Analysis of the fs-laser treatment influence on the bio-fouling properties of the stainless steel surfaceThursday (25.06.2020) 15:40 - 16:00 Room 3
Recent digital flow metering technologies employ ultrasound methods for precise gauging of liquid flow. Stainless steel mirrors that reflect the ultrasound waves ensure corrosion resistance but the permanent contact with domestic water with a high mineral content leads to biofouling which inevitably changes the performance of such smart devices. Laser induced periodic surface structures can modify the surface free energy and thus can be utilized to tailor its wettability . On top of that, it can be additionally controlled by employing hydrophobic amorphous diamond like carbon (a-C:H) films , which could also aid to preserve the nanostructure under constant water flow. Surface free energy (contact angle with water) of SiOx doped a-C:H films is reported to be in relatively wide range depending on the deposition conditions as well as chemical composition of the synthesized film. By combining nano-scale surface roughening with a hydrophobic a-C:H:Si:O coating, the super-hydrophobic surface with a wetting angle around 160° was fabricated .
In this work, the fundamental harmonic (λ=1030 nm) of a linearly polarized Yb:KGW femtosecond laser (Pharos, Light Conversion) beam was scanned over the surface of a stainless steel mirror with a XY galvoscanner (ScanCube 14, ScanLab) and a F-Theta lens of a 100 mm focal length while varying the pulse energy and the laser spot overlap. The laser treatment conditions that ensure a contact angle of 129° for water close to the ablation threshold were obtained. Amorphous DLC films were deposited on virgin and laser treated stainless steel surfaces by employing the direct ion beam synthesis from a hexamethyldisiloxane precursor. The films increased the water contact angle of pristine stainless steel surface by 40° while in the case of laser treated surface it remained constant. The anti-biofouling properties of laser treated and DLC coated surfaces were investigated in a custom-built setup that simulates tap water flow in a domestic system.
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