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Conversion coatings of Mg-alloy AZ91D using trihexyl(tetradecyl) phosphonium bis(trifluoromethanesulfonyl)amide ionic liquid

journal contribution
posted on 01.08.2012, 00:00 authored by Patrick HowlettPatrick Howlett, S Gramet, J Lin, J Efthimiadis, Xiaobo Chen, N Birbilis, Maria ForsythMaria Forsyth
This work reveals the performance of a trihexyl(tetradecyl)phosphonium bis(trifluoromethanesulfonyl)amide ([P6,6,6,14][NTf2]) ionic liquid (IL) conversion coating upon AZ91D. Such conversion coatings represent a novel avenue for chromate replacement. An optimization of coating performance was pursued by careful alloy pretreatment to generate a surface on which the coating performs best, as the AZ91 substrate is distinctly different from pure or dilute Mg alloys. The results reveal that a functional conversion coating can be achieved, retarding anodic dissolution kinetics, causing a significant decrease in corrosion rate. The coating efficacy is closely tied to the pretreatment performed, which dictates both the microstructural and electrochemical heterogeneity of the surface. The resulting coatings were found to contain MgxFx and phosphonium cation related components, the proportions of which were dependent on the pretreatment.

History

Journal

Science China chemistry

Volume

55

Issue

8

Pagination

1598 - 1607

Publisher

Springer

Location

Berlin, Germany

ISSN

1674-7291

eISSN

1869-1870

Language

eng

Publication classification

C1 Refereed article in a scholarly journal