Role of Smart-Release Pigments in Preventing Corrosion Driven Cathodic Disbondment of Organically Coated Hot Dip Galvanised Steel. Issue 1 (1st January 2023)

• Record Type: Journal Article
• Authors: Ansell, P.; Berry, L.; McGettrick, J.; Searle, J.; Wint, N.; McMurray, H. N.; Williams, G.
• Is Part Of: Journal of the Electrochemical Society. Volume 170:Issue 1(2023)
• Publication Date: 2023-01-01
• Subjects: Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/1945-7111/aca8d2
• Languages: English
• ISSNs: 0013-4651

Abstract

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 CO 3 2 − < MoO 4 2 − < NO 3 − < VO 4 3 − < WO 4 2 − < PO 4 3 − < 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.