Quartz Crystal Microbalance Studies of Atomic-Scale Friction

根据最新的估计，改善对摩擦和磨损的关注将为发达国家节省高达1.6%的国民生产总值，仅在美国每年就可以节省超过1000亿美元。20世纪80年代末的S和90年代初的S尤其标志着摩擦学基础领域(摩擦和磨损研究)的复兴，许多新的实验和理论技术能够研究纳米级几何中的摩擦力。这个项目涉及使用一种这样的技术，即石英晶体微天平(QCM)，(1)探索能量耗散机制在最近发现的和越来越有争议的超导相关摩擦现象中的作用，(2)探测简化滑动接触的温度，这个量从理论、实验和计算方法中都很难量化，以及(3)探索在广泛的长度和时间尺度上控制分子薄液膜的摩擦规律的线性。免费教育部分包括(1)本科生持续参与研究，(2)直接向制定该主题课程的教师传播关于摩擦的最新信息，以及通过讲座和书面评论向更广泛的受众传播。技术摘要：20世纪80年代末的S和90年代初的S标志着人们对摩擦学基础领域重新产生了兴趣，这是由于许多新的实验和理论技术能够研究在纳米尺度上定义良好的几何中的摩擦力。该项目涉及使用一种这样的技术，即石英晶体微天平，来探索对该领域具有重要意义的关键问题。第一组实验将探索电子和声子能量耗散机制在最近发现的、越来越有争议的超导摩擦现象中的作用。垂直和平行于在Pb和Nb衬底上滑动的吸附层的磁场将被用来驱动系统进入和离开超导状态。第二组研究包括记录滑动对吸附在具有可变晶格间距的石墨烯薄片上的单层厚氪层的二维熔点的影响。这些研究的目的是探索简化滑动接触的温度，从理论、实验和计算方法中都很难量化这个量。第三组拟议的实验涉及将QCM与IBM Almaden最近开发的排气装置一起操作。这里的目标是探索在广泛的长度和时间范围内控制分子薄液体膜的摩擦定律的线性。免费教育部分包括(1)本科生持续参与研究，(2)直接向制定该主题课程的教师传播关于摩擦的最新信息，以及通过讲座和书面评论向更广泛的受众传播。

By most recent estimates, improved attention to friction and wear would save developed countries up to 1.6% of their gross national product, or over $100 billion annually in the U.S. alone. The late 1980's and early 1990's particularly marked a renaissance in fundamental areas of tribology (the study of friction and wear), sparked by a number of new experimental and theoretical techniques capable of studying the force of friction in geometries which were well defined at the nanometer scale. This project involves the use of one such technique, namely the Quartz Crystal Microbalance (QCM), (1) to explore the role of energy dissipative mechanisms in the recently discovered, and increasingly controversial phenomenon of superconductivity-dependent friction, (2) to probe the temperature of a simplified sliding contact, a quantity that has been exceptionally difficult to quantify from theoretical, experimental and computational approaches, and (3) to explore the linearity of friction laws governing molecularly thin liquid films over a wide range of length and time scales. A complimentary educational component includes (1) ongoing participation of undergraduates in the research, and (2) direct dissemination of state-of-the-art information on friction to instructors developing curriculum on the topic, as well as to more general audiences through lectures and written reviews. Technical Abstract: The late 1980's and early 1990's marked the advent of a renewed interest in fundamental areas of tribology, sparked by a number of new experimental and theoretical techniques capable of studying the force of friction in geometries which were well defined at the nanometer scale. This project involves the use of one such technique, namely the Quartz Crystal Microbalance, to probe critical issues of importance to this field. A first set of experiments will explore the role of electronic and phononic energy dissipative mechanisms in the recently discovered, and increasingly controversial phenomenon of superconductivity-dependent friction. Magnetic fields perpendicular and parallel to adsorbed layers sliding on Pb and Nb substrates will be employed to drive the system in and out of the superconducting state. A second set of studies involves documentation of the impact of sliding on the two-dimensional melting point of monolayer thick Krypton layers adsorbed on Graphene sheets with variable lattice spacing. The goal of these studies is to probe the temperature of a simplified sliding contact, a quantity that has been exceptionally difficult to quantify from theoretical, experimental and computational approaches. The third set of proposed experiments involves operation of a QCM in conjunction with a blowoff apparatus recently developed at IBM Almaden. The goal here is to explore the linearity of friction laws governing molecularly thin liquid films over a wide range of length and time scales. A complimentary educational component includes (1) ongoing participation of undergraduates in the research, and (2) direct dissemination of state-of-the-art information on friction to instructors developing curriculum on the topic, as well as to more general audiences through lectures and written reviews.