MAYSA TERADA
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Artigo IPEN-doc 26654 Effect of cerium addition to a hydrothermal treatment on the corrosion protection of the tartaric-sulfuric acid anodized AA2524-T32019 - TERADA, MAYSA; QUEIROZ, FERNANDA M.; COSTENARO, HELEN; AYUSSO, VICTOR H.; OLIVIER, MARJORIE; COSTA, ISOLDA; MELO, HERCILIO G. deTo protect Al alloys from corrosion, standard procedures in the aerospace industry use chromium-based acid anodizing with subsequent post-treatment steps also containing hexavalent chromium (Cr(VI)) ions. However, environmental and health related concerns associated with Cr(VI) have encouraged the search for new surface treatments providing effective corrosion protection without the drawback of generating toxic residues. In this investigation, a hydrothermal treatment in aqueous solution with cerium ions is proposed as a post-treatment for tartaric-sulfuric acid (TSA) anodizing, and its effects on the AA2524-T3 alloy corrosion resistance investigated. The effect of Ce on the characteristics of the surface film formed, such as morphology and corrosion resistance, is investigated by scanning electron microscopy and electrochemical impedance spectroscopy (EIS). The results show that the hydrothermal treatment in solution containing Ce(III) ions presents a less stable behavior than the treatment in boiling water. However, the results of the EIS experiments show recovery of the protective properties of the system, indicating that some self-healing properties must be imparted to the system.Artigo IPEN-doc 25934 Thermomechanical treatment and corrosion resistance correlation in the AA2198 Al–Cu–Li alloy2019 - ARAUJO, JOAO V. de S.; BUGARIN, ALINE de F.S.; DONATUS, UYIME; MACHADO, CARULINE de S.C.; QUEIROZ, FERNANDA M.; TERADA, MAYSA; ASTARITA, ANTONELLO; COSTA, ISOLDAThe influence of T3, T8 and T851 thermomechanical treatments on the microstructure and corrosion resistance of the AA2198 was investigated. Differential scanning calorimetry and scanning electron microscopy were used for microstructural characterisation, whereas electrochemical methods were employed to analyse the corrosion behaviour of the alloy. The morphology and composition of constituent particles were similar for the T3 and T8 thermomechanical treatments but varied in the T851. There was an inverse relation between T1 phase density and corrosion resistance. The T3 treatment with the highest corrosion resistance was the one with the lowest density of T1 phase. The mechanisms of corrosion varied with the thermomechanical treatments.Artigo IPEN-doc 23520 Correlation between microstructure and corrosion behavior of two Al–Fe–Si alloys2016 - YOSHIKAWA, D.S.; TERADA, M.; ASSIS, S.L.; COSTA, I.; PADILHA, A.F.In this work, the corrosion behavior of the AA4006 alloy made by the twin roll caster process was evaluated using electrochemical impedance spectroscopy (EIS), anodic potentiodynamic polarization curves, and scanning electron microscopy (SEM). This alloy belongs to the Al–Fe–Si system and is present with higher amounts of Fe and Si than AA1050 aluminum. Electrochemical tests were performed in a sulfate solution with or without chloride ions, and two different areas of the AA4006 alloy were tested: at the surface and at the center of the sheet (half thickness). The results obtained were compared to the commercially pure AA1050 aluminum. Electrochemical tests carried out using the solution without chloride ions presented similar results; however, the addition of chloride ions resulted in localized corrosion in all samples. It was possible to compare the corrosion behavior of the studied materials analyzing these electrochemical data and the micrographs obtained by scanning electron microscopy.Artigo IPEN-doc 14872 Use of SECM to study the electrochemical behaviour of DIN 1.4575 superferritic stainless steel aged at 475 sup(o)C2009 - TERADA, M.; PADILHA, A.F.; SIMOES, A.M.P.; MELO, H.G. de; COSTA, I.Artigo IPEN-doc 13023 Corrosion resistance of three austenitic stainless steels for biomedical applications2007 - TERADA, M.; ANTUNES, R.A.; PADILHA, A.F.; COSTA, I.