Electrochemical investigation on the effects of sulfate ion concentration, temperature and medium pH on the corrosion behavior of Mg-Al-Zn-Mn alloy in aqueous ethylene glycol

The effects of sulfate ion concentration, temperature and medium pH on the corrosion of Mg-Al-Zn-Mn alloy in 30% aqueous ethylene glycol solution have been investigated by electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy methods. Surface morphology of the alloy was examined before and after immersing in the corrosive media by scanning electron microscopy (SEM) and energy dispersion X-ray (EDX) analysis. Activation energy, enthalpy of activation and entropy of activation were calculated from Arrhenius equation and transition state theory equation. The obtained results indicate that, the rate of corrosion increases with the increase in sulfate ion concentration and temperature of the medium and decreases with the increase in the pH of the medium.