Ref.: MmeCo35-005

Corrosion resistance of AA2024-T3 anodized in TSA and protected with modified hybrid coating with addition of Ce ions

Apresentador: Oscar Mauricio Prada Ramirez

Autores (Instituição): Prada Ramirez, O.M.(Universidade de São Paulo); De Melo, H.G.(Universidade de São Paulo);

Resumo:
Chromium-based anodizing and post-treatment steps are the benchmark in the aircraft industry. Despite offering good corrosion resistance and self-healing properties, as chromate compounds are toxic for health and the environment, these surface treatments will be prohibited in the aerospace industry in a near future. Tartaric-sulfuric acid (TSA) anodizing is a promising environment compliant alternative, which is already being used at industrial level. However, the corrosion resistance of the anodized layer alone is not sufficient to guarantee the required safety levels for an aircraft and more complex systems should be employed. In this investigation, AA2024-T3 specimens were anodized in TSA and subsequently post-treated in a Ce-H2O2 solution and sealed by a hybrid sol–gel coating (tetraethoxysilane (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS)), modified with addition of Ce ions. The morphology of the sealed anodic films, their thicknesses and the Ce distribution were evaluated by field emission scanning electron microscopy (FE-SEM) and Rutherford Backscattering Spectrometry (RBS) and Transmission electron microscopy (TEM). Aging of the hydrolysis solution was followed by FTIR spectroscopy and viscosity measurements. The corrosion resistance of the samples anodized, and hybrid sol-gel coted was evaluated by electrochemical impedance spectroscopy (EIS). FE-SEM characterization showed good coverage of the anodized surface by the hybrid layer and greater thicknesses for the Ce containing coating. EIS experiments demonstrated improved corrosion resistance for the Ce containing coating.