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 20026 Surface modification by argon plasma treatment improves antioxidant defense ability of CHO-k1 cells on titanium surfaces2014 - QUEIROZ, JANA D.F. de; LEAL, ANGÉLICA M. de S.; TERADA, MAYSA; AGNEZ-LIMA, LUCYMARA F.; COSTA, ISOLDA; PINTO, NADJA C. de S.; MEDEIROS, SILVIA R.B. deArtigo IPEN-doc 20058 Localized corrosion resistance and cytotoxicity evaluation of ferritic stainless steels for use in Implantable dental devices with magnetic connections2014 - MARQUES, ROGERIO A.; ROGERO, SIZUE O.; TERADA, MAYSA; PIERETTI, EURICO F.; COSTA, ISOLDAThe ferromagnetic property of ferritic stainless steels makes them potential materials for use as implantable dental devices with magnetic connections. In this work, the corrosion resistance and cytotoxicity of the AISI 444 ferritic stainless steel (SS) was evaluated in a phosphate buffer solution (PBS) and compared with two materials used for fabrication of implantable materials, specifically, NeoM (a ferritic type of SS) and ISO 5832-1 (an austenitic type of SS). All tested materials showed passivity in the PBS electrolyte used. Susceptibility to pitting corrosion in the test solution used however was only associated to the NeoM steel, that has been used in commercial dental implant devices. A large concentration of precipitates/inclusions of complex nature was found in the microstructure of this steel and it is the probable reason for its low resistance to localized corrosion, much lower than that of the AISI 444 SS used in this study. The AISI 444 stainless steel tested is a Nb and Ti stabilized steel and it presented mainly Nb and Ti rich types precipitates in its microstructure. No pits were seen at the surface of this last steel after polarization tests. The pitting resistance of the AISI 444 steel was compared to that of the ISO 5832-1 austenitic and it was found similar to this last steel that is well known for its good corrosion resistance performance. The results suggested that the AISI 444 steel is a potential candidate for replacement of the commercial ferromagnetic alloys currently used in dental prosthesis.