ORAL

SESSION: AdvancedMaterialsThuAM-R10	Marquis International Symposium on New and Advanced Materials and Technologies for Energy, Environment and Sustainable Development(3rd Intl Symp. on New and Advanced Materials and Technologies for Energy, Environment and Sustainable Development)
Thu Oct, 26 2017	Room: Maria Mercedes & Maria Beatriz
Session Chairs: Rui Vilar; Hideki Koyanaka; Session Monitor: TBA

11:00: [AdvancedMaterialsThuAM01] Keynote
Ultrafast Laser Surface Nanostructuring: Surface Topography, Texture Formation Mechanisms, Surface Properties and engineering applications
Vitor Oliveira¹ ; Rui Vilar² ; ¹Instituto Superior de Engenharia de Lisboa, Lisbon, Portugal; ²Instituto Superior Tecnico, Lisboa, Portugal;
Paper Id: 104 [Abstract]

Ultrafast lasers allow creating a range of nanoscale surface features that allow controlling important surface properties such as wetting and the friction coefficient. The most important of these surface nanostructures in what concerns potential applications are Laser-induced Periodic Surface Structures (LIPSS), which are surface patterns consisting of parallel ripples oriented perpendicularly to the beam polarization that are produced on materials surfaces by laser treatment with fluences slightly higher than the material ablation threshold and for a few tens of laser pulses. Their period is slightly smaller than the radiation wavelength, typically 500-800 nm for near infrared lasers. The formation of these ripples is usually explained by a periodic modulation of the absorbed radiation intensity due to the interference of the incident laser beam with a surface electromagnetic wave generated by the laser radiation on irregularities of the material's surface, but the mechanisms that the lead to the imprinting of this modulation on the surface were scarcely investigated. In the presentation we will describe results of a study of the mechanisms leading to the imprinting of LIPSS on Ni and Ti surfaces of Ni/Ti multi-layered samples prepared by magnetron sputtering and irradiated with ultrafast laser pulses. The analysis of the multilayer cross-sections by TEM and comparison with molecular dynamics Ni ablation simulations carried out by Zhigilei and co-workers show that, in these metals, the periodic variation of the absorbed radiation intensity leads to a variation of the predominant ablation mechanisms and, consequently, of the ablation rate, thus explaining the rippled surface topography. The influence of these nanostructures on the wettability of Ti and Ti-6Al-4V surfaces and on their ability to affect mesenchymal cells behavior in order to improve osseointegration will be presented as well. Other properties of these surfaces and their potential applications will be discussed.