Quartz Crystal Microbalance Studies of Atomic-Scale Friction

这个实验研究项目专注于原子尺度上对摩擦现象的理解，包括液-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)，研究受控环境条件下的摩擦和明确定义的接触几何形状。其中一些课程试图探索滑动界面上能量传递的基本机制，而另一些课程将研究与实际工程应用相关的模型润滑系统。一个要研究的系统由选定的稀有气体和烷烃层组成，这些层在清洁的(111)金属表面滑动。正在研究的模型润滑系统包括与液体接触的原子均匀的C60表面，以及与原子均匀的金属表面接触的己烷和合成润滑剂。在后一种体系中，感兴趣的性质包括紧邻表面形成的分子薄润滑剂层的粘度和滑移率，这些主题与在弹性流体动力和边界润滑之间的过渡区中润滑剂的性能有关。这个实验研究项目致力于提高对摩擦力和相关加热效应的科学认识。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)，寻求对基本原子尺度上的这些影响的理解。这项工作的重点是滑动摩擦过程中的能量传递机制，以及液体润滑剂在固体表面附近的粘性和弹性性质。在这里提高理解是非常重要的，因为涉及机械运动的技术范围很广，具有很大的经济重要性。这项工作本质上是跨学科的，该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. ***