Preparation and corrosion resistance of Ni-Fe layer double hydroxides superhydrophobic film on carbon steel

Abstract

The nickel-ferric layered double hydroxides (NiFe-LDHs) film which are commonly used as catalysts was fabricated on Q235 steel in-situ via two-step hydrothermal method. And the superhydrophobic NiFe-LDH-PFDTES film was obtained by 1 H, 1 H, 2 H, 2 H-perfluorodecyltriethoxysilane (PFDTES) modification. To a certain extent, the application of NiFe-LDHs has been broadened. The structure and composition of NiFe-LDHs film and NiFe-LDH-PFDTES film were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS), and Fourier transform infrared (FT-IR). The wettability of films was analyzed by water contact angle testing. And the corrosion resistance of NiFe-LDHs and NiFe-LDH-PFDTES film in 3.5 wt% NaCl solution were measured by using potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS) techniques. The results show that NiFe-LDHs and NiFe-LDH-PFDTES film were successfully prepared on the surface of Q235 steel. By adjusting the preparation conditions, the NiFe-LDH-PFDTES film with optimal corrosion resistance was prepared in the condition containing the hydrothermal solution concentration is 1 unit and hydrothermal time for 6 h. The hydrophobicity changes little with the hydrothermal parameters, and all reach the state of superhydrophobic, the contact angle is greater than 150°, the sliding angle is less than 1°. For the superhydrophobic film, NiFe-LDHs has excellent synergy with PFDTES, covering of an "air film" on the rough structure of LDHs, blocking the solution from contact with the substrate, thereby providing corrosion resistance. NiFe-LDH-PFDTES film exhibits much better corrosion protective performance than NiFe-LDHs film in 3.5 wt% NaCl solution, the impedance modulus is increased about 4–5 orders of magnitude compared with Q235 steel, and the highest protection efficiency can reach 99.99%.