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2013-04-25 - Colloque/Présentation - communication orale - Anglais - 1 page(s)

Romano Anne-Pascale , Poelman Mireille , Olivier Marie-Georges , "Investigation by electrochemical techniques of delamination and filiform corrosion of steel and aluminium substrates protected by organic coatings" in AETOC 2013 (Application of Electrochemical techniques to Organic Coatings), Emmetten, Suisse, 2013

  • Codes CREF : Chimie des surfaces et des interfaces (DI1327), Corrosion des matériaux (DI2114)
  • Unités de recherche UMONS : Science des Matériaux (F502)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)
  • Centres UMONS : Ingénierie des matériaux (CRIM)

Abstract(s) :

(Anglais) In automotive industry, cataphoretic coating is applied on the body car after assembling. The body car is composed of different metallic substrates such as steel, galvanized steel and aluminium alloys of 6xxx series. All the substrates are more or less sensitive to anodic or cathodic delamination and filiform corrosion… These kinds of undermining corrosion depend on many parameters such as the nature of the substrate, the surface treatment, the coating properties, the nature of the salts species during corrosion initiation... The aluminium alloys were particularly investigated in previous works. However in the last years, due to its low cost and high mechanical properties, steel is again used more currently in the automotive industry. Electrochemical techniques are currently used to investigate the undermining phenomena. Electrochemical impedance spectroscopy can be used to evaluate in short time the sensitivity to filiform corrosion and delamination of the different substrates through the estimation of the exposed metallic area. This is possible if the corrosion products are correctly dissolved before characterization. Their presence may indeed hinder the metal activity leading to an underestimation of the delaminated area. Removing corrosion productions needs to be optimized for each substrate. This study mainly focuses on the different behaviours and operating conditions which allow characterizing the extent of delamination and filiform corrosion for aluminium and steel substrates. In order to obtain more information about the initiation and propagation of delamination, these measurements have to be coupled with localized electrochemical measurements and more particularly Kelvin Probe potential maps. This technique gives cartography of the spatial separation of the anodic and cathodic areas underneath the coating and is used to follow delamination profiles and evidencing the influencing factors.