MARCELLO VERTAMATTI MERGULHAO

MARCELLO VERTAMATTI MERGULHAO

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Heat treatment influence on micromilling of additively manufactured titanium
2024 - GONCALVES, MARIA C.C.; MERGULHAO, MARCELLO V.; BATALHA, GILMAR F.; STOETERAU, RODRIGO L.
Recently, miniaturized products are being used as working tools by many fields, highlighting the medical and dental industries. With the development of Additive Manufacturing (AM) processes, these features can be produced with less material waste and with wide design possibilities by applying a ‘near-net-shape’ technique. Although, the AM parts require post-processing techniques to reach the required material properties, dimensions, and surface roughness and to reduce undesirable residual stresses. In this aspect, the micromilling process is usually applied to attain the desired dimensions and surface roughness and heat treatments to attain the desired material properties and to reduce residual stress. Nonetheless, the micromilling process can be done before or after the heat treatment. In this perspective, this research analyses the surface roughness results for the micromilled AM parts before and after the heat treatment, which is in important for planning the manufacturing route for these parts. Thus, this work aims to compare the surface roughness results of Sa, Sq, Ssk, Sku when performing the micromilling process on AM parts by Laser Powder Bed Fusion (LPBF), with and without heat treatment. For the experiments, the tool size, feed and cutting speed were varied in a full factorial design of experiments. After that, the surface roughness parameters were analyzed and compared for both workpieces. With the achieved results, it can be concluded that the surface texture (Ssk) for the heat-treated and non-heat-treated samples present a predominance of peaks. Also, there is a presence of inordinately high peaks and/or deep valleys on the surface (Sku), which can present an interference of the chips left on the surface not removed by the ultrasonic cleaning. By the analyses of the arithmetic mean deviation (Sa) and the root mean square height (Sq), a better surface quality was achieved when micromilling the samples before the heat treatment for greater tool size, for the specific set of parameters used. With the smaller tool size, a greater surface roughness was achieved if compared to the bigger tool size, though the difference between the samples were not expressive. Moreover, the results achieved in this work can be applied to improve the surface quality of the AM parts used in industry.
Fusão em leito de pó a laser da liga de Co-Cr-Mo: propriedades mecânicas e microestrutura após tratamentos térmicos
2022 - MERGULHAO, MARCELLO V.
A fusão em leito de pó a laser (FLP-L) se destaca entre os principais processos da manufatura aditiva (MA) pela fabricação de peças de geometrias complexas e com alívio de peso, especialmente nas indústrias aeroespacial e biomédica. A adequação de parâmetros do processo da FLP-L e a realização de pós-processamento por tratamentos térmicos são fundamentais para assegurar a qualidade e otimizar a vida útil de próteses e implantes médicos. As ligas de Co-Cr-Mo fabricadas por FLP-L são foco de pesquisa recorrente por possuir grande potencial na fabricação de próteses médicas e odontológicas personalizadas. Até o momento os estudos anteriores enfatizam a otimização de propriedades macroscópicas, como o comportamento de envelhecimento. Nas ligas de Co-Cr-Mo existe pouca literatura abrangendo a janela de processamento e sua relação com as características microestruturais e mecânicas. Este trabalho apresenta uma investigação dos principais parâmetros do processo de FLP-L em uma liga normatizada de Co-Cr-Mo ASTM F75 por meio dos efeitos e das influências da fabricação aditiva por laser por meio de análises mecânicas e microestrutura obtida nas amostras. Adicionalmente, foi feito tratamento térmico por solubilização na liga de Co-Cr-Mo processada por FLP-L. As análises obtidas foram comparadas com a rota convencional de fundição de precisão (FP). Os resultados obtidos permitiram determinar os parâmetros adequados para o processo FLP-L da liga de Co-Cr-Mo, possibilitando uma microestrutura com ausência de defeitos, obtendo densificações superiores que 99 %. As relações investigadas de processo-propriedade são importantes para definir a influência dos parâmetros analisados no processamento e pode embassar o estabelecimento de protocolos na padronização do processo de FLP-L da liga de Co-Cr-Mo.
Análise de amostras da liga de titânio Ti6Al4V impressas por FSL para ensaios de microfresamento
2019 - GONÇALVES, MARIA C.C.; MERGULHAO, MARCELLO V.; STOETERAU, RODRIGO L.; BATALHA, GILMAR F.; NEVES, MAURICIO D.M.
A fabricação de peças metálicas via impressão 3D tem ganhado destaque pela sua eficácia na manufatura de geometrias complexas e com pouco consumo de material. Uma das estratégias de sinterização utilizadas para impressão 3D é a Fusão Seletiva a Laser (FSL), que consiste na completa fusão dos pós metálicos por meio de um feixe laser. As peças obtidas por esse processo apresentam uma superfície com ondulações periódicas e anisotropias relacionadas à direção da sinterização. No entanto, o efeito dessa ondulação e da anisotropia das peças nas suas propriedades mecânicas e na sua usinabilidade é pouco conhecido. Visto isso, este trabalho visa examinar amostras da liga de titânio Ti6Al4V impressas por FSL, mediante análises de dureza, rugosidade e por microscópio óptico para ensaios de microfresamento.
Perspective of additive manufacturing selective laser melting in Co-Cr-Mo alloy in the consolidation of dental prosthesis
2018 - MERGULHAO, MARCELLO V.; PODESTA, CARLOS E.; NEVES, MAURICIO D.M. das
This chapter seeks to compare the properties of samples manufactured by additive manufacturing (AM) by the selective laser melting (SLM) technology and compare with the precision casting (PC) processes using the Co-Cr-Mo (ASTM F75) alloy to manufacture of dental prosthesis. This AM process can be manufactured three-dimensional models by means of a laser beam that completely melts particles of powder deposited layer by layer. However, it is still relevant to know the properties of: performance, dimensional, mechanical and microstructural of this laser melting process and compare with a convencional process. The results of mechanical evaluation showed that the SLM technique provides superior mechanical properties compared to those obtained by the PC technique. It is possible to verify that the consolidation by SLM technique results in lower presence of porosity than PC technique. In addition, PC samples presented a gross dendritic microstructure of casting process. Microstructural analysis of SLM samples results in a characteristic morphology of layer manufacturing with ultrafine grains and a high chemical homogeneity. In this way, the development of the present study evidenced to improve the manufacture of customized components (copings) using the SLM technology.
Investigation of mechanical, microstructural and thermal behavior of CoCrMo alloy manufactured by selective laser melting and casting techniques
2017 - MERGULHAO, MARCELLO V.; PODESTA, CARLOS E.; NEVES, MAURICIO D.M. das
A route of increasing development in additive manufacturing (3D printing) process using metal alloys is the selective laser melting (SLM). 3D building components is possible by laser power that completely melts the metal powder particles. SLM was applied in a biomaterial of CoCrMo alloy, to study the mechanical properties and microstructural characterization in comparison of the conventional technique – lost wax casting. The gas atomized powder was investigated by their physical (as apparent density, bulk density and flow rate) and chemical properties (X-ray fluorescence). Standard samples evaluated the mechanical properties as yield strength, elongation, elastic modulus, transverse rupture strength and the Vickers hardness. Microstructural characterization was performed using optical microscope (OM) and scanning electron microscope (SEM-EDS). Thermal analysis of CoCrMo alloy were investigated using thermomechanical analysis (TMA) and differential scanning calorimetry (DSC) techniques. The results of mechanical properties showed higher values in the SLM specimens compared with the obtained in the cast specimens. The micrographs revealed a typical morphology of consolidation process, characterized by selected layer used in the SLM technique and the dendrites arms in the casting technique. The thermal results confirm the phase’s transitions of CoCrMo alloy.
Characteristics of biometallic alloy to additive manufacturing using selective laser melting technology
2018 - MERGULHAO, MARCELLO V.; NEVES, MAURICIO D.M. das
Biomaterial powders are in high development due to expansion of additive manufacturing (AM) processes. Selective laser melting (SLM) is a particular AM technology, which completely melts a powder bed layer by laser beam. Investigations of appropriated physical properties of feedstock (powder alloy) were the aim of this study. Cobalt-chromium-molybdenum (Co-Cr-Mo) alloy was used to overview of gas-atomized powder properties in different granulometric ranges (D1 12 - 19 μm, D2 20 - 46 μm and D3 76 - 106 μm), as their: physical, chemical properties and thermal analysis. SLM manufactured standard tensile specimens of usually granulometric range powder size provided mechanical, chemical and thermal properties of biocompatible Co-Cr-Mo alloy. The physical properties showed that powders in the range of 20 to 50 μm provide a better flow ability and packed density, which are relevant characteristics to SLM processing. Manufacturing by SLM process provided suitable mechanical properties in the health area, as well as, maintained the biocompatible properties of the Co-Cr-Mo alloy.
Avaliação de propriedades mecânicas e caracterização microestrutural de consolidados de Cobalto-Cromo-Molibdênio obtidos por fusão seletiva a laser e fundição de precisão
2017 - MERGULHÃO, MARCELLO V.
Este trabalho tem por objetivo estudar as propriedades mecânicas e a caracterização microestrutural de espécimes da liga de Co-Cr-Mo obtidos por manufatura aditiva fusão seletiva a laser (do inglês Selective Laser Melting SLM) e por fundição de precisão, visando a confecção de próteses odontológicas. A partir de pós de Co-Cr-Mo atomizados a gás foram realizadas as seguintes etapas: 1) investigação das propriedades físicas, químicas e térmicas dos pós atomizados em diferentes faixas granulométricas (denominadas: D1 < 15 μm, D2 de 20-50 μm e D3 > 75 μm); 2) confecção de espécimes, em dimensões padronizadas, por meio das técnicas de consolidação; 3) caracterização dos consolidados por análise de: citotoxicidade, porosidade, difração de raios X e dilatometria; 4) caracterização mecânica de tração, flexão em três pontos, dureza (macro e micro Vickers) e caracterização microestrutural (microscopia óptica e eletrônica de varredura). De modo geral, os resultados obtidos foram: a granulometria D2 (20-50 μm) é a que melhor se enquadra nas análises de empacotamento para a consolidação por meio de SLM; a biocompatibilidade das amostras obteve resultado positivo para ambas técnicas de processamento; a avaliação mecânica dos espécimes evidencia que a técnica de fusão seletiva a laser propicia propriedades mecânicas (tensão de escoamento, tensão de ruptura, tensão máxima, alongamento e dureza) superiores as obtidas pela técnica de fundição de precisão; a microestrutura obtida pelo processo SLM é composta por grãos ultrafinos e de elevada homogeneidade química. Conclui-se que, o desenvolvimento do presente estudo evidenciou que na fabricação de componentes odontológicos customizados (coroas) a técnica SLM apresenta qualidade superior quando comparada a fundição de precisão.
Mechanical properties and microstructural characterization of Cobalt-Chromium (CoCr) obtained by casting and Selective Laser Melting (SLM)
2017 - MERGULHAO, MARCELLO V.; PODESTA, CARLOS E.; NEVES, MAURICIO D.M. das
The aim of this study is the consolidation of Cobalt-Chromium (CoCr) alloy powder using the additive manufacturing - selective laser melting (SLM) and the investment casting techniques. The research of this study has been applied to their biomaterial applied to development of prosthesis and dental implants. The gas atomized powder are spherical (mean diameter equal to 42,74 μm) and was analyzed by their physical and chemical properties. The microstructure of the powder and specimens was evaluated using optical microscope (OM) and scanning electron microscope with energy-dispersed X-ray spectroscopy (SEM-EDS). The mechanical properties were evaluated of standard samples using a tensile (yield strength, maximum tensile, rupture tensile and elongation), three point bending (transverse rupture strength) and micro hardness tests. The mechanical results indicate higher values for the SLM than casting specimens. The micrographs revealed a characteristic morphology of laser been used in the SLM technique and the dendrites in the casting technique. The microstructure of samples made by SLM is thinner than the samples obtained in the cast.
Valuation of mechanical properties and microstructural characterization of ASTM F75 Co-Cr alloy obtained by Selective Laser Melting (SLM) and casting techniques
2017 - MERGULHAO, MARCELLO V.; PODESTA, CARLOS E.; NEVES, MAURICIO D.M. das
Advances in processes using the powder metallurgy techniques are making this technology competitive compared to the other traditional manufacturing processes, especially in medicine area. The additive rapid prototyping technique – selective laser melting (SLM) was applied in a biomaterial of CoCrMoFe alloy (ASTM F75), to study the mechanical properties and microstructural characterization in comparison between the conventional technique – casting. The gas atomized powder was investigated by their physical (as apparent density, bulk density and flow rate) and the chemical properties. The powder was analyzed using scanning electron microscope with energy-dispersed X-ray spectroscopy (SEM-EDS) and X-ray fluorescence. Specimens of standard samples were manufactured using these techniques to evaluate the mechanical properties as uniaxial tensile (yield strength, rupture tensile and elongation), transverse rupture strength and the micro hardness. The mechanical properties showed higher values in the SLM specimens than the casting specimens. Before the mechanical tests the specimens were examined using optical microscope (OM) and SEM-EDS. The micrographs revealed a microstructure with finer morphology in the SLM technique and the dendrites in the casting technique.
Mechanical and microstructural evaluation of CoCr alloys manufactured via selective laser melting (SLM)
2016 - MERGULHAO, M.V.; PODESTA, C.E.; NEVES, M.D.M. das
Dental prosthesis components are widely produced with CoCr alloys. New near net shape techniques has been used nowadays as an alternative route. The aim of this study was evaluated the mechanical properties and the microstructural characterization of CoCr dental alloys manufactured by SLM and to investigated the correlation of chemical composition between mechanical properties of standard specimens. The tensile specimens was manufactured by SLM technique in standard dimensions by two different composition of CoCr dental alloy and were chemical analyzed using scanning electron microscope with energy-dispersed X-ray spectroscopy (SEM-EDS) and X-ray fluorescence. The mechanical properties as uniaxial tensile (yield strength, maximum tensile, rupture tensile, elongation and elastic modulus) and Vickers hardness were evaluated. The microstructure of the samples were characterized using optical microscope (OM) and SEM-EDS. The mechanical results indicate higher values for both composition of CoCr alloys fabricated via SLM technique. The micrographs revealed a characteristic morphology of layer used in the SLM technique. Keywords: CoCr alloys, selective laser melting, biomaterial, dental prothesis.