MAYSA TERADA
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Resumo IPEN-doc 29187 Study of the effect of nanosecond laser texturing on the corrosion behavior of Ti6Al4V and Ti6Al4V parts produced by powder bed fusion2022 - QUEIROZ, FERNANDA M.; RIBEIRO, GLEICY de L.X.; CASTRO, RENATO S. de; SANTOS, ROGERIO G. dos; PORTO, JOAQUIM F.B.; SILVA, LEANDRO S. da; VIEIRA, ALEXANDRE; SANTOS, LUIS U. dos; TERADA, MAYSA; ROSSI, WAGNER de; COSTA, ISOLDABiomedical industry demands surfaces that facilitate osteointegration, especially in implants. Currently, this functional surface is obtained by coating the metallic implant with ceramic materials, such as hydroxyapatite, or with polymeric materials. However, these layers can suffer from detachment, residual stresses, and cracks during the process, favoring implant corrosion. Laser texturing is a surface structuring process that can improve osteointegration by generating functional hydrophilic surfaces. An alternative for the manufacture of components used as biomaterials can be additive manufacturing, followed by laser texturing. The 3D manufacturing process allows obtaining parts with complex geometry, weight reduction, and customized products that can serve the dental and biomedical sector. Combining metallic additive manufacturing with laser texturing would be an alternative in obtaining parts with functional hydrophilic surfaces, which improves osteointegration. In both cases, a careful study of the corrosion behavior of the surfaces obtained is necessary, since the evolution of this phenomenon can influence the osteointegration of the implant, causing the release of metal ions in the body and even the rejection of the component. This study compared the corrosion behavior of laser texturing Ti6Al4V components with components manufactured using laser power bed fusion of the same alloy followed by laser texturing. The Ti6Al4V components by laser powder bed melting were obtained by varying the scanning speed and power using a Yb laser. For laser texturing of the surfaces, a fiber optic laser of Yb was used. The corrosion behavior of the surfaces was evaluated by electrochemical impedance spectroscopy and characterized by SEM. The wettability was determined by the sessile drop method. The results showed the differences in the corrosion behavior of the surfaces produced by the different methods, in the hydrophilic character and microstructure.Artigo IPEN-doc 28897 Effect of pulsed and spray multipass MAG welding on the corrosion resistance of 316L stainless steel2021 - SILVA, JEFFERSON; REIS, SUELLEN; MAIA, ELOA L.; TERADA, MAYSA; BUGARIN, ALINE; BERBEL, LARISSA; ANDRADE, RAYANNE A.; GUILHERME, LUIS H.; COSTA, ISOLDAIn this study, the corrosion resistance of the ASTM A-240 TP 316L stainless steel submitted to a multipass metal active gas (MAG) welding was investigated. The stainless steel was MAG welded in two modes of metal transfer: pulsed and spray with protective gas (98% Argon and 2% Oxygen). The microstructure and corrosion resistance of base metal (BM) and fusion-zone (FZ) were characterized by scanning electron microscopy (SEM), ferritescope test, and anodic polarization tests. All zones were passive in the test solution (NaCl 1.0 mol L-1) followed by passive film breakdown with a potential increase. The BM showed a higher tendency to film breakdown comparatively to the FZ. The FZ in the spray process presented a passive film with higher breakdown resistance than the pulsed FZ.Artigo IPEN-doc 21675 Aplicação da microscopia eletroquímica de varredura no estudo da corrosão do aço inoxidável DIN W. Nr. 1.4460 com alto teor de nitrogênio2008 - TERADA, MAYSA; RAMASCO, BRUNO T.; SIMOES, ALDA M.P.; PADILHA, ANGELO F.; COSTA, ISOLDANeste trabalho, a microscopia eletroquímica de varredura (SECM) foi usada para investigar a concentração de espécies químicas liberadas pela corrosão e avaliar a resistência à corrosão localizada do aço inoxidável austenítico DIN W. Nr. 1.4460 com alto N. Este material apresenta potencialidade para aplicação como biomaterial pela completa ausência de fases ferromagnéticas. O potencial do ultra microeletrodo detectou não somente íons Fe2+ nas áreas anódicas, mas também o empobrecimento em oxigênio nas regiões catódicas. O aço foi ensaiado nas condições como recebido e solubilizado. Os resultados indicaram que o material como recebido apresenta superfície mais ativa que a do solubilizado. Análise da superfície por “Field Emission Gun” (FEG-SEM) mostrou grande quantidade de Cr2N os quais atuaram como nucleadores de pites, e que a corrosão se inicia na interface precipitado de nitreto/matriz.Resumo IPEN-doc 26831 Investigation of the evolution and influence of hardening phases on the corrosive behavior of AA21982019 - BUGARIN, ALINE F.S.; TERADA, MAYSA; POLITANO, RODOLFO; COSTA, ISOLDAThe Al-Li alloys are 2XXX series aluminum alloys and has been gaining space in the aeronautical applications. Adding 1% by weight of Li to aluminum, reducing by 3% at the final density and increasing by an average of 6% in the modulus of elasticity of the material. The characteristics and advantages presented by the Al- Li alloys, together with the growing interest of the aeronautical industry, have resulted in the interest in studying the relationship between the microstructure and its corrosion behavior. Alloy 2198 is a third generation of Al-Li alloys. Alloy elements such as Cu, Li and Mg promote the increase of the mechanical strength of the alloy by solid solution and the precipitation of phases T1 (Al2CuLi), Ɵ '(Al2Cu) or S (Al2LiMg). Phase T1 is the main hardening phase of the material and because it is more electrochemically active, it decreases the corrosion resistance. In this work, the AA2198 as received was solubilized at 500 °C to clear the thermal history of the material. A homogenization treatment was carried out for 1 h and 4 h with mechanical vacuum and an oven with argon controlled atmosphere. Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) tests were performed to verify the kinetics and influence of phase precipitations on the mechanical response of the material. The resistance to corrosion of the different homogenization conditions was investigated with electrochemical tests, such as Open Circuit Potential (OCP) and Polarization.Resumo IPEN-doc 26827 Effect of Ce on the corrosion resistance of anodized AA2024-T3 FSWed2019 - AGUIAR, DEIZE B. dos S.; QUEIROZ, FERNANDA M.; VERISSIMO, NATHALIA C.; AYUSSO, VICTOR H.; PEREIRA, VICTOR F.; FONSECA, EDUARDO B. da; MELO, HERCILIO G. de; COSTA, ISOLDA; TERADA, MAYSA; BUGARIN, ALINE F.S.Friction stir welding (FSW) is a solid-state joining technique, which has numerous advantages over conventional fusion techniques, such as automation and reproducibility, environmentally friendly, and capability to weld large thicknesses in a single pass. AA2024 are widely used in the aerospace industry due to their properties as lightweight, high specific strength and durability. However, they are prone to localized corrosion due to its high amount of intermetallics. New anodizing and sealing processes have been studied due to the environmental and health problems related to the sealing treatment containing hexavalent chromium ions. This has encouraged the search for new processes for surface treatment of metals. Recent studies are pointing towards tartaric-sulphuric anodizing, as a viable alternative for the corrosion protection of aluminum alloys, including surface treatments with cerium ions. Other promising method to protect the exposed metal surface is to use eco-friendly alternative corrosion inhibitors in combination with a barrier coating system. Sol–gel coatings have also been extensively studied as potential pre-treatments not associated to toxic residues for aluminum alloys surface preparation prior to paint. It has been demonstrated an efficient alternative for replacement of the chromate technology. In this study, friction stir welded samples were anodized and then sealed in an aqueous solution with the addition of cerium ions at 70 °C. The effect of Ce on the characteristics of the surface film formed, such as morphology and corrosion resistance, was investigated by SEM and electrochemical impedance spectroscopy. Samples unsealed or hydrothermally sealed were also tested for comparison. The EIS results showed that the addition of Ce (III) ions improved the corrosion resistance of the AA 2024-T3 TSA anodized and hydrothermal sealed.Resumo IPEN-doc 26826 Corrosion behavior of friction stir welded API X70 steel joints2019 - GIAROLA, JOSEANE M.; PEREIRA, GUALTER S.; KUGELMEIER, CRISTIE L.; TERADA, MAYSA; MARCOMINI, JOSE B.; ROVERE, CARLOS A.D.; AVILA, JULIAN A.; BOSE FILHO, WALDEK W.The ever-increasing demand for fossil fuels has pushed the oil and gas industry to search for new deep water wells and in more aggressive environmental conditions, such as the pre salt where the presence of CO2 and H2S concentrations, has led to the development of new materials and manufacturing processes. For pipeline construction, Friction Stir Welding (FSW) process is a promising candidate to be used in the girth welding procedure, and research studies must be carried out to understand the effect of this new processing on the pipeline life under the in-service conditions (environment, fatigue). The present work is part of a research project aiming to investigate the effect of a saline environment on the mechanical properties of an API-5L-X70 steel, welded by FSW. Therefore, in this work, the results of the corrosion behavior analysis carried out on the FSW welded joint, considering a 3.5% NaCl solution, are presented. The corrosion behavior was investigated based on potentiodynamic polarization tests on the different regions of FSW welded joint, i.e., the base metal (BM) and stirred zone (SZ). Gel visualization tests, considering the whole welded joint, were also conducted. The two FSW regions showed similar polarization curves in terms of corrosion potential (Ecorr), corrosion current density (icorr) as well as anodic current density values. In the gel tests, a preferential localized attack on any of the regions of the FSW welded joint was not observed. These results can be interpreted as evidence that the corrosion behavior of the FSW welded joint was not significantly affected by the different metallurgical microstructures formed by the FSW processing.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 25752 Corrosion resistance of tartaric-sulfuric acid anodized AA2024-T3 sealed with Ce and protected with hybrid sol–gel coating2019 - TERADA, M.; QUEIROZ, F.M.; AGUIAR, D.B.S.; AYUSSO, V.H.; COSTENARO, H.; OLIVIER, M.G.; MELO, H.G. de; COSTA, I.2024 aluminum alloys are widely used in the aerospace industry due to properties as lightweight, high specific strength and durability. However, they are prone to localized corrosion due to its high amount of intermetallics. A promising method to protect the exposed metal surface is to use eco-friendly alternative corrosion inhibitors in combination with a barrier coating system. In this study, a treatment in an aqueous solution with the addition of cerium ions has been proposed and its effects on the corrosion resistance of the AA2024-T3 alloy were investigated. Samples were anodized, hydrothermally treated in aqueous solutions, containing or not cerium ions at the boiling temperature and then coated with sol-gel. The effect of Ce ions in the characteristics of the surface film formed, such as morphology and corrosion resistance, was investigated by scanning electron microscopy and electrochemical impedance spectroscopy (EIS). The EIS results showed that the addition of Ce(III) ions improved the corrosion resistance of the AA 2024-T3 TSA anodized and hydrothermally treated.Resumo IPEN-doc 23379 Pitting corrosion resistance of friction stir welded lean duplex stainless steel UNS S82441 evaluated by cyclic potentiodynamic polarization and critical pitting temperature (CPT)2016 - LEITE, ANTONIO M. dos S.; TERADA, MAYSA; FONSECA, EDUARDO B. da; PEREIRA, VICTOR F.; COSTA, ISOLDADuplex stainless steels have been widely used in the manufacture of equipment and piping for different segments, such as chemical, pulp & paper and oil & gas. The major limitation of these steels is the precipitation of deleterious phases whenever they are exposed to high temperatures. This fact drastically reduces the corrosion resistance and mechanical properties of these materials. The friction stir welding (FSW) has been considered an alternative to replace fusion welding processes. FSW is a solid state welding process avoiding many of the weldability problems associated to conventional fusion techniques. In this paper, the corrosion resistance of friction stir welded lean duplex grade 2404 (UNS S82441) was evaluated by cyclic potentiodynamic polarization and critical pitting temperature (CPT) in Cl- containing media . The results indicated that for the conditions adopted the FSW process did not have a significant effect on the pitting corrosion resistance of the steel studied.