Connecting campuses to promote excellence in math and science


Brian Borovsky

St. Olaf College
The Origins of Friction: Micro/nanoscale studies of high speed sliding contacts with a combined nanoindenter and quartz microbalance
What gives rise to the force of friction? Today there is a growing interdisciplinary effort to determine the mechanisms of friction at the atomic scale. Such knowledge has remained elusive, even as new experimental methods and theoretical models have greatly expanded our understanding of surfaces over the last few decades. Friction poses inherent challenges to researchers because it is difficult to probe inside a sliding interface and because the phenomenon incorporates a wide range of length and time scales. In this talk, I will discuss a new technique that combines a nanoindenter with a quartz crystal microbalance to form an apparatus capable of studying frictional forces at very small, high-speed contacts. So far, this apparatus has helped answer some important questions about the structure of interfaces: when two surfaces that are not perfectly smooth come together, how many true points of contact form, how many atoms across are they, and how far apart? Recent results have also shown how the apparatus can track the extent of relative motion at an oscillating interface. Knowledge of these small-scale details plays an important role in understanding friction and is needed to guide development of theoretical models. Future plans call for a collaboration with Prof Erin Flater at Luther College in order to study the frictional properties of organic lubricant films with a thickness of one molecule. Understanding such molecularly thin films may prove essential for the ultimate success of a new generation of microscopic mechanical devices, known as microelectromechanical systems or MEMS.
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