Preparation Of Corrosion-Resistant Superhydrophobic Surfaces On N80 Steel Substrate

N80 steel is one of the most widely used steels in oil and gas pipelines.It is prone to generate pitting and stress corrosion crack under the synergistic effect of H₂S,CO₂,O₂ and Cl^-.Superhydrophobic surface can generate resistance for water droplets to pass through the metal surface,and then enhance its corrosion resistance.This method has potential application in metal protection.In this paper,three kind of micro-nanostructures were prepared by hydrothermal treatment and annealing treatment under different conditions on N80 steel surface,and then some low surface energy materials were added to generate the superhydrophobic surfaces.The wetting behavior,microstructure,chemical composition and electrochemical properties of them were systematically studied.The main research results are as follows:?1?A new approach to construct micro-octahedral structure on N80 steel by hydrothermal treatment is proposed.It has been found the nanoparticles can formed on the surface after annealing in air or O₂.Based on contact angle analysis,it is found annealing in N₂ and then annealing in O₂ can generate higher made the superhydrophobicity film than only O₂ or N₂.In this condition,the films have the highest contact angle?158.3°?and the lowest sliding angle?3.3°?,which performs good corrosion resistance.?2?A new way to prepare rod-shaped Fe₂O₃/Fe₃O₄ composite films by two-step hydrothermal synthesis is proposed.It is found that the concentration of NaOH in the second step of hydrothermal treatment will greatly affect the microstructure of films.When the concentration of NaOH is less than 0.2 M,it shows a sheet-like structure,and when the concentration of NaOH is larger than 0.2 M,it becomes a rod-like structure.It is found the superhydrophobic surface exhibits contact angle of 159.6°and sliding angle of 2.2°,showing good corrosion resistance when the NaOH concentration is 0.2 M.?3?A new method to prepare needle-shape Fe₂O₃/Fe₃O₄ composite films on the surface of N80 steel is proposed.It is found that annealing in the atmosphere after egg white burning can produce a needle-like structure on the micro-octahedron of the surface.And the time the annealing treatment will affect the length of needle-like structure.And the optimized annealing time is 2 h.In this condition,the contact angle reached 157.3°and the sliding angle was 8.1°.