Preparation of Cu/CuO@Stearic acid layer with superhydrophobicity to provide multiple barriers for corrosion protection of carbon steel

Abstract

Carbon steel is a widely used metallic material. It is prone to corrosion. In this study, we designed and fabricated a superhydrophobic layer with corrosion resistance for protection of carbon steel substrate. Multiple layers were formed that acted as barriers to protect the substrate from corrosion. This superhydrophobic layer reduced the contact area between the substrate and the corrosive medium owing to the superhydrophobicity. The experimental results showed that a copper layer uniformly covered the carbon steel substrate, and the outer surface of the copper layer was converted into copper oxide, which had a multi-scale structure. The Cu/CuO double layer was modified with stearic acid (SA) to form a Cu/CuO@SA superhydrophobic layer. The superhydrophobic layer exhibited a high water contact angle (up to 160°) and a low sliding angle (<3°). The superhydrophobic layer also exhibited repulsive effect to salt, acidic and alkaline solutions. Atmospheric stability test and UV irradiation test were conducted and the results indicated that the superhydrophobic layer was stable throughout the test period. The corrosion potential of the superhydrophobic sample was −0.18 V and the corrosion current density was 7.72 × 10−7 A cm−2, which was one order of magnitude lower than that of the carbon steel substrate. These results indicate that the superhydrophobic sample had a low corrosion tendency and corrosion rate. The polarization resistance and impedance modulus of the superhydrophobic sample were two orders of magnitude higher than the bare steel sample, indicating corrosion resistance and effective protection to the carbon steel substrate.