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

该项目将提供一种新的工具，用于测量非常薄的膜，边界润滑条件的特性，在真实的，金属对金属的接触。目前的技术用于测量非常薄的润滑膜的一个限制是，它使用一个脆弱的，二氧化硅间隔层，这使得它难以在滑动条件下使用。另一个是润滑油中常用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旨在开发一种没有二氧化硅间隔层但比通常更厚的铬层的光学干涉测量方法。该项目的第二阶段致力于适应电容测量弹性流体动力润滑特性的非常薄的薄膜。在第一阶段开发的改进的光学干涉测量技术将用于校准电容测量。电容法校准后，将用于研究两种常用添加剂体系在金属-金属滑动接触中的成膜性能。这项研究将获得有关滚动/滑动、金属-金属接触中润滑剂行为的基础科学信息，对润滑剂和机械部件生产商具有重要价值。这项研究是必不可少的，使未来的研究，使用介电谱的润滑膜的流变性。

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.