Effects of friction on topography and vice versa

Abstract Experimental results of friction and topography measurements are presented which demonstrate the mutual modification of friction and contact topography. The effect of topographical ‘landmarks’ on friction was tested by Al 2 O 3 -balls sliding over Ti-ridges on Ti-surface and by Si 3 N 4 -balls sliding over grooves in SiO 2 -surfaces. However, experiments of 100Cr6-balls sliding against 100Cr6-substrates in ultrahigh vacuum, Al 2 O 3 -balls sliding on DLC coated 100Cr6 and Si 3 N 4 -balls sliding on SiO 2 -surfaces reveal that the formation of triboreaction layers and moreover the creation of wear particles can screen the effect of the topographical ‘landmarks’ completely. Wear particles and their exact behaviour in the contact area can affect friction in a stochastical and hence unpredictable way. Most modern friction theories have difficulties in coping with this problem.