On the Derjaguin Offset in Boundary-Lubricated Nanotribological Systems

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• 作者：Stefan J. Eder ; Andr谩s Vernes ; Gerhard Betz
• 刊名：Langmuir
• 出版年：2013
• 出版时间：November 12, 2013
• 年：2013
• 卷：29
• 期：45
• 页码：13760-13772
• 全文大小：978K
• 年卷期：v.29,no.45(November 12, 2013)
• ISSN：1520-5827

文摘

We performed molecular dynamics simulations of boundary-lubricated sliding, varying the boundary lubricant type, its molecular surface coverage, the substrate roughness, and the load. The resulting load versus friction behavior was then analyzed to study how changes in lubricant type, coverage, and roughness affect the extrapolated friction force at zero load, the so-called Derjaguin offset. A smooth-particle-based evaluation method by the authors, applied here for the first time to visualize the sliding interface between the two layers of boundary lubricant, allowed the definition and calculation of a dimensionless normalized sliding resistance area, which was then related to the Derjaguin offset. This relationship excellently reflects the molecular surface coverage, which determines the physical condition of the lubricant, and can differentiate between some lubricant-specific frictional properties.