Potentiostatic control of ionic liquid surface film formation on ZE41 magnesium alloy

Jim Efthimiadis, Wayne Neil, Andrew Bunter, Patrick Howlett, Bruce Hinton, Douglas Macfarlane, Maria Forsyth

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The generation of potentially corrosion-resistant films on light metal alloys of magnesium have been investigated. Magnesium alloy, ZE41 [Mg−Zn−Rare Earth (RE)-Zr, nominal composition ∼4 wt % Zn, ∼1.7 wt % RE (Ce), ∼0.6 wt % Zr, remaining balance, Mg], was exposed under potentiostatic control to the ionic liquid trihexyl(tetradecyl)phosphonium diphenylphosphate, denoted [P6,6,6,14][DPP]. During exposure to this IL, a bias potential, shifted from open circuit, was applied to the ZE41 surface. Electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA) were used to monitor the evolution of film formation on the metal surface during exposure. The EIS data indicate that, of the four bias potentials examined, applying a potential of −200 mV versus OCP during the exposure period resulted in surface films of greatest resistance. Both EIS measurements and scanning electron microscopy (SEM) imaging indicate that these surfaces are substantially different to those formed without potential bias. Time of flight-secondary ion mass spectrometry (ToF-SIMS) elemental mapping of the films was utilized to ascertain the distribution of the ionic liquid cationic and anionic species relative to the microstructural surface features of ZE41 and indicated a more uniform distribution compared with the surface following exposure in the absence of a bias potential. Immersion of the treated ZE41 specimens in a chloride contaminated salt solution clearly indicated that the ionic liquid generated surface films offered significant protection against pitting corrosion, although the intermetallics were still insufficiently protected by the IL and hence favored intergranular corrosion processes.
Original languageEnglish
Pages (from-to)1317 - 1323
Number of pages7
JournalACS Applied Materials and Interfaces
Volume2
Issue number5
DOIs
Publication statusPublished - 2010

Cite this

Efthimiadis, Jim ; Neil, Wayne ; Bunter, Andrew ; Howlett, Patrick ; Hinton, Bruce ; Macfarlane, Douglas ; Forsyth, Maria. / Potentiostatic control of ionic liquid surface film formation on ZE41 magnesium alloy. In: ACS Applied Materials and Interfaces. 2010 ; Vol. 2, No. 5. pp. 1317 - 1323.
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abstract = "The generation of potentially corrosion-resistant films on light metal alloys of magnesium have been investigated. Magnesium alloy, ZE41 [Mg−Zn−Rare Earth (RE)-Zr, nominal composition ∼4 wt {\%} Zn, ∼1.7 wt {\%} RE (Ce), ∼0.6 wt {\%} Zr, remaining balance, Mg], was exposed under potentiostatic control to the ionic liquid trihexyl(tetradecyl)phosphonium diphenylphosphate, denoted [P6,6,6,14][DPP]. During exposure to this IL, a bias potential, shifted from open circuit, was applied to the ZE41 surface. Electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA) were used to monitor the evolution of film formation on the metal surface during exposure. The EIS data indicate that, of the four bias potentials examined, applying a potential of −200 mV versus OCP during the exposure period resulted in surface films of greatest resistance. Both EIS measurements and scanning electron microscopy (SEM) imaging indicate that these surfaces are substantially different to those formed without potential bias. Time of flight-secondary ion mass spectrometry (ToF-SIMS) elemental mapping of the films was utilized to ascertain the distribution of the ionic liquid cationic and anionic species relative to the microstructural surface features of ZE41 and indicated a more uniform distribution compared with the surface following exposure in the absence of a bias potential. Immersion of the treated ZE41 specimens in a chloride contaminated salt solution clearly indicated that the ionic liquid generated surface films offered significant protection against pitting corrosion, although the intermetallics were still insufficiently protected by the IL and hence favored intergranular corrosion processes.",
author = "Jim Efthimiadis and Wayne Neil and Andrew Bunter and Patrick Howlett and Bruce Hinton and Douglas Macfarlane and Maria Forsyth",
year = "2010",
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journal = "ACS Applied Materials and Interfaces",
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Efthimiadis, J, Neil, W, Bunter, A, Howlett, P, Hinton, B, Macfarlane, D & Forsyth, M 2010, 'Potentiostatic control of ionic liquid surface film formation on ZE41 magnesium alloy', ACS Applied Materials and Interfaces, vol. 2, no. 5, pp. 1317 - 1323. https://doi.org/10.1021/am900889n

Potentiostatic control of ionic liquid surface film formation on ZE41 magnesium alloy. / Efthimiadis, Jim; Neil, Wayne; Bunter, Andrew; Howlett, Patrick; Hinton, Bruce; Macfarlane, Douglas; Forsyth, Maria.

In: ACS Applied Materials and Interfaces, Vol. 2, No. 5, 2010, p. 1317 - 1323.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - Potentiostatic control of ionic liquid surface film formation on ZE41 magnesium alloy

AU - Efthimiadis, Jim

AU - Neil, Wayne

AU - Bunter, Andrew

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AU - Hinton, Bruce

AU - Macfarlane, Douglas

AU - Forsyth, Maria

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AB - The generation of potentially corrosion-resistant films on light metal alloys of magnesium have been investigated. Magnesium alloy, ZE41 [Mg−Zn−Rare Earth (RE)-Zr, nominal composition ∼4 wt % Zn, ∼1.7 wt % RE (Ce), ∼0.6 wt % Zr, remaining balance, Mg], was exposed under potentiostatic control to the ionic liquid trihexyl(tetradecyl)phosphonium diphenylphosphate, denoted [P6,6,6,14][DPP]. During exposure to this IL, a bias potential, shifted from open circuit, was applied to the ZE41 surface. Electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA) were used to monitor the evolution of film formation on the metal surface during exposure. The EIS data indicate that, of the four bias potentials examined, applying a potential of −200 mV versus OCP during the exposure period resulted in surface films of greatest resistance. Both EIS measurements and scanning electron microscopy (SEM) imaging indicate that these surfaces are substantially different to those formed without potential bias. Time of flight-secondary ion mass spectrometry (ToF-SIMS) elemental mapping of the films was utilized to ascertain the distribution of the ionic liquid cationic and anionic species relative to the microstructural surface features of ZE41 and indicated a more uniform distribution compared with the surface following exposure in the absence of a bias potential. Immersion of the treated ZE41 specimens in a chloride contaminated salt solution clearly indicated that the ionic liquid generated surface films offered significant protection against pitting corrosion, although the intermetallics were still insufficiently protected by the IL and hence favored intergranular corrosion processes.

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JF - ACS Applied Materials and Interfaces

SN - 1944-8244

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