Lithium Carbonate and Oxalate Salts as Corrosion Inhibitors for Magnesium Alloy AZ31B in NaCl Solution Available to Purchase

The corrosion inhibition effectiveness of dissolved Li₂CO₃ and Li₂C₂O₄ was studied for Mg alloy AZ31B in 0.1 M NaCl solution. The electrochemical and corrosion inhibition properties of Li salts were studied using potentiodynamic polarization, linear polarization resistance, electrochemical impedance spectroscopy, and H₂ evolution measurement methods. The corrosion inhibition efficiency as a function of immersion time was also investigated. The morphology and chemical composition of AZ31B surfaces after 24 h immersion in 0.1 M NaCl with and without the addition of dissolved Li salts revealed considerable differences in corrosion properties. The role of Li⁺ ions, ions, and on corrosion inhibition of AZ31B was focused and their role in corrosion inhibition was discussed. Li₂CO₃ had better corrosion inhibition efficiency compared to Li₂C₂O₄ in 0.1 M NaCl solution at ambient temperature. The optimum concentration of Li₂CO₃ was 50 mM to provide the highest corrosion inhibition efficiency of 96.75%, while the optimum concentration and inhibition efficiency for Li₂C₂O₄ were 3 mM and 82.84%, respectively. Surface characterization of the Li₂CO₃-inhibited AZ31B revealed that the enhanced corrosion protection was due to formation of a protective layer mainly composed of MgCO₃. Corrosion studies over time showed that Li₂CO₃ could effectively provide corrosion protection for 48 h, while Li₂C₂O₄ became ineffective after 12 h of immersion in 0.1 M NaCl.