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Autor

  • Kirner, Sabrina V. (16)
  • Bonse, Jörn (14)
  • Krüger, Jörg (14)
  • Kirner, Sabrina (5)
  • Spaltmann, Dirk (5)
  • Baumgartner, W. (3)
  • Höhm, S. (3)
  • Mimidis, A. (3)
  • Plamadeala, C. (3)
  • Rosenfeld, A. (3)
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Erscheinungsjahr

  • 2019 (1)
  • 2018 (4)
  • 2017 (14)
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  • Zeitschriftenartikel (10)
  • Beitrag zu einem Tagungsband (4)
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Schlagworte

  • Laser-induced periodic surface structures (LIPSS) (14)
  • Femtosecond laser ablation (11)
  • Steel (6)
  • Surface functionalization (6)
  • Biomimetics (4)
  • Fluid transport (4)
  • Friction (4)
  • Laser ablation (4)
  • Tribology (4)
  • Femtosecond laser (3)
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Organisationseinheit der BAM

  • 6 Materialschutz und Oberflächentechnik (21)
  • 6.4 Technologien mit Nanowerkstoffen (21)
  • 6.3 Makro-Tribologie und Verschleißschutz (10)
  • 6.6 Nano-Tribologie und Nanostrukturierung von Oberflächen (2)
  • 6.7 Oberflächenmodifizierung und -messtechnik (2)
  • 5 Werkstofftechnik (1)
  • 5.1 Materialographie, Fraktographie und Alterung technischer Werkstoffe (1)
  • 6.1 Oberflächenanalytik und Grenzflächenchemie (1)

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Tribological performance of titanium samples oxidized by fs-laser radiation, thermal heating, or electrochemical anodization (2018)
Kirner, Sabrina V. ; Slachciak, Nadine ; Elert, Anna M. ; Griepentrog, Michael ; Fischer, Daniel ; Hertwig, Andreas ; Sahre, Mario ; Dörfel, Ilona ; Sturm, Heinz ; Pentzien, Simone ; Koter, Robert ; Spaltmann, Dirk ; Krüger, Jörg ; Bonse, Jörn
Commercial grade-1 titanium samples (Ti, 99.6%) were treated using three alternative methods, (i) femtosecond laser processing, (ii) thermal heat treatment, and (iii) electrochemical anodization, respectively, resulting in the formation of differently conditioned superficial titanium oxide layers. The laser processing (i) was carried out by a Ti:sapphire laser (pulse duration 30 fs, central wavelength 790 nm, pulse repetition rate 1 kHz) in a regime of generating laser-induced periodic surface structures (LIPSS). The experimental conditions (laser fluence, spatial spot overlap) were optimized in a sample-scanning setup for the processing of several square-millimeters large surface areas covered homogeneously by these nanostructures. The differently oxidized titanium surfaces were characterized by optical microscopy, micro Raman spectroscopy, variable angle spectroscopic ellipsometry, and instrumented indentation testing. The tribological performance was characterized in the regime of mixed friction by reciprocating sliding tests against a sphere of hardened steel in fully formulated engine oil as lubricant. The specific tribological performance of the differently treated surfaces is discussed with respect to possible physical and chemical mechanisms.
Laser-induced periodic surface structures on steel for tribological applications (2017)
Kirner, Sabrina V.
Laser-induced periodic surface structures (LIPSS) can be generated by irradiation of almost any material with linearly polarized laser beams, particularly when using ultrashort laser pulses. Within this work, different types of steel were irradiated at optimized conditions for the processing of large surface areas. For these nanostructured surfaces, the coefficient of friction (COF) using different lubricants was determined and the corresponding wear tracks were characterized by scanning electron microscopy (SEM). Our experiments provide a qualification of the tribologicalperformance of the fs-LIPSS on different steel surfaces, which are relevant for technical applications.
Femtosecond laser texturing of surfaces for tribological applications (2018)
Bonse, Jörn ; Kirner, Sabrina V. ; Griepentrog, Michael ; Spaltmann, Dirk ; Krüger, Jörg
Laser texturing is an emerging technology for generating surface functionalities on basis of optical, mechanical, or chemical properties. Taking benefit of laser sources with ultrashort (fs) pulse durations features outstanding precision of machining and negligible rims or burrs surrounding the laser-irradiation zone. Consequently, additional mechanical or chemical post-processing steps are usually not required for fs-laser surface texturing (fs-LST). This work aimed to provide a bridge between research in the field of tribology and laser materials processing. The paper reviews the current state-of-the-art in fs-LST, with a focus on the tribological performance (friction and wear) of specific self-organized surface structures (so-called ripples, grooves, and spikes) on steel and titanium alloys. On the titanium alloy, specific sickle-shaped hybrid micro-nanostructures were also observed and tribologically tested. Care is taken to identify accompanying effects affecting the materials hardness, superficial oxidation, nano- and microscale topographies, and the role of additives contained in lubricants, such as commercial engine oil.
Mimicking lizard-like surface structures upon ultrashort laser pulse irradiation of inorganic materials (2017)
Hermens, U. ; Kirner, Sabrina ; Emonts, C. ; Comanns, P. ; Skoulas, E. ; Mimidis, A. ; Mescheder, H. ; Winands, K. ; Krüger, Jörg ; Stratakis, E. ; Bonse, Jörn
Inorganic materials, such as steel, were functionalized by ultrashort laser pulse irradiation (fs- to ps-range) to modify the surface’s wetting behavior. The laser processing was performed by scanning the laser beam across the surface of initially polished flat sample material. A systematic experimental study of the laser processing parameters (peak fluence, scan velocity, line overlap) allowed the identification of different regimes associated with characteristic surface morphologies (laser-induced periodic surface structures, grooves, spikes, etc.). Analyses of the surface using optical as well as scanning electron microscopy revealed morphologies providing the optimum similarity to the natural skin of lizards. For mimicking skin structures of moisture-harvesting lizards towards an optimization of the surface wetting behavior, additionally a two-step laser processing strategy was established for realizing hierarchical microstructures. In this approach, micrometer-scaled capillaries (step 1) were superimposed by a laser-generated regular array of small dimples (step 2). Optical focus variation imaging measurements finally disclosed the three dimensional topography of the laser processed surfaces derived from lizard skin structures. The functionality of these surfaces was analyzed in view of wetting properties.
Femtosecond laser-induced microstructures on Ti substrates for reduced cell adhesion (2017)
Heitz, J. ; Plamadeala, C. ; Muck, M. ; Armbruster, O. ; Baumgartner, W. ; Weth, A. ; Steinwender, C. ; Plessberger, H. ; Kellermair, J. ; Kirner, Sabrina V. ; Krüger, Jörg ; Bonse, Jörn ; Guntner, A. S. ; Hassel, A. W.
Miniaturized pacemakers with a surface consisting of a Ti alloy may have to be removed after several years from their implantation site in the heart and shall, therefore, not be completely overgrown by cells or tissue. A method to avoid this may be to create at the surface by laser-ablation self-organized sharp conical spikes, which provide too little surface for cells (i.e., fibroblasts) to grow on. For this purpose, Ti-alloy substrates were irradiated in the air by 790 nm Ti:sapphire femtosecond laser pulses at fluences above the ablation threshold. The laser irradiation resulted in pronounced microstructure formation with hierarchical surface morphologies. Murine fibroblasts were seeded onto the laser-patterned surface and the coverage by cells was evaluated after 3–21 days of cultivation by means of scanning electron microscopy. Compared to flat surfaces, the cell density on the microstructures was significantly lower, the coverage was incomplete, and the cells had a clearly different morphology. The best results regarding suppression of cell growth were obtained on spike structures which were additionally electrochemically oxidized under acidic conditions. Cell cultivation with additional shear stress could reduce further the number of adherent cells.
Femtosecond laser-induced periodic surface structures on titanium nitride coatings for tribological applications (2016)
Kirner, Sabrina
Laser-induced periodic surface structures (LIPSS) were generated on titanium nitride (TiN) hardcoating surfaces (deposited on metallic substrates) upon irradiation with multiple linearly polarized femtosecond laser pulses in air (30 fs duration, 790 nm wavelength, 1 kHz pulse repetition rate). The conditions were optimized in a sample-scanning geometry for the processing of large surface areas (5 mm x 5 mm) covered homogeneously by nanostructures with sub-wavelength periods ranging between ~200 nm and 700 nm. For these nanostructures the coefficient of friction was characterized under reciprocating sliding condition against a ball of hardened steel at 1 Hz using different lubricants (regime of mixed friction). After 1000 cycles, the corresponding wear tracks were characterized by optical and scanning electron microscopy. High-resolution energy dispersive X-ray analyzes (EDX) allowed the visualization of chemical alterations within the wear tracks. For specific conditions, the nanostructures endured the tribological treatment. Our experiments provide a qualification of the tribological performance of the fs-LIPSS on TiN surfaces.
Modelling periodic structure formation on 100Cr6 steel after irradiation with femtosecond-pulsed laser beams (2018)
Tsibidis, G. D. ; Mimidis, A. ; Skoulas, E. ; Kirner, Sabrina V. ; Krüger, Jörg ; Bonse, Jörn ; Stratakis, E.
We investigate the periodic structure formation upon intense femtosecond pulsed irradiation of chrome steel (100Cr6) for linearly polarised laser beams. The underlying physical mechanism of the laser-induced periodic structures is explored, their spatial frequency is calculated and theoretical results are compared with experimental observations. The proposed theoretical model comprises estimations of electron excitation, heat transfer, relaxation processes, and hydrodynamics-related mass transport. Simulations describe the sequential formation of sub-wavelength ripples and supra-wavelength grooves. In addition, the influence of the laser wavelength on the periodicity of the structures is discussed. The proposed theoretical investigation offers a systematic methodology towards laser processing of steel surfaces with important applications.
Surface functionalization by laser-induced periodic surface structures (LIPSS) (2018)
Bonse, Jörn ; Kirner, Sabrina V. ; Epperlein, Nadja ; Spaltmann, Dirk ; Krüger, Jörg
In this contribution the mechanisms of formation and current applications of LIPSS are reviewed, including the colorization of technical surfaces, the control of surface wetting properties, the mimicry of the natural texture of animal integuments, the tailoring of surface colonization by bacterial biofilms, and the improvement of the tribological performance of nanostructured metal surfaces.
LiNaBioFluid Laser-induced nanostructures as biomimetic model of fluid transport in the integument of animals (2017)
Kirner, Sabrina V.
Laser-induced Nanostructures as Biomimetic Model of Fluid Transport in the Integument of Animals”, aims on laser-fabrication of biomimetic surfaces with unique wetting properties, which are inspired by the hierarchical micro- and/or nano- structures of animal body surfaces. LiNaBioFluid is a Research and Innovation Action funded by the European Commissions’ Horizon 2020 - FET Open Programme, which supports early-stage research on any idea for a new technology (Grant Agreement no: 665337). It brings together 7 partners from 4 different countries and is strongly interdisciplinary combining renowned experts from the fields of zoology, physics, mechatronics, life sciences, materials sciences, laser-matter interaction, production technology, tribology, and biomimetics. www.laserbiofluid.eu/
Applications of femtosecond-laser processed surfaces (2017)
Kirner, Sabrina V.
Applications of femtosecond laser processed surfaces are reviewed. This includes the colorization of technical surfaces, the control of surface wetting, the tailoring of surface colonization by bacterial biofilms, the reduction of cell adhesion on novel pacemakers, and the improvement of the tribological performance of nanostructured metal surfaces.
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