At the micro-scale level, the adhesion force dominates the friction force when the normal load approaches zero. For determining the effects of micro wear on the adhesion (pull-off) force, the wear-induced changes in surface topography of asperities and the pull-off force between the asperities and leaf springs were determined. First, single asperities were formed on a single-crystal gold plate and the asperities were rubbed with a silicon leaf spring attached to an AFM (atomic force microscope). A focused ion beam (FIB) system was used to form gold pyramid-shaped asperities on the surface of a single crystal gold plate. The FIB was also used to create the two types of single crystal silicon leaf springs tested here; single and parallel. The single leaf spring was created by flattening the probe-head of a commercially available AFM cantilever for AC mode. The parallel leaf spring was created by removing the central portion of a single-crystal silicon beam (25 μm×50 μm×300 μm). For the single leaf spring, the pull-off force no longer increased when the sliding distance exceeded 5 mm at a load of more than 200 nN. On the other hand, for the parallel leaf spring, the pull-off force increased monotonically with sliding distance, showing a more rapid increase at the higher normal load. The worn area of the asperity peak (measured by using an ordinary AFM probe) was proportional to the pull-off force. The wear volume per unit distance (i.e., wear rate) was estimated from the change in pull-off force, and was found to increase monotonically with the external load. There was no effect of adhesion force on the wear volume. [S0742-4787(00)01102-4]
Wear Tests and Pull-Off Force Measurements of Single Asperities by Using Parallel Leaf Springs Installed on an Atomic Force Microscope
Contributed by the Tribology Division for publication in the JOURNAL OF TRIBOLOGY. Manuscript received by the Tribology Division March 1, 1999; revised manuscript received August 10, 1999. Associate Technical Editor: Y.-W. Chung.
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Ando, Y. (August 10, 1999). "Wear Tests and Pull-Off Force Measurements of Single Asperities by Using Parallel Leaf Springs Installed on an Atomic Force Microscope ." ASME. J. Tribol. July 2000; 122(3): 639–645. https://doi.org/10.1115/1.555414
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