Corrosion behaviour of ionic liquids

Abstract

The corrosion behaviour of carbon steel, austenitic stainless steel, nickel-based alloy C22, copper, brass and aluminium (AlMg3) was investigated in seven ionic liquids (ILs) with different chemical structure under flow conditions at temperatures up to 90 °C. Stainless steel proved resistant in all water-free and water-diluted systems tested. Alloy C22 generally was not attacked, however, it was also moderately corroded in a diluted IL with dimethyl phosphate as anion. For carbon steel and aluminium the corrosivity of IL media strongly depends on the chemical structure of the cationic moiety and the nature of anion in the IL molecule. Anions like tosylate and dimethyl phosphate generally trigger higher corrosivity specifically in water-diluted ILs. In general, the aluminium alloy performed better than carbon steel, specifically in water-free ILs. Copper and brass generally suffer from severe attack in IL media at higher temperatures. However, it was demonstrated that corrosion inhibition is possible.