Assessment of AA5005 aluminum alloy corrosion resistance by Direct Blue 15 inhibitor in sodium chloride medium

Abstract

The effect of Direct Blue 15 dye (DB-15) on the corrosion of aluminum AA5005 in 3% NaCl solution was studied using gravimetric techniques. The results indicate that the DB-15 acts as an inhibitor in the NaCl environment by adsorption on the metal surface. The inhibition efficiency was found to increase with dye concentration and attained 90.8% at 400 ppm. The effect of temperature on the corrosion behavior of aluminum in 3% NaCl was studied in the range 298 K and 328 K. The inhibition performance was also tested by immersing aluminum in 3% NaCl solution using electrochemical methods; potentiodynamic polarization (PP) curves and electrochemical impedance spectroscopy (EIS). PP measurements showed that DB-15 can be considered as mixed-type inhibitor with predominant anodic action and with inhibition efficiencies that improve with concentration. Electrochemical impedance spectroscopy measurements reveal that the corrosion resistance of oxide film increases with dye inhibitor concentrations. The adsorption of the inhibitor on the AA5005 aluminum alloy surface obeyed the Langmuir adsorption isotherm. The values of inhibition efficiency calculated from weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy are in good agreement.