ARMANDO CIRILO DE SOUZA

ARMANDO CIRILO DE SOUZA

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Microstructural characterization of Zr1Nb alloy after hot rolling
2019 - SOUZA, ARMANDO C.; ARISTONE, FLAVIO; ROSSI, JESUALDO L.; MARTINEZ, LUIS G.; CIONE, FRANCISCO C.; TSAKIROPOULOS, PANOS; GRANDINI, CARLOS R.; SILVA, WALLACE F. da
The nuclear industries have large interest on the development of new alloys involving zirconium (Zr) because this material presents extraordinary mechanical properties, outstanding resistance to corrosion and high permeability to thermal neutrons, being suitable for applications in areas such as energy and human health. The alloy studied in this paper is formed by Zr and niobium (Nb), normally expressed as Zr1Nb. These two elements have large chemical affinities with oxygen, carbon, and nitrogen, elements that normally are responsible for a series of damages in the alloy. The principal goal of this work is to obtain Zr1Nb alloys and to perform microstructural characterizations before and after the hot rolling process. The resulting alloys were subjected to a process of heat treatment, the temperature was increased at a rate of 10 K/min up to 1273 K and maintained for 2 h, after which it was cooled down at −10 K/min until room temperature, with the only purpose of relieving residual stresses. The next step was to apply the hot rolling process to the alloy. The sample initially measured, approximately, 1.5 cm of thickness when it was inserted into the furnace at 1203 K to start the hot rolling. Every pass on the hot rolling reduced the thickness by 0.5 mm, originating uniform and homogeneous samples of 2.5mm thickness. Auxiliary technical tools, such as XRD (X-Ray Diffraction), SEM (Scanning Electron Microscopy), and EDS (Energy Dispersive X-Ray Spectroscopy), were used to analyze the microstructure of the samples before and after the hot rolling process. The XRD results show the formation of only a single α-HCP (Hexagonal Close Packed) phase for our samples, indicating that they are free of other phases that can damage the material. This result is consistent and coherent with both SEM and EDS analysis. The observed homogeneity of our samples is very good; proving that both techniques employed to obtain Zr1Nb as well as the hot rolling process was well succeeded. Therefore, the obtained alloy can be directly used in the pipes of nuclear combustible industries.
A Study of Production of Tungsten Copper Alloy by Powder Metallurgy, Applied to Radioactive Shielding of Transport Equipment for Pharmaceutical Products
2015 - CIONE, FRANCISCO C.; SOUZA, ARMANDO C. de; SENE, FRANK F.; RIZZUTTO, MARCIA de A.; ROSSI, JESUALDO L.
Safety is of paramount importance for the storage and transportation of radiopharmaceutical products, being directly dependent on the radiation shielding material used in specific devices. The focus of present work, part of a larger project, is to minimize the use of harmful materials, as lead and depleted uranium, in such devices construction. The radioactive energy reduction varies according to density of material used as shielding. Because Tungsten has a high density and, implicitly, good shielding properties without to be harmful, but has poor workability, researches were focused on Tungsten - copper heavy alloys. The objective of the performed research was the optimization of alloy composition in order to achieve the best linear absorption coefficient. The studied compositions were 15, 20 and 25 wt.% copper. The linear absorption coefficient was similar either for the green and sintered compacts, thus the porosity level did not have measurable effect on the radiation attenuation.
Measurements of residual stresses in aluminum wheels using the techniques of XRD, strain gages and FEA simulation - a comparison
2016 - CIONE, FRANCISCO C.; SOUZA, ARMANDO; MARTINEZ, LUIZ; ROSSI, JESUALDO; BETINI, EVANDRO G.; ROLA, FABIO; COLOSIO, MARCO A.
Studying the formation and distribution of residual stress fields will improve the wheel safety operational criteria among other gains. Many engineering specifications, manufacturing procedures, inspection and quality control have begun to require that the residual stress of a particular component to be evaluated. It is known that these residual stress fields could be added to the effects of a system load (tare weight plus occupation of vehicle, traction, braking and torque combined). The mathematical tools for modeling and simulations using finite elements had evolved following the increasing computing power and hardware cost reduction. On the other hand, the experimental testing, offers specific physical component behavior and with the use of statistical tools, it is possible to predict the real behavior of the component when in operation. The experiments undertaken used the X-ray diffraction technique and the drilling method with rosette type strain gages. The experimental results were convergent with similarity to those obtained using FEA simulation over critical region for global and superficial in the principal stresses mode. The relevance of the present study and research on residual stresses meets safety improvements in car’s wheel industry.
The shielding against radiation produced by powder metallurgy with tungsten copper alloy applied on transport equipment for radio-pharmaceutical products
2015 - CIONE, FRANCISCO C.; RIZZUTTO, MARCIA A.; SENE, FRANK F.; SOUZA, ARMANDO C. de; BETINI, EVANDRO G.; ROSSI, JESUALDO L.
Residual stresses measurements using strain gages - aluminium wheels
2012 - CIONE, F.C.; ROSSI, J.L.; SOUZA, A.C.; DELIJAICOV, S.; COLOSIO, M.A.