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2014-09-11 - Colloque/Présentation - communication orale - Anglais - 1 page(s)

Recloux Isaline, Mouanga Maixent, Khelifa Farid, Olivier Marie-Georges , "Silica mesoporous thin films hosting benzotriazole for protection of 2024 aluminum alloy – Study of healing mechanism" in EUROCORR 2014, Pise , Italie, 2014

  • Codes CREF : 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) Sol-gel coatings are increasingly studied for the replacement of hexavalent chromium based conversion due to their strong adhesion to metallic substrates and due to their high corrosion protection. However, due to their nature, they only act as passive physical barriers and cannot hamper corrosion propagation when the film presents failures. The introduction of organic or inorganic corrosion inhibitors in the layer has already been reported as a solution to provide defect-healing ability to the coating. The incorporation way of these agents is particularly important to obtain high performance. For example, introducing directly inhibitive compounds in the sol in high concentration may induce a deterioration of integrity and physical barrier properties of the sol-gel matrix. The use of inert nanostructures (such as halloysite, ion-exchange clays, nanoparticles…) as mediators to encapsulate corrosion inhibitors has consequently been considered to prevent detrimental interactions between the chemical compound and the sol-gel medium. In case of scratch or when stimulated by external action, nanocontainers release active species which form a local protective layer healing the defect. In the present work, a silica mesoporous thin film synthesized through “Evaporation Induced Self-Assembly” process was used as inhibitor nanocontainer for 2024 aluminum protection. The mesoporosity developed through the layer was employed to host benzotriazole which is known as an efficient corrosion inhibitor of AA 2024. From transmission electron microscopy (TEM) and adsorption porosimetry measurements, it was possible to determine high specific surface area and well-organized pores providing high-load ability for active species [1]. The inhibitor loading as well as the releasing rate from the film were determined by desorption in aqueous medium using UV/visible spectroscopy. A second copolymer based layer was applied on the loaded mesoporous film as a topcoat to confine corrosion inhibitors close to the metallic surface. An enhanced anticorrosion protection was observed using Electrochemical Impedance Spectroscopy (EIS) when the corrosion inhibitor is incorporated in the porosity. EIS measurements were complemented with Scanning Vibrating Electrode Technique (SVET) measurements in order to get a better understanding of the positive effect related to benzotriazole and to highlight healing mechanism. [1] I. Recloux, M. Debliquy, A. Baroni, Y. Paint, A. Lanzutti, L. Fedrizzi, M-G. Olivier, Optimization of synthesis parameters of mesoporous silica sol-gel thin films for application on 2024 aluminum alloy substrates, Applied Surface Science, 277 (2013) 201-210.