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This work presented a novel method for fabricating corrosion-resistant and fluorine-free superhydrophobic Al2O3/nickel hydroxide (NiOxHy)/stearic acid (STA) composite coating on the Al alloys. The Al2O3/NiOxHy composite film with an ideal micro-nanostructure was assembled on Al alloys by a one-step anodizing method. This facile and low-cost technique for fabricating superhydrophobic coating includes high-temperature anodizing in oxalic acid aqueous solution with Ni2+ and subsequent spin coating of the STA layer. The superhydrophobicity of as-fabricated film results from the hierarchical micro-nanostructure of Al2O3/NiOxHy and the coverage of STA with low surface energy, while the micro-nanostructure is beneficial to providing the appropriate roughness and maintaining more STA in its interstices and surface. The Al alloys with an optimal superhydrophobic coating displayed a static water contact angle of 164°, excellent self-cleaning ability, and superb corrosion-resistant efficiency of 99.6%. This facile method offers an effective strategy to fabricate corrosion-resistant protective coating on metallic substrates, which can significantly prolong the working lifetime of metallic materials in harsh environments. [ABSTRACT FROM AUTHOR]

Superhydrophobic coatings, known for their water‐repelling properties, play an important role in corrosion resistance and self‐cleaning applications. This study addresses the pressing need for eco‐friendly and durable fabrication methods for metal surfaces, particularly Al alloys, recognized for their inherent low mechanical properties. The innovative electroplating technique successfully fabricates superhydrophobic coatings on Al alloy surfaces, incorporating a high‐hardness Ni–Cr alloys layer and a low‐surface‐energy stearic acid layer. The resulting coatings exhibit outstanding mechanical durability, corrosion resistance, and self‐cleaning capabilities. With a water contact angle of 165° and a corrosion protection efficiency of 98.6%, these coatings offer a substantial improvement over traditional methods. Moreover, the Leeb hardness of the coated alloy experiences an impressive 83% increase compared to pristine Al alloy. This universally applicable approach opens avenues for developing mechanically robust superhydrophobic coatings on various metallic substrates, with broad implications for engineering applications. [ABSTRACT FROM AUTHOR]

This work presents a facile method to fabricate high‐white and robust superhydrophobic film on Al alloy surface. Ni/Al2O3 film with appropriate roughness and high‐white surface is constructed on the Al alloy by a simple chemical bath method via placing the Al alloy into the Ni2+ aqueous solution. Then the surface energy is reduced by spin‐coating the stearic acid (STA) to achieve excellent superhydrophobicity. As expected, the reflectivity, self‐cleaning, corrosion resistivity, and mechanical durability of Al alloy after modification have all displayed dramatic enhancements. The reflectance of the modified Al alloy is far above the pristine Al alloy at all wavelengths (200–2,000 nm). This high‐white film with remarkable reflectivity can effectively reduce its surface temperature and improve visibility in practical applications. Finally, a champion water contact angle of 161° and corrosion resistivity of 97.6% are attained by coating Ni/Al2O3‐STA composite film on Al alloy. The Leeb hardness of superhydrophobic film‐coated Al alloy is enhanced from 325 to 461 after coating superhydrophobic film on Al alloy. This work provides a framework for the development of superhydrophobic Al alloy with high‐whiteness and robustness. [ABSTRACT FROM AUTHOR]

The development of aluminum (Al) alloys with superb anti‐corrosion and self‐cleaning properties for prolonging the working life and reducing maintenance cost is a hot topic of concern. Since anodic oxidation has been proven to be an effective technique to prepare micro or nanostructures on Al alloys surface, this study proposes a novel and scalable multiple anodic oxidations method with gradient current densities for fabricating hierarchical micro‐nanostructure film with appropriate roughness on Al alloys, while the SiO2‐silane film reduced the surface free energy and enhanced the surface chemical inert state. As expected, the surface of Al alloys modified with the multiple anodic oxidations and SiO2‐silane film has the most substantial hydrophobic properties, with contact angle up to 166°, rolling angle as low as 3.17° and excellent non‐sticking effect of water droplets. This method enables the Al alloys surface to have excellent self‐cleaning performance and corrosion resistance with protection efficiency up to 98.81 %. This multiple anodic oxidations method has a wide range of references for the modulation of micro‐nanostructure on Al alloys surface and other metallic substrates to assemble superhydrophobic protective films. [ABSTRACT FROM AUTHOR]

In this study, typical electrodeposition method was proposed to fabricate uniform CuO hierarchical micro‐nanostructure on aluminum (Al) substrate. The superhydrophobic protective film was then fabricated by modifying stearic acid (STA) on this hierarchical CuO film. The static water contact angle reached up to 163° by coating CuO/STA film on Al substrate, and the rolling‐off angle was as low as 3.7°. In addition, CuO/STA coated Al displayed wonderful non‐sticking performance when the free‐falling water droplets contact the surface. As expected, superb anti‐corrosion properties of Al were achieved by coating superhydrophobic CuO/STA film on Al. The corrosion current density of CuO/STA coated Al decreased 2 orders of magnitude comparing with that of pristine Al, and the corrosion protection efficiency of CuO/STA coated Al reached up to 98 % in comparison with pristine Al. Therefore, superhydrophobic CuO/STA film coated Al substrate greatly prolong the working life of Al materials in harsh working condition. The universal method used in this study also provides a potential route for coating superhydrophobic and anti‐corrosion protective film on other metallic substrates or conductive substrates. [ABSTRACT FROM AUTHOR]

In this study, a novel and smart electroplating method was presented to fabricate a mechanically robust superhydrophobic coating on Al alloys. The superhydrophobic coating was composed of Ni-W alloy film with high hardness and stearic acid (STA) with low surface energy, providing excellent abrasive resistance, anti-corrosion properties, and self-cleaning ability. Specifically, a thin transition layer of Al-Ni-W was pre-electroplated on the Al alloy substrate by utilizing Al as anode and Al alloys as cathode in Ni-W ions aqueous solution, which overcome the difficulty of directly electroplating alloys coating on the Al alloys surface. Finally, a robust composite superhydrophobic film was achieved after coating STA layer on Al alloy/Al-Ni-W/Ni-W substrate. As anticipated, the as-prepared Al alloys demonstrates excellent mechanical durability and chemical stability, including wear resistance, hardness, corrosion resistance and self-cleaning with a champion water contact angle of 163° and corrosion protection efficiency of 99.4%. The Leeb hardness of superhydrophobic film coated Al alloys was enhanced by 87.1% compared to the pristine Al alloys, increasing from 325 ± 3 to 608 ± 4. This method provides a universal pathway for fabricating robust superhydrophobic film on the active metallic substrates. • A smart electroplating method was utilized to fabricate Ni-W alloy coating on Al alloy. • Al-Ni-W transition layer was pre-electroplated by utilizing Al as anode and Al alloy as cathode. • The hardness of superhydrophobic film coated Al alloy was enhanced significantly. • Composite coating of Al alloys/Al-Ni-W/Ni-W/STA exhibited excellent anti-corrosion ability. [ABSTRACT FROM AUTHOR]

In this study, we presented a universal and convenient method to prepare superhydrophobic film on the substrates of Al, Al alloy, indium-tin oxide (ITO), fluorine doped tin oxide (FTO) and glass slide respectively. The precursor solution of silane mixture was recovered by dissolving the pre-synthesized powders of silane in alcohol, which is easy to prepare and store, stable and portable. As expected, all of the five substrates achieved superhydrophobic properties with contact angle of more than 160° after spin-coating the above precursor on their surface. In addition, the effect of superhydrophobic film thickness on light transmittance was investigated by spin-coating different concentrations of precursor solutions on ITO substrates. There is a certain transmission enhancement effect on the wavelength range of 525–675 nm, indicating the good light transmittance of superhydrophobic film prepared by this method. Electrochemical measurements confirmed that the superhydrophobic film coated Al and its alloys possess excellent anti-corrosion properties. • A universal and convenient method to prepare superhydrophobic protective film on various substrates was presented. • The precursor solution was recovered by dissolving the pre-synthesized powders in alcohol. • Excellent superhydrophobic, self-cleaning and anti-corrosion properties were achieved. • The superhydrophobic film possess good light transmittance in visible region. [ABSTRACT FROM AUTHOR]