The effect of benzotriazole gradual change on the corrosion performance of nanocomposite multilayer self-healing coating based on Titania-Alumina-Benzotriazole on AA7075

Abstract

Abstract Today, lots of coatings are being used for protection against the corrosion; however, if a crack or scratch damage the coated surface, it could not protect itself. Nano-structured titanium oxide coatings have oxidation and corrosion resistance. Also, aluminum oxide coatings are widely used because of wear and corrosion resistance. In the present study, a combination of Titania and alumina and benzotriazole (C6H5N3) as an inhibitor was synthesized to create a corrosion resistant coating with self-healing properties via Sol-gel method. The gradual change in the amount of benzotriazole in layers produced different corrosion behaviors in the coatings. Microstructural and morphological behaviors of the coatings were characterized by Grazing Incidence X-ray Diffraction (GIXRD) analysis, Raman Spectroscopy, Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscope (AFM), respectively. According to GIXRD results, the structure of the formed coatings was utterly amorphous. FESEM images showed that the coatings were homogeneously formed in all specimens and achieving the nanostructured coatings with uniform distribution of grains depends on the optimal amount of Benzotriazole. According to AFM results, the thickness of all coatings was less than 200 nm. Raman spectroscopy results identified the chemical bond types such as Ti–O–Ti, Ti–O, and O–C–C groups. The corrosion behavior and self-healing properties of hybrid ceramic coating were investigated by electrochemical measurements, including Electrochemical Impedance Spectroscopy (EIS) and polarization test in the solution of 3.5 wt % NaCl in different periods. The results showed that benzotriazole could prevent corrosion progression due to self-healing capabilities and improve the corrosion resistance of the uncoated sample about 130 times after immersion for 96 h.