Influence of friendly pre-treatments composition on aluminium surface morphology

During aluminium alloy processing and storage, oils or temporary corrosion control measures might be applied, producing organic residuals on the alloy surface. For those reasons, prior to application of a permanent corrosion protection treatment, it is necessary to perform a pre-treatment in order to remove all organic contaminants, the near-surface deformed layer and to activate the surface. This ensures a homogeneous and reproducible response to the subsequent protective treatment. Such pre-treatment generally involves the immersion of the part in a chromium-based electrolyte. In this paper the effect of friendly pre-treatment solutions on the final surface morphology of AA2024-T3 has been investigated by scanning electron microscopy observations and energy dispersive X-ray spectrometry measurements. Electrochemical impedance spectroscopy and potentiodynamic polarization analysis were applied to disclose the corrosion behaviour after pre-treatments.