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Corrosion of mg alloy ZE41 and its mitigation using ionic liquids

conference contribution
posted on 01.01.2010, 00:00 authored by W Neil, Maria ForsythMaria Forsyth, Bruce HintonBruce Hinton
Magnesium alloy ZE41 (Mg-Zn-RE-Zr), which is used extensively in the aerospace industry, possesses excellent mechanical properties albeit poor corrosion resistance. This work investigates the mechanism of corrosion, and the interaction between the grain boundary intermetallic phases, the zirconium (Zr)-rich regions within the grains and the bulk Mg rich matrix in both the as-cast and heat-treated conditions. The results of optical and scanning electron microscopy (SEM) show the importance of the microstructure in the initiation and propagation of corrosion in an aqueous environment. The Zr-rich regions play a distinct role in the early stages of corrosion with this alloy. The second part of this work investigates the interaction of two different ionic liquids (ILs) with the surface of the ZE41 alloy. ILs based on trihexyltetradecylphosphonium (P 6,6,6,14) coupled with either diphenylphosphate (DPP) or bis(trifluoromethanesulfonyl) amide (Tf 2N) have been shown to react with Mg alloy surfaces, leading to the formation of a surface film that can improve the corrosion resistance of the alloy. The interaction of the ILs with the ZE41 surface has been investigated by optical microscopy and SEM. Surface characterization has been performed using Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) and X-ray Photoelectron Spectroscopy (XPS). The surface characterization and microscopy revealed the preferential interaction with the grain boundaries and grain boundary phases. Thus the morphology and microstructure of the Mg surface seems critical in determining the nature of the interaction with the IL. The corrosion protection of the IL films formed on the ZE41 surface was investigated by SEM and potentiodynamic polarisation.

History

Event

Australasian Corrosion Association. Conference (50th :2010 : Adelaide, South Australia)

Pagination

431 - 445

Publisher

Australasian Corrosion Association

Location

Adelaide, South Australia

Place of publication

Melbourne, Vic.

Start date

14/11/2010

End date

17/11/2010

ISBN-13

9781617824791

Language

eng

Notes

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Publication classification

E1.1 Full written paper - refereed

Copyright notice

2010, Australasian Corrosion Association

Title of proceedings

ACA 2010 : Corrosion and Prevention : Proceedings of the 2010 Australasian Corrosion Association Conference