Initial stages of localized corrosion at cut-edges of adhesively bonded Zn and Zn-Al-Mg galvanized steel

authors	Yasakau, KA; Kallip, S; Lisenkov, A; Ferreira, MGS; Zheludkevich, ML
nationality	International
journal	ELECTROCHIMICA ACTA
author keywords	galvanized steel; cut-edge; localized corrosion; in situ AFM; adhesive
keywords	ZN(MG,AL) COATED STEEL; MECHANISTIC APPROACH; POLYMERIC COATINGS; ZINC; DELAMINATION; RESISTANCE; INHIBITION; ALLOYS; DEFECT; MODEL
abstract	The mechanisms of the initial stages of localized corrosion at cut edges were investigated for adhesively bonded Zn (Z) and Zn-Al-Mg (ZM) galvanized steel. The results provided strong evidence for the localized nature of corrosion of galvanized coatings at the cut edges and at the adhesive/zinc interface. In both cases a defined localized corrosion attack on zinc in Z sample was observed. On the contrary, in the case of the ZM specimen both zinc solid solution and eutectics exhibited local corrosion. The local attack at the adhesive/Z(ZM) interface was correlated with an anodic undermining process. It develops near the cut-edge surface and at the buried deep adhesive-zinc interface and results in adhesive disbonding in the buried interface. The electrochemical studies revealed that the corrosion kinetics at the metal cut-edges decreases during immersion, which could be due to formation of corrosion products on both steel and zinc surfaces. (C) 2016 Elsevier Ltd. All rights reserved.
publisher	PERGAMON-ELSEVIER SCIENCE LTD
issn	0013-4686
year published	2016
volume	211
beginning page	126
ending page	141
digital object identifier (doi)	10.1016/j.electacta.2016.06.045
web of science category	Electrochemistry
subject category	Electrochemistry
unique article identifier	WOS:000380904100016