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Descripción
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| UV nanosecond pulsed direct laser writing (DLW) has been employed on a high strength titanium alloy (Ti-6Al-4V) in order to create periodic square micro-pillars. IR femtosecond pulsed direct laser writing (DLW) was used to generate low spatial frequency LIPSS on top of the nanosecond patterned structure to create a dual-scale structure. Two storage conditions, air and polyethylene bags, were used for keeping the samples after the laser process to evaluate the aging process of the samples. After one month of storage, nanosecond processed samples kept in the polyethylene bag showed a clear shift away from hydrophilic behavior and achieving a hydrophobic effect, reaching values over 150°. Hierarchical structures became hydrophobic and recorded a SCA value over 150°. For the dual-scale hierarchical structures, SCA values showed an increase against the non-hierarchical structures, either kept on air or polyethylene bags, demonstrating that a hierarchical roughness is more prone to achieve a better hydrophobic state. Nevertheless, the hierarchical surfaces kept in polyethylene bags showed a higher SCA, over 160°, in comparison with the hierarchical surfaces kept on air which showed a SCA around 120°. The XPS data show that, after 1 month of storage in a polyethylene bag, the contribution of the different polar carbon molecules are almost negligible to the total chemistry composition of the surface, with the non-polar carbon molecules (C-C and C-H) the principal contributors. The XPS results suggest that the observed change in wettability can be attributed to a certain extend to the absences of carbon polar compounds, as well as H2O molecules, as they were not detected on the sample with the highest SCA. | |
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Internacional
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Si |
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Nombre congreso
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International School on Laser Micro/Nanostructuring and Surface Tribology |
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Entidad organizadora
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CNR Institute for Photonics and Nanotechnologies of Bari |
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Nacionalidad Entidad
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ITALIA |
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Lugar/Ciudad de impartición
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Bari, Italia |
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Fecha inicio
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01/10/2018 |
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Fecha fin
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05/10/2018 |