EIS investigation of a Ce-based posttreatment step on the corrosion behaviour of Alclad AA2024 anodized in TSA

Autor(es)

Prada Ramirez, Oscar Mauricio ; Queiroz, Fernanda Martins ; Terada, Maysa ; Donatus, Uyime ; Costa, Isolda ; Olivier, Marie-Georges ; de Melo, Hercilio Gomes

• Tipo de documento: Artigo Científico
• Fonte: SURFACE AND INTERFACE ANALYSIS; v. 51, n. 12, p. 16-pg., 2019-12-01.

Resumo

In the aircraft industry, anodizing and posttreatment steps use Cr (VI) compounds, which, despite offering good corrosion resistance and self-healing properties, are highly toxic and carcinogenic. Ce compounds are recognized as efficient corrosion inhibitors for Al alloys, and several works report self-healing ability for these chemicals. In this investigation, the corrosion resistance of Alclad AA2024-T3 alloy anodized in tartaric-sulphuric acid (TSA) bath and posttreated in a solution comprising cerium nitrate without and with hydrogen peroxide was evaluated. The purpose is to investigate the potentiality of using hydrothermal treatment in Ce nitrate solution as candidate to replace Cr (VI) posttreatment. The aim is to provide a posttreatment step which, while improving the corrosion resistance, does not plug the mouths of the pores maintaining the adhesion properties of the porous anodic layer. Microstructural characterization was carried out by SEM-EDS whereas corrosion resistance was evaluated by EIS. The surface analysis showed that the posttreatments, all performed at 50 degrees C, kept the open structure of the pores. EIS analysis showed that the posttreatments performed in the H2O2 solution for short immersion times were the most effective in improving the corrosion resistance of the samples, whereas electrical equivalent circuit (EEC) fitting of the data indicated sealing of the porous layer during the immersion of the different samples in the test solution. SEM-EDS analysis of the samples posttreated in the H2O2 containing solution, prior and after the corrosion test, showed the presence of Ce oxy-hydroxide randomly deposited on the sample surface, indicating that Ce could be incorporated/stored in the anodic layer. (AU)

• Processo FAPESP: 18/01096-5 - Estudo da corrosão da liga AA2024-T3 anodizada em TSA e protegida com íons Ce e por revestimento híbrido sol-gel
• Beneficiário: Hercílio Gomes de Melo
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 13/13235-6 - Estudo da corrosão localizada e caracterização da resistência à corrosão associada à fadiga na região de solda em ligas de alumínio de elevada resistência soldadas por fricção (FSW)
• Beneficiário: Isolda Costa
• Modalidade de apoio: Auxílio à Pesquisa - Temático