RAFAEL EMIL KLUMPP
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Resumo IPEN-doc 30341 Corrosion and anodizing behavior of dissimilar AA5052-H32 and AA6061-T6 alloys joined by metal inert gas welding2023 - KLUMPP, RAFAEL E.; AKBARZADEH, SAJJAD; DELAUNOIS, FABIENNE; COSTA, ISOLDA; OLIVER, MARIE-GEORGESEnormous efforts have been made to reduce fossil fuel consumption and greenhouse gas emissions in several sectors, such as the transport and agricultural sectors. Weight reduction is an efficient way to reduce fuel consumption. In this context, Aluminum alloys are excellent choices due to their properties of lightweight and high strength. However, corrosion is a major concern when using dissimilar alloys joined by welding. This might result in galvanic corrosion. Also, thermal effects during welding might affect the microstructure and the material corrosion resistance. Consequently, the study of dissimilar materials joined by welding is of great importance. In order to decrease corrosion susceptibility, surface protection of aluminum alloys against corrosion is a core issue in these applications. In this work, the corrosion resistance of the AA5052- H32 and AA6061-T6 alloys welded by metal inert gas (MIG) welding, with or without TSA anodizing, was investigated. The corrosion resistance was evaluated by immersion tests in sodium chloride solution and monitored by electrochemical impedance spectroscopy (EIS) and as scanning vibrating electrode technique (SVET). The anodic layers formed by TSA anodizing were analyzed and characterized by Scanning Electron Microscopy with EnergyDispersive Spectroscopy (SEM-EDS) and Transmission Electron Microscopy (TEM). The results present the correlation between corrosion resistance, microstructure and surface film characteristics.Resumo IPEN-doc 29501 The effect of tartaric-sulfuric acid (TSA) anodizing on the corrosion resistance of the AA7475-T7612022 - ARAUJO, JOAO V.; MILAGRE, MARIANA X.; GABBARDO, ALINE D.; KLUMPP, RAFAEL E.; COSTA, ISOLDAThe microstructure of the high strength aluminum alloy, AA7475–T761, in the as-received condition was characterized by optical microscopy, scanning electron microscopy and transmission electron microscopy, and statistical analyses of grain size and micrometer precipitates distribution and density were performed. An anodic aluminum oxide (AAO) film was potentiostatically grown on the alloy in tartaric sulfuric acid (TSA). The anodizing behavior of the alloy and the mechanisms of localized corrosion initiation and propagation in bare (not anodized) and anodized conditions were discussed. The alloy corrosion behavior was investigated in sodium chloride solutions using electrochemical techniques (cyclic potentiodynamic polarization) and the morphology and extent of corrosion propagation was investigated through optical microscopy, optical profilometry and scanning electron microscopy analyses. It was observed that the two alloy surface conditions (bare and anodized) play different roles in the propagation of the localized corrosion process. The bare alloy presented lower localized corrosion potentials and the propagation of the localized corrosion was shallower, but more heavily distributed, than in the anodized condition. However, the alloy in the anodized condition presented lower repassivation potentials due to the deeper pits formed. In addition, the variability of pitting potentials for the anodized condition was high, due to the heterogenous structure of the AAO film formed, and dependent on the time and drying storage conditions previous to electrochemical characterizations. The electrochemical results were correlated with the microstructural characteristics of the oxide surface film of the alloy in both conditions, bare (not anodized) and anodized.Resumo IPEN-doc 29258 Selagens ambientalmente amigáveis para a nova geração de ligas de alumínio-lítio, AA2198-T851 anodizadas2022 - PEREIRA, BRUNO N.; COSTA, ISOLDA; KLUMPP, RAFAEL E.Artigo IPEN-doc 29079 A cerium-based nanocoating for corrosion protection of the AA1230 as clad material for the AA2024-T3 alloy2022 - KLUMPP, RAFAEL E.; ARAUJO, JOAO V. de S.; ANTUNES, RENATO A.; VIVEIROS, BARBARA V.G. de; MAGNANI, MARINA; COSTA, ISOLDAAluminum alloys are the state-of-art materials for structural components of aircrafts. As they are susceptible to localized corrosion, this kind of damage can become a major threat for its safe use in aircraft components. Therefore, surface protection of aluminum alloys against corrosion is a core issue in these applications. In this work, an alternative eco-friendly cerium-based surface pretreatment was developed and applied on the AA1230 clad of the AA2024-T3 alloy for corrosion protection. The corrosion resistance evaluation of this modified surface was evaluated by several techniques. The results were compared to chromium based conventional treatments and revealed that the coating layer, composed of spherical nodular nanostructures of cerium, obtained with the proposed eco-friendly treatment, improved the corrosion resistance of the alloy. Moreover, it was comparable to the corrosion behavior of chromate-treated alloy, showing that this treatment is a promising alternative to replace chromate based surface treatments.Resumo IPEN-doc 28892 A cerium-based nanocoating for corrosion protection of clad on AA 2024-T3 alloy2021 - KLUMPP, RAFAEL E.; MACHADO, CARULINE de S.C.; ARAUJO, JOAO V. de S.; ANTUNES, RENATO A.; MAGNANI, MARINA; COSTA, ISOLDAAluminum alloys are susceptible to localized corrosion resulting in a major risk for aircrafts due to the extensively use of this material in their structures. Therefore, the surface protection of these alloys against corrosion is fundamental. In this work, an eco-friendly surface pretreatment cerium based for corrosion protection alternatively to chromate based ones was developed and applied on the clad of the 2024-T3 aluminum alloy. The corrosion resistance of the modified surface was evaluated by electrochemical impedance spectroscopy, polarization and Scanning Vibrating Electrode Techniques The results obtained were compared to a chromium based conventional treatment and revealed that the coating layer resulting from the tested treatment resulted in a film composed by spherical nodular nanostructures of cerium that improved the corrosion resistance of the alloy studied and it was comparable to the effect of treatment with hexavalent chromium showing it is an promising alternative to replacing treatments based on environmental harmful treatments.Artigo IPEN-doc 28770 TSA anodising voltage effects on the near-surface coarse intermetallic particles in the AA2024-T3 and AA2198-T8 alloys2022 - ARAUJO, JOAO V. de S.; MILAGRE, MARIANA X.; KLUMPP, RAFAEL E.; AYUSSO, VICTOR H.; DONATUS, UYIME; COSTA, ISOLDAIn this study, the behaviour of the micrometric particles of the AA2198-T8 alloy during anodising at various voltages and the effect of anodising voltage on the anodised surface morphology have been investigated in a tartaric-sulfuric acid anodising solution. The results were compared with that of the AA2024-T3 alloy. For the AA2198-T8 alloy, partial dissolution of these particles occurred at 0, 3 and 4 V. Besides, for potentials above 5 V, there is a preferential dissolution of the intermetallic particles. For the AA2024-T3 alloy, the results indicated a total dissolution of the micrometric particles at 0 V and a partial dissolution at 3 V, whereas above 4 V total dissolution occurred. Between 1 and 2 V, no dissolution was observed for both alloys. The preferential dissolution of the micrometric particles resulted in defects in the anodic film and cavities on the anodised surfaces.Artigo IPEN-doc 28531 Influence of chloride ions concentration on the development of severe localised corrosion and its effects on the electrochemical response of the 2198-T8 alloy2021 - MACHADO, CARULINE de S.C.; SILVA, REJANE M.P. da; ARAUJO, JOAO V. de S.; MILAGRE, MARIANA X.; DONATUS, UYIME; VIVEIROS, BARBARA V.G. de; KLUMPP, RAFAEL E.; COSTA, ISOLDAThe development of severe localised corrosion (SLC) on the 2198-T8 alloy was investigated in solutions of various NaCl concentrations (0.001, 0.005 and 0.01 mol L−1). Immersion tests, optical profilometry, conventional and local electrochemical analyses were performed to evaluate the corrosion behaviour of the alloy. Immersion tests showed that the alloy is susceptible to SLC in all conditions, although the pits sizes were dependent on the solution concentration. The largest anodic areas, corresponding to SLC sites, were observed for the sample immersed in 0.001 mol L−1 NaCl, whereas pits with similar sizes were observed for the samples immersed in solutions with 0.005 and 0.01 mol L−1 of NaCl. Moreover, the maximum depth of attack was observed for the sample immersed in 0.001 mol L−1 NaCl. These results were in agreement with the scanning ionselective electrode technique (SIET) maps which showed stronger acidification on the sample exposed to 0.001 mol L−1 NaCl solution.Artigo IPEN-doc 28150 O processo de anodização do alumínio e suas ligas2021 - ARAUJO, JOAO V. de S.; SILVA, REJANE M.P. da; KLUMPP, RAFAEL E.; COSTA, ISOLDAAl and its alloys are found in several industrial applications. However, like most metals, this material is not immune to corrosion, being necessary to be protected against corrosion. One of the methods most commonly employed to improve the corrosion resistance of Al alloys is the anodizing process, which consists of thickening of the natural oxide (Al2O3) presents in Al through anodic oxidation. The anodizing process is accomplished by immersion of the Al alloy into an acid bath and passing an electric current through it. This process produces two layers: a barrier layer thicker than the natural oxide and a layer with regular arrangement of nanopores (porous layer). This duplex structure forms the anodized layer with a large specific surface area. With the advent of nanotechnology, this layer has been applied in other areas due to its low cost, stability, absence of toxicity, and biocompatibility. In this context, this paper addresses a historical and electrochemical review of the anodizing process of Al and its alloys, presenting the main events that culminated in the development of the current processes and the understanding of the relationship between the chemical reactions and the mechanisms that occur during nucleation and development of the oxide layer.Artigo IPEN-doc 27812 How microstructure affects localized corrosion resistance of stir zone of the AA2198-T8 alloy after friction stir welding2021 - MACHADO, CARULINE de S.C.; DONATUS, UYIME; MILAGRE, MARIANA X.; ARAUJO, JOAO V. de S.; VIVEIROS, BARBARA V.G. de; KLUMPP, RAFAEL E.; PEREIRA, VICTOR F.; COSTA, ISOLDAIn this study, the microstructure and corrosion resistance of the stir zone (SZ) of the AA2198-T8 Al-Cu-Li alloy welded by friction stir welding (FSW) were investigated by microscopy, immersion tests and electrochemical techniques such as measurements of open circuit potential variation with time, and scanning vibrating electrode technique (SVET) measurements. A low chloride-containing solution (0.005 mol L−1 NaCl) was employed in the corrosion studies and severe localized corrosion (SLC) was observed in the SZ related to intergranular attack. The results were compared to those of the non-affected areas by FSW, also known as base metal (BM). In the BM, SLC was found and the type of attack related to it was intragranular. In both zones, BM and SZ, SLC was due to precipitates of high electrochemical activity, specifically T1 (Al2CuLi) phase in the BM, whereas TB (Al7Cu4Li) / T2 (Al6CuLi3) in the SZ. Scanning vibrating electrode technique (SVET) analysis was very useful in the study of SLC in the AA2198-T8 alloy showing the development of high anodic current densities at the mouth of the SLC sites.Artigo IPEN-doc 27712 Corrosion protection of the AA2198-T8 alloy by environmentally friendly organic-inorganic sol-gel coating based on bis-1,2-(triethoxysilyl) ethane2021 - KLUMPP, RAFAEL E.; DONATUS, UYIME; SILVA, REJANE M.P. da; ANTUNES, RENATO A.; MACHADO, CARULINE de S.C.; MILAGRE, MARIANA X.; ARAUJO, JOAO V. de S.; VIVEIROS, BARBARA V.G. de; COSTA, ISOLDAIn this work, a surface coating composed of organic‐inorganic hybrid sol‐gel based on bis‐1,2‐(triethoxysilyl) (BTSE) ethane was applied on AA2198‐T8 samples, and its effect on corrosion resistance was investigated and compared with that of a chromate layer formed in a solution with hexavalent chromium ions. The corrosion resistance of BTSE coated samples was evaluated by immersion tests in sodium chloride solution (0.005 mol/L NaCl) and monitored by global electrochemical techniques such as electrochemical impedance spectroscopy (EIS) and local electrochemical techniques such as scanning vibrating electrode technique (SVET) and scanning electrochemical microscopy (SECM). The formed coating layers were characterized by X‐ray photoelectron spectroscopy (XPS). The results pointed out that the BTSE is an effective alternative coating for corrosion protection of new generation Al‐Cu‐Li alloys and could replace chromates obtained in toxic and carcinogenic CrVI containing solutions leading to improved corrosion protection.