Effect of sodium vanadate on corrosion of AD31 aluminum alloy in acid media

Resumo

Scanning electron microscopy, potentiodynamic polarization method, and electrochemical impedance spectroscopy were used to study the corrosion behavior of AD31 (AA6063) aluminum alloy in acid (pH 3) 0.05 M NaCl solutions containing 3 mmol dm^–3 of NaVO₃ inhibitor. It was found that the corrosion of AD31 alloy in acid sodium chloride solutions predominantly occurs locally at aluminum/intermetallic particle phase boundaries and is limited by the electrochemical stage of charge transfer. It was shown that introduction of sodium vanadate can reduce the rate of selective dissolution of magnesium from the alloy and provides a protective effect on the level of 7–10%.