FERNANDA MARTINS QUEIROZ
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Artigo IPEN-doc 29855 Investigation on the Effect of a Chromium-Free Sealing Treatment for the Corrosion Resistance of AA2198-T851 after Tartaric Sulphuric Anodizing (TSA)2023 - QUEIROZ, FERNANDA M.; BUGARIN, ALINE de F.S.; AYUSSO, VICTOR H.; TERADA, MAYSA; COSTA, ISOLDAThe AA 2198-T851 is a third-generation Al-Li alloy developed for use in the aircraft industry. Al-Li alloys are susceptible to localized corrosion due to their complex microstructure resulting from the used thermomechanical treatment. In order to prevent localized corrosion, these alloys are usually protected by anodizing in order to avoid a corrosive environment. Subsequently, for anodizing, a sealing treatment is usually performed for parts. Some sealing treatments use hexavalent-chromiumion-containing solutions. In this investigation, a chromium-free sealing treatment in a solution with cerium ions has been carried out, and the effect on the corrosion resistance of the AA2198-T851 alloy was investigated. Hydrothermally sealed or unsealed samples were also tested for corrosion resistance for comparison reasons. The corrosion resistance of the anodized aluminum alloy, either hydrothermally sealed or in a cerium-ion-containing solution, was evaluated in a sodium chloride solution by electrochemical impedance spectroscopy as a function of immersion time. The samples sealed in a cerium-containing solution increased their corrosion resistance when compared to the hydrothermally sealed. The effectiveness of the sealing process with cerium that was observed in the electrochemical tests indicated that after the corrosive attack of the barrier layer, there was a “sealing” process of the sample surface.Artigo IPEN-doc 24726 On the AA2198-T851 alloy microstructure and its correlation with localized corrosion behaviour2018 - DONATUS, UYIME; TERADA, MAYSA; OSPINA, CARLOS R.; QUEIROZ, FERNANDA M.; BUGARIN, ALINE F.S.; COSTA, ISOLDAThe corrosion behaviour of AA2198-T851 alloy has been investigated using a combination of immersion tests and different microscopy techniques. Results showed that severe localized corrosion initiated within 1 h of corrosion immersion test in 0.01 mol L−1 NaCl solution. The corrosion mechanism in this alloy is intragranular and it propagates crystallographically. The propagation occurs through grain orientation dependent bands and it can be likened to the movement of dislocation through slip planes. Corrosion rings around stable pits result from pH variations. Secondary pits form around primary pits within corrosion rings and are preceded by hydrogen evolution.Artigo IPEN-doc 23605 Monitoramento da corrosão em ligas de alumínio dissimilares unidas por processo de soldagem por fricção e mistura (FSW) utilizadas no setor aeronáutico2016 - BUGARIN, A.F.S.; QUEIROZ, F.M.; TERADA, M.; MELO, H.G. de; COSTA, I.The corrosion behavior of the aluminum alloys ( AA2024 -T3 and AA7475 - T761 ) joined by the friction and mixing welding process (FSW) was monitored by immersion test in 10 mM NaCl solution as a function of exposure time to the test solution. The corrosion resistance was also evaluated by a gel test (agar- agar) by means of which the galvanic coupling between the two alloys was observed. The AA2024 alloy acted as the cathode and the AA7475 as the anode of the galvanically coupled pair. The immersion tests showed galvanic coupling in the mixed region (ZM) or nugget. The zone most affected by corrosion was the thermomechanically affected zone (ZTMA) at the interface with the thermally affected one (ZTA) on the side of the AA7475 alloy. At this interface, intergranular corrosion was seen from the first two hours of immersion.