Experimental and theoretical studies on corrosion inhibition behavior of three imidazolium-based ionic liquids for magnesium alloys in sodium chloride solution

The corrosion inhibition behavior for the AZ31B Mg alloy in 0.5 wt% NaCl solution by three imidazolium-based ionic liquids (ILs), namely 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide [EMIm][NTf2], 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide [HMIm][NTf2], and 1decyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide [DMIm][NTf2] was explored by using electrochemical measurements coupled with theoretical computations. Scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) were used for the evaluation of the corrosion results. The present results reveal that the inhibition efficiency of three ILs on the Mg alloy follows the order: [DMIm][NTf2] > [HMIm] [NTf2] > [EMIm][NTf2]. This indicates that [DMIm][NTf2] exhibits the best inhibition performance among these ILs studied, which may be ascribed to the largest steric body of [DMIm][NTf2] with respect to other two analogues, thus leading to a highest surface coverage. In addition, adsorptions of all studied ILs obey the Langmuir isotherm with the character of dominantly chemical adsorption. Finally, the possible corrosive products were estimated and the inhibition mechanism was suggested. (C) 2021 Elsevier B.V. All rights reserved.