Combined surface hardening and laser patterning approach for functionalising stainless steel surfaces

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

A.Garcia-Giron, J.M.Romano, Y.Liang, B.Dashtbozorg, H.Dong, P.Penchev, S.S.Dimov (2018) Combined surface hardening and laser patterning approach for functionalising stainless steel surfaces. Applied Surface Science, Volume 439, 1 May 2018, Pages 516-524.

Abstract

The paper reports a laser patterning method for producing surfaces with dual scale topographies on ferritic stainless steel plates that are hardened by low temperature plasma surface alloying. Nitrogen and carbon based gasses were used in the alloying process to obtain surface layers with an increased hardness from 172 HV to 1001 HV and 305 HV, respectively. Then, a nanosecond infrared laser was used to pattern the plasma treated surfaces and thus to obtain super-hydrophobicity, by creating cell- or channel-like surface structures. The combined surface hardening and laser patterning approach allowed super-hydrophobic surfaces to be produced on both nitrided and carburised stainless steel plates with effective contact angles higher than 150°. The hardened layers on nitrided samples had cracks and was delaminated after the laser patterning while on plasma carburised samples remained intact. The results showed that by applying the proposed combined approach it is possible to retain the higher hardness of the nitrided stainless steel plates and at the same time to functionalise them to obtain super-hydrophobic properties.

Link(s)

Controlling the wettability of polycarbonate substrates by producing hierarchical structures using Direct Laser Interference Patterning

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

Sabri Alamri, Alfredo I. Aguilar-Morales, Andrés F. Lasagni (2018) Controlling the wettability of polycarbonate substrates by producing hierarchical structures using Direct Laser Interference Patterning. European Polymer Journal. Volume 99, February 2018, Pages 27–37.

Abstract

New strategies for the fabrication of surface structures using Direct Laser Interference Patterning are presented in this work, aiming to fabricate hierarchical structures with selective wetting properties. Polycarbonate sheets have been structured employing a two-beam interference arrangement using an ultraviolet (263 nm) nanosecond-pulsed laser, creating line- and pillar-like structures with simple and hierarchical geometries. Two different methods for producing hierarchical structures are here provided, both relying on a pixel-wise structuring technique and able to achieve high structure depths. The produced surface patterns are characterized by confocal microscopy, scanning electron microscopy and the influence of the surface topography on the water contact angle is investigated. The correlation between structure geometry and wettability response, in terms of structure height and directionality of the droplet shape is reported.

Link(s)

The Laser4Fun Project is sponsoring the DIWOK classroom

DIWOKAs part of the outreach of the Laser4Fun project to the general public, the “DIWOK classroom” is sponsored. This “classroom” is a workshop where youngsters among 13 and 18 years old have the chance to work with new technologies, scientific background and shared knowledge. DIWOK is short for  “Do It With Others”. In fact, the first activity has been launched on “Laser cutting techniques”. The DIWOK classroom, which will open every Wednesday.

This workshop takes place in the Etopia Center for Art & Technology (www.etopia.es), where also the Mid-Term Review of Laser4Fun took place on 26th October 2017. Etopia is a project by Zaragoza City Council and Zaragoza City of Knowledge Foundation, with support from the Spanish Ministry of Industry, Energy and Tourism. It has been conceived as a global centre for creativity, innovation and entrepreneurship in the digital city. In fact, all the Laser4Fun ESR have been allocated here, during the Mid-Term review, so they could profit from networking and team building.

More information: http://www.etopiakids.es/noticias/nace-aula-diwok-espacio-trabajo-colaborativo-chavales-chavalas-13-18-anos-38.html

 

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

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The paper

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)

with results of the work in the Laser4Fun project, was presented by Sabri Alamri at the SPIE Photonics West conference in the USA. A video of the presentation is available at https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10092/1/Direct-laser-interference-patterning-of-transparent-and-colored-polymer-substrates/10.1117/12.2251740.full?SSO=1

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.

Link(s)

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.

Link(s)

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.

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