Tribo-Induced Temperature Rise and Melting at a Single Asperity Sliding Contact

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Date

2010-04-29

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Abstract

The fundamental issue of temperature rise at a rubbing interface due to frictional energy dissipation is of great practical and theoretical importance. Many tribological phenomena, such as tribo-chemistry and wear rates, have been attributed at least in part to the temperature rise felt at the contact between rubbing asperities. However, the difficulty of investigating this interface has lead to a lack of in situ experimental results. In this study, the interfacial mechanics of a sliding interface are probed using a combined quartz crystal microbalance and scanning tunneling microscope in ultra high vacuum conditions. The unique capability of a quartz crystal microbalance to monitor sensitive changes in the contact region, along with the wide range of surface velocities that are readily attainable, allow for a novel investigation of interfacial phenomena at the asperity contact formed by the tip contacting the oscillating crystal surface. The imaging ability of the scanning tunneling microscope permits the detailed characterization of the surface before and after indentation, as well as a method for calibrating the velocity of the QCM surface by directly measuring the crystal amplitudes. I have employed Indium as the substrate due to its low melting point, and a velocity and temperature dependent transition in the response of the quartz crystal microbalance is observed. This transition is attributed to the contact region melting or becoming liquid-like due to frictional energy dissipation. This is the first time such a velocity dependent transition has been observed at the scales studied here.

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Keywords

wear, frictional melting, vapor phase lubrication, surface melting, frictional temperature rise, nanotribology

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Degree

PhD

Discipline

Physics

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