Corrosion behaviour of aluminum and copper in dimethyl- and diethyl phosphate ionic liquids

The effect of phosphonium-based ionic liquids (ILs): 1,3-dimethyl-imidazolium dimethyl phosphate, [C1C1IM] 1 C 1 IM] [DMP], 1-ethyl-1-methylpyrrolidinium dimethyl phosphate, [C1C2PYR][DMP], 1 C 2 PYR][DMP], 1-hydroxyethyl-1-methylpyrrolidinium dimethyl phosphate, [C1C2OHPYR][DMP], 1 C 2OH PYR][DMP], 1-methylpyridinium dimethyl phosphate, [C1Py][DMP], 1 Py][DMP], 1ethyl-1-methylmorpholinium dimethyl phosphate, [C1C2MOR][DMP], 1 C 2 MOR][DMP], 1-ethyl-1-methylpiperidinium dimethyl phosphate, [C1C2PIP][DMP], 1 C 2 PIP][DMP], N,N,N-trimethyl- N-methylammonium dimethyl phosphate, [N1,2,2,2][DMP], 1,2,2,2 ][DMP], 1ethyl-3-methylimidazolium diethyl phosphate, [C1C2IM][DEP], 1 C 2 IM][DEP], 1-ethyl-1-methylpyrrolidinium diethyl phosphate, [C1C2PYR][DEP], 1 C 2 PYR][DEP], 1-ethyl-1-methyl-morpholinium diethyl phosphate, [C1C2MOR][DEP] 1 C 2 MOR][DEP] and tri(butyl) ethylphosphonium diethyl phosphate, [P2,4,4,4][DEP] 2,4,4,4 ][DEP] on the corrosion of aluminium and copper were investigated using potentiodynamic polarization. All tested ionic liquids formed a passivation layer on the surface of the tested metals and due to their low affinity to promote corrosion of Cu and Al, can be used in refrigeration technology.