The impact of novel diamine based aqueous and water lean solvents on the corrosion of carbon steel

Two diamine based water lean solvents PNH and ENH (N,N-dimethyl-1,3-propanediamine (DMPDA) and N,N-dimethyl-1,2-ethanediamine (DMEDA) respectively) using N-methyl pyrrolidone (NMP) as a diluent together with their corresponding aqueous solvents were investigated for their corrosivity of carbon steel. Siderite (FeCO3) film is demonstrated to provide stronger corrosion resistance than chukanovite (Fe2(CO3)(OH)2) film formed in aqueous solvents, DMEDA-H2O and DMPDA-H2O. Diamine water lean solvents ENH and PNH showed more severe corrosion behavior (ten-fold higher dissolved iron concentration) due to a lack of film protection. Improved anti-corrosion ability was observed in diamine water lean solvents by increasing the water content to 40%.