LIPSS for metallic surface functionalization: the role of process parameters on surface chemical modificationsWednesday (24.06.2020) 14:50 - 15:10 Room 2
Industrial markets (e.g. automotive, aerospace, biomedical or tooling) need to produce high added-value products through the improvement of the material surface properties. The use of laser technologies allows surface texturing in the micro/nanometer scale, enabling the creation of tailored functional properties such as wetting, hydrophobicity, tribological characteristics of surfaces, reflectivity, aesthetics or even anti-bacterial properties. In this context, surface functionalization with ultrashort pulses via Laser Induced Surface Periodic Structures (LIPSS) has emerged as a good candidate for metal industrial applications. Laser systems in the range of ultra-short pulses (≤ 10-12 sec.) offers a set of advantages for the functionalisation of metallic surfaces via LIPSS: high resolution features (in the range of 150-800 nm) can be defined in precise locations of the component, no addition of extra materials or coatings are necessary and are especially suited for mass customisation.
In the last decades, numerous and intensive studies have been focused on the interaction between ultrashort laser pulses and solid surfaces to create micro- and nanostructures in metals to change their surface properties. In particular, Laser Induced Periodic Surface Structures (LIPSS) have been widely explored to produce surface corrugations for this purpose. Apart from the aforementioned topographical micro- and/or nano-modifications, most of the available studies report a laser induced modification of the material composition, together with an associated effect on the surface functionalities -either by increasing the wettability or by improving cell adhesion among others-. However, little efforts have been made in order to establish a correlation between the laser processing conditions and the resulting chemical modifications in the ultrashort pulse regime. In this work, we present an EDX and XRD analysis of the oxide formation on Ti6Al4V, Stainless Steel and Copper surfaces as a function of the laser irradiation parameters. Two different regimes were found: Low Spatial Frequency LIPSS with no oxide formation for low accumulated fluences and High Spatial Frequency LIPSS with an increasing oxygen content for higher accumulated fluences. The effect of the repetition rate of the laser source on the oxidation process is also reported.
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