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Open AccessFeature PaperArticle

Fabrication of Zinc Substrate Encapsulated by Fluoropolyurethane and Its Drag-Reduction Enhancement by Chemical Etching

1
School of Materials Science & Engineering, Nanyang Technological University, Singapore 639798, Singapore
2
Department of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, China
3
School of Chemical Engineering, Sichuan University, Chengdu 610065, China
4
Energy Research Institute @ NTU ([email protected]), CleanTech One, Singapore 637141, Singapore
*
Author to whom correspondence should be addressed.
Coatings 2020, 10(4), 377; https://doi.org/10.3390/coatings10040377
Received: 23 March 2020 / Revised: 8 April 2020 / Accepted: 9 April 2020 / Published: 10 April 2020
(This article belongs to the Special Issue Surface Modification of Metals and Alloys)
A fluoropolyurethane-encapsulated process was designed to rapidly fabricate low-flow resistance surfaces on the zinc substrate. For the further enhancement of the drag-reduction effect, Cu2+-assisted chemical etching was introduced during the fabrication process, and its surface morphology, wettability, and flow-resistance properties in a microchannel were also studied. It is indicated that the zinc substrate with a micro-nanoscale roughness obtained by Cu2+-assisted nitric acid etching was superhydrophilic. However, after the etched zinc substrate is encapsulated with fluoropolyurethane, the superhydrophobic wettability can be obtained with a contact angle of 154.8° ± 2.5° and a rolling angle of less than 10°. As this newly fabricated surface was placed into a non-standard design microchannel, it was found that with the increase of Reynolds number, the drag-reduction rate of the superhydrophobic surface remained basically unchanged at 4.0% compared with the original zinc substrate. Furthermore, the prepared superhydrophobic surfaces exhibited outstanding reliability in most liquids. View Full-Text
Keywords: fluoropolyurethane; zinc substrate; Cu2+-assisted etching; superhydrophobic/hydrophilic; drag reduction fluoropolyurethane; zinc substrate; Cu2+-assisted etching; superhydrophobic/hydrophilic; drag reduction
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MDPI and ACS Style

Li, Y.; Cui, Z.; Zhu, Q.; Narasimalu, S.; Dong, Z. Fabrication of Zinc Substrate Encapsulated by Fluoropolyurethane and Its Drag-Reduction Enhancement by Chemical Etching. Coatings 2020, 10, 377.

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