Comparative study between macrotribology and nanotribology

The behavior of different materials under macrotribological and nanotribological conditions has been compared. The materials, hydrogenated amorphous diamondlike carbon, highly ordered pyrolitic graphite, and mica, were submitted to a fretting test (macrotribological behavior) and a combined atomic force microscopy/lateral force microscopy (AFM/LFM) (nanotribological behavior). The coefficient of friction in the macroscopic regime under fixed experimental conditions considerably changed with the test duration, whereas the friction coefficient measured from the nanoscopic regime was relatively constant during the test. In the macroscopic regime, evident wear, elastoplastic deformation, and material transfer were noticed, while in the nanoscopic regime under the used testing conditions no wear phenomena were observed. The coefficient of friction showed some dependence on the amplitude and frequency of lateral movement of the sample relative to the counterbody in both the fretting and AFM/LFM tests as well as on the normal load in the fretting test. This work leads to the conclusion that although some similitudes could be found, the macrotribological behavior of materials cannot simply be related to their nanotribological behavior due to the different wear and friction processes. (C) 1998 American Institute of Physics. [S0021-8979(98)00319-3].