Electrochemical properties of the superhydrophobic coatings on metals and alloys

• Superhydrophobic (SHP) coatings on PEO-pretreated titanium, steel and Mg-alloy are investigated.
• Coatings significantly improve anticorrosion properties of investigated metals.
• Coating increases the corrosion resistance of Mg-alloy by 5 orders of magnitude.

Superhydrophobic layers were prepared by means of nanoparticle dispersions deposition on PEO (plasma electrolytic oxidation)-pretreated metal/alloy (titanium, low-carbon steel, and magnesium) substrates. The contact angles on the surface of the fabricated coatings were higher than 160°. The comprehensive analysis of the data obtained by electrochemical method provides the possibility to study variations in the surface conditions due to the electrochemical reaction associated with the corrosion process. It was found that the combined effect of PEO treatment and textured hydrophobic layer deposition results in inhibition of the corrosion reactions and ensures the anticorrosive behavior of the coatings. As follows from the electrochemical data analysis, the corrosion protection for nanocomposite superhydrophobic coatings formed on the PEO-layer is provided by small area of real contact with the electrolyte solution and higher ohmic barrier for corrosion reactions. In case of superhydrophobic layers, the mass transfer of electrolyte solution through the coating to the metal surface is substantially hindered.