**Possibilities of Dry and Lubricated Friction Modification Enabled by Different Ultrashort Laser-Based Surface Structuring Methods**

**Stefan Rung 1,\*, Kevin Bokan 1, Frederick Kleinwort 2, Simon Schwarz 1, Peter Simon 2, Jan-Hendrik Klein-Wiele 2, Cemal Esen <sup>3</sup> and Ralf Hellmann <sup>1</sup>**


Received: 16 April 2019; Accepted: 13 May 2019; Published: 17 May 2019

**Abstract:** In this contribution we report on the possibilities of dry and lubricated friction modification introduced by different laser surface texturing methods. We compare the potential of Laser-Induced Periodic Surface Structures and Laser Beam Interference Ablation on 100Cr6 steel in a linear reciprocating ball-on-disc configuration using 100Cr6 steel and tungsten carbide balls with load forces between 50 mN and 1000 mN. For dry friction, we find a possibility to reduce the coefficient of friction and we observe a pronounced direction dependency for surfaces fabricated by Laser Beam Interference Ablation. Furthermore, Laser-Induced Periodic Surface Structures result in a load-dependent friction reduction for lubricated linear reciprocating movements. This work helps to identify the modification behaviour of laser generated micro structures with feature sizes of approximately 1 μm and reveals new possibilities for surface engineering

**Keywords:** laser-induced periodic surface structures; laser beam interference ablation; dry friction; lubricated friction; laser surface texturing; smart surfaces
