Abstract
Bio-inspired superhydrophobic coatings have been demonstrated to be promising anticorrosion materials. However, developing robust superhydrophobic coatings through simple one-step fluorine-free procedures to meet various functional requirements remains a major challenge. In this study, we fabricated an eco-friendly superhydrophobic Al2O3@PDMS composite coating with mechanical robustness based on Al2O3 NPs, PDMS, and spray coating technique. To characterize surface morphologies, chemical compositions, surface wettability, and anticorrosion properties, FE-SEM, EDS, XPS, contact angle meter, electrochemical impendence spectroscopy, and potentiodynamic polarization techniques were employed. The electrochemical results show that |Z|0.01 Hz and Rct values of the superhydrophobic Al2O3@PDMS coating were four orders of magnitude higher than bare Q235 carbon steel, indicating a significant improvement in corrosion resistance. Furthermore, the deliquescence behaviors of NaCl salt particles and the instantaneous self-coalescence phenomenon were recorded under high atmospheric humidity to suggest that a superhydrophobic surface with Cassie–Baxter interfacial contacts can serve as an efficient barrier to suppress the formation of saline liquid thin films and protect the underlying substrate from corrosion. This robust superhydrophobic Al2O3@PDMS coating is expected to be easily applied to a variety of substrates and to find potential applications for liquid repellency, self-cleaning, corrosion resistance, and other properties.
Highlights
Carbon steels are widely used for structural applications in industrial and engineering constructions because of their high specific strength, weldability, machinability, and low cost (Oguzie et al, 2010; Zhang S. et al, 2020; Tan et al, 2020)
The results show that this substrate-independent superhydrophobic Al2O3@PDMS composite coating exhibits superior adaptability and corrosion suppression performance
The self-coalescence–induced salt deliquescence behavior of the as-fabricated superhydrophobic Al2O3@PDMS coating demonstrates that the Cassie–Baxter interfacial phase contacts of the superhydrophobic surface can serve as an efficient barrier to suppress the formation of thin saline liquid electrolyte film and protect the underlying substrate from being corroded under the atmospheric service environments with high relative humidity
Summary
Carbon steels are widely used for structural applications in industrial and engineering constructions because of their high specific strength, weldability, machinability, and low cost (Oguzie et al, 2010; Zhang S. et al, 2020; Tan et al, 2020). Despite significant advances in scientific community, many limitations remain in large-scale fabrication and widespread practical applications, such as strict experimental conditions, complicated preparation procedures, and fluorine-containing toxic compounds (Anitha et al, 2018; Wang and Zhang, 2020) Given these concerns, it is significant to design and develop facile one-step, low cost, and fluorine-free eco-friendly superhydrophobic coatings for efficient anticorrosion applications. The electrochemical impendence spectroscopy (EIS) and the potentiodynamic polarization of bare Q235 carbon steel and superhydrophobic Al2O3@PDMS composite coating were measured in 3.5 wt.% NaCl aqueous solution under open circuit potential with an amplitude of 10 mV. The mechanical robustness of the fabricated superhydrophobic Al2O3@PDMS composite coating was assessed using the tape-peeling test and sandpaper abrasion tests. After various tape-peeling and sandpaper abrasion cycles, the water contact angles and sliding angels of the samples were measured using a contact angle meter
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