Nanotribology: Size-dependent friction coefficient and surface evolution
Wear and abrasion occur during sliding friction of metallic body and counter-body. Surface roughness is purposefully introduced into the metal to reduce wear and abrasion and to increase the lubricant flow.
As both bodies slide past each other, solid - solid micro-contacts develop because the lubricant only partially covers the surface in most applications.
Wear track in austenitic stainless steel and plasticity evolution depending on the crystal orientation
To mimic the micro-contacts and the plastic micro-plowing during run-in, we use a diamond sphere as counter-body for the studied metals. During the deformation process, forces and displacements in the normal and tangential direction are recorded and this time-dependent data is analyzed using spectral analysis. Post-deformation measurements of the surface roughness by atom force microscopy (AFM) and confocal microscopy allow to determine the real contact area and the traces of the metal stick-slip behavior.
Images from the scanning electron microscope (SEM) show the microstructure evolution.