C. Greiner, P. Matz
Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM-CMS), Karlsruhe, Germany and Microtribology Centre µTC, Karlsruhe, Germany
In a time in which the public discussion is about climate change and energy efficiency, friction and wearing play an important role for designing technological systems containing moving parts. While conventional surface texturing have proven to be successful in terms of reducing friction in tribological contacts, the bio-inspired approach in creating morphological surface textures is a relatively new field of research.
Here, we characterized Bio-inspired scale-like laser textured surfaces under dry sliding conditions in unidirectional sliding contact. The tribological pin-on-disc tests were carried out in a model test rig with a normal force of 2 N, for a sliding distance of 1000m and at a sliding speed of 0.1ms?1. For the laser texturing, bearing steel 100Cr6 pins were used and as counter material, sapphire discs with a diameter of 50mm and a thickness of 5mm were chosen. The steel samples were polished and three textures with different diameters of the scales (13 µm, 27µm and 43 µm) were created.
The results of the tribological experiments show a dependency between the friction reduction and the diameter of the scales. While the large scales with a diameter of 43 µm were causing a reduction of the friction coefficient up to 46 % compared to an untextured sample (µ = 0,71), the friction were reduced by 32 % by the small scales.
Latest experiments with larger scales (diameter 150 µm) show a friction coefficient about 0,55 and therefore an increase of friction compared to the scales with 43 µm diameter.