In this study, a composite coating of polytetrafluoroethylene (PTFE) and fluorinated alkyl silane (FAS, C 16 H 19 F 17 O 3 Si) is prepared on AISI 304 L stainless steel. Scanning electron microscope and X-ray photoelectron spectroscopy are used to analyze the microstructure and chemical group changes of PTFE-FAS coating (PF coating) before and after sulfuric acid (H 2 SO 4 ) corrosion and after heat treatment. In addition, differential scanning calorimeter is performed to study the thermodynamic properties of PF coating. The corrosion resistance of PF coating under the above conditions is tested by the electrochemical experiment. The results show that acid and abrasion treatments can reduce the hydrophobic properties of the coatings, and the damage caused by acid is more serious. Heat treatment can repair the hydrophobic properties of the coating damaged by acid and abrasion. In addition, PF coating has an excellent corrosion resistance, but after H 2 SO 4 treatment, the protection efficiency (PE) decreases from 89.09% to 2.51%, indicating that the corrosion resistance of PF is severely damaged. However, PE of PF coating increases to 76.83% after heat treatment. This repair ability improves the corrosion resistance of the coating. At the same time, the related mechanism is also clarified.

In this paper, superhydrophobic ceramic coatings were successfully prepared on stainless steel substrates (S304) by sol-gel method, and the effects of pore content and pH conditions on the corrosion resistance of hydrophobic ceramic coatings were studied. As the porosity increases, the contact angle of the coating increases. Among them, the contact angles of the coatings with 15% and 20% porosity in different pH solutions are all greater than 150 • , achieving superhydrophobic surfaces. The contact angle results before and after corrosion show that the solution with a higher pH has a greater damage to the hydrophobicity of the coating. The corrosion resistance of the coatings was evaluated comparatively from polarization curves and electrochemical impedance spectroscopy. As the hydrophobicity improves, the corrosion resistance of the hydrophobic ceramic coating is enhanced. The impedance moduli at .01 Hz of the coating are 1.04 × 10 3 times (pH 4), .13 × 10 3 times (pH 7), and .74 × 10 3 times (pH 10) of the bare steel, respectively. With the increase of pH, the corrosion resistance of hydrophobic ceramic coatings decreases, because OH − in the corrosion solution is more easily adsorbed on the surface of the coating, thereby destroying the long hydrophobic chains.

In this study, microcapsules are prepared by in situ polymerization using the repairing agent fluorinated alkyl silane (FAS) as the core material and urea‐formaldehyde as the covering shell. Self‐healing coatings (FEP coatings) with repairing ability in water are prepared by adding FAS microcapsules in an epoxy resin matrix. The morphology, composition, and thermal properties of the microcapsules are studied. In addition, electrochemical impedance spectroscopy is used to study the barrier properties and self‐healing properties of the coating. The results show that FEP coating has good self‐healing ability, with the semiquantitative index of 105 Ω·cm2, which is greater than that of pure epoxy coating (EP coating). This is because that FAS leaked from the microcapsules reacts with water molecules to form a dense water‐insoluble film, which blocks the contact of corrosive ions with the substrate and inhibits the progress of metal corrosion. Moreover, the scratch width and depth results of the FEP coating after self‐healing also confirm the formation of the new film by FAS.