MARCO ANTONIO STANOJEV PEREIRA

MARCO ANTONIO STANOJEV PEREIRA

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Corrosion characterization of the 6061 Al–Mg–Si alloy in synthetic acid rain using neutron tomography
2022 - MILAGRE, MARIANA X.; PEREIRA, MARCO S.; GOMES, ANTONIO A.; SCAPIN, MARCOS; FRANCO, MARGARETH; YOKAICHIYA, FABIANO; GENEZINI, FREDERICO; COSTA, ISOLDA
Neutron tomography has gained increasing importance as an imaging technique for materials characterization. In general, neutron beams are able to show microstructure features of hydrogenous materials, even enfolded with thick metal layers. In the present paper, neutron tomography and observation of cross section images were successfully applied to investigate the corrosion features of the 6061 Al–Mg–Si alloy. The results showed good agreement between neutron 3D tomography and the cross section images obtained in the high attenuation areas of the samples, whereas significant differences in depth of corrosion penetration were obtained between the results from Neutron Tomography and 3D optical profilometry.
Concentration and distribution of oil in the reservoir mineral Dolomite studied by neutron tomography
2020 - PUGLIESI, R.; STANOJEV PEREIRA, M.A.; ANDRADE, M.L.
Neutron Tomography – NT is a non-destructive technique, ideal for imaging hydrogen-rich substances even when wrapped up by thick rock layers. In the present study, the NT was employed for investigating the oil concentration and distribution in the mineral Dolomite, a natural oil reservoir. Two types of Dolomite samples, one of which dry, and the second one in oil-saturated were prepared. The applied oil was EMCAplus® 070 usually employed in permeability experiments to reproduce conditions of natural oil reservoirs. Three small fragments of the dry sample and three of the oil sample were inspected by NT and the comparison between the obtained results enabled, to distinguish several regions in which the oil is stored, to indicate that the oil is dispersed throughout the volume of the samples, and to quantify the storage concentration. The obtained data for oil concentration, for the three fragments, were compared to each other and to the one obtained by the conventional gravimetric technique, and they agreed within their uncertainties, demonstrating the viability of the NT technique to inspect, either in a qualitative as in a quantitative level, this oil reservoir mineral.
Estudo da mineralização de cobre em basaltos do Grupo Serra Geral, utilizando difratometria de raios X, microscopia eletrônica de varredura-espectroscopia por energia dispersiva e tomografia com nêutrons
2019 - GARDA, GIANNA M.; FILGUEIRA, DIEGO A.; PUGLIESI, REYNALDO; PEREIRA, MARCO A.S.; SAYEG, ISAAC J.
Mineralizações de cobre do tipo Michigan ocorrem nos derrames basálticos do Grupo Serra Geral na região de Nova Prata do Iguaçu, sudoeste do estado do Paraná. Nessas mineralizações, o cobre nativo é o principal mineral de minério e, com a alteração supérgena, transforma-se em óxidos de cobre, malaquita e crisocola, sendo esta encontrada na forma de um precipitado gelatinoso que preenche amígdalas e impregna fraturas no basalto, além de recobrir minerais secundários e outros produtos de alteração. Neste estudo, foram utilizadas as técnicas de difratometria de raios X e microscopia eletrônica de varredura-espectroscopia por energia dispersiva (MEV-EDS) para a caracterização do grau de cristalinidade e composição química da crisocola e a identificação de outros materiais hidrogenados, como subsídio para o imageamento 3D por tomografia com nêutrons. A crisocola destacou-se como um eficiente atenuador de nêutrons, obtendo-se coeficiente de atenuação linear da ordem de 0,8–1,3 cm-1, ao passo que, para o corpo de minério (basalto), obteve-se 0,5–0,6 cm-1. O contraste entre os coeficientes permitiu a obtenção de imagens tomográficas e filmes de boa resolução, em que se pôde visualizar a distribuição da crisocola na amostra de basalto e estimar como fração volumétrica de crisocola no corpo de minério valores entre 0,9 e 1,4%, obtendo-se o valor de 7,8% em volume de crisocola para uma das amostras. A utilização integrada das três técnicas analíticas demonstrou que esta pode ser uma ferramenta para avaliação do potencial mineral nas fases iniciais da prospecção mineral, especialmente quando as substâncias de interesse são ricas em hidrogênio.
Study of the fish fossil Notelops brama from Araripe-Basin Brazil by Neutron Tomography
2019 - PUGLIESI, REYNALDO; PEREIRA, MARCO A.S.; ANDRADE, MARCOS L.G.; BASSO, JULIANA M.L.; VOLTANI, CIBELE G.; GONZALES, IVONE C.
In the last decade, Neutron Tomography significantly gained importance as an analyzing tool to inspect samples of paleontological interest. In general, neutrons are able to provide new and complementary information when compared to the ones provided by X-rays imaging methods. Specifically, in the present paper, the Neutron Tomography equipment of the IPEN-CNEN/SP was successfully applied to investigate the internal structure of a fish fossil, embedded in a calcareous concretion. The resulting images, which will be presented, has revealed different contrast between several regions within the specimen enabling the differencing of osteological structures of the fossil, information about its state of conservation, degree of embedding, inclusions as well as regions within the concretion which could be related to humidity or to other substances and minerals containing hydrogen naturally added to the fossil. The technique is non-destructive and non-invasive allowing a close analysis of the specimen. Furthermore, the obtained images have demonstrated the feasibility of the equipment at IPENCNEN/ SP for investigating this kind of sample.
Spatially resolved oxygen reaction, water, and temperature distribution
2019 - LOPES, THIAGO; BERUSKI, OTAVIO; MANTHANWAR, AMIT M.; KORKISCHKO, IVAN; PUGLIESI, REYNALDO; STANOJEV, MARCO A.; ANDRADE, MARCOS L.G.; PISTIKOPOULOS, EFSTRATIOS N.; PEREZ, JOELMA; FONSECA, FABIO C.; MENEGHINI, JULIO R.; KUCERNAK, ANTHONY R.
In situ and ex situ spatially-resolved techniques are employed to investigate reactant distribution and its impacts in a polymer electrolyte fuel cell. Temperature distribution data provides further evidence for secondary flows inferred from reactant imaging data, highlighting the contribution of convection in heat as well as reactant distribution. Water build-up from neutron tomography is linked to component degradation, matching the pattern seen in the reactant distribution and thus suggesting that high, non-uniform local current densities shape degradation patterns in fuel cells. The correlations shown between different techniques confirm the use of the versatile reactant imaging technique, which is used to compare commonly used flow field designs. Among serpentine-type designs, the single serpentine is superior in both equivalent current density and reactant distribution, showing large contributions from convective flow. On the other hand, the interdigitated design is shown to produce larger equivalent current densities, while showing a somewhat poorer reactant distribution. Considering the correlations drawn between the techniques, this suggests that the interdigitated design compromises durability in favour of power output. The results highlight how established techniques provide a robust background for the use of a new and flexible imaging technique toward designing advanced flow fields for practical fuel cell applications.
Penetration of the consolidant Paraloid (R) B-72 in Macuxi indigenous ceramic vessels investigated by neutron tomography
2018 - PEREIRA, MARCO A.S.; PUGLIESI, REYNALDO
The neutron tomography technique was applied in studying the penetration of the consolidant Paraloid (R) B-72 in contemporary indigenous ceramic vessels. The study was carried out for two distinct and controlled air humidity conditions, 40% and 90%, in which the vessels were exposed, before the consolidant application. The obtained images have proved that the penetration of Paraloid (R) B-72 in the ceramic does not depend on the humidity condition in which it was applied, moreover allowed a macro-visualization of the consolidant penetration in the ceramic vessel. As the vessels used in the present work were manufactured by an indigenous artisan, Macuxi, according to the same procedures and raw materials used by the ancient artisans, the results obtained can be used as a guide to assist experts, both in the study of archeological objects of Macuxi origin, as well as other objects that had been made by other tribes that lived in the same Amazon region, in Brazil.
Method to evaluate the L/D ratio of neutron imaging beams
2017 - PUGLIESI, R.; PEREIRA, M.A.S.; SCHOUERI, R.M.
An alternative simple method to evaluate the L/D ratio of neutron imaging beams is proposed. It is based on the behavior of the ratio “x/Ut”, which asymptotically tends to L/D for large values of the parameter “x”, that corresponds to the distance separating a gadolinium test object to the scintillator plane, where its image is formed. The method was applied to the neutron imaging equipment of the Nuclear and Energy Research Institute IPENCNEN/ SP and the obtained result was L/D = (104 ± 4). The consistency of the proposed method was verified by comparing this value with those ones obtained by a well - known and established procedure.
Penetração e distribuição do consolidante Paraloid® B-72 em cerâmica branca estudada por tomografia com nêutrons
2017 - PEREIRA, MARCO A.S.; PUGLIESI, REYNALDO; ANDRADE, MARCOS L.G.; PRUDENCIO, MARIA I.
ASSESSMENT OF PARALOID® B-72 PENETRATION IN WHITE CERAMIC STUDIED BY NEUTRON TOMOGRAPHY. The neutron tomography technique was employed to study the penetration and distribution of the consolidant Paraloid® B-72 in ceramic. This study was carried out in white contemporary ceramic vessels which were maintained in two distinct and controlled air humidity conditions, 35% and 90%, before the consolidant application (brushing technique). The results showed that the treatment with Paraloid® B-72 is more effective when applied in the drier vessel. The depth of penetration for the vessel at 35%, reaches (3.3 ± 0.1) mm in the wall, while for the one at 90%, (1.9 ± 0.1) mm, and the maximal concentration impregnation was 26% higher. The 3D images allowed a visualization of the impregnation process, that is, its distribution, failures, homogeneity, boundary between materials. These results demonstrated the feasibility of the neutron tomography technique and of the equipment of IPEN-CNEN/SP, in support the expert work in the field of preservation and restoration of ceramic objects.
Investigating early/middle bronze age copper and bronze axes by micro X-ray fluorescence spectrometry and neutron imaging techniques
2016 - FIGUEIREDO, ELIN; PEREIRA, MARCO A.S.; LOPES, FILIPA; MARQUES, JOSE G.; SANTOS, JOANA P.; ARAUJO, M.F.; SILVA, RUI J.C.; SENNA MARTINEZ, JOAO C.
Study of pixel damages in CCD cameras irradiated at the neutron tomography facility of IPEN-CNEN/SP
2015 - PUGLIESI, R.; ANDRADE, M.L.G.; DIAS, M.S.; SIQUEIRA, P.T.D.; PEREIRA, M.A.S.