Effect of sealing treatment on the corrosion behavior of anodized AA2099 aluminum-lithium alloy

The corrosion behavior of the sulphuric-anodized AA2099 using two different current densities, 0.19 or 1.0 A.cm(2), with two different sealing treatments in H2O and 6 wt.% Na2Cr2O7 at 95 degrees C was studied in 3.5 wt.% NaCl and 10 vol.% H2SO4 solutions. The AA2099 is widely used in aeronautical applications, thus it is essential to present good corrosion performance in chloride and acid rain environments. The surface morphology of the anodized film was characterized by scanning electron microscopy (SEM), the electrochemical corrosion behavior was studied using electrochemical impedance (EIS), and finally characterization of the surface chemical composition was revealed by X-ray photoelectron spectroscopy (XPS). It was found the 6 wt.% Na2Cr2O7 sealing treatment imparts a more homogeneous and compact passive layer, and tends to increase the charge transfer resistance, thus improving the corrosion behavior of the anodized AA2099.