Filtern
Dokumenttyp
- Vortrag (32) (entfernen)
Sprache
- Englisch (32)
Referierte Publikation
- nein (32) (entfernen)
Schlagworte
- Laser-induced periodic surface structures (LIPSS) (32) (entfernen)
Organisationseinheit der BAM
- 6 Materialchemie (27)
- 6.2 Material- und Oberflächentechnologien (27)
- 9 Komponentensicherheit (7)
- 9.5 Tribologie und Verschleißschutz (7)
- 6.1 Oberflächen- und Dünnschichtanalyse (4)
- 4 Material und Umwelt (2)
- 4.1 Biologische Materialschädigung und Referenzorganismen (2)
- 6.6 Physik und chemische Analytik der Polymere (1)
This talk presents multi-wavelength, multi-material prediction tools serving as useful models for researchers working in the field of laser-induced periodic surface structures (LIPSS). These models explain the role of surface plasmon polaritons (SPPs) in the formation of LIPSS. They particularly consider the cases of (i) “lossy” materials (where the imaginary part of the dielectric permittivity should not be neglected) and (ii) the excitation of SPPs in a thin film configuration (where two film interfaces become plasmonically active and couple to each other).
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.
Nature provides countless examples of surface structures featuring extraordinary properties such as directional fluid transport. In order to mimic the morphology and outstanding wetting behaviour of bark bugs, ultrashort laser pulses with durations in the fs- to ps-range were employed for large area surface processing of steel. By scanning the laser beam across the surface of initially polished flat sample surfaces and systematically varying the laser processing parameters (peak fluence, scan velocity, line overlap), different regimes associated with characteristic surface morphologies (laser-induced periodic surface structures (LIPSS), grooves, spikes, etc.) could be identified. Additionally, different laser processing strategies were applied, varying laser wavelength, pulse duration and repetition rates, which allowed to achieve a range of morphologies that resemble different structures found on bark bugs. For identifying the ideal combination of parameters for mimicking such bug-like structures, the surfaces were inspected by means of optical and scanning electron microscopy.
Complementary to the morphology study, the wetting behaviour of the surface structures for water and oil was examined intensively in terms of fluid transport and philic/-phobic nature. Additionally, with these results in hand, tribological tests investigating the wear resistance of the laser-induced nano- and microstructures were carried out. Our results demonstrate that the functionality of surface structures found in nature could be transferred to technologically relevant materials, such as steel, providing a huge potential for industrial applications for instance in friction and wear reduction.
Ultrashort laser pulses with durations in the fs- to ps-range were used for large area surface processing of steel aimed at mimicking the morphology and extraordinary wetting behaviour of bark bugs (Aradidae) found in nature. The processing was performed by scanning the laser beam across the surface of initially polished flat sample surfaces. A systematic variation 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 (LIPSS), grooves, spikes, etc.). Additionally, we show that different laser processing strategies, varying laser wavelength, pulse duration and repetition rates, allowed to achieve a range of morphologies that resemble different structures found in bark bugs. For identifying the ideal combination of parameters for mimicking bug-like structures, the surfaces were inspected by optical and scanning electron microscopy.
Complementary to the morphology study, the wetting behaviour of the surface structures for water and oil was examined intensively in terms of philic/-phobic nature and fluid transport. With these results in hand, tribological tests were carried out investigating the wear resistance of the laser-induced nano- and microstructures. Our results demonstrate a route towards reproducing complex structures inspired by nature and their functional response in technologically relevant materials.
Applications of laser-induced periodic surface structures (LIPSS, ripples) upon irradiation of solid materials by fs-laser pulses are reviewed. This includes the colorization of technical surfaces, the control of surface wetting, the mimicry of the natural texture of animal integuments for realizing specific fluid transport functionalities, the tailoring of surface colonization by bacterial biofilms, and the improve-ment of the tribological performance of nanostructured metal surfaces.
During the past few years significantly increasing research activities in the field of laser-induced periodic surface structures (LIPSS, ripples) have been reported since the generation of LIPSS in a single-step process provides a simple way of surface nanostructuring towards a control of optical, mechanical or chemical surface properties. In this contribution the current research state in this field is reviewed. The formation of LIPSS upon irradiation of metals, semiconductors and dielectrics by multiple linearly polarized Ti:sapphire fs-laser pulses (30-150 fs) is studied experimentally and theoretically. Different types of LIPSS with periods even below 100 nm can be generated. Their dynamics and formation mechanisms are analyzed and identified in ultrafast optical experiments. Complementing theoretical calculations of the laser-induced carrier dynamics address transient changes of the optical properties of the irradiated materials and reveal the importance of surface plasmon polaritons in the early stage of LIPSS formation. Various applications of these nanostructures are outlined.
Laser-induced periodic surface structures (LIPSS, ripples) are a universal phenomenon that can be observed on almost any material after the irradiation by linearly polarized laser beams, particularly when using ultrashort laser pulses with durations in the femtosecond to picosecond range.
During the past few years significantly increasing research activities have been reported in the field of LIPSS, since their generation in a single-step process provides a simple way of nanostructuring and surface functionalization towards the control of optical, mechanical, biological, or chemical surface properties. 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, the advancement of medical pacemakers, and the improvement of the tribological performance of nanostructured metal surfaces.
Chemical effects during the formation of femtosecond laser-induced periodic surface structures
(2019)
The processing of laser-induced periodic surface structures (LIPSS, ripples) on metals and semiconductors in ambient air is usually accompanied by superficial oxidation effects – a fact that is widely neglected in the current literature. In this contribution, chemical, structural, and mechanical alterations in the formation of femtosecond LIPSS are characterized by a variety of surface analytical techniques, including energy dispersive X-ray analyses (EDX), X-ray photoelectron spectroscopy (XPS), micro Raman spectroscopy (µ-RS), and depth-profiling Auger electron microscopy (AEM). Alternative routes of electrochemical and thermal oxidation allow to qualify the relevance of superficial oxidation effects on the tribological performance in oil lubricated reciprocating sliding tribological tests (RSTT). It is revealed that the fs-laser processing of near-wavelength sized LIPSS on metals leads to the formation of a few hundreds of nanometers thick graded oxide layers, consisting mainly of amorphous oxides. Regardless of reduced hardness and limited thickness, this nanostructured surface layer efficiently prevents a direct metal-to-metal contact in the RSTT and may also act as an anchor layer for specific wear-reducing additives contained in the used engine oil.
Laser-induced periodic surface structures: from nanoscaled light localization to applications
(2019)
In this contribution the current state in the field of Laser-Induced Periodic Surface Structures (LIPSS) is reviewed. This includes the mechanisms of formation and current applications, particularly the colorization of technical surfaces, the control of surface wetting properties, the tailoring of surface colonization by bacterial biofilms, and the improvement of the tribological performance of nanostructured metal surfaces.
Laser-induced periodic surface structures (LIPSS, ripples) are a universal phenomenon that can be observed on almost any material after the irradiation by linearly polarized laser beams, particularly when using ultrashort laser pulses with durations in the femtosecond to picosecond range. During the past years significantly increasing industrial and research activities have been reported in the field of LIPSS, since their generation in a single-step process provides a simple way of nanostructuring and surface functionalization towards the control of optical, mechanical, biological, or chemical surface properties. In this contribution the mechanisms of formation and current trends and applications of LIPSS are reviewed, including the colorization of technical surfaces, the control of surface wetting properties, the mimicry of the natural texture of animals, the tailoring of surface colonization by bacterial biofilms, the advancement of leadless medical pacemakers, and the improvement of the tribological performance of nanostructured metal surfaces.