Multiscale study of the durability of anodized aluminum alloys
Etude multi-échelle de la durabilité d’alliages d’aluminium anodisés
Résumé
Two aluminum alloys 2017A and 5083 are anodized in a sulfuric acid bath by varying two parameters of the anodizing process, which are the anodization time and the applied current. For each material, the microstructure and the thickness of the oxide layer are examined under a scanning electron microscope (SEM). The ImageJ software is used to quantify, from SEM images of the analyzed samples, the distribution of the pores size as well as their surface density. The same samples are subjected to scratch tests with a constant and variable load successively, in order to study their resistance to this type of solicitation using post-mortem SEM observations. To estimate the durability against friction, cyclic friction tests are performed with a constant load. It has been found that the anodization time and applied current are for both alloys favorable for pore size, oxide layer thickness, scratch resistance and durability. As regards the porosity density, this increases for the 2017A alloy but remains constant or even decreases for the 5083 alloy. In addition to these results, microscopic observations and profilometric analyzes have made it possible to construct a scenario of the oxide layer growth rate and a tribological model correlating the properties of the oxide layers of the alloys studied with the Two aluminum alloys 2017A and 5083 are anodized in a sulfuric acid bath by varying two parameters of the anodizing process, which are the anodization time and the applied current. For each material, the microstructure and the thickness of the oxide layer are examined under a scanning electron microscope (SEM). The ImageJ software is used to quantify, from SEM images of the analyzed samples, the distribution of the pores size as well as their surface density. The same samples are subjected to scratch tests with a constant and variable load successively, in order to study their resistance to this type of solicitation using post-mortem SEM observations. To estimate the durability against friction, cyclic friction tests are performed with a constant load. It has been found that the anodization time and applied current are for both alloys favorable for pore size, oxide layer thickness, scratch resistance and durability. As regards the porosity density, this increases for the 2017A alloy but remains constant or even decreases for the 5083 alloy. In addition to these results, microscopic observations and profilometric analyzes have made it possible to construct a scenario of the oxide layer growth rate and a tribological model correlating the properties of the oxide layers of the alloys studied with the evolution of their friction coefficients and wear mechanisms. evolution of their friction coefficients and wear mechanisms
Deux alliages d’aluminium 2017A et 5083 sont anodisés dans un bain d’acide sulfurique en faisant varier deux paramètres du processus d’anodisation, que sont la durée d’anodisation et la densité de courant. Pour chaque matériau, la microstructure et l’épaisseur de la couche d’oxyde sont examinées au microscope électronique à balayage (MEB). Le logiciel ImageJ est utilisé pour quantifier à partir d'images MEB des échantillons analysés, la distribution de la taille des pores ainsi que leur densité surfacique. Les mêmes échantillons sont soumis à des tests de rayure avec une charge successivement constante et variable, afin d’étudier leur résistance à ce type de sollicitation grâce à des observations MEB post-mortem. Pour estimer la durabilité vis-à-vis du frottement, des essais cycliques de frottement sont réalisés avec une charge constante. Il a été trouvé que la durée d’anodisation et la densité de courant sont pour les deux alliages, favorables à la taille des pores, l’épaisseur de la couche d’oxyde, la résistante aux rayures et la durée de vie vis-à-vis du frottement. Pour ce qui est de la densité de porosité, celle-ci augmente pour l’alliage 2017A mais reste constante voire diminue pour l’alliage 5083. En plus de ces résultats, des observations microscopiques et des analyses profilométriques ont permis d’échafauder un scénario de croissance de la couche d’oxyde et un modèle tribologique corrélant les propriétés des couches d’oxyde des alliages étudiés à l’évolution de leurs coefficients de frottement et mécanismes d’usure.
Domaines
Matériaux| Origine | Version validée par le jury (STAR) |
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