Effects of corrosion inhibiting pigment lanthanum 4-hydroxy cinnamate on the filiform corrosion of coated steel

Rainier Catubig, Marianne Seter, Wayne Neil, Maria Forsyth, Bruce Hinton

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Corrosion protection by lanthanum hydroxy cinnamate (La(4OH-cin) 3) in a polyurethane based varnish coating for mild steel has been investigated. Filiform scribe tests, energy-dispersive X-ray spectroscopy (EDXS) and potentiodynamic polarisation (PP) techniques have been powerful tools to better understand the corrosion process at defects and under the coating. Filiform scribe tests showed that La(4OH-cin)3, as a pigment in a coating, inhibited the initiation and propagation of both delamination and filiform corrosion (FFC) on coated steel. The PP experiments provided an insight into the fundamental mechanism of FFC. The results suggest that La(4OH-cin)3 behaves as a mixed inhibitor and stifles the initiation and propagation of FFC. In this paper, the theory of delamination leading to FFC and the likely mechanism of inhibition by the La(4OH-cin)3 will be discussed.

Original languageEnglish
JournalJournal of the Electrochemical Society
Issue number11
Publication statusPublished - 2011
Externally publishedYes

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