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Corrosion behaviour of brazed multilayer material AA4343/AA3003/AA4343: Influence of coolant parameters

Tierce, Séverin and Pébère, Nadine and Blanc, Christine and Casenave, Christian and Mankowski, Georges and Robidou, Herveline Corrosion behaviour of brazed multilayer material AA4343/AA3003/AA4343: Influence of coolant parameters. (2007) Corrosion Science, vol. 49 (n° 12). pp. 4581-4593. ISSN 0010-938X

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Official URL: http://dx.doi.org/10.1016/j.corsci.2007.04.013

Abstract

This paper is the second part of a work devoted to corrosion in brazed AA4343/AA3003/AA4343 materials on the water side of automotive heater cores. In the first part of the study [S. Tierce, N.Pébère, C. Blanc, C. Casenave, G. Mankowski, H. Robidou, Electrochim. Acta 52 (2006) 1092], corrosion initiation in the surface layer (i.e. the residual cladding) has been investigated. It has been associated to defective sites in the passive film covering the alloy. The defective sites are linked to a-Al(Mn,Fe)Si particles built up during brazing process. Interactions between a-Al(Mn,Fe)Si particles and the matrix are responsible for the observed behaviour. The present study focuses on the propagation of corrosion through the material in neutral water–ethylene glycol mixtures with and without chlorides. Comparison of the electrochemical behaviour of the three layers of the brazed material (i.e. the residual cladding, the "band of dense precipitates (BDP)" and the core material) revealed that the residual cladding was nobler than the BDP and the core material and thus that the corrosion should propagate through the inner layers due to galvanic coupling: the inner layers constitute the anode and the residual cladding the cathode. Increasing the ethylene glycol content in the water–ethylene glycol mixture decreased the rate of consumption of the materials whereas addition of chloride ions increased it. Mass variation measurements of brazed material in different solutions containing the degradation products of ethylene glycol showed that only glycolate ions had a slight detrimental effect. Corrosion tests performed in heater core tubes allowed the propagation mechanisms to be confirmed.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at Corrosion Science website : http://www.sciencedirect.com/science/journal/0010938X
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:Other partners > VALEO (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
French research institutions > Centre National de la Recherche Scientifique - CNRS
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Deposited By: Celine Cabaup

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