On the duration of the protective effectiveness of superhydrophobic coatings

• L.E. Tsygankova, A.A. Uryadnikov, L.D. Rodionova and M.N. Uryadnikova

Derzhavin State University, ul. Internatsyonalnaya, 33, 392000 Tambov, Russian Federation

Abstract: The durability of superhydrophobic coatings obtained on St3 carbon steel by nanosecond laser texturing of the surface, ultraviolet radiation treatment in ozone plasma, and deposition of a fluoroxysilane film has been studied. The contact angle of wetting of the coating, on average, is 172°. After 112 days of exposure to 100% humidity, the samples with the superhydrophobic coating did not show signs of corrosion damage, retaining the original wetting angle. Studies conducted for 100 days in an atmosphere with 100% humidity and containing corrosion stimulants CO₂, H₂S, NH₃ in pairs and simultaneously all three in the maximum permissible concentrations typical for livestock buildings showed a decrease in the contact angle to 167–162° in the absence of signs of corrosion damage. After the tests, the samples were kept for 19 months in desiccators in a chemical laboratory, after which the contact angle on the superhydrophobic surface was 167–168°. Further, with these samples, corrosion tests were carried out in the gas and liquid phases of solutions with 50 g/L NaCl or NACE (5 g/L NaCl+0.25 g/L CH₃COOH), saturated with CO₂ up to 1 excess atmosphere, or solutions of SO₂ (1 and 3 wt.%). After testing in the gas phase, the coatings retained superhydrophobicity, and after the liquid phase – hydrophobicity with contact angles of the order of 130–140° after testing with SO₂ and about 100° after testing with CO₂. Subsequent exposure of the samples to air for 2 weeks led to a sharp increase in the contact angles.

Keywords: superhydrophobicity, protective efficiency, wetting angle, corrosion promoters, durability

Int. J. Corros. Scale Inhib., 2023, 12, no. 3, 1211-1223
doi: 10.17675/2305-6894-2023-12-3-23

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