Formation and Properties of Superhydrophobic Al Coatings on Steel

Abstract

Thermal sprayed aluminum coatings are widely scalable to corrosion protection of the offshore steel structure. However, the corrosion rate of the Al coating increases considerably due to the severe marine environment. It has remained a challenge to improve the corrosion resistance and protective ability of Al coatings. The superhydrophobic surface provides a potential way to improve the corrosion resistance of metal materials. Hence, the development of superhydrophobic Al coatings with superior corrosion resistance is of great interest. In this work, the feasibility of the preparation of superhydrophobic Al coatings on a steel substrate was explored. First, Al coatings were prepared onto the steel substrate by the arc-spraying process, followed by ultrasonic etching with 0.1 M NaOH solution, and afterward passivated using 1% fluorosilanes. The effects of the etching time on morphology, contact angle, and corrosion resistance of the Al coatings were evaluated. The schematic model of the fluorosilane passivation process on the Al coating surface was provided. The micro/nanoscale surface structure of the low-surface-energy fluorosilanes promotes the wetting angle of 153.4°and a rolling angle to 6.6°, denoting the superhydrophobic properties. The superhydrophobic Al coating surface displays excellent self-cleaning performance due to its weak adhesion to water droplets. The corrosion current density of the superhydrophobic Al coating (1.36 × 10 −8 A cm −2 ) is 2 orders of magnitude lower than that of the as-sprayed Al coating (1.18 × 10 −6 A cm −2 ). Similarly, the charge-transfer resistance is found to be 12 times larger for the superhydrophobic Al coating and the corresponding corrosion inhibition efficiency reaches 98.9%. The superhydrophobic Al coating displays superior corrosion resistance and promising applications in a marine corrosion environment.

Superhydrophobic Materials: Versatility and Translational Applications

“…prepared superhydrophobic Al coatings by combining arc‐spraying, ultrasonic etching, and fluorosilane modification. [ 69 ] Compared to the thermal sprayed Al coatings (1.18 × 10 −6 A cm −2 ), the I corr (1.36 × 10 −8 A cm −2 ) is 2 orders of magnitude lower, which highlights the good corrosion resistance. Superhydrophobic surfaces with high anti‐fouling efficiency are also produced by either simply coating a composite of a silicone matrix and ZnO nanorods, [ 70 ] or by combining sandblasting, autoclaving, and low surface energy substrate modification.…”

Superior Corrosion and UV-Resistant Highly Porous Poly(vinylidene fluoride-co-hexafluoropropylene)/alumina Superhydrophobic Coating

“…Superhydrophobic coatings (SHCs) have been used to isolate and protect metal surfaces from wet aggressive media. If the water contact with the metal surface can be minimized and controlled, corrosion resistance could significantly improve . Interaction of water with metal surfaces could be minimized by reducing the surface energy using suitable material with low surface energy.…”

“…If the water contact with the metal surface can be minimized and controlled, corrosion resistance could significantly improve. 2 Interaction of water with metal surfaces could be minimized by reducing the surface energy using suitable material with low surface energy. Accordingly, such coatings can increase the hydrophobicity of the metal surfaces with a water contact angle (WCA) of more than 150°.…”

An Ultra Facile Debonding Method to Develop a Superhydrophobic Surface Based on a Polymer Composite Film

“…Artificial nanomorphology surface also faced challenges in heat stability, chemical stability, corrosion protection and low thermal conductivity, and it was more suitable to achieve superhydrophobicity for rigid, thick, and metallic materials. [10][11][12] When it came to flexible and thin material, especially for polymer films whose thickness were less than 100 μm, relative research work had less reported. As for modifying free energy strategy, materials employed for chemical modification such as fluorochemicals owned an intrinsically low surface energy characteristic due to nonpolar chemistries, and closely packed, stable atomic structures can exhibit water repellency.…”