tailieunhanh - Handbook of Micro and Nano Tribology Part 5

The Derjaguin Approximation • Electrostatic Forces • Electrodynamic Forces • Electromagnetic Forces • Forces in and Due to Liquids • Overview Adhesive Forces Anelasticity • Adhesion Hysteresis in Elastic Continuum Contact Mechanics • Adhesion in Nanometer-Sized Contacts • Overview | Burnham . and Kulik . Surface Forces and Adhesion Handbook of Micro Nanotribology. Ed. Bharat Bhushan Boca Raton CRC Press LLC 1999 1999 by CRC Press LLC 5 Surface Forces and Adhesion Nancy A. Burnham and Andrzej J. Kulik Introduction Goals and Motivations Surfaces Forces vs. Adhesion Previous Knowledge Assumed Carte Routière Pertinent Instrumental Background The Instrument Family What Are You Measuring Probe Geometry Surface Forces The Derjaguin Approximation Electrostatic Forces Electrodynamic Forces Electromagnetic Forces Forces in and Due to Liquids Overview Adhesive Forces Anelasticity Adhesion Hysteresis in Elastic Continuum Contact Mechanics Adhesion in Nanometer-Sized Contacts Overview Closing Words Interpreting Your Data Outlook Acknowledgments References Introduction Goals and Motivations Small bits of eraser cling to your homework assignments yet the eraser itself easily slides off a piece of paper. Why What is different about the interaction of small things with a surface as opposed to big things The goal of this chapter is to familiarize you on a conceptual basis with the forces acting between asperities or between an asperity and a flat surface. Asperity behavior is thought to determine the most famous relationship in macrotribology Amon-ton s law Ff LlN. As the normal load N is increased the frictional force Ff also increases with a constant proportionality factor Ll the coefficient of friction. Remembering that even atomically flat surfaces have finite corrugation and that most surfaces exhibit roughnesses well in excess of atomic dimensions increasing the normal load causes more asperities to touch which as a consequence augments the real area of contact between the two bodies. In nanotribology where one considers the interaction of a single asperity contact the researcher has the luxury of studying an ideologically far simpler system. Not only is this an area of intensive research 1999 by CRC Press LLC in .