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Le contrôle de réactivité d'aluminium en peinture anti-corrosion résistant à la haute température

Abstract : The aim of this work is to understand Al reactivity at a fundamental level and to use this knowledge for the development of Cr(VI)-free sacrificial paints for high temperature aeronautic applications.Pure Al, Al intermetallics and alloys are studied. The atomic emission spectroelectrochemistry is used to isolate the individual phenomena during paint degradation. A linear relationship between cathodic current and Al dissolution is shown and interpreted with a simple model where OH- generation, Al(OH)3 formation/dissolution and Al(OH)4− diffusion are kinetically coupled. For early formulations significant binder dissolution is measured under cathodic polarization, while Al reactivity is suppressed. Similar Al behavior is observed for Al-Mg intermetallics. In terms of the cathodically generated hydroxide mechanism these results are interpreted as the reaction of either Si or Mg with OH-. These results confirm the cathodic Al reactivity model. The loss of anodic activity is explained by the loss of electrical contact at the metal/oxide/polymer/substrate interfaces and the oxide layer modifications are studied to circumvent this problem. It is found that Mg2+ ions retard Al passivation and improve conductivity due to the formation of semiconducting spinel. Finally, two major factors are found to be critical for the Al reactivity control: solution pH and oxide properties. Using additives to control them, the new coating formulation stable up to 550°C and protective more than 1000H in salt spray test is developed
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https://tel.archives-ouvertes.fr/tel-00836639
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Submitted on : Friday, June 21, 2013 - 12:05:14 PM
Last modification on : Monday, December 14, 2020 - 9:48:23 AM
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  • HAL Id : tel-00836639, version 1

Citation

Maria Serdechnova. Le contrôle de réactivité d'aluminium en peinture anti-corrosion résistant à la haute température. Chimie théorique et/ou physique. Université Pierre et Marie Curie - Paris VI, 2012. Français. ⟨NNT : 2012PAO66287⟩. ⟨tel-00836639⟩

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