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Search Results: 1 - 10 of 144094 matches for " José Carlos Santos;Garcia "
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Study of the nature of non-metallic inclusions in samples of aluminum and silicon killed low carbon steels, collected in the refining treatment and continuous casting stages
Pires, José Carlos Santos;Garcia, Amauri;
Materials Research , 2004, DOI: 10.1590/S1516-14392004000400002
Abstract: the amount, distribution, size and chemical composition of non-metallic inclusions have a direct influence on steel properties. by controlling size and chemical composition of these inclusions, it is possible to get a product with good quality. the identification of the nature and the control of inclusion formation are very important for steel cleanness. the behavior of these inclusions is predictable, in some extent, by the determination of the chemical composition of non-metallic phases that form such inclusions. with the objective of studying the chemical composition, the size and the distribution of such inclusions, samples of aluminum and silicon killed low carbon steels were collected in a national steel industry in the secondary refining and continuous casting stages. these samples were analyzed in the scanning electron microscope (sem) coupled to an energy dispersive analysis system (eds). from the results, it was possible to evaluate the nature of inclusions and to analyze the effectiveness of the refining process in the reduction of the number and area fraction of the inclusions. it was also possible to verify that the inclusions that remained after treatment, are less damage both to the steel properties as to the continuous casting process (clogging of the submerged valve).
Avalia??o do tamanho, da morfologia e da composi??o química de inclus?es n?o metálicas em a?o baixo carbono desoxidado ao alumínio
Pires, José Carlos dos Santos;Fernandes Neto, Marcolino;Garcia, Amauri;
Rem: Revista Escola de Minas , 2002, DOI: 10.1590/S0370-44672002000100006
Abstract: the endogenous and exogenous non-metallic inclusions, which are normally present in steel, affect its castability and its mechanical properties. in the last decades, the control of amount, size, morphology and chemical composition of non-metallic inclusions has been extensively investigated, especially at the stage of refinement of steels. by controlling amount, size, distribution and chemical composition of inclusions, a steel product of better quality can be produced. to identify the nature of inclusions and the stages of the manufacturing process where they are formed is extremely important for the production of clean steels. the present work has as a main objective to investigate non-metallic inclusions in low carbon steel (sae 1015), killed by aluminum. a method, which uses the expedient of dissolving totally or partially the ferritic matrix, is used. a scanning electronic microscope (sem) connected to an energy-dispersive spectrometer system is then used to obtain, in a more accurate way, size, morphology and chemical composition of such inclusions without any interference caused by the ferritic matrix.
Avalia o do tamanho, da morfologia e da composi o química de inclus es n o metálicas em a o baixo carbono desoxidado ao alumínio
Pires José Carlos dos Santos,Fernandes Neto Marcolino,Garcia Amauri
Rem: Revista Escola de Minas , 2002,
Abstract: A presen a de inclus es n o metálicas endógenas e exógenas prejudica a lingotabilidade e as propriedades mecanicas dos a os. A busca contínua pelo controle da quantidade, do tamanho, da morfologia e da composi o química de inclus es n o metálicas tem sido tema de estudos nas últimas décadas, em especial durante o processo de refino secundário dos a os. Através do controle, principalmente, do tamanho e da composi o química das inclus es, é possível obter um produto final de boa qualidade. A identifica o da natureza e o controle da forma o de inclus es s o de suma importancia para a obten o de a os limpos. Este trabalho tem como objetivo fazer uma investiga o de inclus es n o metálicas em a o de baixo teor de carbono(SAE 1015), desoxidado ao alumínio, através de um método de dissolu o parcial e total da matriz metálica e posterior análise ao Microscópio Eletr nico de Varredura (MEV), acoplado a um sistema de análise por energia dispersiva (EDS), permitindo uma visualiza o do tamanho, da forma e da composi o química das inclus es com maior precis o, sem interferência da matriz ferrítica.
Characterization of dissolved organic matter in the Piauí river estuary, Northeast Brazil
Costa, Adnivia Santos;Passos, Elisangela de Andrade;Garcia, Carlos A. B.;Alves, José do Patrocinio H.;
Journal of the Brazilian Chemical Society , 2011, DOI: 10.1590/S0103-50532011001100017
Abstract: fluorescence spectroscopy and dissolved organic carbon (doc) measurements were used to characterize the dissolved organic matter (dom) in the piauí river estuary, a tropical estuary situated in the state of sergipe, northeast brazil. fluorescence intensities were greater during the rainy period than the dry period, demonstrating that variability in the fluorescence properties of the dom was determined mainly by the fluvial discharge and the dilution processes occurring in the estuary. during the rainy period, tryptophan-like and humic substances were the main components of the dom, while during the dry period there was a significant increase of protein-like constituents. relationships identified between fluorescence intensities and salinity were indicative of non-conservative behavior of the fluorescent dom. doc showed behavior that was conservative during the dry period, and non-conservative during the rainy period, with production of doc in the upper reaches of the estuary. the complexation of dom with cu(ii), studied using the fluorescence suppression technique, showed the complexation potentials of protein, tryptophan and humic type fluorophores.
Espa?amento entre fileiras e densidade de semeadura do sorgo forrageiro para a regi?o norte de Minas Gerais
Albuquerque, Carlos Juliano Brant;Pinho, Renzo Garcia Von;Rodrigues, José Avelino Santos;Brant, Renata da Silva;
Ciência e Agrotecnologia , 2011, DOI: 10.1590/S1413-70542011000300009
Abstract: due to its resistance to drought, forage sorghum used as silage, is one of the most common feeds for ruminants on farms in the northern part of the state of minas gerais. the present research evaluated three planting densities and three forms of row spacing to determine their efficiency in the production of mass under the semiarid climatic conditions. two experiments were conducted in two agricultural years. in each year, the experiments were conducted in contiguous areas using row spacing of 50, 70 and 90 cm and three different plant densities. each experiment used a random blocks design in a 4 x 3 factorial scheme with three replicates, four cultivars and three sowing densities. the viability of reducing the space between rows was found to be dependent on the characteristics of each cultivar as well as the climatic conditions. increasing sowing density resulted in a proportional reduction in the production of dry matter.
Investiga??o de inclus?es n?o metálicas em fios elétricos de alumínio
Fernandes Neto, Marcolino;Pires, José Carlos Santos;Garcia, Amauri;Pinto, Fernando Nicoletti;
Rem: Revista Escola de Minas , 2002, DOI: 10.1590/S0370-44672002000200005
Abstract: actually, one of the biggest challenge for the national electrical aluminum conductors industries has been the occurrence of non-metallic inclusions. these inclusions cause the rupture of the wires during the rolling, drawing and bunchering process. then, the presence of non-metallic inclusions in these materials has significant impact in the capacity of small diameter wire's production, such as to reach rigorous requirements of strength's resistance and fatigue established for these materials. this study analyzes the aluminum wire's non-metallic inclusions that have caused those rupture during the drawing process, using conventional metallographic method with scanning electron microscope (sem) connect to an energy-dispersive spectrometry (eds), in order to identify the inclusions' source. it was also developed a method of isolation of non-metallic inclusions by dissolving the aluminum matrix in a hcl solution. the analysis of isolated inclusions allowed a ampler investigation of the size, form and amount of the inclusions. the results showed that the inclusions responsible by wires' break are of the alumina type and their source is the aluminum oxide dragged of part of the layer that protects the liquid metal in the chutes covered with refractory material.
Modelagem física do sistema de alimenta??o do processo Twin Roll para lingotamento contínuo de tiras de a?o inoxidável
Spinelli, José Eduardo;Santos, Carlos Alexandre dos;Garcia, Amauri;Spim Junior, Jaime Alvares;
Rem: Revista Escola de Minas , 2002, DOI: 10.1590/S0370-44672002000300004
Abstract: it can be understood by process modeling the development of a quantitative or qualitative representation of the physical phenomena associated to the process. important factors in the design of a metal feeding system for thin strip casting of steels are size and shape of tundish, type and location of flow control devices. in this article, simulations concerning the twin roll continuous caster of steels process at ipt (technologic research institute) are performed. in order to optimize steel flow a 1:1 water model was designed and constructed with components made of acrylic, water as the simulation fluid and potassium permanganate as a pigment. the use of an appropriate arrangement of turbulence inhibiting dams and weirs can provide an output fluid flow pattern suitable for input to a thin strip caster. the simulator has contributed to improve the productivity and cleanliness of the strip casting of steel.
Modelagem física do sistema de alimenta o do processo Twin Roll para lingotamento contínuo de tiras de a o inoxidável
Spinelli José Eduardo,Santos Carlos Alexandre dos,Garcia Amauri,Spim Junior Jaime Alvares
Rem: Revista Escola de Minas , 2002,
Abstract: Entende-se, por modelagem de processo, o desenvolvimento de uma representa o quantitativa ou qualitativa dos fen menos físicos associados ao processo. O tipo e a forma do distribuidor, o controle do fluxo e o posicionamento de obstáculos s o importantes fatores no projeto do sistema de alimenta o de metal líquido para o lingotamento contínuo de tiras de a o. Nesse trabalho, s o realizadas simula es do processo Twin Roll de lingotamento contínuo de tiras de a os, utilizando, como referência tecnológica, o equipamento-piloto instalado nas dependências do Instituto de Pesquisas Tecnológicas do Estado de S o Paulo (IPT). Foi construído um simulador a frio do distribuidor do equipamento (em escala 1:1), com componentes feitos de acrílico, com água como fluido de simula o e com permanganato de potássio como corante. O simulador contribuiu para melhorias de produtividade e para a limpeza do produto.
Investiga o de inclus es n o metálicas em fios elétricos de alumínio
Fernandes Neto Marcolino,Pires José Carlos Santos,Garcia Amauri,Pinto Fernando Nicoletti
Rem: Revista Escola de Minas , 2002,
Abstract: Atualmente, um dos grandes desafios enfrentados pelas empresas nacionais fabricantes de condutores elétricos, de alumínio, tem sido a ocorrência de inclus es n o metálicas. Tais inclus es causam a ruptura dos fios ao longo dos processos de lamina o, trefila o e encordoamento. Assim, a presen a de inclus es n o metálicas nesses materiais tem impactos significativos na capacidade de produzir fios elétricos com pequenos diametros, bem como no atendimento dos rigorosos requisitos de resistência à tra o e à fadiga estabelecidos para esses materiais. Nesse sentido, o presente trabalho analisou as inclus es n o metálicas em fios elétricos de alumínio, que causaram a ruptura dos mesmos na etapa do processo de trefila o, através do método metalográfico convencional com auxílio do MEV/EDS, na busca de identificar a origem das inclus es. Também foi desenvolvido, nesse trabalho, um método de separa o de inclus es n o metálicas, presentes nos fios elétricos de alumínio, através da dissolu o da matriz de alumínio em solu o de ácido clorídrico. A análise das inclus es isoladas da matriz de alumínio permitiu uma investiga o mais ampla quanto ao tamanho, à forma e à quantidade de tais inclus es. Os resultados mostraram que as inclus es responsáveis pelo rompimento dos fios s o do tipo alumina e que as mesmas s o provenientes do arraste de parte da camada de óxido de alumínio que protege o metal líquido nas calhas revestidas com material refratário.
Effect of microbiological characteristics of raw milk on the quality of whole milk powder
Oliveira Carlos Augusto Fernandes de,Mestieri Lucinéia,Santos Marcos Veiga,Moreno José Franchini Garcia
Brazilian Journal of Microbiology , 2000,
Abstract: The relationship between microbiological characteristics of raw milk and the quality of high-heat whole powder made from it was investigated. To this end, 16 lots of milk standardized for fat and non-fat solids were used. Powder average levels of mesophiles and psychrotrophs were 7.8 x 101 and 4.0 x 101 CFU/g, respectively, and these values correlated positively (P < 0.05) with the corresponding raw milk counts (8.1 x 10(6) and 1.8 x 10(7) CFU/g, respectively). A significant positive correlation (P < 0.05) was also observed between raw milk psychrotroph counts and titratable acidity of milk powder (range: 0.15 - 0.19 as % lactic acid). Samples of powder produced from raw milk with higher psychrotroph levels were found to have higher insolubility indexes, yet this relationship was not statistically significant. The importance of milk hygienic control as a basic instrument to warrant commercial milk powder quality is discussed.
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