Ionic Liquids (ILs) are salts composed of large and non symmetrical ions [I]. Such irregular shapes prevent the ions packing neatly, so that the salts are liquids ...
3rd Microsymposium: Corrosion and Protection o f Materials
CORROSION O F M ETALS AND ALLOYS IN IONIC LIQUIDS Perissi I.'. C aporali S.1, Fossati A .', Lavacchi A.2
1Dipartimento di Chimica, Universita degli Studi di Firenze, Sesto Fiorentino, Italy, 2Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), Sesto Fiorentino, Italy Ionic Liquids (ILs) are salts composed o f large and non symmetrical ions [I]. Such irregular shapes prevent the ions packing neatly, so that the salts are liquids even at room and lower temperatures. The own conductivity permits the electrons transfer from metallic material to the media, and, potentially, corrosion phenomena may occur. During the last few years, they have been widely investigated for a variety o f applications: the use as solvents for chemical synthesis [2,3], media for electrodeposition of metals [4-6], electrolyte for electrochemical devices such as batteries , supercapacitors [8 ], fluids for thermal storage and exchange in solar concentrating power plants , as additives to prevent corrosion in aqueous solutions . Many o f such industrial applications have required investigating the interactions between metals and alloys and the ILs to establish their chemical activity as possible corrosive agents. The study is resulted challenger because o f both the not trivial chemical-physical characterization o f the room temperature molten salts (thermal stability, conductivity, viscosity, vapor pressure, mass transport issues and so on) as well as the need o f a deep revision o f the application o f the model and the methods o f the corrosion study used in aqueous solution or in molecular liquids solvents. The corrosion behavior of several ILs, especially based on bis(trifluoromethylsulphonyl)imide anion were investigated in contact with a variety o f metals and alloys (copper, nickel, brass, carbon and stainless steels, Inconel) by room temperature electrochemistry techniques and by immersion tests up to 200 °C. The nature o f corrosion morphology has been deeply investigated by SEM and EDAX analysis and the depth profile o f the interaction layer by SIMS spectrometry. All the investigations were conducted in the ILs ‘as purchased’ and in open to air conditions. The results show a complex behavior o f the different combinations o f substrate and ILs. In several cases, important corrosion phenomena were observed that can be attributed at the presence o f ILs impurities and at the presence o f dissolved oxygen (from air). The investigated topics will be the object o f future studies being crucial in the path for the characterization o f the ILs corrosion behaviors. References M.J. Earle, K.R. Seddon, Pure Appl. Chem. 72 (7), (2000) 1391-1398. J.D. Holbrey, K.R. Seddon, Clean Prod. Proc. (1999) 223-236. T. Welton, Chem. Rev. 99 (1999) 2071. F. Endres, ChemPhysChem 3-236 (2002) 144-154. Y.F Lin, I. Wen Sun, Electrochim. Acta 44 (1999) 2771-2777 S. Takahashi, N. Koura, S. Kohara, M.L. Saboungi, L.A. Curtiss Plasmas Ions, 2 (1999) 91-105. 7. J.F. Brennecke, E.J. Magin, AIChEJ. 47 (2001) 2384-2389/ 8. A. Balducci, U. Bardi, S. Caporali, M. Mastragostino, F. Soavi, Electrochem. Commun. 6 (2004) 566-570. 9. 1. Perissi, U. Bardi, S. Caporali, A. Fossati, A. Lavacchi, Sol. Energy Mater. Sol. Cells (2008)510-517. 10. Q. Zhang, Y. Hua, Mater. Chem. Phys. 119 (2010) 57-64.
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