Micro-scale friction force

Miyata and Yamaoka [26] used scanning probe microscopy (SPM) to determine the micro-scale friction force of a silicone-treated polymer film surface. PU acrylates cured by an electron beam were used as the polymer films. The micro-scale friction force obtained by SPM was compared with macro-scale data, such as surface free energy determined by the Owens-Wendt method and the macro-scale friction coefficient determined by the ASTM D1894 method [27]. These comparisons showed that a good linear relationship existed between the surface free energy and the friction force, which was insensitive to the nature of the polymer specimens or to the silicone... 

As is known, microscale friction and wear is important in microtribology. However, it is not easy to get real friction force on micro/nano scale during the tests. The surface morphology at nanometer scale, the scanning direction of the FFM, etc., have significant effects on friction force measurement. Even nowadays for commercial SPM we are not quite sure if the friction force we get is a real one or not. 

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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