Controlling the stainless steel surface wettability by nanosecond direct laser texturing at high fluences

• Published in: Applied physics. A, Materials science & processing Materials science & processing, 2017-12, Vol.123 (12), p.1-8, Article 766
• Main Authors: Gregorčič, P., Šetina-Batič, B., Hočevar, M.
• Format: Article
• Language: English
• Subjects: Applied physics; Characterization and Evaluation of Materials; Condensed Matter Physics; Contact angle; Electron backscatter diffraction; Electron microscopy; Hydrophobic surfaces; Laser beam texturing; Machines; Manufacturing; Materials science; Morphology; Nanotechnology; Optical and Electronic Materials; Physics; Physics and Astronomy; Processes; Pulse duration; Scanning electron microscopy; Semiconductor lasers; Stainless steel; Stainless steels; Surfaces and Interfaces; Thin Films; Wettability; YAG lasers
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-017-1392-5

This work investigates the influence of the direct laser texturing at high fluences (DLT-HF) on surface morphology, chemistry, and wettability. We use a Nd:YAG laser ( λ = 1064 nm) with pulse duration of 95 ns to process stainless steel surface. The surface morphology and chemistry after the texturing is examined by using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD), while the surface wettability is evaluated by measuring the static contact angle. Immediately after the texturing, the surface is superhydrophilic in a saturated Wenzel regime. However, this state is not stable and the superhydrophilic-to-superhydrophobic transition happens if the sample is kept in atmospheric air for 30 days. After this period, the laser-textured stainless steel surface expresses lotus-leaf-like behavior. By using a high-speed camera at 10,000 fps, we measured that the water droplet completely rebound from this superhydrophobic surface after the contact time of 12 ms.