Quartz Crystal Microbalance Studies of Atomic-Scale Friction

这个实验研究项目的重点是在原子尺度上理解摩擦现象，包括在液-固界面上的摩擦现象。将进行一系列实验，包括石英晶体微天平（QCM）在受控环境条件和明确定义的接触几何形状下的摩擦研究。其中一些旨在探索滑动界面能量传递的基本机制，而另一些将研究与实际工程应用相关的模型润滑系统。要研究的一个系统包括选定的稀有气体和烷烃层在清洁的金属表面上滑动。正在研究的模型润滑系统包括与液体接触的原子均匀C60表面；己烷和合成润滑剂与原子均匀的金属表面接触。在后一种系统中，感兴趣的特性包括与表面相邻形成的分子薄润滑层的粘度和滑移，这些主题与润滑剂在弹性流体动力和边界润滑之间的过渡区域的性能有关。这个实验研究项目致力于提高对摩擦力和相关热效应的科学认识。利用先进的实验技术，包括可以检测单原子单层的石英晶体微天平（QCM），寻求在基本原子尺度上理解这些影响。主要研究滑动摩擦过程中的能量传递机制；而液体润滑剂的粘性和弹性特性接近于固体表面。提高对这方面的理解是非常重要的，因为涉及机械运动的技术范围很广，具有很大的经济意义。这项工作本质上是跨学科的，这个项目的研究生将接受良好的教育，为他们在工业、政府或教育领域的就业做好准备。＊＊＊

w:\awards\awards96\num.doc 9705259 Krim This experimental research project focuses on the atomic scale understanding of frictional phenomena, including those at liquid- solid interfaces. A set of experiments involving quartz crystal microbalance (QCM) studies of friction in controlled environmental conditions and well-defined contact geometries will be performed. Some of these seek to explore the fundamental mechanisms of energy transfer at a sliding interface, while others will investigate model lubrication systems which are of relevance to actual engineering applications. One system to be studied consists of selected rare gas and alkane layers sliding on clean (111) metal surfaces. Model lubrication systems under study include atomically-uniform C60 surfaces in contact with a liquid; and hexanes and synthetic lubricants in contact with atomically uniform metal surfaces. In the latter systems properties of interest include the viscosity and slippage of molecularly thin lubricant layers forming immediately adjacent to the surface, topics which are related to the performance of a lubricant in the transition region between elastohydrodynamic and boundary lubrication. %%% This experimental research project is devoted to improving the scientific understanding of friction forces and related heating effects. An understanding of these effects on the basic atomic scale is sought, making use of advanced experimental techniques, including the quartz crystal microbalance (QCM) which can detect single atomic monolayers. The work focuses on mechanisms of energy transfer during sliding friction; and the viscous and elastic properties of liquid lubricants close to a solid surface. Improvements in understanding here can be of great importance, because the range of technology involving mechanical motions is broad and has great economic importan ce. The work is interdisciplinary in its nature and the graduate students in this program will receive an excellent education preparing them for employment in industry, government or education. ***