Characterization by TEM and ToF-SIMS of the oxide layer formed during anaphoretic paint electrodeposition on Al-alloys

The present study assesses the formation of an interfacial oxide layer on aluminum alloys concomitant to the electrodeposition of an anaphoretic coating. The morphology, size, chemical composition and corrosion resistance properties are investigated for 2024-T3 clad aluminum substrate. The morphology and thickness of the oxide layer was examined using TEM. On the other hand, a ToF-SIMS method combining depth profiling and high resolution imaging has been developed as a new approach to determine simultaneously the chemical composition, the thickness and the homogeneity of the oxide layer. The results obtained with this method are validated through comparison with those from the TEM standard approach. Finally the two complementary methods have been used to investigate the growing mechanism of the oxide layer.