Conference Agenda

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Program for LiM 2021
Micro: Surface Functionalization 3
Wednesday, 23/June/2021:
1:30pm - 2:30pm

Session Chair: Dr. Stephan Roth, Bayerisches Laserzentrum GmbH (blz), Germany
Location: Room 4
ICM 1st Floor 433

1:30pm - 1:45pm

Enhanced forming behavior of conditioning lines by inserted microstructures for the production of 3D waveguides

Alexander Wienke1, Mohd Khairulamzari Hamjah2, Gerd-Albert Hoffmann1, Jürgen Koch1, Peter Jäschke1, Jörg Franke2, Ludger Overmeyer1, Stefan Kaierle1

1Laser Zentrum Hannover e.V., Germany; 2Institute for Factory Automation and Production Systems, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany

In today's increasingly connected world, more and more data is being produced and processed. To meet these challenges, the OPTAVER research group is conducting research on an innovative manufacturing process for 3D waveguides. In this process, so-called conditioning lines are first applied to a PMMA substrate by means of flexographic printing. Between those the waveguide is applied by aerosol-jet in a subsequent process. If the degree of forming is too high, the conditioning lines crack and become unusable, since material accumulation of the waveguide material leads to strong scattering and high attenuation of the waveguides. By inserting microstructures in the flexographic printing form at points where a high degree of forming is to be expected, material voids occur in the printing. These act as a predetermined breaking point, leaving the critical areas of the conditioning line untouched. This can significantly increase the 3D capability, as demonstrated in forming tests.

1:45pm - 2:00pm

Femtosecond laser structuring of nodular cast iron for anti-corrosion and thermally stable superhydrophobic surface

Dhiraj Kumar, Gerhard Liedl

Institute of Production Engineering and Photonics Technologies, TU Wien, Austria

The superhydrophobic surface has many applications, such as anti-corrosion, anti-icing, and self-cleaning. In this paper, we describe superhydrophobic surfaces on nodular cast iron produced by femtosecond laser pulses. A rapid transformation of surface characteristics from hydrophilic to superhydrophobic has been achieved after placing the samples in a high vacuum chamber for 10 hours, indicating a significant reduction in the storage time required to develop hydrophobic properties. Thermal stability has been assessed after heating the samples at different temperatures for an hour in a furnace. Consequently, the static contact angle has been measured after cooling at room temperature. Samples irradiated at 0.63 J/cm2 and 3.18 J/cm2 with hatch distance of 20 µm show stable superhydrophobic characteristics up to 180°C. Corrosion tests have also been carried out on untreated and lasertreated samples at room condition in a 3.5% NaCl solution. Results indicate that a superhydrophobic surface has better resistance toward corrosion.

2:00pm - 2:15pm

Structural coloration and wettability control of stainless steel by a DLIP process

Tamara Delgado, Clovis Alleaume, Sara M. Vidal, Francisco J. Gontad, Félix Ares, Pablo Romero, Nerea Otero

AIMEN - Laser Centre, Spain

We present the use of a Direct Laser Interference Patterning (DLIP) process to modify both optical and wettability properties of stainless steel. A picosecond (30 ps) pulsed Ytterbium fiber laser operating at its fundamental wavelength (1030 nm) was combined with a DLIP setup based on the use of a Michelson interferometer. A line-like pattern with a 6 µm spatial period and a good intensity contrast was produced by the interference of two beams. Thus, line-like periodic microstructures were engraved on the surface of stainless steel samples by a laser surface texturing process. Through the modification of the surface topography, both structural coloration and wettability control were achieved.

2:15pm - 2:30pm

Superhydrophobic surfaces using ultra-short pulse structuring of thin metal layers

Fabian Schäfer, Simon Ruck, Max-Jonathan Kleefoot, Wadim Schulz, Florian Köhn, Joachim Albrecht, Harald Riegel

Aalen University, Germany

Fabrication of superhydrophobic surfaces induced by ultra short pulse lasers is a hotspot of surface studies. We report a way of generating superhydrophobic surfaces on stainles steel (304S15). The method for fabricating this water-repellant surfaces is to microstructure by irridating with ultra short pulses. Contact angle measurements were used to investigate the wettability of the surface in relation to the laser parameters (laser fluence and scan line separation). The steady conctact angle was investigated in the range of 140°.

Investigations with optical measuring methods (white light interferometer, light microscope) could be confirmed by scanning electron images. The generated surface shows hierarchical structures with nano and micro roughness similar to a lotus leaf. In further experiments, different materials shall be sputtered to obtain a thin stainless steel surface. Subsequent laser structuring should produce a functional surface with water repellent properties