New Insights into the Fundamental Chemical Nature of Ionic Liquid Film Formation on Magnesium Alloy Surfaces

Forsyth, Maria and Neil, Wayne C. and Howlett, Patrick C. and Macfarlane, Douglas R. and Hinton, Bruce R. W. and Rocher, Nathalie and Kemp, Thomas F. and Smith, Mark E. (2009) New Insights into the Fundamental Chemical Nature of Ionic Liquid Film Formation on Magnesium Alloy Surfaces. ACS Applied Materials and Interfaces, 1 (5). pp. 1045-1052. ISSN 1944-8244

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Abstract

Ionic liquids (ILs) based on trihexyltetradecylphosphonium coupled with either diphenylphosphate or bis(trifluoromethanesulfonyl)amide have been shown to react with magnesium alloy surfaces, leading to the formation a surface film that can improve the corrosion resistance of the alloy. The morphology and microstructure of the magnesium surface seems critical in determining the nature of the interphase, with grain boundary phases and intermetallics within the grain, rich in zirconium and zinc, showing almost no interaction with the IL and thereby resulting in a heterogeneous surface film. This has been explained, on the basis of solid-state NMR evidence, as being due to the extremely low reactivity of the native oxide films on the intermetallics (ZrO2 and ZnO) with the IL as compared with the magnesium-rich matrix where a magnesium hydroxide and/or carbonate inorganic surface is likely. Solid-state NMR characterization of the ZE41 alloy surface treated with the IL based on (Tf)2N− indicates that this anion reacts to form a metal fluoride rich surface in addition to an organic component. The diphenylphosphate anion also seems to undergo an additional chemical process on the metal surface, indicating that film formation on the metal is not a simple chemical interaction between the components of the IL and the substrate but may involve electrochemical processes.

Item Type:
Journal Article
Journal or Publication Title:
ACS Applied Materials and Interfaces
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/2500
Subjects:
?? MATERIALS SCIENCE(ALL) ??
Departments:
ID Code:
65103
Deposited By:
Deposited On:
07 Jun 2013 12:09
Refereed?:
Yes
Published?:
Published
Last Modified:
17 Sep 2023 01:24