LUIS AUGUSTO MENDES DOS REIS

LUIS AUGUSTO MENDES DOS REIS

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Processing of zirconium sponge and zirconium alloys in an electric arc furnace
2022 - REIS, L.A.; MORAIS, N.W.; BETINI, E.G.; PEREIRA, L.T.; POLITANO, R.; BARBOSA, L.P.; MARTINEZ, L.G.; MUCSI, C.S.; ROSSI, J.L.
Zirconium and its alloys, as well as titanium and its alloys, are mostly used in the nuclear and aeronautical industries, respectively. A nuclear-grade zirconium sponge is the main component for obtaining nuclear fuel element cladding for nuclear power plants and other components, such as grids and springs. The zirconium sponge is also an important raw material in obtaining various alloys for nuclear fuels from small and medium power reactors, such as U-Zr-Nb. Thus, this project has relevance, since the clean melting of zirconium sponge will provide part of the domain of nuclear fuel technology. In this work, high entropy alloys (Ti-Zr-Nb-Ta-Fe-Cr) were produced in order to evaluate the evolution of the microstructure and modulus of elasticity as a function of temperature and heat treatment. A high entropy alloy with a composition different from those found in the literature is proposed. The materials were separated and melted in an electric arc furnace under a non-consumable electrode vacuum. These alloys were consolidated in the form of bars 220 mm long and thicknesses ranging from 8 to 12 mm. After melting, annealing was carried out at 1100 °C for 24 hours to homogenize the material obtained. The initial microstructural analyzes showed two very distinct phases with defined grain boundaries, the chemical etching to reveal the microstructure was a solution of 100 ml deionized H2O + 10 ml HNO3 + 2 ml HF. The samples are being quenched in oil and X-ray diffraction tests will be carried out in a hot chamber and the results will be presented at this congress.
Effect of shielding gas on thermal properties of thin plates of duplex stainless steel welded by pulsed GTAW process
2022 - BETINI, E.G.; TERUI, C.; REIS, L.A.; MUCSI, C.S.; LUZ, T.d.; ORLANDO, M.T.; ROSSI, J.L.
In this work, UNS32304 duplex stainless steel welds were evaluated by observing the influence of the pulsed GTAW welding process on thermal properties of this material. 1.8 mm duplex stainless steel sheets were welded by the GTAW process varying the shielding gases between pure Ar and Ar + 2%N2 without filler metal. The thermal welding cycles were studied by a type K and S thermocouple system fixed close to the welding line. The temperature distribution along the welding line was determined by reaching values within the phase transformation range of this material. Through a quantitative and semiquantitative evaluation of elements the Creq/Nieq ratio was calculated for the ferrite, austenite and secondary austenite grains of the solidified zone, ZAC and base metal. The addition of 2% N2 in the shielding gas caused an increase of the austenite formation in the solidified zone if compared to welding without N2 addition, being the most suitable atmosphere for welding in duplex stainless steels. The thermophysical properties were studied by laser flash method (MFL) used to determine the thermal diffusivity of the material in the thickness direction. The specific heat and Curie temperature of the solidified zone of welds was obtained by the thermal analysis by differential exploratory calorimetry (DSC). Measurements of porosities and specific mass of the solidified zone were obtained and compared with the base metal and metal as received. With this information it was possible to evaluate the thermal conductivity of the material after welding process. Increased thermal conductivity was found for both welded samples and suggest correlation with increased ferritic phase and decreased porosity also observed for solidified zone.
Uma discussão sobre a aeroelasticidade de quadricópteros não tripulados, drones, oferecendo subsídios para projetos
2018 - MUCSI, C.S.; ROSSI, J.L.; ALENCAR, M.C.; REIS, L.A.M.; ROSSI, A.C.
Os veículos aéreos não tripulados vem ganhando grande notoriedade, face à ampla gama de suas aplicações científicas e tecnológicas. Estes apresentam construções tão simples como brinquedos até equipamentos com altíssimo valor técnico científico agregado, destinados à missões relevantes. O presente trabalho visa apresentar uma discussão sobre a aeroelasticidade destes equipamentos na escala métrica, assunto árido e escasso nesta nova aeronáutica. São apresentados resultados de simulações numéricas relacionando o comportamento dos componentes estruturais em função dos esforços mecânicos, mormente os relacionados à mudança de atitude do equipamento, rotações e inclinações. Os resultados obtidos indicam a necessidade de cuidado e atenção no projeto dos braços dos quadcópteros, com especial atenção às suas seções transversais e à raiz do braço, na junção com o corpo; para evitar instabilidades que de outra maneira sobrecarregariam o processador do estabilizador de vôo. Estes dados estão servindo de base para o projeto e construção de um equipamento voltado à detecção e localização de fontes radioativas.
Comparative study on extensômetria and finite element simulation for deformation for torsion
2018 - ALENCAR, M.C.; CIONE, F.C.; REIS, L.A.M.; MUCSI, C.S.; SOUZA, M.M.; ROSSI, J.L.; ARANHA, L.C.
The use of finite element simulation has been widely employed by industry and academia, for design and development of mechanical systems; and with that there's a considerable savings in time, financial and manpower. In this project we will be evaluating and comparing the results of the behavior of a piece by computer simulation by finite elements, using the software Ansys ® Academic, for a bar with strain concentration profile, where this will be applied to twist. With the results of the simulations, compared with the results of the same piece materialized and with installation of strain gages to measure the deformation exerted on the. These sensors convert the mechanical deformation in electrical signal by formation of a Wheatstone bridge. In this way, with the results of the two reviews, simulation and measurement, we note that there is similarity between the results, Since we work within the component's elastic deformation curve.
Development of primary system for calibration of torque measuring instruments
2018 - ALENCAR, M.C.; MUCSI, C.S.; GOMES, C.D.; REIS, L.A.M.; SOUZA, M.M.; ROSSI, J.L.
The importance of torque measurement is already known in the academic, scientific and industrial, but the reliability of these measurements can be questioned when the equipment has no calibration. That's why the periodic calibration of such equipment is essential to ensure that the measurements that will be performed on this instrument are trusted. With that comes the proposal of building a device for calibration of torque measuring instruments, where we had the premise of the development of a primary system torque generation, so that we can calibrate torque measuring instruments of any class of accuracy. The development followed mechanical and geometrical construction standards to ensure the best design and balance between the positions of load application. In conjunction with torque application system was scaled and constructed a set of calibrated masses, He served as charge for applying torque, so we can define precisely the value of the torque to be applied.
Study development and characterization of micro torque transducer applied on screw elements analysis
2018 - ALENCAR, M.C.; REIS, L.A.M.; MUCSI, C.S.; SOUZA, M.M.; ARANHA, L.C.; ROSSI, J.L.
The measurement of torque in threaded elements currently is an important step in fixing of components, because knowing the torque applied can ensure the life of this component, ensuring that the same will not be failed for lack of grip or excess. Micro torque measurement to the control becomes more critical, Yes because working with very low torques, until 1 N.m, It is necessary that the instrument has greater sensitivity to be able to measure with accuracy required. The development of a micro torque measurement system, where he studied and developed a micro torque transducer, Since the design of the shaft and the design of the concentration of efforts, using the help of the software of computer simulation by finite element analysis Ansys Academic, to ensure that this work on elastic and with a uniform distribution of forces in the specified region. After the shaft machining, was installed as sensor element four precision strain gage, to form a wheatstone bridge, where converted to mechanical tension due to the torque generated in electrical signal. Being possible to correlate the mechanical deformation in ?? with the electrical signal generated in mV/V. With this micro torque transducer mounted the metrological characterization, defined its properties and measurement accuracy. From the statistical evaluation of the results obtained during the tests, it was possible to quantify the uncertainty of measurement for the transducer, that can be used in further work carried out in this equipment.
Valve seat insert: air quenching and characterization of components obtained with AISI M3:2 high-speed steel
2018 - GOMES, M.P.; SANTOS, I.P.; REIS, L.A.M.; COUTO, C.P.; BETINI, E.G.; MUCSI, C.S.; COLOSIO, M.A.; ROSSI, J.L.
The development of components ecologically correct is something more and more necessary. The first developement of valve seat inserts (VSI) take in account the use of cobalt and lead in its chemical composition. Such elements are avoided in the current applications due to its high cost and toxicological effects, respectively. In the present work was used VSI developed with a new chemical composition. The aim of this work were to air quench and characterize such components. The studied VSI were obtained with AISI M3:2 high-speed steel admixed with iron powder and another additives such as manganese sulphide, graphite, zinc stearate and carbides. All the air quenched VSI were double tempered, for one hour each, at seven equidistant temperature from 100 °C until 700 °C. The air quenched components had its mechanical and physical properties determined by means of its apparent density, apparent hardness and crush radial strength. The chemical composition was measured through the gases analyses and energy dispersive X-ray fluorescence spectrometry techniques. Microstructural and phase characterizations were performed with the support of optical microscopy, scanning electron microscopy and energy dispersive spectroscopy. Regarding the VSI required properties, the best results were obtained with the components air quenched and double tempered at 600 °C.
Experimental study of the weld pool temperature of thin plates of UNS S32304 duplex stainless steel by GTAW process
2018 - BETINI, E.G.; BATLLE, J.; MUCSI, C.S.; LUZ, T.S.; ORLANDO, M.T.; ROSSI, J.L.; SOUZA, A.C.; REIS, L.A.M.
The aim of the experimental arrangement is the measurement of the weld pool temperature during the application of the conventional arc GTA-welding on autogenous thin plates of UNS S32304 duplex stainless steel. Grade UNS S32304 was developed for the most severe applications including off-shore. The stationary arc welding was applied with a DC current for two minutes using pure argon as shielding gas in center of the duplex stainless steel disc. For the temperature into the weld pool were used a S-type (Pt-Rh) and K-type (Ni-Cr) thermocouples connected close to weld pool. The temperatures were measured in top and botton sides of the plates. It was observed an overheating temperature into the weld pool on the top side and as expected the fusion point was verified in corresponding at the bottom side. The microstructure was characterized and an increase of ferrite phase in solidified zone and heat affected zone was observed. The hardness mapping provided information about mechanical properties behaviour. A numerical analysis of temperature distributions were used to simulate welding cycles associated to microstructure evolution.
Recycling process viability from zirconium alloys scraps of lathe melted in the vacuum arc remelting (VAR) furnace
2018 - REIS, L.A.M.; ALENCAR, M.C.; GOMES, M.P.; PEREIRA, L.A.T.; BARBOSA, L.P.; MUCSI, C.S.; ROSSI, J.L.
Pressurized water reactors (PWR) commonly use U235 enriched uranium dioxide pellets as a nuclear fuel, these are assembled and cladded in zirconium alloy (M5, Zirlo, Zircaloy) tubes and end caps. During the machining of these components, large amounts of turning lathe chips are generated which are contaminated with cutting fluid. Its storage presents safety and environmental risks due to its pyrophoric and reactive nature. Recycling industry has shown interest in its recycling due to its strategic importance of these scraps. This paper presents the steps on the recycling processes and the results for the search of an efficient way on the cleaning, quality control, manufacturing, and melting of electrodes for Vacuum Arc Remelting (VAR) furnace. The process starts with cutting oil washout and this step consists of a water dissolution followed by a degreasing process, the water rinse by continuous flow of water and finally drying in hot air. Process evaluation was first made by means the X-ray fluorescence tests in order to define the quality of the scraps that after washing were pressed in 20 mm diameter briquettes, melted and subjected to such analysis. The next step consists in the pressing with a die square section with 40 mm2 and 500 mm long, producing an electrode with 20% of the Zircaloy bulk density. The electrode was melted in a laboratory scale VAR furnace located at the CCTM – IPEN producing a 0.8 kg ingot. The microstructural and macro structural characterization is being done by analyzes performed in the optical microscope and scanning electron microscope (from portuguese Microscópio Eletronico de Varredura - MEV). Gas analyzes were carried out with the intention of evaluating possible gases resulting from the melting and evaluating their influence. X-ray diffraction analyzes were also performed to identify the phases present in the material after the melting process The authors conclude that the samples obtained from the fuel element industry can be melting in a VAR furnace reducing 40 times the storage volume, however, it is necessary to remelt the ingots by correcting their composition intended for reuse.
Melting of zircaloy 4 scraps in a laboratory var furnace
2016 - MUCSI, C.S.; REIS, L.M. dos; ROSSI, J.L.; JESUS, E.R.B.; SOUZA, M.M.
The melting process in VAR furnaces places interesting and important challenges to the industry. One of these challenges is the use of electrodes with densities very close to the bulk material. In order to melt electrodes made of Zircaloy 4 scraps with low densities in relation to the bulk material, a special device was developed to allow the use of electrodes with cross sections bigger than the ingot cross section. This is desirable in order to obtain the highest resulting melted ingot mass, i.e., to maximize the amount of scraps to be melted. Zircalloy electrodes were melt with the IPEN laboratory VAR furnace, producing massive ingots with densities close to the bulk material density. These ingots were then welded together to be used in a secondary melting to obtain larger ingots following the Vacuum Arc Remelting process.