@article{BettscheiderGr{\"u}tzmacherRosenkranz2017,
  author    = {Bettscheider, Simon and Gr{\"u}tzmacher, Philipp and Rosenkranz, Andreas},
  title     = {Low Friction and High Solid-Solid Contact Ratio—A Contradiction for Laser-Patterned Surfaces?},
  journal   = {Lubricants},
  volume    = {5},
  number    = {3},
  issn      = {2075-4442},
  doi       = {10.3390/lubricants5030035},
  url       = {http://www.mdpi.com/2075-4442/5/3/35},
  pages     = {35},
  year      = {2017},
  abstract  = {Recording of Stribeck-like curves is a common way to study the effect of laser-patterned surfaces on the frictional efficiency. However, solely relying on the coefficient of friction when identifying the lubrication regime and the underlying working principles can be misleading. Consequently, a ball-on-disc tribometer was combined with an electrical resistivity circuit to simultaneously measure Stribeck-like curves and solid-solid contact ratios for polished and laser-patterned samples. Line-like surface patterns with different periodicities were produced by direct laser interference patterning on steel substrates (AISI304). The reference shows a Stribeck-like behavior well correlating with the contact ratios. The behavior deviates for high sliding velocities (high contact ratios) due to a loss of lubricant induced by centrifugal forces pulling the lubricant out of the contact zone. In contrast, the solid-solid contact ratio of the laser-patterned samples is around 80\% for all sliding velocities. Those values can be explained by higher contact pressures and the structural depth induced by the surface topography which make a full separation of the surfaces unlikely. Despite those high values for the contact ratio, laser-patterning significantly reduces friction, which can be traced back to a reduced real contact area and the ability to store oil in the contact zone.},
  language  = {en}
}