Protective Action of Sodium Metavanadate Against Corrosion of AD31 Aluminum Alloy in Neutral Chloride-Containing Media

摘要

The mechanism of corrosion of AD31 (AA6063) aluminum alloy in 0.05 M NaCl solutions containing 0.03-5 mmol/dm(3) NaVO3 as an inhibitor was studied. Using the data from potentiodynamic polarization measurements, the protective effect of the inhibitor is calculated, the Langmuir adsorption isotherm is constructed, and the effective activation energy of the anodic process is found. NMR spectroscopy is used to determine the ionic forms of vanadium compounds in aqueous solutions containing 3 mmol/dm(3) NaVO3. It is shown that the mechanism of the corrosion inhibition of AD31 alloy by soluble vanadates is the physical adsorption of inhibitor ions on the metal surface. This prevents the adsorption of oxygen, thus slowing its rate of cathodic reduction.