Study of Film Thickness in Elastohydrodynamic Contacts using a Novel Technique Based on Electrical Capacitance

该项目将提供一个新的工具来测量非常薄的薄膜，边界润滑条件的特点，在真实的，金属对金属接触。目前测量非常薄的润滑膜的技术的一个限制是，它使用了一个脆弱的硅间隔层，这使得它很难在滑动条件下使用。另一个原因是，通常用于润滑油的润滑剂添加剂的化学性质强烈依赖于接触表面的性质。因此，该项目的第一阶段将致力于开发一种光学干涉测量方法，不需要硅间隔层，而是比通常更厚的铬层。该项目的第二阶段致力于测量弹性流体动力润滑特性的极薄薄膜的电容的适应。第一阶段开发的改进光学干涉测量技术将用于校准电容测量。一旦电容方法被校准，它将被用于研究两种常见添加剂体系在滑动金属对金属触点中的成膜特性。这项研究将使人们能够获得关于润滑剂在滚动/滑动、金属对金属接触中的行为的基本科学信息，对润滑剂和机器部件生产商具有相当大的价值。该研究对进一步利用介电光谱研究润滑膜的流变性具有重要意义。

This project will provide a new tool for measuring very thin films, characteristic of boundary lubrication conditions, in real, metal-on-metal contacts.One limitation of the current technique for measuring very thin lubricating films is that it uses a fragile, silica spacer layer, which makes it difficult to use under sliding conditions. The other is that the chemistry of lubricant additives, commonly used in lubricating oils, is strongly dependant on the nature of the surfaces in contact. The first stage of the project will thus be aimed at the development of an optical interferometry method without a silica spacer layer, but a thicker than usual, chromium layer. The second stage of the project is dedicated to the adaptation of electrical capacitance for measuring very thin films characteristic to elastohydrodynamic lubrication. The modified optical interferometry technique, developed in the first stage, will be employed to calibrate capacitance measurements. Once the capacitance method is calibrated, it will be used to study film forming properties of two common additive systems, in sliding, metal-on-metal contacts.This study will enable fundamental scientific information to be gained on lubricant behaviour in rolling/sliding, metal-on-metal contacts and it will be of considerable value to lubricants and machine component producers. The research is essential to enable a future study on the rheology of the lubricating films using dielectric spectroscopy.