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Role of Smart-Release Pigments in Preventing Corrosion Driven Cathodic Disbondment of Organically Coated Hot Dip Galvanised Steel

Philip Ansell, Lewis Berry, James McGettrick Orcid Logo, Justin Searle Orcid Logo, Natalie Wint, Hamilton McMurray, Geraint Williams Orcid Logo

Journal of The Electrochemical Society, Volume: 170, Issue: 1, Start page: 011502

Swansea University Authors: Philip Ansell, Lewis Berry, James McGettrick Orcid Logo, Justin Searle Orcid Logo, Natalie Wint, Hamilton McMurray, Geraint Williams Orcid Logo

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Abstract

The role of smart-release corrosion inhibitive pigments in preventing cathodic delamination of organically coated hot-dip galvanized steel (HDG) is investigated. The pigments consisted of hydrotalcite (HT) exchanged with a range of inorganic and organic anionic species and were dispersed in a model...

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Published in: Journal of The Electrochemical Society
ISSN: 0013-4651 1945-7111
Published: The Electrochemical Society 2023
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa62641
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Abstract: The role of smart-release corrosion inhibitive pigments in preventing cathodic delamination of organically coated hot-dip galvanized steel (HDG) is investigated. The pigments consisted of hydrotalcite (HT) exchanged with a range of inorganic and organic anionic species and were dispersed in a model PVB coating. A scanning Kelvin probe (SKP) technique was used to determine cathodic delamination rates, and the inhibition efficiencies obtained for inorganic ions increased in the order ${{{\rm{CO}}}_{3}}^{2-}$ < ${{{\rm{MoO}}}_{4}}^{2-}$ < ${{{\rm{NO}}}_{3}}^{-}$ < ${{{\rm{VO}}}_{4}}^{3-}$ < ${{{\rm{WO}}}_{4}}^{2-}$ < ${{{\rm{PO}}}_{4}}^{3-}$ < ${{{\rm{CrO}}}_{4}}^{2-}.$ The inhibition efficiencies for organic-based pigments increased in the order triazole <phenylphosphonate <trans-cinnamate <benzoate <salicylate <benzotriazole. The inhibition efficiency afforded by the best performing organic inhibitor, benzotriazole (BTA), rivalled that of HT containing stored chromate anions. Findings are consistent with HT-BTA acting to sequester anions from the underfilm electrolyte, releasing BTA− which subsequently strongly adsorbs on the underfilm metal surface but can also form an insoluble Zn-BTA precipitate at the coating-defect boundary.
College: Faculty of Science and Engineering
Funders: The authors would like to thank TATA Steel for providing the samples and EPSRC for the funding of the EngD studentships via the Collaborate Training Account (GR/T11333/01). We would also like to acknowledge the assistance provided by Swansea University College of Engineering AIM Facility, which was funded in part by the EPSRC (EP/M028267/1), the European Regional Development Fund through the Welsh Government (80708) and the Ser Solar project via Welsh Government. Furthermore, we would like to thank everyone at SPECIFIC IKC which was funded by WEFO (c80892) and EPSRC (EP/N020863/1) for their help support and guidance.
Issue: 1
Start Page: 011502