@article{RungBokanRutschetal.2018, author = {Rung, Stefan and Bokan, Kevin and Rutsch, Kevin and Schwarz, Simon and Esen, Cemal and Hellmann, Ralf}, title = {Laser Induced Periodic Surface Structures on 100Cr6 Steel for Modification of Friction Demonstrated with Stribeck Test}, series = {Journal of Laser Micro/Nanoengineering}, volume = {13}, journal = {Journal of Laser Micro/Nanoengineering}, number = {3}, doi = {10.2961/jlmn.2018.03.0004}, pages = {160 -- 165}, year = {2018}, abstract = {In this contribution, we report on surface functionalization by introducing laser induced periodic surface structures on 100Cr6 bearing steel to modify complex tribological properties. The advanced approach of this study is the measurement of the coefficient of friction by performing a ball-on-disk Stribeck test on laser structured surfaces with polytetrafluoroethylene balls in a lubricant environment. The Stribeck test reveals the modified friction behavior using translation speeds up to 106 mm/min and load forces between 100 mN and 5000 mN. Our results show increased stiction and coefficient of friction for laser structured surfaces in the regime of boundary lubrication which is attributed to the laser induced surface asperities. Decreased coefficient of friction is observed in the regime of mixed and hydrodynamic lubrication, i.e. for velocities higher than 1000 mm/min, for surfaces covered by laser induced periodic surface structures with low spatial frequency.}, subject = {Laser}, language = {en} } @article{RungBokanKleinwortetal.2019, author = {Rung, Stefan and Bokan, Kevin and Kleinwort, Frederick and Schwarz, Simon and Simon, Peter and Klein-Wiele, Jan-Hendrik and Esen, Cemal and Hellmann, Ralf}, title = {Possibilities of Dry and Lubricated Friction Modification Enabled by Different Ultrashort Laser-Based Surface Structuring Methods}, series = {Lubricants}, volume = {7}, journal = {Lubricants}, number = {43}, doi = {10.3390/lubricants7050043}, pages = {1 -- 13}, year = {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 50mN 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 1μm and reveals new possibilities for surface engineering}, subject = {Laser}, language = {en} } @article{RungBokanSchwarzetal.2020, author = {Rung, Stefan and Bokan, Kevin and Schwarz, Simon and Esen, Cemal and Hellmann, Ralf}, title = {Influence of laser wavelength on the modification of friction between 100Cr6 steel and polytetrafluoroethylene by femtosecond laser-induced periodic surface structures}, series = {Journal of Laser Applications}, volume = {32}, journal = {Journal of Laser Applications}, number = {3}, doi = {10.2351/7.0000036}, pages = {032017-1 -- 032017-6}, year = {2020}, subject = {Femtosekundenlaser}, language = {en} }