The inhibition behavior of novel ionic liquids for magnesium alloy in NaCl solution: Experimental and theoretical investigation

Abstract

Three pyrazolium ionic liquids 1-n-butyl-2-hexylpyrazole bis(trifluoromethylsulfonyl)amide ([BHPz][NTf2]), 1-n-butyl-2-octylpyrazole bis(trifluoromethylsulfonyl)amide ([BOPz][NTf2]), and 1-n-butyl-2-decylpyrazole bis(trifluoromethylsulfonyl)amide ([BDePz][NTf2]) are firstly synthesized and their corrosion inhibition for AZ91D magnesium alloys in 0.05 wt% NaCl solution is investigated. The highest inhibition efficiency is 90.0% under optimal test conditions. The inhibition performance is measured by electrochemical tests, and follows the Langmuir adsorption model. The surface morphology is determined by scanning electron microscopy (SEM) and atomic force microscopy (AFM), which testifies the formation of protective films on Mg alloy surface. The possible inhibited mechanism is proposed according to X-ray photoelectron spectroscopy (XPS) analysis and the density functional theory (DFT) calculation.