Evolution of the True Contact Area of Laser Textured Tungsten Under Dry Sliding Conditions

Despite the great importance of the real contact area, it is a parameter which, depending
on the tribological system, is difficult or impossible to obtain experimentally. In this
work, a combination of methods was used to estimate the development of the real
contact surface, and the results were compared with the friction coefficient course. The
measurements were carried out with a home-built in situ tribometer, which records a
3D image of the surface after each individual friction cycle. A tungsten sample was
treated by laser interference with a line-like pattern to produce a deterministic surface.
This allowed for more precise tracking of the real contact area when combined with the
use of an inert corundum sphere as a counter-body. The real contact area was calculated
numerically from the height information obtained using a contact application. Finally, the
true contact surface was compared with the parallel-recorded friction values. After a short
running-in phase, the friction behavior and the real contact surface showed comparable
courses. This indicates that the changes in the real contact area could explain the friction
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behavior of the laser-patterned sample, and the methodology was proven to be suitable
for experimentally estimating the real contact area.