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Science 27 October 1995:
Vol. 270. no. 5236, pp. 605 - 608
DOI: 10.1126/science.270.5236.605
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Reports

Nano-Elastohydrodynamics: Structure, Dynamics, and Flow in Nonuniform Lubricated Junctions

Jianping Gao,  W. D. Luedtke,  Uzi Lman (1)

Structure, flow, and response characteristics of molecularly thin films of hexadecane, sheared by topographically nonuniform solid gold surfaces sliding at a relative velocity of 10 meters per second, were investigated with molecular dynamics simulations. The simulations reveal three characteristics: spatial and temporal variations in the density and pressure of the lubricant in the region confined by the approaching asperities, accompanied by asperity-induced molecular layering transitions that are reflected in oscillatory patterns in the friction force; asperity deformations and microstructural transformations mediated by the lubricant; and an onset of cavitated zones in the lubricant after the asperity-asperity collision process. The simulations extend micrometer-scale elastohydrodynamic investigations into the nanometer-scale regime and provide molecular-scale insights into the fundamental mechanisms of ultrathin film lubrication phenomena under extreme conditions.


School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA.
(1) To whom correspondence should be addressed.

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Science. ISSN 0036-8075 (print), 1095-9203 (online)