Robust bioinspired ceramic-based superhydrophobic Al2O3-STA@WPU composite coating via air spraying: A strategy in enhancing mechanical stability and corrosion resistance for steel 45

Steel 45 is widely used in mechanical manufacturing, construction engineering, automotive product, petrochemical industry, and marine engineering. Although it possesses superior strength, toughness, and comprehensive mechanical property, it is highly susceptible to corrosion, which directly leads to a shortened service life. This work proposes a simple, low-cost, and efficient air spraying technology for preparing a ceramic-based superhydrophobic Al 2 O 3 -STA@WPU composite coating to address the corrosion problem of steel 45. The results show that the static water contact angle of the designed coating is as high as 162.20°, and the rolling angle is as low as 6.20°, indicating superior superhydrophobicity. After a sandpaper friction test, the coating still exhibits excellent mechanical stability and durability. Furthermore, electrochemical tests have shown that an air layer is formed in such rough coating, thus effectively hindering the interfacial interaction and mass transfer of corrosive species, resulting in significantly improved corrosion resistance. Such a robust, simple, low-cost, and efficient superhydrophobic coating has important economic value and practical significance for the corrosion protection of metals and structural components. It effectively addresses the engineering issue of poor mechanical stability often encountered with traditionally reported superhydrophobic surfaces during service. • A bioinspired robust Al 2 O 3 -STA@WPU coating is fabricated by one-step spraying. • The coating provides durable barriers against seawater corrosion and fluid adhesion. • It shows universal adaptability with enhanced self-cleaning and antifouling features. • The mechanisms underlying multifunctional performances are systematically revealed.