Insight into the Role of Cerium (III) Addition to a MgAl-LDH Coating on AA6082

Featured Application Corrosion protection of aluminium alloys. In this work, Ce doped MgAl-LDHs layers have been developed through an in-situ synthesis method on 6082 aluminum surface. The aim was to gain mechanistic insight into the role of Ce(III) as an active corrosion inhibitor embedded in the LDHs layer. The development of the LDH structure was verified by checking the presence of the characteristic XRD peaks, the platelet morphology (evaluated by SEM-EDXS) and the functional groups (by FTIR-ATR analyses). The same techniques were employed to assess the effect of a prolonged immersion time in 0.1 NaCl on the Ce doped MgAl-LDH coatings. Electrochemical impedance spectroscopy (EIS) was employed to monitor the evolution of the electrochemical properties of the coatings during prolonged immersion in saline solutions. The findings suggest a crystallization/dissolution/precipitation mechanism which implies: (i) the formation of crystalline cerium compounds, such as Ce(OH)(3), in the LDH structure during the synthesis; (ii) the dissolution upon exposure to the NaCl solution, thus leading to cerium ions release; (iii) the precipitation of amorphous Ce oxides/hydroxides at the cathodic sites when the metal starts to corrode; (iv), the consequent mitigation of the electrochemical activity of the metal and, thus, the reduction of the extent of corrosion.

Automated summary

This study focuses on corrosion protection of aluminium alloys by developing Ce-doped MgAl-LDHs layers on the aluminum surface. The LDH structure development was confirmed through XRD peaks, SEM-EDXS evaluation, and FTIR-ATR analyses, with electrochemical impedance spectroscopy used to monitor the coatings' properties during prolonged immersion in saline solutions. The findings suggest a mechanism involving crystallization, dissolution, and precipitation of cerium compounds to mitigate corrosion of the metal.