Influence of ambient conditions on the evolution of wettability properties of an IR-, ns-laser textured aluminium alloy

Results of the work in the Laser4Fun project has been published as:

J. T. Cardoso, A. Garcia-Girón, J. M. Romano, D. Huerta-Murillo, R. Jagdheesh, M. Walker, S. S. Dimov and J. L. Ocaña Influence of ambient conditions on the evolution of wettability properties of an IR-, ns-laser textured aluminium alloy. RSC Advances, 63, 2017

Abstract

Micro cell structures of different sizes were patterned using a nanosecond near-infrared laser source on Al2024 aluminium alloy plates with 2 mm thickness. The influence of laser parameters on the shape and size of the produced patterns were studied together with the evolution of wettability properties over time for different storage conditions. Samples were found to be superhydrophobic from a single step laser patterning, requiring no further treatment. Exposure to ambient air was shown to be a key factor in the property changes of the samples over time. The produced surface patterns with different laser parameter settings were correlated with the contact angle measurements, revealing a great influence of the amount of recast material on the hydrophobic properties. X-Ray photoelectron spectroscopy was used to study the impact of surface chemistry changes on hydrophobicity, analysis of elemental composition proved that chemisorbed organic molecules present in the ambient air were responsible for the hydrophilic to superhydrophobic transition.

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Texturing metal surface with MHz ultra-short laser pulses

Results of the work in the Laser4Fun project has been published as:

Fotis Fraggelakis, Girolamo Mincuzzi, John Lopez, Inka Manek-Hönninger, and Rainer Kling. Texturing metal surface with MHz ultra-short laser pulses. Optics Express 25(15), pp. 18131-18139, 2017

Abstract

We show, for the first time to our knowledge, the role the heat accumulation plays on the evolution of ultra-short pulse laser-induced surface structures morphology when varying fluence, the number of scans and the repetition rate from 100 kHz up to 2 MHz. We demonstrate how to tailor the size of micro-spikes from nearly ten microns to several tens of microns by a systematic variation of both fluence and overlap. We believe our results will contribute to an in deep understanding of the mechanisms underlying laser surface structuration at high repetition rates.

Link(s)

Fabrication of multi-scale periodic surface structures on Ti-6Al-4V by direct laser writing and direct laser interference patterning for modified wettability applications

Results of the work in the Laser4Fun project has been published as:

D. Huerta-Murillo, A.I. Aguilar-Morales, S. Alamri, J.T. Cardoso, R. Jagdheesh, A.F. Lasagni and J.L. Ocaña. Fabrication of multi-scale periodic surface structures on Ti-6Al-4V by direct laser writing and direct laser interference patterning for modified wettability applications. Optics and Lasers in Engineering, 98, 2017.

Abstract

In this work, hierarchical surface patterns fabricated on Ti-6Al-4V alloy combining two laser micro-machining techniques are presented. The used technologies are based on nanosecond Direct Laser Writing and picosecond Direct Laser Interference Patterning. Squared shape micro-cells with different hatch distances were produced by Direct Laser Writing with depths values in the micro-scale, forming a well-defined closed packet. Subsequently, cross-like periodic patterns were fabricated by means of Direct Laser Interference Patterning using a two-beam configuration, generating a dual-scale periodic surface structure in both micro- and nano-scale due to the formation of Laser-Induced Periodic Surface Structure after the picosecond process. As a result a triple hierarchical periodic surface structure was generated. The surface morphology of the irradiated area was characterized with scanning electron microscopy and confocal microscopy. Additionally, static contact angle measurements were made to analyze the wettability behavior of the structures, showing a hydrophobic behavior for the hierarchical structures.

Link(s)

Announcement: Summer school 2017

From August 21st to 25th 2017, the Chair of Laser Processing of the University of Twente organizes its 1st international summer school on “Advanced laser processing”.  This event will be venue for the second Laser4Fun summerschool and it aims to give the participants a “full-immersion” experience in the world of laser materials processing.
For the preliminary program, topics, and instructions on how to register, download the PDF leaflet.

University of Twente Summer school 2017 – Leaflet

Vittorio Vercillo, as a Marie Curie Ambassador, at the Open Day of the MSc in Nanotechnology Engineering of the University of Rome Sapienza

Vercillo-openday-20170511During the Open Day of the MSc in Nanotechnology Engineering of the University of Rome Sapienza (Italy) on May 11th, 2017, Vittorio Vercillo, presented as a Marie Curie Ambassador his progress on “Micro-/nano-structuring of surfaces for improved functionalities in aerospace applications” to graduate students. He was invited as an ex-alumnus of the department.

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Development of a General Model for Direct Laser Interference Patterning of Polymers

Results of the work in the Laser4Fun project has been published as:

S. Alamri, A.F. Lasagni (2017): Development of a General Model for Direct Laser Interference Patterning of Polymers, Optics Express, 25, 9, 287359

Abstract

This study investigates the general mechanism of Direct Laser Interference Patterning (DLIP) involved in the structuring process of polymer materials. An empirical model is developed taking into account experimental observations of DLIP-treated pigmented and transparent polycarbonate substrates with UV (263 nm) and IR (1053 nm) laser radiation. Depending on the used laser processing conditions, the type of material as well as the spatial period of the interference pattern, four different structuring mechanisms can be identified. The treated surfaces are investigated using confocal microscopy, scanning electron microscopy and focus ion beam and as a result from the experimental data analysis, the developed model predicts the material surface topography after the patterning process, by means of a set of material-dependent coefficients.

Links

Ultrashort pulse laser-induced texturing of stainless steel at 1 MHz and high average power: impact of process parameters

Results of the work in the Laser4Fun project has been published as:

Fotis Fraggelakis, Girolamo Mincuzzi, John Lopez, Inka Manek-Hönninger, and Rainer Kling. Texturing metal surface with MHz ultra-short laser pulses. Optics Express 25(15), pp. 18131-18139, 2017

Abstract

Exploitation of surface texturing by ultra-short pulse laser (UPL) technology for commercial purposes requires the undertaking of several issues including a reliable and robust set-up compatible with large area and high throughput production. A technological strategy to rise to this challenge could be the use of polygon scanner which can deflect a laser beam with unprecedented speed (up to some hundreds of m/s) over an optical field of some tens of cm, jointly with high average power UPL delivering pulse energies of few tens of micro joule and repetition rates in the range of MHz. Nevertheless, unwanted thermal effects are expected to arise, when utilising average power as high as several tens of Watts, compromising the surface texturing morphology. Here a study is reported on the surface texturing of stainless steel carried out utilising an industrial UPL emitting both in the near infrared (λ = 1030 nm) and visible (λ = 515 nm) with high average power (up to 20 W) and operating at high repetition rate (1 MHz). The impact of the fundamental process parameters like single pulse fluence, beam scan speed, number of successive scans and energy dose has been studied. The evolution of the surface morphology has been investigated using scanning electron microscopy (SEM) analysis. We believe our results will contribute to an in deep understanding of the UPL laser texturing with high power, as preliminary step to increase in the next future surface texturing by UPL technological readiness.

Link(s)

Direct laser interference patterning of transparent and colored polymer substrates: ablation, swelling, and the development of a simulation model

Results of the work in the Laser4Fun project has been published as:

Sabri Alamri and Andrés F. Lasagni (2017) Direct laser interference patterning of transparent and colored polymer substrates: ablation, swelling, and the development of a simulation model. Proc. SPIE 10092, Laser-based Micro- and Nanoprocessing XI, 1009219 (February 17, 2017)

Abstract

It is well known that micro and sub-micrometer periodical structures play a significant role on the properties of a surface. Ranging from friction reduction to the bacterial adhesion control, the modification of the material surface is the key for improving the performance of a device or even creating a completely new function. Among different laser processing techniques, Direct Laser Interference Patterning (DLIP) relies on the local surface modification process induced when two or more beams interfere and produce periodic surface structures. Although the produced features have controllable pitch and geometry, identical experimental conditions applied to different polymers can result on totally different topologies. In this frame, observations from pigmented and transparent polycarbonate treated with ultraviolet (263 nm) and infrared (1053 nm) laser radiation permitted to identify different phenomena related with the optical and chemical properties of the polymers. As a result from the experimental data analysis, a set of material-dependent constants can be obtained and both profile and surface simulations can be retrieved, reproducing the material surface topography after the surface patterning process.

Links

Summer school 2016

The Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS organised and hosted, from August 29 until September 2, 2016, the first Summer school “Short Pulsed Laser Micro/Nanostructuring of Surfaces” for (and by) PhD students of the “Laser4Fun” project, supported by the European Commission (Marie Sklodowska-Curie Actions. This summer school was combined with the “5th International Summer School on Trends and new developments in Laser Technology”, organised by the Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS and the Technical University of Dresden. This one-week International Summer School brought about 40 undergraduate and PhD students together for an intensive programme of study on fundamental and applied aspects of laser technology. The main programme consisted of lectures by renowned experts, supplemented by poster presentations and informal discussion sessions, as well as practices in the laboratory. The course aimed to enable the exchange of new ideas across these fields.

Participants of the Summer school 2016 in Dresden (Germany)
Participants of the Summer school 2016 in Dresden (Germany)