Recording of Stribeck-like curves is a common way to study the effect of laser-patterned\nsurfaces on the frictional efficiency. However, solely relying on the coefficient of friction when\nidentifying the lubrication regime and the underlying working principles can be misleading.\nConsequently, a ball-on-disc tribometer was combined with an electrical resistivity circuit to\nsimultaneously measure Stribeck-like curves and solid-solid contact ratios for polished and\nlaser-patterned samples. Line-like surface patterns with different periodicities were produced by\ndirect laser interference patterning on steel substrates (AISI304). The reference shows a Stribeck-like\nbehavior well correlating with the contact ratios. The behavior deviates for high sliding velocities\n(high contact ratios) due to a loss of lubricant induced by centrifugal forces pulling the lubricant out\nof the contact zone. In contrast, the solidââ?¬â??solid contact ratio of the laser-patterned samples is around\n80% for all sliding velocities. Those values can be explained by higher contact pressures and the\nstructural depth induced by the surface topography which make a full separation of the surfaces\nunlikely. Despite those high values for the contact ratio, laser-patterning significantly reduces friction,\nwhich can be traced back to a reduced real contact area and the ability to store oil in the contact zone.
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