Investigation of the corrosion protection performance of hybrid sol-gel coating containing 2-hydroxypropyl-β-cyclodextrin on aa7075-t6 surface

This study includes the development and characterization of hybrid sol-gel coatings to improve the corrosion resistance of AA7075-T6 aluminum alloy. The coatings were prepared using tetraethyl orthosilicate (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) precursors, and 2-hydroxypropyl-β-cyclodextrin (2-HP-β-CD) was added as an inhibitor. Within the scope of optimizing the composition, coatings containing 100% TEOS, 75% TEOS-25% GPTMS, 50% TEOS-50% GPTMS, 25% TEOS-75% GPTMS, and 100% GPTMS were prepared, and the composition providing the best corrosion protection performance was determined. The corrosion resistance of the coatings was evaluated by linear potentiodynamic polarization (Tafel) curves and electrochemical impedance spectroscopy (EIS) methods in a solution containing 0.5 mol L‒1 NaCl. Additionally, the structural characterization and surface morphology of the coatings were investigated using Fourier Transform Infrared Spectroscopy (FT-IR) and Field Emission Scanning Electron Microscopy (FE-SEM) analyses. When the electrochemical test results were compared, it was observed that the coating with a ratio of 75% TEOS and 25% GPTMS exhibited the lowest corrosion current and the highest impedance resistance values. This ratio was determined to be the composition that provided the optimum protection. Then, 2-hydroxypropyl-β-cyclodextrin (2-HP-β-CD) was added to the solution containing the optimized TEOS/GPTMS ratio as an inhibitor at a specific concentration. The effective and controlled distribution of this component in the coating matrix increased the corrosion protection performance of the coating.