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In this investigation distinctive self-compacting concretes (SCC) containing both marble + granite (MG) powder and hooked-end steel fibers (HESF) are investigated. A mixture of conventional SCC (reference), and other five samples containing MG and steel fiber (SF) contents are provided, i.e. 20MG, 20SF, 30MG + 10SF, 20SF and 30MG + 20 SF. Both the fresh and hardened properties of the modified self-compacting concretes are evaluated. Workability of the SCC samples represented by slump flow, L-box, V-funnel, J-ring and flowability T500 is examined. The properties of hardened state of the SCC samples at 7 and 28 days are also evaluated. Modulus of elasticity, water absortion, voids index (indicatig porosity), and specific mass are attained. Comparisons among specific strengths and consumptions of cement per compressive strengths are also provided. The SCC/30MG/10SF sample has a specific strength ∼50% higher than the conventional SCC sample. When a ratio involving porosity per cement consumption per tensile strength is evaluated, the SCC/30MG/10SF sample has this ratio ∼80% higher than the SCC reference. Additionally, the best result of consumption of cement (CC) per compressive strength (CS) (1.28x lower than the SCC reference) at 28 days is that of the SCC/30MG/10SF sample (5.03 kg/m3. MPa−1). This indicates that an environmentally friendly aspect associated with low relative cost, which is an important parameter to consider in future SCC mixture designing.
Beatriz C Xavier; Amauri E Gomes; Mirian Lnm Melo; Rosa C Cecche Lintz; Luísa A Gachet; Wislei R Osório. Study of three distinct self-compacting concretes containing marble/granite powder and hooked-end steel fiber contents. Journal of Composite Materials 2021, 55, 2823 -2838.
AMA StyleBeatriz C Xavier, Amauri E Gomes, Mirian Lnm Melo, Rosa C Cecche Lintz, Luísa A Gachet, Wislei R Osório. Study of three distinct self-compacting concretes containing marble/granite powder and hooked-end steel fiber contents. Journal of Composite Materials. 2021; 55 (20):2823-2838.
Chicago/Turabian StyleBeatriz C Xavier; Amauri E Gomes; Mirian Lnm Melo; Rosa C Cecche Lintz; Luísa A Gachet; Wislei R Osório. 2021. "Study of three distinct self-compacting concretes containing marble/granite powder and hooked-end steel fiber contents." Journal of Composite Materials 55, no. 20: 2823-2838.
In this work an Al-7Si-0.4Mg-1.2Fe alloy (wt.%) was subjected to a horizontal solidification experiment using a water-cooled solidification device equipped with thermocouples to obtain temperature vs. time data which in turn allowed solidification thermal parameters, such as growth and cooling rates (VL and TR, respectively), to be determined. In turn, tribological behavior of samples with different secondary dendritic spacing (λ2) and β-Al5FeSi platelets length (βFe) were assessed by means of dry sliding wear testing performed in a rotating fixed ball machine, with wear volume and rate (WV and WR, respectively) being the two main investigated wear parameters. Quantitative metallography by optical and scanning electron microscopy along with energy dispersive X-ray spectroscopy enabled both as-cast microstructures and worn craters to be characterized. More significant variations in wear resistance of the investigated alloy were found for ranges of λ2 and βFe that lie within 12−20 μm and 14–36 μm, respectively, with the coarsening of the microstructure constituted by Al-rich primary phase dendrites surrounded by α-Al + Si + θ-Mg2Si + β-Al5FeSi eutectic structures favoring reduced WV and WR values. For λ2 and βFe values higher than 24 and 48 μm, respectively, both WV and WR stabilize assuming constant values that depend on the sliding distance. In addition to power type equations relating λ2 and βFe to VL and TR, mathematical expressions for variations of WV and WR with λ2 and βFe are also proposed. Finally, a comparative analysis with the literature is presented.
Angela Vasconcelos; Hugo Azevedo; André Barros; Otávio Rocha; Mirian Motta Melo. Influence of the dendritic microstructure and β-Al5FeSi phase on the wear characteristics in a horizontally solidified Al-7Si-0.4Mg-1.2Fe alloy. Materials Today Communications 2021, 26, 102099 .
AMA StyleAngela Vasconcelos, Hugo Azevedo, André Barros, Otávio Rocha, Mirian Motta Melo. Influence of the dendritic microstructure and β-Al5FeSi phase on the wear characteristics in a horizontally solidified Al-7Si-0.4Mg-1.2Fe alloy. Materials Today Communications. 2021; 26 ():102099.
Chicago/Turabian StyleAngela Vasconcelos; Hugo Azevedo; André Barros; Otávio Rocha; Mirian Motta Melo. 2021. "Influence of the dendritic microstructure and β-Al5FeSi phase on the wear characteristics in a horizontally solidified Al-7Si-0.4Mg-1.2Fe alloy." Materials Today Communications 26, no. : 102099.
Por meio desta pesquisa, objetivou-se analisar as influências da modalidade de home office nas conversas informais nas organizações, durante a pandemia de COVID-19. Mediante entrevistas on line assíncronas, entrevistaram-se 40 trabalhadores e profissionais que, devido à pandemia, migraram para a modalidade de home office, cujos relatos foram analisados por meio da análise de conteúdo. Os resultados mostram que a maior parte dos participantes passou a se utilizar de tecnologias digitais da informação e da comunicação, como aplicativos de comunicação remota e dispositivos móveis, para manter suas conversas informais. Contudo, para muitos participantes, ocorreu a redução da frequência de conversas informais e, em alguns casos, elas não ocorreram mais. Considerando-se, de um lado, os efeitos positivos da comunicação informal sobre o trabalho e a integração e, de outro, a possível intensificação do isolamento físico e social decorrente do home office em tempos de pandemia, os resultados sugerem a ocorrência de potenciais impactos negativos na eficiência dos processos de trabalho executados, bem como na qualidade de vida e bem-estar no trabalho. Pela perspectiva teórica, a investigação contribui ao desvelamento de efeitos da modalidade de home office na comunicação informal, em uma situação de intenso isolamento físico e social. Pela perspectiva prática, tal compreensão pode contribuir para que organizações e seus gestores contemplem, em seus processos de implementação do teletrabalho, a dimensão da comunicação informal, o que implica em considerar-se a adoção de práticas voltadas à interação face a face, como reuniões de trabalho e momentos informais presenciais periódicos, assim como a intensificação das possibilidades de comunicações virtuais mais significativas.
Pedro Motta Ravacci Pires; Mirian De Lourdes Noronha Motta Melo; Henrique Geraldo Rodrigues. As influências da modalidade de home office nas conversas informais, nas organizações, durante a pandemia de COVID-19. Research, Society and Development 2020, 9, 1 .
AMA StylePedro Motta Ravacci Pires, Mirian De Lourdes Noronha Motta Melo, Henrique Geraldo Rodrigues. As influências da modalidade de home office nas conversas informais, nas organizações, durante a pandemia de COVID-19. Research, Society and Development. 2020; 9 (11):1.
Chicago/Turabian StylePedro Motta Ravacci Pires; Mirian De Lourdes Noronha Motta Melo; Henrique Geraldo Rodrigues. 2020. "As influências da modalidade de home office nas conversas informais, nas organizações, durante a pandemia de COVID-19." Research, Society and Development 9, no. 11: 1.
O mercado global de implantes dentários estima o valor de US $ 13,01 bilhões até 2023 contra US $ 9,50 bilhões em 2018. O estudo dos materiais para a fabricação dos implantes tem aumentado com o objetivo de estender a vida útil do material evitando sua substituição. Assim, neste estudo investigamos o comportamento eletroquímico de corrosão, molhabilidade e atividade antimicrobiana do titânio e da liga binária Ti-30Ta. O titânio foi cortado em discos de 10 mm de diâmetro. A liga Ti-30Ta foi obtida a partir de titânio e tântalo em forno a arco voltaico, homogeneizada em vácuo a 1000ºC por 24 horas, trabalhada a frio e solubilizada a 950 ºC por 2 horas seguido de resfriamento em água . Em seguida, as barras foram cortadas em discos. Os testes de resistência à corrosão avaliaram o comportamento eletroquímico, a molhabilidade das superfícies do substrato foi investigada usando o método da gota séssil e a formação de biofilme foi investigada por de S epidermidis. Este estudo tem como objetivo investigar a resistência à corrosão do Ti cp e da liga Ti-30Ta em solução eletrolítica NaCl 0,15M + NaF 0,03M e formação de biofilme testado. Pelos resultados obtidos concluímos que o comportamento eletroquímico de ambas as superfícies apresenta boa resistência à corrosão e comportamento hidrofílico (< 90 °). No entanto, a liga Ti-30Ta diminui a adesão da bactéria S epidermidis.
Patrícia Capellato; Mariana Da Silva Novakoski; Lucas Victor Benjamim Vasconcelos; Tainara Aparecida Nunes Ribeiro; Mirian De Lourdes Noronha Motta Melo; Gilbert Silva; Roberto Zenhei Nakazato; Maria Gabriela Araújo Ranieri; Ana Paula Rosifini Alves Claro; Daniela Sachs. Atividade antimicrobiana e corrosão do titânio e da liga Ti-30Ta. Research, Society and Development 2020, 9, 1 .
AMA StylePatrícia Capellato, Mariana Da Silva Novakoski, Lucas Victor Benjamim Vasconcelos, Tainara Aparecida Nunes Ribeiro, Mirian De Lourdes Noronha Motta Melo, Gilbert Silva, Roberto Zenhei Nakazato, Maria Gabriela Araújo Ranieri, Ana Paula Rosifini Alves Claro, Daniela Sachs. Atividade antimicrobiana e corrosão do titânio e da liga Ti-30Ta. Research, Society and Development. 2020; 9 (11):1.
Chicago/Turabian StylePatrícia Capellato; Mariana Da Silva Novakoski; Lucas Victor Benjamim Vasconcelos; Tainara Aparecida Nunes Ribeiro; Mirian De Lourdes Noronha Motta Melo; Gilbert Silva; Roberto Zenhei Nakazato; Maria Gabriela Araújo Ranieri; Ana Paula Rosifini Alves Claro; Daniela Sachs. 2020. "Atividade antimicrobiana e corrosão do titânio e da liga Ti-30Ta." Research, Society and Development 9, no. 11: 1.
The inadequate disposal of household appliances by consumers and industries have annually been generating enormous amounts of polymeric waste (PW). So, the interest in reuse of PW in civil construction has increased. The production of new cementitious materials, such as concrete with PW, proves to be a promising solution to inappropriate disposal of this waste. In this study, self-compacting concrete (SCC) was developed with partial replacement of the coarse aggregates by polymeric waste (PW) from the recycling of refrigerators. In the SCC reference mixture, Portland cement, silica fume, sand, gravel and superplasticizer were used. The study also grouped the gravel as replaced by 5%, 10%, 15% and 20% of PW. In order to analyze the samples, the following tests were used: spreading, viscosity, passing ability, compressive strength, tensile strength, microstructure, modulus of elasticity, specific gravity, absorption, voids index and electrical resistivity. The SCC found showed adequate homogeneity and viscosity, staying within the normative parameters. The mechanical resistance was above 20 MPa; specific mass between 1870 to 2260 kg/m3; modulus of elasticity ranged from 34 to 14 GPa; and electrical resistivity between 319 to 420 ohm.m. Due to the mechanical resistance, the SCC with PW can be used for structural purposes and densely reinforced structures such as pillars, beams and foundation elements.
Lucas Silva; Josimara Silva; Matheus Francisco; Vander Ribeiro; Michel Souza; Patricia Capellato; Marcelo Souza; Valquíria Santos; Paulo Gonçalves; Mirian Melo. Polymeric Waste from Recycling Refrigerators as an Aggregate for Self-Compacting Concrete. Sustainability 2020, 12, 8731 .
AMA StyleLucas Silva, Josimara Silva, Matheus Francisco, Vander Ribeiro, Michel Souza, Patricia Capellato, Marcelo Souza, Valquíria Santos, Paulo Gonçalves, Mirian Melo. Polymeric Waste from Recycling Refrigerators as an Aggregate for Self-Compacting Concrete. Sustainability. 2020; 12 (20):8731.
Chicago/Turabian StyleLucas Silva; Josimara Silva; Matheus Francisco; Vander Ribeiro; Michel Souza; Patricia Capellato; Marcelo Souza; Valquíria Santos; Paulo Gonçalves; Mirian Melo. 2020. "Polymeric Waste from Recycling Refrigerators as an Aggregate for Self-Compacting Concrete." Sustainability 12, no. 20: 8731.
With little success, researchers has been searching for alloys with elements such as tantalum to improve the long-term life of implants. The Ti–30Ta alloy presents an elastic modulus E = 69 GPa that is close to that of bone (E = 17–25 GPa) than Ti cp (E = 105 GPa). In addition, nanostructure surface modification influences cell behavior and antimicrobial activity. So, this study investigates the corrosion behavior of surface modification by TiO2 nanotube grown on Ti–30Ta alloy after anodization process in the electrolyte glycerol + NH4F 0.25% at 30 V, for nine hours without annealing and annealed in 450 °C, 530 °C and 600 °C (5 °C/min). The electrochemical behavior was evaluated by three electrodes cell. The counter-electrode of graphite, reference-electrode of saturated calomel electrode and working-electrode at electrolyte of 0.15 M NaCl + 0.03 M NaF, with pH = 6 for 8000 s. The scanned region ranged from −0.8 V to values up to 3.5 V with a sweep rate 0.166 mV/s. Potentiodynamic polarization curves were obtained with a potentiostat. The sample was characterized by scanning electron microscopy (SEM) imaging, X-ray diffraction analysis (XRD) and wettability with a contact angle goniometer. We concludes from the obtained results that all treatment surfaces are hydrophilic (2 nanotube crystallinity showed anatase phase after annealing at 450 °C, 530 °C and 600 °C; the exceptions were the anodized-without-annealing treatment and without-surface-modification alloys. The electrochemical behavior of the five groups investigated showed similar high resistance to corrosion solution under all conditions.
Patricia Capellato; Daniela Sachs; Filipe Bueno Vilela; Mirian M. Melo; Gilbert Silva; Geovani Rodrigues; Cecilia A. De C. Zavaglia; Roberto Z. Nakazato; Ana Paula R. A. Claro. Influence of Annealing Temperature on Corrosion Resistance of TiO2 Nanotubes Grown on Ti–30Ta Alloy. Metals 2020, 10, 1106 .
AMA StylePatricia Capellato, Daniela Sachs, Filipe Bueno Vilela, Mirian M. Melo, Gilbert Silva, Geovani Rodrigues, Cecilia A. De C. Zavaglia, Roberto Z. Nakazato, Ana Paula R. A. Claro. Influence of Annealing Temperature on Corrosion Resistance of TiO2 Nanotubes Grown on Ti–30Ta Alloy. Metals. 2020; 10 (8):1106.
Chicago/Turabian StylePatricia Capellato; Daniela Sachs; Filipe Bueno Vilela; Mirian M. Melo; Gilbert Silva; Geovani Rodrigues; Cecilia A. De C. Zavaglia; Roberto Z. Nakazato; Ana Paula R. A. Claro. 2020. "Influence of Annealing Temperature on Corrosion Resistance of TiO2 Nanotubes Grown on Ti–30Ta Alloy." Metals 10, no. 8: 1106.
The current metallic biomaterial still presents failures associated with the bulk alloy and the interface of material/human body. In previous studies, titanium alloy with tantalum showed the elastic modulus decrease in comparison with that of commercially pure (cp) titanium. In this study, surface modification on Ti-30Ta alloy was investigated. Titanium and tantalum were melted, homogenized, cold-worked by a rotary swaging process and solubilized. The anodization process was performed in electrolyte contained glycerol + NH4F 0.25% at 30 V using seven different durations—4 h, 5 h, 6 h, 7 h, 8 h, 9 h, and 10 h and annealed at 530 °C for 1 h. The surface topography was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) measurements, X-ray diffraction analysis (XRD), and contact angle. From the results, we conclude the time of anodization process influences the shape and morphology of the anodized layer. The 5 h-anodization process produced a smooth and porous surface. The 4-, 6-, 7-, 8-, 9-, and 10-h conditions showed nanotubes morphology. All surfaces are hydrophilic (<90°). Likewise, all the investigated conditions present anatase phase. So, this surface modification presents potential for biomedical application. However, more work needs to be done to better understand the influence of time on the anodization process.
Patricia Capellato; Daniela Sachs; Lucas V. B. Vasconcelos; Miriam M. Melo; Gilbert Silva; Maria G. A. Ranieri; Cecilia A. De C. Zavaglia; Roberto Z. Nakazato; Ana P. R. Alves Claro. Optimization of Anodization Parameters in Ti-30Ta Alloy. Metals 2020, 10, 1059 .
AMA StylePatricia Capellato, Daniela Sachs, Lucas V. B. Vasconcelos, Miriam M. Melo, Gilbert Silva, Maria G. A. Ranieri, Cecilia A. De C. Zavaglia, Roberto Z. Nakazato, Ana P. R. Alves Claro. Optimization of Anodization Parameters in Ti-30Ta Alloy. Metals. 2020; 10 (8):1059.
Chicago/Turabian StylePatricia Capellato; Daniela Sachs; Lucas V. B. Vasconcelos; Miriam M. Melo; Gilbert Silva; Maria G. A. Ranieri; Cecilia A. De C. Zavaglia; Roberto Z. Nakazato; Ana P. R. Alves Claro. 2020. "Optimization of Anodization Parameters in Ti-30Ta Alloy." Metals 10, no. 8: 1059.
Nos últimos anos, diversas pesquisas têm sido realizadas buscando o desenvolvimento de materiais para aplicações biomédicas. E, um dos objetivos desses estudos, é otimizar o comportamento da interface material/meio biológico. Dentre os materiais mais utilizados, estão o titânio e suas ligas devido às suas propriedades como resistência à corrosão e biocompatibilidade. Estudos constataram que o comportamento celular pode ser influenciado por alterações na morfologia das superfícies. Dessa maneira, o objetivo deste estudo foi associar a deposição de fibras poliméricas de PCL com o crescimento de nanotubos de TiO2 na superfície da liga Ti-30Ta para aplicações biomédicas. O processo de eletrofiação foi usado para a produção de nanofibras de polímero com 200 nm, devido em grande parte, ao aumento do interesse em propriedades e tecnologias em nanoescala. O uso de polímeros biocompatíveis para a viabilidade do crescimento celular é uma alternativa promissora para melhorar a osseointegração. Técnicas de caracterização como microscopia eletrônica de varredura (MEV-FEG) foi usado para investigar a superfície das amostras. Também foram utilizadas células-tronco adultas derivadas de tecido adiposo humano (ADSC) para estudar a resposta celular desses biomateriais. A viabilidade celular foi determinada pelo ensaio Cell Titer-Blue após 1 e 7 dias. Os resultados indicaram que as alterações na nanoarquitetura das características morfológicas das nanoestruturas na micro-topografia, podem ser promissoras no campo biomédico devido à modulação da resposta celular.
Patrícia Capellato; Gilbert Silva; Maria Gabriela Araújo Ranieri; Mirian De Lourdes Noronha Motta Melo; Samira Esteves Afonso Camargo; Cecilia Amélia De Carvalho Zavaglia; Ana Paula Rosifini Alves Claro; Tainara Aparecida Nunes Ribeiro; Mariana Da Silva Novakoski; Daniela Sachs. Avaliação da biocompatibilidade do polímero PCL recobrindo a liga Ti-30Ta. Research, Society and Development 2020, 9, 1 .
AMA StylePatrícia Capellato, Gilbert Silva, Maria Gabriela Araújo Ranieri, Mirian De Lourdes Noronha Motta Melo, Samira Esteves Afonso Camargo, Cecilia Amélia De Carvalho Zavaglia, Ana Paula Rosifini Alves Claro, Tainara Aparecida Nunes Ribeiro, Mariana Da Silva Novakoski, Daniela Sachs. Avaliação da biocompatibilidade do polímero PCL recobrindo a liga Ti-30Ta. Research, Society and Development. 2020; 9 (8):1.
Chicago/Turabian StylePatrícia Capellato; Gilbert Silva; Maria Gabriela Araújo Ranieri; Mirian De Lourdes Noronha Motta Melo; Samira Esteves Afonso Camargo; Cecilia Amélia De Carvalho Zavaglia; Ana Paula Rosifini Alves Claro; Tainara Aparecida Nunes Ribeiro; Mariana Da Silva Novakoski; Daniela Sachs. 2020. "Avaliação da biocompatibilidade do polímero PCL recobrindo a liga Ti-30Ta." Research, Society and Development 9, no. 8: 1.
The Al4.5wt%Cu is an aeronautical and automobile alloy with extensive use in industry for structural purposes. The aim of this work was to evaluate two different solidification processes of the Al4.5wt%Cu alloy, conventional and unidirectional, as well as its recrystallization process. Firstly, the Al4.5wt%Cu alloy was deformed by cold rotary forging and then heat treated at temperatures that varied from 250 to 450 °C. The samples for analysis were obtained after 54, 76 and 91% of reductions in area. Tests of optical microscopy, scanning electron microscopy and Vickers microhardness were performed to evaluate the recrystallization process. The results indicated that the recrystallization started at 350 ºC, being that the conventional samples presented full recrystallization after 5 minutes, while the unidirectional samples presented only partial recrystallization. In general, both solidification processes presented similar results for all of the analysis performed.
Roberta Alves Gomes Matos; Jonas Mendes; Bruna Horta Bastos Kuffner; Mirian De Lourdes Noronha Motta Melo; Gilbert Silva. Recrystallization Study of the Al4.5wt%Cu Alloy Conventionally and Unidirectionally Solidified, Deformed and Heat Treated. Materials Research 2020, 23, 1 .
AMA StyleRoberta Alves Gomes Matos, Jonas Mendes, Bruna Horta Bastos Kuffner, Mirian De Lourdes Noronha Motta Melo, Gilbert Silva. Recrystallization Study of the Al4.5wt%Cu Alloy Conventionally and Unidirectionally Solidified, Deformed and Heat Treated. Materials Research. 2020; 23 (5):1.
Chicago/Turabian StyleRoberta Alves Gomes Matos; Jonas Mendes; Bruna Horta Bastos Kuffner; Mirian De Lourdes Noronha Motta Melo; Gilbert Silva. 2020. "Recrystallization Study of the Al4.5wt%Cu Alloy Conventionally and Unidirectionally Solidified, Deformed and Heat Treated." Materials Research 23, no. 5: 1.
The aim of this study was to provide an experimental investigation on the novel method for recycling chips of duplex stainless steel, with the addition of vanadium carbide, in order to produce metal/carbide composites from a high-energy mechanical milling process. Powders of duplex stainless steel with the addition of vanadium carbide were prepared by high-energy mechanical ball milling utilizing a planetary ball mill. For this proposal, experiments following a full factorial design with two replicates were planned, performed, and then analyzed. The four factors investigated in this study were rotation speed, milling time, powder to ball weight ratio and carbide percentage. For each factor, the experiments were conducted into two levels so that the internal behavior among them could be statistically estimated: 250 to 350 rpm for rotation speed, 10 to 50 h for milling time, 10:1 to 22:1 for powder to ball weight ratio, and 0 to 3% carbide percentage. In order to measure and characterize particle size, we utilized the analysis of particle size and a scanning electron microscopy. The results showed with the addition of carbide in the milling process cause an average of reduction in particle size when compared with the material without carbide added. All the four factors investigated in this study presented significant influence on the milling process of duplex stainless steel chips and the reduction of particle size. The statistical analysis showed that the addition of carbide in the process is the most influential factor, followed by the milling time, rotation speed and powder to ball weight ratio. Significant interaction effects among these factors were also identified.
Claudiney Mendonça; Patricia Capellato; Emin Bayraktar; Fábio Gatamorta; José Gomes; Adhimar Oliveira; Daniela Sachs; Mirian Melo; Gilbert Silva. Recycling Chips of Stainless Steel Using a Full Factorial Design. Metals 2019, 9, 842 .
AMA StyleClaudiney Mendonça, Patricia Capellato, Emin Bayraktar, Fábio Gatamorta, José Gomes, Adhimar Oliveira, Daniela Sachs, Mirian Melo, Gilbert Silva. Recycling Chips of Stainless Steel Using a Full Factorial Design. Metals. 2019; 9 (8):842.
Chicago/Turabian StyleClaudiney Mendonça; Patricia Capellato; Emin Bayraktar; Fábio Gatamorta; José Gomes; Adhimar Oliveira; Daniela Sachs; Mirian Melo; Gilbert Silva. 2019. "Recycling Chips of Stainless Steel Using a Full Factorial Design." Metals 9, no. 8: 842.
Brazilian aeronautical industries report that, due to the high mechanical properties presented commercially, AA2024-T351 alloy presents fissures and non-homogeneous deformations during the mechanical processing. This work proposes a manufacturing process capable of increasing the ductility of the material to withstand tensions during processing and a subsequent treatment to recover the mechanical strength of the alloy. The sequence of operations begins with the super-heat treatment at 415ºC 2.5 h, solubilization at 495ºC 2.0 h, mechanical conformation with a degree of area reduction from10% to 90% and artificial aging at 190ºC at times of 2, 4, 6 and 8 hours. The results allowed to obtain an operational sequence where it is possible to form the alloy in the desired component, without loss of mechanical properties and structural defects, in the shortest time possible of heat treatment, reducing the manufacturing costs and increasing productivity.
Marcelo Luis Siqueira; Aline Da Silva; Mirian De Lourdes Noronha Motta Melo; Geovani Rodrigues. Mechanical Properties Analysis of Al2024 alloy Submitted to Different Aging Time and different Cold Plastic Deformation degree. Materials Research 2019, 22, 1 .
AMA StyleMarcelo Luis Siqueira, Aline Da Silva, Mirian De Lourdes Noronha Motta Melo, Geovani Rodrigues. Mechanical Properties Analysis of Al2024 alloy Submitted to Different Aging Time and different Cold Plastic Deformation degree. Materials Research. 2019; 22 (4):1.
Chicago/Turabian StyleMarcelo Luis Siqueira; Aline Da Silva; Mirian De Lourdes Noronha Motta Melo; Geovani Rodrigues. 2019. "Mechanical Properties Analysis of Al2024 alloy Submitted to Different Aging Time and different Cold Plastic Deformation degree." Materials Research 22, no. 4: 1.
Due to the increased consumption of raw materials, energy, and the waste it generates, recycling has become very important and fundamental for the environment and the industrial sector. The production of duplex stainless–steel powders with the addition of vanadium carbide in the high energy mechanical milling process is a new method for recycling materials for the manufacture of components in the industrial sector. This study aims to reuse the chips from the duplex stainless–steel UNS S31803 by powder metallurgy with the addition of Vanadium carbide (VC). The mechanical milling was performed using a planetary ball mill for 50 h at a milling speed of 350 rpm and a ball-to-powder weight ratio of 20:1, and the addition of 3 wt % of VC. The material submitted to milling with an addition of carbide has a particle size of less than 140 μm. After milling, the sample went through a stress relief treatment performed at 1050 °C for 1 h and the isostatic compaction process loaded with 300 MPa. The sintered powders and material was characterized by scanning electron microscopy, X-ray diffraction, and micro-hardness tests. The milling process with an addition of 3% VC produced a particle size smaller than the initial chip size. The measurement of micrometric sizes obtained was between 26 and 132 μm. The sintered material had a measurement of porosity evaluated at 15%. The obtained density of the material was 84% compared to the initial density of the material as stainless–steel duplex UNS S31803. The value of the microhardness measurement was 232 HV. The material submitted for grinding presented the formation of a martensitic structure and after the thermal treatment, the presence of ferrite and austenite phases was observed. Thus, in conclusion, this study demonstrates the efficacy in the production of a metal-ceramic composite using a new method to recycle stainless–steel duplex UNS S31803 chips.
Mendonça Claudiney; Oliveira Adhimar; Sachs Daniela; Capellato Patricia; Ribeiro Vander; Junqueira Mateus; Melo Mirian; Silva Gilbert. A New Method to Recycle Stainless–Steel Duplex UNS S31803 Chips. Metals 2018, 8, 546 .
AMA StyleMendonça Claudiney, Oliveira Adhimar, Sachs Daniela, Capellato Patricia, Ribeiro Vander, Junqueira Mateus, Melo Mirian, Silva Gilbert. A New Method to Recycle Stainless–Steel Duplex UNS S31803 Chips. Metals. 2018; 8 (7):546.
Chicago/Turabian StyleMendonça Claudiney; Oliveira Adhimar; Sachs Daniela; Capellato Patricia; Ribeiro Vander; Junqueira Mateus; Melo Mirian; Silva Gilbert. 2018. "A New Method to Recycle Stainless–Steel Duplex UNS S31803 Chips." Metals 8, no. 7: 546.
The aluminum bronze alloy is part of a class of highly reliable materials due to high mechanical strength and corrosion resistence being used in the aerospace and shipbuilding industry. It's machined to produce parts and after its use cycle, it's discarded, but third process is considered expensive and besides not being correct for environment reasons. Thus, reusing this material through the powder metallurgy (PM) route is considered advantageous. The aluminum bronze chips were submitted to high energy ball milling process with 3% of niobium carbide (NbC) addition. The NbC is a metal-ceramic composite with a ductile-brittle behaviour. It was analyzed the morphology of powders by scanning electron microscopy as well as particle size it was determined. X ray diffraction identified the phases and the influence of milling time in the diffractogram patterns. Results indicates that milling time and NbC addition improves the milling efficiency significantly and being possible to obtain nanoparticles.
Alexandre Nogueira Ottoboni Dias; Aline Da Silva; Carlos Alberto Rodrigues; Mirian De Lourdes Noronha Motta Melo; Geovani Rodrigues; Gilbert Silva. Effect of High Energy Milling Time of the Aluminum Bronze Alloy Obtained by Powder Metallurgy with Niobium Carbide Addition. Materials Research 2017, 20, 747 -754.
AMA StyleAlexandre Nogueira Ottoboni Dias, Aline Da Silva, Carlos Alberto Rodrigues, Mirian De Lourdes Noronha Motta Melo, Geovani Rodrigues, Gilbert Silva. Effect of High Energy Milling Time of the Aluminum Bronze Alloy Obtained by Powder Metallurgy with Niobium Carbide Addition. Materials Research. 2017; 20 (3):747-754.
Chicago/Turabian StyleAlexandre Nogueira Ottoboni Dias; Aline Da Silva; Carlos Alberto Rodrigues; Mirian De Lourdes Noronha Motta Melo; Geovani Rodrigues; Gilbert Silva. 2017. "Effect of High Energy Milling Time of the Aluminum Bronze Alloy Obtained by Powder Metallurgy with Niobium Carbide Addition." Materials Research 20, no. 3: 747-754.
Maria Luiza Grillo Renó; Ricardo Carrasco Carpio; Felipe Martins Torres; Rogério José Da Silva; Mirian De Lourdes Noronha Motta Melo. Analysis of CO2 Emissions of the Cement Production Applying Wastes. The Journal of Solid Waste Technology and Management 2014, 40, 357 -363.
AMA StyleMaria Luiza Grillo Renó, Ricardo Carrasco Carpio, Felipe Martins Torres, Rogério José Da Silva, Mirian De Lourdes Noronha Motta Melo. Analysis of CO2 Emissions of the Cement Production Applying Wastes. The Journal of Solid Waste Technology and Management. 2014; 40 (4):357-363.
Chicago/Turabian StyleMaria Luiza Grillo Renó; Ricardo Carrasco Carpio; Felipe Martins Torres; Rogério José Da Silva; Mirian De Lourdes Noronha Motta Melo. 2014. "Analysis of CO2 Emissions of the Cement Production Applying Wastes." The Journal of Solid Waste Technology and Management 40, no. 4: 357-363.
This work proposes a methodology to obtain the carbon fiber/epoxy composite limit strain for structures surviving 120000 cycles. The damage progression was also evaluated using stiffness reduction and hysteresis loop analysis in order to obtain dynamic and secant modulus. The results provide information about composite fatigue behavior. This approach determined a limit strain range from 0.83 to 0.87%, a fatigue stress limit of 0.8% of the static strength, stiffness degradation (damage index) of about 5% (within the limit strain). The methodology presented herein may be used for determining of material design allowable when fatigue is key consideration.
C. Ancelotti; M.L.M. Noronha Melo; Vanderlei O. Gonçalves; K. Garcia; L.C. Pardini. Experimental Methodology for Limit Strain Determination in a Carbon/Epoxy Composite under Tensile Fatigue Loading. Materials Science Forum 2014, 805, 311 -318.
AMA StyleC. Ancelotti, M.L.M. Noronha Melo, Vanderlei O. Gonçalves, K. Garcia, L.C. Pardini. Experimental Methodology for Limit Strain Determination in a Carbon/Epoxy Composite under Tensile Fatigue Loading. Materials Science Forum. 2014; 805 ():311-318.
Chicago/Turabian StyleC. Ancelotti; M.L.M. Noronha Melo; Vanderlei O. Gonçalves; K. Garcia; L.C. Pardini. 2014. "Experimental Methodology for Limit Strain Determination in a Carbon/Epoxy Composite under Tensile Fatigue Loading." Materials Science Forum 805, no. : 311-318.
The AISI 52100 steel is a material widely used in the industry due to its high fatigue resistance, dimensional stability, high hardness and wear resistance. This steel is used for production of ball bearings, stamping tools, etc. In case of production of ball bearings and its track this material is spherodized because, due to its high content of carbon, about 1%, it has high mechanical strength making it impossible to cold forming. To obtain a wear resistant surface, after forming, this material is hardened and tempered. Normally to obtain the AISI 52100 steel, arc electric melting furnace is used. This work aims the reuse of AISI 52100 steel by powder metallurgy route, starting from the machined chips using high energy mill (planetary) to obtain the powder. Then, the powder was uniaxially pressed into a press with a load of 4 tons, to form the specimen, later on pressed in an isostatic press at a pressure of 300MPa to obtain a better densification. To analyze the powder morphology and the phases obtained after sintering, was used a scanning electron microscope and X-ray diffraction to calculate the crystallite size. It was verified that with more than 10 hours of grinding, the crystallite size does not change significantly, the particles gained rounded shapes with a size distribution between 30 and 5μm. The microstructure obtained by the two routes was nearly identical after sintering.
Wellington S. Diogo; Dalton G.B. De Souza; Rayana F. Rodrigues Lourenço; M.L.M. Noronha Melo; Katia Regina Cardoso; Gilbert Silva. Recycling of Steel AISI 52100 Gotten by the Route of Powder Metallurgy. Materials Science Forum 2014, 805, 325 -330.
AMA StyleWellington S. Diogo, Dalton G.B. De Souza, Rayana F. Rodrigues Lourenço, M.L.M. Noronha Melo, Katia Regina Cardoso, Gilbert Silva. Recycling of Steel AISI 52100 Gotten by the Route of Powder Metallurgy. Materials Science Forum. 2014; 805 ():325-330.
Chicago/Turabian StyleWellington S. Diogo; Dalton G.B. De Souza; Rayana F. Rodrigues Lourenço; M.L.M. Noronha Melo; Katia Regina Cardoso; Gilbert Silva. 2014. "Recycling of Steel AISI 52100 Gotten by the Route of Powder Metallurgy." Materials Science Forum 805, no. : 325-330.
The refractory metals and their alloys show excellent mechanical behavior in high temperatures and high resistance to corrosion and to wear and good thermal conductivity. The metals that constitute this group are, traditionally, tantalum, molybdenum, tungsten and niobium. Niobium (Nb) is a metal with 2468°C melting point, density 8.57 g/cm3 and CCC crystalline structure, is characterized by its excellent ductility and reasonable mechanical resistance in high temperatures. Due to these properties, o Nb is applied in chemical, nuclear and electrical industry and in the superconductor wire production. One of the processes used in niobium plastic deformation is the swage that consists in one direct deformation process, which can be done at hot or cold temperature, used to modify the transversal section area of bars, tubes and wires. The microstructure evolution during a plastic deformation is very important in the relation of deformation mechanism, mechanical property and texture formation. The aim of this work is to evaluate the microstructural and mechanical behavior of metal cold rotary forging – swage using the techniques of Scanning Electronic Microscopic – SEM e microhardeness Vickers. Metallographic analysis of the microstructure of Nb after deformation of 96.4%, shows a distorted shape called "ripple". The Vickers microhardeness results indicate that there is a gradual increase in the microhardness of Nb up to 80% reduction in area taking place stabilization after this value. It may be noted that in both directions, the center of sample had higher hardness values
Dalton Garcia Borges; Márcia Regina Baldissera; Geovani Rodrigues; Mirian De Lourdes Noronha Motta Melo; Rayana Fernanda Ribeiro Lourenço; Gilbert Silva. Microstructural and Mechanical Characterization of the Niobium Cold Deformed-Swage. Materials Science Forum 2014, 805, 362 -367.
AMA StyleDalton Garcia Borges, Márcia Regina Baldissera, Geovani Rodrigues, Mirian De Lourdes Noronha Motta Melo, Rayana Fernanda Ribeiro Lourenço, Gilbert Silva. Microstructural and Mechanical Characterization of the Niobium Cold Deformed-Swage. Materials Science Forum. 2014; 805 ():362-367.
Chicago/Turabian StyleDalton Garcia Borges; Márcia Regina Baldissera; Geovani Rodrigues; Mirian De Lourdes Noronha Motta Melo; Rayana Fernanda Ribeiro Lourenço; Gilbert Silva. 2014. "Microstructural and Mechanical Characterization of the Niobium Cold Deformed-Swage." Materials Science Forum 805, no. : 362-367.
In machining processes the chip is considered the disposal of no interest and so little analysis of the morphology observed as the types and forms submitted. The machining does not equal the composition of the physical properties of metal forming, it involves forces or active and inactive stocks. The combination of parameters, conditions and variables of the machining is a means of speculating and trying to explain the phenomena. Such actions reflect directly on the wear of tooling, and structural integrity. The experimental study of machining is of essential importance for the theory of plasticity can not explain satisfactorily the observed phenomena. The speed and the deformations are very large in the machining process, compared with those treated in this theory. This material may reveal why this chip segmented nature which are characterized by continuous large deformation in narrow bands between segments with little or no strain in their interiors. This is a very different from the continuous chip. With the aid of a tool in the expanding area of technology and scientific processing and analysis of images could provide a better analysis of the chips. The goal of this study was to relate the microstructure of the chips of superalloy Aluminum Bronze (C 63020) with milling parameters used in the process of turning on a CNC lathe Nardini - LOGIC 175, in order to analyze the behavior of even through a mechanical process.
Daniel Assis Amancio; José Veríssimo Ribeiro De Toledo; João Ferreira; Mirian De Lourdes Noronha Motta Melo; Gilbert Silva; Luiz Eduardo Paes. Morphological Analysis of Chip Generated by the Process of Turning on Bronze Aluminium Industry Used in Aeronautics via Electronic Scanning Microscopy. Materials Science Forum 2014, 805, 374 -379.
AMA StyleDaniel Assis Amancio, José Veríssimo Ribeiro De Toledo, João Ferreira, Mirian De Lourdes Noronha Motta Melo, Gilbert Silva, Luiz Eduardo Paes. Morphological Analysis of Chip Generated by the Process of Turning on Bronze Aluminium Industry Used in Aeronautics via Electronic Scanning Microscopy. Materials Science Forum. 2014; 805 ():374-379.
Chicago/Turabian StyleDaniel Assis Amancio; José Veríssimo Ribeiro De Toledo; João Ferreira; Mirian De Lourdes Noronha Motta Melo; Gilbert Silva; Luiz Eduardo Paes. 2014. "Morphological Analysis of Chip Generated by the Process of Turning on Bronze Aluminium Industry Used in Aeronautics via Electronic Scanning Microscopy." Materials Science Forum 805, no. : 374-379.
In this work was carried out the microstructural characterization and evaluation of mechanical properties of steel with different microstructures. The intercritical region and the existing phases in function of temperature were determined using the THERMOCALC software. The samples of steel were quenched at different temperatures to obtain differents microstructures consisting of ferrite, pearlite and martensite. The microstructural characterization of the samples was performed by qualitative and quantitative metallography. The determination of volume was performed with the "Image J" software. The mechanical properties were determined by uniaxial stress test, which determined the parameters: yield strength, tensile strength, breaking point and total elongation.
Alexandre Nogueira Ottoboni Dias; Márcia Regina Baldissera; Eduardo Carvalho Rossi; Gilberto Carvalho Coelho; Andersan Dos Santos Paula; Mirian De Lourdes Noronha Motta Melo; Geovani Rodrigues. Microstructural Characterization and Evaluation of Mechanical Properties of Steel with Different Biphasic Microstructures Obtained from LNE 500 Steel. Materials Science Forum 2014, 805, 227 -230.
AMA StyleAlexandre Nogueira Ottoboni Dias, Márcia Regina Baldissera, Eduardo Carvalho Rossi, Gilberto Carvalho Coelho, Andersan Dos Santos Paula, Mirian De Lourdes Noronha Motta Melo, Geovani Rodrigues. Microstructural Characterization and Evaluation of Mechanical Properties of Steel with Different Biphasic Microstructures Obtained from LNE 500 Steel. Materials Science Forum. 2014; 805 ():227-230.
Chicago/Turabian StyleAlexandre Nogueira Ottoboni Dias; Márcia Regina Baldissera; Eduardo Carvalho Rossi; Gilberto Carvalho Coelho; Andersan Dos Santos Paula; Mirian De Lourdes Noronha Motta Melo; Geovani Rodrigues. 2014. "Microstructural Characterization and Evaluation of Mechanical Properties of Steel with Different Biphasic Microstructures Obtained from LNE 500 Steel." Materials Science Forum 805, no. : 227-230.
Superduplex stainless steel is an important class of stainless steels because it combines the benefits of ferrite and austenite phases, resulting in steels with better mechanical properties and corrosion resistance. However, a significant problem of this steel is the precipitation of deleterious phases during heat treatment. Among these precipitated phases, the most relevant is the sigma phase, because it causes higher loss of properties. The objective of this work therefore is to study the sigma phase precipitation in the superduplex stainless steel UNS S32520 when submitted to heat treatment of solubilization in three different temperatures (1050 C, 1150o C and 1250° C) and subsequently aged in the temperature of 850oC during 10 minutes, 30 minutes, 60 minutes, 3 hours and 10 hours, followed by water quenching. The results showed that as the solubilization temperature increases, there is a significant grain growth and an increase of the ferrite volumetric fraction, which delays the sigma phase precipitation in this superduplex stainless steel. Moreover, it can be verified that the hardness of the material is directly related to volumetric fraction of sigma present in the steel.
Aline Da Silva; Carlos Alberto Rodrigues; Antonio Carlos Ancelotti; Edmilson Otoni Corrêa; M.L.M. Noronha Melo. Effect of Solubilization Temperature on the Sigma Phase Precipitation of a Superduplex Stainless Steel. Materials Science Forum 2014, 805, 305 -310.
AMA StyleAline Da Silva, Carlos Alberto Rodrigues, Antonio Carlos Ancelotti, Edmilson Otoni Corrêa, M.L.M. Noronha Melo. Effect of Solubilization Temperature on the Sigma Phase Precipitation of a Superduplex Stainless Steel. Materials Science Forum. 2014; 805 ():305-310.
Chicago/Turabian StyleAline Da Silva; Carlos Alberto Rodrigues; Antonio Carlos Ancelotti; Edmilson Otoni Corrêa; M.L.M. Noronha Melo. 2014. "Effect of Solubilization Temperature on the Sigma Phase Precipitation of a Superduplex Stainless Steel." Materials Science Forum 805, no. : 305-310.