International. Cassie's low interfacial adhesion strength, low surface energy, and air-cushion-induced multiphase contacts contribute to the remarkable anti-corrosion and anti-wetting ability of saline droplets.
The research team led by Professors Hou Baorong and Duan Jizhou of the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS) has reported a robust superhydrophobic mechanical coating ZnO@STA@PDMS with fluorine-free reagents through a wide application and substrate-independent spray coating method.
Lotus-inspired superhydrophobicity attracts the interest of researchers due to its unique multiphase contact properties and non-interfacial moisturizers. However, fragile hierarchical structures, the use of fluorine-containing chemicals, and strict requirements for substrate scopes remain thorny challenges.
Therefore, achieving water-repellent superhydrophobic coatings, with improved mechanical robustness using fluorine-free chemical reagents and substrate-independent processes, is crucial and urgent for real applications of superhydrophobic materials.
The porous microscale hierarchical rough structure, nanoscale particles and extremely low surface energy of the ZnO@STA@PDMS coating contribute to the eventual water-repellent superhydrophobicity.
The value | Z|10mHz of the manufactured superhydrophobic coating is 3.7 × 105 Ω·cm2, which is three orders of magnitude larger than Q235 carbon steel (7.3 × 102 Ω·cm2).
Substrate Icorr decreases two orders of magnitude after spray coating with a ZnO@STA@PDMS superhydrophobic coating, suggesting superior corrosion resistance performance.
In addition, the prepared superhydrophobic coating can withstand more than 30 tape peeling cycles and an abrasion distance of 400 cm, demonstrating good mechanical stability.
Likewise, in simulated marine atmospheric conditions with high relative humidity, the hygroscopic behaviors and deliquescence of NaCl salt particles were first recorded and showed an interesting phenomenon of instantaneous autocoalescence.
"This phenomenon provides a new type of anti-corrosion mechanism for superhydrophobic materials served in a marine atmospheric environment with high relative humidity, and guides future research in this field," said Associate Professor ZHANG Binbin, first author and corresponding author.
Corrosion damage to the edge of the saline drop in bare Q235 carbon steel is more severe than inside due to faster ion transfer and oxygen abundance. While the superhydrophobic coating possesses promising atmospheric corrosion inhibition performance based on salt deliquescence and instantaneous autocoalescence phenomenon.
