Month: October 2017

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

Alamri20170217

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.

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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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