Corrosion properties of metals in dicyanamide-based ionic liquids

• Corrosion properties in ILs are totally different from those in aqueous solution.
• The constituent anions of ILs determine the IL corrosivity toward materials.
• Ni, 304 SS, Ti, and Al have great corrosion resistances in DCA-based ILs.
• Cu, CS, and Mg show high corrosion susceptibility in DCA-based ILs.
• Corrosion resistance of materials depends on the IL type and applied potential.

Corrosion behavior of metals in 1-ethyl-3-methylimidazolium–dicyanamide, butylmethylpyrrolidinium–dicyanamide, and 1-ethyl-3-methylimidazolium chloride–chloroaluminate ionic liquids (ILs) is studied. The constituent anions, rather than the cations, are the predominant species that govern the IL corrosivity toward materials. Among the materials investigated, Ni shows the lowest corrosion current and the best resistance against anodic dissolution in the three ILs. In the dicyanamide-based ILs, 304 stainless steel, Ti, and Al also exhibit satisfactory anti-corrosion characteristics. However, the use of Cu, carbon steel, and Mg in the same environment should be avoided due to their poor corrosion resistance, especially under anodic polarization conditions.