Microstructural and electrochemical characterization of environmentally friendly conversion layers on aluminium alloys

Journal of the Brazilian Chemical Society

Luis Enrique M. Palomino¹  João Fábio W. De Castro¹  Idalina V. Aoki¹  Hercílio G. De Melo¹ 

[1] ,Universidade de São Paulo Departamento de Engenharia Química São Paulo SP ,Brazil

关键词: AA2024;    EIS;    EDX;    cerium conversion layer;    Cu content;   

DOI  :  10.1590/S0103-50532003000400024

来源: SciELO

【 摘 要 】

Cerium conversion layers (CeCL) have been investigated as a replacement for chromium conversion layers to protect Al alloys against corrosion. In this work the microstructure and the electrochemical behaviour of aluminium alloy 2024 with and without CeCL were investigated using, respectively, SEM-EDX and EIS. EDX results have shown that the presence of dispersed plated Cu particles on the alloy surface enhances the formation of the CeCL increasing the intensity of Ce peaks in the EDX spectra. EIS measurements on conversion-coated samples have shown that the presence of the layer increases the impedance, and that its presence is detected by the presence of a high frequency time constant. Results of potentiodynamic experiments have shown that the corrosion protection afforded by the conversion layer is due to the hindrance of the oxygen reduction reaction and that the pitting potential of the alloy is not changed.

【 授权许可】

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