Non-Uniform Laser Surface Texturing of an Un-Tapered Square Pad for Tribological Applications

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

Antonio Ancona, Gagandeep Singh Joshi, Annalisa Volpe, Michele Scaraggi, Pietro Mario Lugarà and Giuseppe Carbone. Non-Uniform Laser Surface Texturing of an Un-Tapered Square Pad for Tribological Applications. Lubricants 2017, 5, 41.

Abstract

Femtosecond laser surface micro-texturing has emerged as a promising technology to enhance the tribological properties of different kinds of lectromechanical devices. In this research paper, we have exploited the intrinsic flexibility and micrometric accuracy of femtosecond laser ablation to realize complex micro-structural modifications on the surface of a laboratory prototype of a steel thrust bearing (un-tapered) pad. The Bruggeman Texture Hydrodynamics theory (BTH) is employed for the design of the anisotropic and non-uniform texture maximizing the thrust load of the pad prototype. The preliminary experimental results, reported in this work, show that the non-uniform micro-texture largely affects the friction characteristics of the contact. In particular, in agreement with the BTH predictions, the tribo-system shows friction properties that are strongly
sensitive to the direction of the sliding speed, as a consequence of the micro-fluid dynamics which are designed to occur only in a specific sliding direction. We suggest that the joint action of virtual prototyping (BTH lubrication theory) and ultrafast laser micro-prototyping can lead to unconventional and impressive results in terms of enhanced or tailored contact mechanics properties of the generic lubricated tribopair.

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Micro-fabrication of high aspect ratio periodic structures on stainless steel by picosecond direct laser interference patterning

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

Alfredo I. Aguilar-Morales, Sabri Alamri, Andrés Fabián Lasagni. Micro-fabrication of high aspect ratio periodic structures on stainless steel by picosecond direct laser interference patterning. Journal of Materials Processing Technology. Volume 252, February 2018, Pages 313-321.

Abstract

We have studied the fabrication of line-like and pillar-like periodic microstructures on stainless steel by means of direct laser interference patterning. A picosecond (10 ps) pulsed Nd:YAG laser operating at 1064 nm wavelength was used to produce the microstructures with spatial periods ranging from 2.6 μm to 5.2 μm. By varying the laser parameters (laser fluence, pulse-to-pulse overlap) structure depths ranging from 500 nm to nearly 11.5 μm could be obtained. Furthermore, low and high frequency laser induced periodic surface structures (LIPSS) have been generated, resulting in three-level multi-scaled patterns. The orientation of the laser induced periodic structures with respect to the interference patterns could be adjusted by controlling the laser beam polarization. Finally, static water contact angle measurements are performed to investigate its correlation with the surface morphology. The treated surfaces are characterized using confocal and scanning electron microscopy.

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ESRs and supervisors at EUROMAT2017 conference

EUROMAT is the premier international congress in the field of materials in Europe, and is organised by the the Federation of European Materials Societies (FEMS). The EUROMAT2017 congress was held in Thessaloniki, Greece, from 17 – 22 September, 2017.

Prof. Andrés-Fabián Lasagni and prof. Gert-willem Römer, both supervisors in the Laser4Fun project, co-organized with prof. Rob Eason (University of
Southampton, UK) and prof. Ioanna Zergioti (National Technical University of Athens, Greece) a Symposium on “Laser-based processing and manufacturing” at this conference. At this symposium, some results of the Laser4Fun project were presented by prof. Antonio Ancona, Tobias Stark and Alfredo Aguilar.

EUROMAT2017-C2-xs

EUROMAT2017-Laser4Fun-xs

Vacancy: Early Stage Researcher (ESR) position

One Early Stage Researcher (ESR) position is available from September 2017 to work in the framework of the Laser4Fun project. This job opening covers research position in the frame of a PhD doctoral programme, aiming at a PhD degree awarded by the University of Zaragoza (Spain). The ESRs will undertake research focused on the characterization of antibiofilm properties in samples provided by other partners in the consortium of the project. For more information, consult the vacancies page of this website.

Summer School on Advanced Laser Processing 2017

Participants in the 2nd Laser4Fun Summer school
Participants in the 2nd Laser4Fun Summer school

In total 22 persons attended and contributed to the 1st international Summer School & 2nd Laser4Fun Summer School on Advanced Laser Processing. From August 21st to 25th, the participants were “fully-immersed” into the world of advanced laser materials processing. Lectures and presentations by academic experts, specialists from industry, as well as of the participants alternated, with ample time for discussions. The summer school also included practical exercises and workshops in state-of-the-art laser-laboratories.

Topics included, but were not limited to:

  • Fundamentals of laser-material interaction
  • Pulsed laser surface ablation
  • Pulsed laser processing of bulk materials
  • Laser-induced Periodic Surface Structures (LIPSS)
  • Micro/nano structuring
  • New trends in laser processing
  • Laser cladding
  • Laser-induced Forward Transfer (LIFT)
  • Applications of laser processing
  • Training on generic research relevant skills

The Summer School was organised and hosted by the Chair of Laser Processing at the University of Twente in the Netherlands.

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.

Link(s)

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)