Inhibitive Behaviour of Zinc Gluconate on Aluminium Alloy in 3.5 % Nacl Solution

Abstract

The present work investigates corrosion behaviour of aluminium alloy in 3.5 % sodium chloride medium at 28 °C in the absence and presence of 0.5, 1.0, 1.5 and 2.0 % g/v concentrations of zinc gluconate using gravimetric and electrochemical techniques. The aluminium alloy was cut to corrosion coupons, and immersed into 3.5 % sodium chloride solution containing different inhibitor concentrations (0.5, 1.0, 1.5 and 2.0 % g/v) within a period of twenty-eight days. The surface morphology of the metal was examined by high resolution scanning electron microscopy equipped with energy dispersive spectroscopy (HR-SEM/EDS). From the results, it was found that the adsorption of zinc gluconate reduced aluminium alloy corrosion in the sodium chloride medium. Experimental results also showed that inhibition efficiency increased with an increase in zinc gluconate concentration. Furthermore, potentiodynamic polarization results revealed decrease in corrosion rates (CR), corrosion current densities (Icorr), and increasing corrosion resistance (Rp) in the presence of zinc gluconate in 3.5 % NaCl solution. Tafel polarization analyses indicated that zinc gluconate is a mixed type inhibitor. The adsorption of zinc gluconate on the aluminium alloy surface followed Langmuir adsorption isotherm.