Dimensionamento de trocadores de calor aplicados à refrigeração da água do molde de um processo de lingotamento contínuo

This study aims to determine the most suitable type of heat exchanger to be applied to the water cooling the mold of a continuous casting process. Basically been studied four types of heat exchangers: shell and tube operating in counterflow, shell and tube operating in parallel flow, plate type and operating counterflow and plates operating in parallel flow. Initially is displayed design of heat exchangers for the conditions of the proposed application. With the heat exchangers dimensioned comparisons were made in order to set the heat exchanger more suitable for application. In the study, one comes to the conclusion that the plate type heat exchangers operating shows counterflow major advantage for this application

Processo de fabricação de tarugos pelo método HotTop de ligas de alumínio da série 6XXX e as não conformidades desse processamento

The goal of this work is to report some problems that occur in the in the production of aluminum billets (series 6XXX) produced by the hot top process in the Alcoa aluminum Inc. The aluminum fabrication process is described from its first stage, since the mining until the reduction, smelting and treatment of the metal. One of the plant’s final product, are billets for clients that produce profiles by extrusion. The product’s final quality highly depends on the whole production process. Therefore it’s necessary to use good practices in the treatment of the metal, follow up its fabrication and control its thermal treatment, in order to meet the required standards to satisfy the clients. The billet’s production method and its variables will be detailed through temperature and casting speed, cone of water flow, cooling rate, duration of thermal treatment, degassing and metal “in line “filtering, in other words when it’s still found in its liquid state. The non-conformities of the process were studied by metallographic analysis, both macrostutural and microstructural that will be described and discussed in this work

Caracterização estrutural da Liga Al-1% Si

The aim of this study is to characterize the macrostructure and microstructure of Al - 1%Si alloy obtained in sand and metallic molds. Aluminium has good mechanical properties, but adding silicon, even in small quantities, can change the microstructure and improves mechanical behavior. Workpieces were castings in metallic and sand molds and one can see a difference in their cooling curve, macroscopic and microscopic structures. The sand mold casting has lower cooling rate and so its grains are larger. Due to the lower concentration of grain boundary, the hardness is lower compared to that found in metallic molds, which has smaller grains and a higher hardness. Therefore, it can be concluded that the cooling rate and alloying elements affect the final microstructure of the workpiece

Estudo da influência do agente nucleante )ALTi5%B1%) na microestrutura de chapas AA8011 obtidas por lingotamento contínuo

The aluminum includes several properties with excellent relation between weight and mechanical resistance. With technological advances, increasingly demand the development of new alloys and other production processes in order to reduce the cost of production and insert these new alloys in broader applications. The process of continuous caster (TRC promoted the unite of the aluminum smelting process with the first stage of rolling, making it most economical through the merger these two phases besides transform the continuous casting process. The AA8xxx series is one of the most versatile aluminum alloys and the most often used in continuous caster process provided a great potential application in the market. In order to further, optimize the process it is necessary to increase awareness of the aluminum solidification phenomena associated with the addition of grain refiner, and control of some aluminum production parameters in the process (production rate, metal temperature, etc.). In this study, AA8011 alloy samples were taken in the raw state obtained by the continuous casting process. The samples were laminated to a thickness of 7mm during the process itself and analyzed at three points along its width by microstructural analysis throughout its thickness, the variation rate of addition of the grain refiner in order to assess the influence of this addition with crystallographic formation and some formation of intermetallic precipitates during the solidification. Through this work, it was possible to improve the knowledge related to the addition of refiner with the monitoring of these production processes

Um problema de programação da produção numa fundição automatizada

Este trabalho apresenta a modelagem de um problema particular de Programação da Produção numa Fundição Automatizada e sua resolução por um algoritmo de busca heurística, que explora a estrutura do problema.

Determinação de dureza de ligas de cobre, na forma como são recebidas e após a fundição, em função das técnicas de fusão.

It was evaluated the Vickers hardness of five high-copper casting alloys, in their original package form and after casting, according to the casting method used. That way, ten ingots, supplied by the manufacturers of each alloy, were included in self-curing acrylic resin, polished, numerated and submitted to Vickers hardness test at load of 200 g during 30 seconds. Afterwards the numerated ingots were removed from the acrylic resin and five of those were cast in an electrical casting machine and the other five in a centrifugal casting machine with an air/gas torch. The specimens obtained were included in self-curing acrylic resin, polished and submitted to Vickers hardness test. As a result it was verified that there is a variation of hardness among the alloys tested, and the use of the electrical casting machine produced lower hardness values than those produced when used the centrifugal casting machine with an air/gas torch. Also, there is a decrease of hardness of the cast alloys when they are tested in their original form and after casting.

EFEITOS DA INFUSAO CONTINUA DO PROPOFOL SOBRE A FUNCAO RENAL DO CAO. ESTUDO COMPARATIVO COM O PENTOBARBITAL SODICO

Little research has been done with propofol in relation to renal function. The aim of this study was to evaluate the effects of the continuous infusion of propofol on renal function in dogs. Sixteen dogs, previously anesthetized with pentobarbital sodium (30 mg.kg-1) for surgical preparation, catheterism and monitoring, were studied. The dogs were mechanically ventilated with air and received alcuronium (0.2 mg.kg-1 in bolus and 0.06 mg.kg-1 - maintenance). The following parameters were studied: heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), aortic blood flow (A(o)BF - by electromagnetic flowmeter installed in the ascending aortic), aortic vascular resistance index (A(o)VRI), renal plasma flow (ERPF - by para-aminohipurate clearance), glomerular filtration rate (GFR - by creatinine clearance), effective renal blood flow (ERBF = ERPF/1 - hematocrit), urinary volume (UV), renal vascular resistance (RVR = MAP.80/ERBF.10-3), urinary sodium excretion (UE(Na)), fractionated sodium excretion (FE(Na)), osmolar clearance (C(osm)) and free water clearance (C(H2O)). These parameters were studied at 15 (M1), 30 (M2), 45 (M3) and 60 (M4) min after beginning pentobarbital sodium infusion (5 mg.kg-1.h-1). The dogs were allocated into two groups of eight animals each: G1 (control-pentobarbital sodium) and G2 (propofol). In G1, pentobarbital was given at the four times studied. G2 dogs received the same treatment as G1 dogs at M1 and M2; infusion of pentobarbital was substituted by propofol (3 mg.kg-1 bolus, followed by 12 mg.kg-1.h-1 continuous infusion) at M3 and M4. Profile Analysis was used to analyze the results statistically. In G1 (pentobarbital), there was a significant increase in RVR (M1 < M4) and a decrease in ERPF and ERBF (M1 > M4). In G2 (propofol) there was only a significant increase in A(o)BF (M1 < M2 = M3). In comparison among groups, these was a significant alteration of FE(Na) at M3 (pentobarbital > propofol). It was observed that the continuous infusion of propofol in dogs, at the given doses, did not alter the basic variables of renal function and hemodynamics studied. We concluded that propofol can be one of the drugs of choice to provide base anesthesia in studies of renal function in dogs.

Análise de variáveis dinâmicas na fundição centrifugada de cilindros de laminação

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Projeto, construção de equipamento para obtenção de compósitos de matriz metálica particulados, utilizando o processo de fundição com agitação mecânica

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito de tratamentos térmicos na resistência à tração e na dureza Vickers do Ti c.p. e da liga Ti-6Al-4V obtidos por fundição odontológica

Pós-graduação em Reabilitação Oral - FOAR

Influência do tipo de fundição e uso de retificação na interface pilar/cilindro protético na adaptação marginal e tensão peri-implantar sobre conexão protética tipo Micro-Unit

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação da desadaptação marginal de estruturas metálicas obtidas com variações quanto aos tipos de cera e às técnicas de inclusão e fundição

Pós-graduação em Odontologia - FOA

Comparação da desadaptação marginal de infra-estruturas metálicas obtidas com variações na técnica de fundição, revestimentos e material para obtenção dos padrões

Pós-graduação em Odontologia - FOA

Comparação da adaptação cervical de estruturas metálicas para metalo-cerâmica obtidas através de técnica de fundição rápida e convencional, utilizando três revestimentos comerciais

Pós-graduação em Odontologia - FOA

Estudo comparativo da influência de três diferentes métodos de fundição na resistência da interface metal-cerâmica, por meio do teste de cisalhamento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)