Corrosion inhibition of aluminum in sodium hydroxide solutions using some inorganic anions

Abstract

The rates of corrosion of aluminum and hydrogen gas production in sodium hydroxide solutions without and with the additions of chromate, phosphate, and tungstate anions were examined. Potentiometric, weight loss, thermometric, gasometric, galvanostatic polarization, and electrochemical impedance spectroscopy techniques were used. The data show that these anions favored oxide film formation and mitigate hydrogen production. The inhibition efficiency, η, was calculated and found to depend on the anion-type and concentration, as well as, temperature. The inhibition mechanism is assumed to take place through an adsorption process obeying Temkin's isotherm. The thermodynamic parameters for the adsorption process K ads and ΔG°ads are calculated and discussed. The surface examination was investigated using SEM and EDX spectroscopy.