Graduate at Engenharia Metalúrgica from Centro Universitário da FEI (1982), graduate at Engenharia Civil from Universidade Guarulhos (1998), master's at Mechanical Engineering from Universidade Estadual de Campinas (1986) and PhD at Tecnologia Nuclear Materiais from Universidade de São Paulo (2005). Has experience in Material and Metallurgical Engineering, focusing on Welding, Powder Metallurgy and Additive Manufacturing , acting on the following subjects: welding, microstructure, and powder metallurgy. Is currently a professor of the graduate program at the University of São Paulo. Currently been active in the mechanical and microstructural behavior of metallic biomaterials processed by casting, machining or by powder metallurgy.and additive manufacturing. Published 4 book chapters, 42 articles in specialized journals and 126 works in the annals of events. It has 10 technological products, processes or techniques, 1 with registration. In terms of guidelines completed or in progress, there are 15 master's dissertations and 5 doctoral theses, in addition to supervising 13 scientific initiation works and 22 course completion works in the areas of Mechanical Engineering and Materials / Metallurgical and Civil Engineering. In the last 20 years he participated in 3 research projects and 14 technological development projects. Provides technical consultancy and teaches courses on industrial processes in companies. Participated in several processes of technology transfer to the industry and in several technological developments in partnerships with numerous companies. (Text obtained from the Currículo Lattes on November 17th 2021)

Possui graduação em Engenharia Metalúrgica pelo Centro Universitário da FEI (1982), graduação em Engenharia Civil pela Universidade Guarulhos (1998), mestrado em Engenharia Mecânica pela Universidade Estadual de Campinas (1986) e doutorado em Tecnologia Nuclear- Materiais pelo Instituto de Pesquisas Energéticas e Nucleares (IPEN) da Universidade de São Paulo (2005). Foi pesquisador do IPEN de 1984 até 2018. Iniciou funções de Professor na Faculdade de Engenharia Industrial (FEI) em fevereiro de 1992, encerrando-as em junho de 2020 na disciplina de Soldagem e Estruturas de construção Metálica. Atualmente é professor e orientador credenciado do programa de pós-graduação do Instituto de Pesquisas Energéticas e Nucleares / Universidade de São Paulo e pesquisador voluntário da Comissão Nacional de Energia Nuclear. Tem experiência na área de Engenharia de Materiais/ Metalúrgica, com ênfase em materiais metálicos nos processamentos envolvendo: Soldagem, Metalurgia do Pó e Manufatura Aditiva, além de em caracterização microestrutural e mecânica de componentes fabricados por estas técnicas. Tem atuado na área de processamento, comportamento mecânico e caracterização microestrutural de biomateriais metálicos. Atua na área de ensino e projeto de estruturas metálicas na construção civil. Publicou 4 capítulos de livros, 42 artigos em periódicos especializados e126 trabalhos em anais de eventos. Possui 10 produtos tecnológicos, processos ou técnicas, sendo 1 com registro. Em termos de orientações concluídas ou em andamento são 15 dissertações de mestrado e 5 teses de doutorado, além de ter orientado 13 trabalhos de iniciação científica e 22 trabalhos de conclusão de curso nas áreas Engenharia Mecânica e Engenharia de Materiais/Metalúrgica e Civil. Nos últimos 20 anos participou de 3 projetos de pesquisa e 14 projetos de desenvolvimento tecnológico. Presta consultoria técnica e ministra cursos sobre processos industriais em empresas. Participou de diversos processos de transferência tecnológica à indústria e de diversos desenvolvimentos tecnológicos em parcerias com inúmeras empresas. (Texto extraído do Currículo Lattes em 17 nov. 2021)

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Agora exibindo 1 - 10 de 187
  • Resumo IPEN-doc 30291
    Corrosion analyses of anodized aluminum for biomedical purposes
    Introduction and objective: Anodic aluminum oxide has attracted a lot of interest due to the regular arrangement of nanopores, ease of control of the nanopores diameter, large specific surface area, low cost, good thermal stability, absence of toxicity and biocompatibility. The geometric arrangement of nanopores makes it possible to use alumina as a mold for the synthesis of various nanostructures, such as nanopores, nanotubes, nanorods and nanowires that have many advantages in advanced application areas due to their unique chemical, physical, mechanical, and optical properties [1,2]. The objective of this work was to study the corrosion susceptibility of anodized aluminum samples for biomedical applications. Methodology: In the present work, the localized corrosion resistance of AA6061aluminum alloy anodized in oxalic acid solution (C2H2O4) and sulfuric acid (H2SO4) was evaluated by electrochemical techniques. Prior to the anodization stage, the samples were electrolytically polished in a solution of perchloric acid and ethanol. Results and discussion: All samples showed a protective behavior on their surfaces, higher corrosion potentials in relation to the standard reference sample and a shift towards lower values of corrosion current densities in relation to the sample without passivation treatment. These results indicate that the anodizing treatments of AA6061 aluminum surfaces in oxalic or sulfuric acid are effective in producing surfaces resistant to localized corrosion and can therefore be used to coat this type of surface, ensuring an increase in the useful life of the devices. Conclusions: The results indicated superior corrosion resistance in the anodized samples in both conditions. Therefore, it is necessary to constantly advance research on the use of nanoporous anodic alumina coatings on biomaterials surfaces.
  • Resumo IPEN-doc 30290
    Surface investigation of a laser etched metallic biomaterial
    Introduction and objective: Surface treatments are used to improve characteristics, such as: markings, texturing and polishing. The texturizations are produced to provide roughness and, consequently, adherence in specific locations of implantable medical devices of permanent character, that is, implants of prolonged use. Sometimes this process can generate stress concentrators and regions with probability for the occurrence of failures that can lead to fracture; in addition to damaging the passive layer, favouring the initiation of various forms of corrosion [1]. This work aims to evaluate the effect of the laser beam texturing technique in metallic implants on the corrosion resistance of ASTM 316L stainless steel. Methodology: Samples were prepared from the stainless steel textured by fiber optic laser doped with ytterbium (Yb) by changing the values of the frequency of the laser pulse cadence and keeping the other parameters constant. As a comparison, samples of the biomaterial without any type of laser treatment were also evaluated. The electrochemical tests performed consisted of open circuit corrosion potential (OCP) monitoring and cyclic potentiodynamic polarization measurements, determined after hours of immersion at 37°C body temperature. The scanning vibrating electrode electrochemical technique (SVET) was used as a tool to determine the corrosion current density in 0.1M NaCl solution. Results and discussion: The results obtained revealed the highest anodic current densities in the regions engraved by the laser beam and cathodic current densities in the regions farthest from the engravings, which indicates that laser engraving, in addition to increasing the roughness of the surfaces, makes them essentially anodic, changes the passive layer, affects the distribution of corrosion current densities and decreases the resistance to localized corrosion of this biomaterial. Conclusions: The change in the laser pulse frequency values is directly related to the behaviour observed on the analysed surfaces, indicating that the laser texturing treatment affects the passive layer of the material decreasing the resistance to localized corrosion.
  • Resumo IPEN-doc 30289
    Magnetic properties evaluation of 316L stainless steel produced by additive manufacturing for biomedical use
    Introduction and objective: The modern additive manufacturing (AM) techniques represent the current state of the art of industry 4.0. Advanced selective laser melting techniques allow the production of parts with the most varied sizes, shapes and complex geometries, which would be difficult to obtain previously with casting, joining, machining, among others. In addition to saving material, they are automated, do not generate wear to the tooling and little waste. The durability of surgical instruments, implants, and prostheses with this type of manufacturing can be considered greater than that using conventional methods with cutting tools [1]. Austenitic stainless steels have been widely used for the manufacture of implants due to their good mechanical and electrochemical properties and their relative low cost. The present work evaluated the variation of some laser beam conditions, regarding the magnetic susceptibility in AISI 316L stainless steel samples produced by additive manufacturing (AM). Methodology: The magnetic susceptibility of AISI 316L stainless steel was measured on samples produced by selective laser melting (SLM), in the dimensions: (12 x 35 x 3) [mm], layer thickness: 30 [μm], power: 53, 73, 93, 132 [W] and scanning speed: 800, 900, 1000, 1100 [mm/s]; seeking to meet requirements of: adequate surface finish, i.e. low roughness, high density (with low porosity index), according to the standard for metallic materials obtained by additive manufacturing (ASTM F3122-14). Results and discussion: This occur because there is a microstructural transformation of the austenitic steel surface from the temperature increase generated by the laser beam energy. As the austenitic phase is paramagnetic, but the altered phase is ferromagnetic, a magnetic method was used to identify this transformation. The amount of altered material is tiny, and so the magnetic method must be extremely sensitive. To this end, a device like a susceptibility balance was set up. The use of an analytical balance allowed the measurement of this transformation with acceptable uncertainties. Conclusions: The powder metallurgy production process using selective laser melting induced the formation of magnetic phases on the surfaces of the evaluated samples, resulting in small but significant changes in the magnetic susceptibility values.
  • Resumo IPEN-doc 30246
    Biotribological characterization of laser textured Ti6Al4V produced by addictive manufacturing
  • Resumo IPEN-doc 30245
    Tribological characterization of nanoporous anodized anodic alumina coatings for biomedical applications
  • Artigo IPEN-doc 30213
    Fracture toughness of vacuum sintered AISI M3:2 high speed steels
    The aim of this investigation was to study and evaluate the fracture toughness (KICV) of an AISI M3:2 high speed steel that was prepared by powder metallurgical processing, which consisted of uniaxial cold compaction of irregularly shaped water atomized powders, without and with 0.3% of carbon in the form of graphite, followed by vacuum sintering to obtain compacts with densities close to its theoretical value. The sintered steels were then hardened by austenitizing, quenching and triple tempering. Chevron fracture toughness test samples were prepared from the compacts and the tests conducted to determine KICV. The microstructures of the specimens were examined by scanning electron microscopy (SEM), and the composition of the phases determined by x-ray diffraction analysis (XRD). The sizes of the primary carbides and of the austenite grains were determined using Quantikov digital analysis software. No significant difference in fracture toughness (KICV) between the two high speed steels AISI M3:2, austenitized at the different temperatures, was observed.
  • Artigo IPEN-doc 30226
    Residual stress and fracture toughness study in A516 Gr70 steel joints welded and repaired by arc processes
    2023 - BARROS, REGIS de M.C. de; NEVES, MAURICIO D.M. das
    Structural components made of steel are used in several areas and require welding for assembly. In some situations, repair of the weld bead, also performed by electric arc welding, can be used to correct, and eliminate any discontinuities. However, electric arc welding causes the presence of residual stresses in the joint, which can impair its performance and not meet specific design requirements. In this paper, welded joints made of ASTM A 516 GR 70 steel plates, with a thickness of 30.5 mm, welded by the MAG—Metal Active Gas process (20% CO2) and using a “K” groove were analysed. The joints were manufactured with seven welding passes on each side of the groove. After welding, one batch underwent repair of the bead by TIG welding (Tungsten Insert Gas) and another batch underwent two repairs by TIG welding. Were presented results of the behaviour of the residual stress profile measured by X-ray diffraction and the Vickers microhardness profile in the joints as well the fracture toughness in the conditions only welded and submitted to repairs. The results indicated that the greater number of repair passes reduced the residual compressive stress values obtained in the material manufacturing process and caused a stabilization on the Vickers hardness values. It was concluded that compressive residual stresses did not play a major role in the R-curve results. The presence of discontinuities in the welded joint caused greater influence on the behaviour of the R curve.
  • Resumo IPEN-doc 30166
    Syringe cell method to study the corrosion resistance of the UNS S32101 lean duplex stainless steel welded by the gas tungsten arc welding double fusion (GTAW-DF)
    This work aims to investigate the corrosion performance of the UNS S32101 lean duplex stainless steel (LDSS) welded by the gas tungsten arc welding double fusion (GTAW-DF). In the study, six welded samples were manufactured with different welding parameters. A Syringe cell was used to characterize the electrochemical behavior of the different welded zones by potentiodynamic polarization tests in NaCl 3,5 % (w.t.) and in a solution of citric acid with addiction of NaCl to simulate the food industry. The results showed that the welding parameters tested significantly affected the corrosion resistance of the LDSS UNS S32101. Besides, a correlation was stablished between microstructure and electrochemical behavior of fusion line (FL), heat affected zone (HAZ) and fusion zone (FZ).
  • Resumo IPEN-doc 30165
    Study of residual stresses and fracture toughness in welded and repaired joints using A516 Gr70 steel
    2023 - BARROS, REGIS de M.C. de; NEVES, MAURICIO
    The properties of welded joints subjected to cyclic loading is an important subject in several áreas[1]. In this scenario, aiming to study this subject, welded joints made of ASTM A 516 GR 70 steel plates, with a thickness of 30.5 mm, welded by the MAG – Metal Active Gas process (20% CO2) with the use of a K-bevel were analyzed. to allow full penetration due to the high thickness [2]. The joints were manufactured with seven welding passes on each side of the chamfer. After welding, one set was subjected to a repair pass, for remelting the surface of the bead using the TIG (Tungsten Inert Gas) process, while another set was subjected to two repair passes. This study aimed to analyze aspects of welded and repaired joints: dimensions (height and width) of the bead, behavior of the residual stress profile measured by X-ray diffraction, Vickers microhardness profile and fatigue crack nucleation with based on ASTM E466 and E606 standards. The results indicated that the greater number of repair passes decreased the compressive residual stress values in the transverse and longitudinal directions, from -350 MPa to 50 MPa. There was greater uniformity in hardness Vickers values (value between 200 and 210 HV) with the use of cord repairs. It was observed that the fracture toughness presented values of 1500 J/mm (without repair) and 900 J/mm (one pass and two repair passes), lower than that found in the material without welding (3500 J/mm). Therefore, as the repair passes were performed, the residual stresses in the weld bead tended to positive values, the hardness tended to stabilize with values of 200 HV due to the increase in the number of repair passes and the fracture toughness decreased in the welded material when compared to the values of the non-welded material. There was no significant difference in fracture toughness between repair passes.
  • Resumo IPEN-doc 30162
    Effect of EBW process welding parameters on AISI 304L stainless steel bead geometry
    One important field in the welding researches is the study of the relationship between the welding bead geometry and welding machine parameters. In electron beam welding (EBW) process, the fine controlled parameters enable a detail understand of the weld profile. EBW provides a concentrated beam of energy which can result in a high ratio of weld depth to bead width, which can be called a keyhole. EBW is widely study because of its importance in nuclear and aerospace application, mainly as a result of keyhole bead geometry. The relationship between the welding bead geometry, width root and depth with welding machine parameters is presented in this work by setting beam current and beam deflection frequency. All experiments were carried out on samples of AISI 304L alloy with a thickness (t) = 10 mm, accelerating voltage U = 60 KV, beam current range I = 34 – 43 mA, welding speed v = 480 mm/min, vacuum p < 10-4 mbar, beam deflection width d = 1.2 mm and beam deflection frequency f = 400 / 600 Hz. The weld joint geometry has changed by varying of beam current and beam deflection frequency. The weld penetration was increased by increment of beam current and deflection frequency. Set the frequency at f = 600 Hz and changing the beam current from 34 mA to 39 mA, it was observed that penetration rise from 7.38 mm to 8.46 mm, respectively. On the other hand, when was modified deflection frequency from 400 Hz to 600 Hz, the average welding penetration surged 6.3%. Moreover, with deflection frequency kept in f = 400 Hz, a beam current increment from I = 37 mA to I = 43 mA led to grow the welding penetration from 7.56 to 8.63, respectively. The results of weld width root showed no variation due to an increase of beam current, however applying a change of electron beam deflection frequency from 600 Hz to 400 Hz was verified a slight increase in it. In conclusion, the welding bead geometry is directly affected by varying of current beam and deflection frequency parameters.