Improvement of Corrosion Behavior of Al ۲۰۲۴ by Applied Titania- Alumina- Benzotriazole Functionally Graded Nanocomposite Self- Healing Coating

Nowadays, self healing nanocomposite coatings are the perfect solution for corrosion protection of Al alloys. So, in this paper, tetra butyl orthotitanat and aluminum alkoxide precursor with different percentage and functionally graded of Benzotriazole as an inhibitor used to applied titania- alumina- benzotriazole functionally graded hybrid coating on Al ۲۰۲۴ alloys by the sol-gel method and dipcoating process. Then phase, structure properties and morphology have been investigated by using GIXRD, FESEM and AFM , respectively, as well as the corrosion behavior and self healing properties of the coating was investigated by electrochemical impedance spectroscopy and polarization at ۳.۵% NaCl solution. The results of FESEM images show the grain size of titania, titania-alumina, titania- alumina- benzotriazole and functionally graded coating are ۲۸, ۱۸, ۲۳ and ۲۰ nm, respectively. Due to the size of the grain surface coatings and electrochemical investigations have been conducted, the results of polarization and electrochemical impedance spectroscopy of  functionally graded coating show the best performance, corrosion resistance and self healing behavior with corrosion current density of ۱۹×۱۰-۶  mA/Cm۲ and charge-transfer resistance (Rct) of ۱۷۴۲۸۶ Ω.Cm۲ compared to titania, titaniaalumina and titania-alumina-benzotriazole with charge-transfer resistance, ۱۰۸۴۶۹, ۹۵۷۶۲ Ω.Cm۲, respectively.