Microscopic Friction Nanotribology

In the previous section, we learned that the relevant processes of friction occur at microcontacts. To get a better understanding of friction phenomena, one should therefore study friction at the micro- and nanoscale. This field of micro- and nanotribology evolved with the availability of suitable experimental techniques, namely, FFM, SFA, and QCM. Reviews can be found in Refs [975-978]. Recent books on this topic are Refs. [979, 980]. 

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The field of nanotribology evolves around the attempts to understand the relationship between macroscopic frictional forces and the microscopic properties of the embedded system. Recent revival of interest in friction [/, 2, 3, 4, 5, 6, 7, 8] has unraveled a broad range of phenomena and new behaviors which help shed light on some fundamental concepts which are already considered textbook material. These include the static and kinetic friction forces, transition to sliding, thinning, and memory effects, which have been widely discussed but whose microscopic origins are still lacking. 

Nanoindentation and nanotribology have been active research topics since the introduction of experimental tools such as the surface forces apparatus (SFA) and the atomic force microscope (AFM). These tools allow for detailed investigations of frictional properties of confined molecular systems at nanometer length scales(i,2,5,, 5). 

Braun, O.M., and Naumovets, A.G, Nanotribology Microscopic Mechanisms of Friction , Surface Science Reports, 60, 79-158, 2006. 

Fundamental rmderstanding of friaion on the atomic and nanometer scales is critical for design of micro- and nanoe-lectromechanical systems. There are two powerful instruments in nanotribology the surface force apparatus and the atomic force microscope. AFM experiments allow high-resolution mapping of friction properties between solids on the nanometer scale and usually indude measurements of friction forces by friction force microscopy (FFM) and adhesion by CFM. In FFM, as a sharp tip scans across a surface in the... 

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