Anti-corrosion protection of steel with superhydrophobic coatings based on nickel and zinc

Two types of suprehydrophobic (SHP) coatings with contact angles of 153 +/- 2 degrees 3 +/- 2 degrees and 155 +/- 3 degrees 5 +/- 3 degrees were obtained on St3 carbon steel by electrodeposition of nickel and zinc respectively followed by exposure to an ethanol solution of myristic acid. Their protective effectiveness was studied at 100% humidity, in distilled water, in gas and liquid phases of SO2 solutions (1 and 3%) for 10 days, in a sodium chloride solution (50 g/L) for 168 hours, in a salt fog chamber before the first signs of corrosion appear. The methods of gravimetry, potentiodynamic polarization, impedance spectroscopy, scanning electron microscopy, and contact angle measurements were used. After testing at 100% humidity and in distilled water, the state of the SHP coatings remained virtually unchanged. In both phases of solutions with 1% SO2 and in the gas phase of 3% SO2 solution, the SHP coatings were degraded to some extent, although hydrophobicity was retained, as in the NaCl solution. The protective properties of SHP coatings based on Zn were shown to have a superiority to Ni-based SHP coatings.