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R Fürbacher, G. Liedl:
"Investigations on the wetting and deicing behavior of laser treated hydrophobic steel surfaces";
Keynote Lecture: Laser-based Micro- and Nanoprocessing, online only (invited); 2021-03-05; in: "Proceedings SPIE", SPIE, 11674 (2021), Paper ID 1167417, 10 pages.

Biomimetic technical surfaces are very interesting for a wide field of possible applications in material science and engineering. For example, changing the wetting and deicing properties of components used in cold environmental conditions can help to reduce ice or snow aggregation, and thereby improve functionality and operational stability. In this study we investigate the correlation between wetting and deicing behavior of micro- and nanostructured stainless steel samples (1.4301). The samples were modified using a Ti:Sapphire femtosecond laser system with 800 nm central wavelength, a pulse duration of 30 fs and a repetition rate of 1 kHz. We generated two fundamentally different types of hydrophobic and superhydrophobic structures by varying the laser fluence and the number of applied pulses, thereby creating hierarchical structures in the micrometer regime and laser induced periodic surface structures (LIPSS) in the nanometer regime. The static water contact angle has been measured to quantify wetting properties of laser treated samples. To determine the ice adhesion shear stresses at the ice/steel-interface, cuvette encased ice columns were frozen onto the structured samples and sheared off by a push rod, while recording the forces. Several icing/deicing cycles have been carried out to investigate a possible decline in wetting behavior due to wear or other mechanisms. We could show, that surfaces with hierarchical microstructures and superhydrophobic wetting behavior will lose its ability to repel the applied water while freezing. Larger structures with higher surface roughness lead to increased ice adhesion shear stresses compared to the initial unstructured surface. LIPSS on the other hand might be not as hydrophobic, but showed lower ice adhesion in the range of the reference sample.

Surface modification, laser structuring, laser induced periodic surface structures (LIPSS), icephobic, hydrophobic, ice adhesion, deicing

http://dx.doi.org/10.1117/12.2578138

Project Head Gerhard Liedl:
NICE