stiffness may be critical for many cases. The reduction in the stiffness of slider air bearings due to the surface force may be one of the most important mechanisms of the glide avalanche. The predicted take-off height to overcome the surface force is about several nano-meters. Increasing the pitch angle tends to decreases the take-off height. A lubricant film of about 1 nm will reduce the risk of the glide avalanche in some extent, but increasing the film thickness has little effect. Less