Effect of cerium (IV) on thin sulfuric acid anodizing of 2024-T3 alloy

Chromic acid anodizing (CAA) is still being used today for corrosion protection of fatigue critical components in the aeronautic industry due to the lack of feasible alternatives. Cecontaining sulfuric acid anodizing (SAA) has been identified as a promising strategy for the development of alternatives to toxic CAA. This work explores thin sulfuric acid anodizing (TSAA) focusing on the following effects: (i) current density and voltage values; (ii) concentration of Ce(IV). Screening of the optimum combination in search of minimum thickness and the best corrosion resistance was performed using electrochemical impedance spectroscopy (EIS). Two Ce-containing anodic films were selected and further investigated in comparison with the inhibitor-free film in terms of morphology (FEG-SEM, TEM), composition (RBS), corrosion resistance (EIS, NSST), high-cycle fatigue and paint adhesion. The results indicate that the path to approach the CAA performance lies through thin (<1 mm) SAA-Ce films formed at low current density. (c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Chromic acid anodizing (CAA) is still commonly used in the aeronautic industry for corrosion protection, but Ce-containing sulfuric acid anodizing (SAA) has been identified as a promising alternative. This study found that thin sulfuric acid anodizing (TSAA) films containing Ce formed at low current density can approach the performance of CAA.