Preparation and corrosion resistance of superhydrophobic Ni–Co–Al2O3 coating on X100 steel

Abstract

X100 steel is easy to be corroded because of the high salt content in alkaline soils. The Ni–Co coating can slow down the corrosion but still cannot meet the requirements of modern demands. Based on this, in this study, on the basis of adding Al₂O₃ particles to the Ni–Co coating to strengthen its corrosion resistance, combined with superhydrophobic technology to inhibit corrosion, a micro/nano layered Ni–Co–Al₂O₃ coating with a new combination of cells and papillae was electrodeposited on X100 pipeline steel, and superhydrophobicity was integrated into it using a low surface energy modification method to improve wettability and corrosion resistance. SEM, XRD, XPS, FTIR spectroscopy, contact angle, and an electrochemical workstation were used to investigate the superhydrophobic materials' microscopic morphology, structure, chemical composition, wettability, and corrosion resistance. The co-deposition behavior of nano Al₂O₃ particles can be described by two adsorption steps. When 15 g L⁻¹ nano Al₂O₃ particles were added, the coating surface became homogeneous, with an increase in papilla-like protrusions and obvious grain refinement. It had a surface roughness of 114 nm, a CA of 157.9° ± 0.6°, and –CH₂ and –COOH on its surface. The corrosion inhibition efficiency of the Ni–Co–Al₂O₃ coating reached 98.57% in a simulated alkaline soil solution, and the corrosion resistance was significantly improved. Furthermore, the coating had extremely low surface adhesion, great self-cleaning ability, and outstanding wear resistance, which was expected to expand its application in the field of metal anticorrosion.