997 resultados para Ensaios de caracterização


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Engenharia Civil - FEIS

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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A energia eólica é uma forma de energia que seu uso encontra-se em expansão, e junto a esse crescimento, tem-se também o aumento da quantidade de resíduos gerados na fabricação das pás eólicas. Uma forma correta de destinação e aproveitamento desses resíduos é a reciclagem. Porém, esses são constituídos de materiais compósitos, geralmente a resina epóxi e a fibra de vidro; e por possuírem um polímero termofixo (a resina epóxi) na sua composição, a reciclagem convencional via fusão não é possível. Desta forma, a reciclagem química via pirólise apresenta-se como uma alternativa para o aproveitamento desses resíduos, em especial da fibra de vidro que o contém. Após caracterização do resíduo de uma indústria de pás eólicas, verificou-se que se tratava de um material com mais de 70% de fibra de vidro e muito densas. Foram realizados ensaios de pirólise a seco e com óleo de babaçu, considerado o mais interessante perante vários possíveis e no qual o resíduo fica totalmente imerso, facilitando o inchamento e a troca de calor. Em um sistema de aquecimento com vácuo, foram obtidas mais de 97% de fibras em 30 minutos a 310 oC, justamente a temperatura em que uma análise termogravimétrica apontou ser a de início de altas taxas de degradação térmica.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Microbiologia Agropecuária - FCAV

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Ananas erectifolius (curaua) is a fibrous vegetable that can be found in North and Central West regions of Brazil. It is a bromeliaceae family plant which physico-chemical features provides great potential in the automobilistic industry as a source of fibers. As commonly described in other bromeliaceae species, it contains significant levels of bromelain, of high commercial value and wide range of aplications in food, pharmaceutical and cosmetic industry. In this paper, experimental tests were performed to evaluate the extraction of the proteolytic enzymes of the Ananas erectifolius under different pH and temperature conditions to determine in which ones the enzymatic activity would be the maximum for later purification of the bromelain. The two commercially available curaua varieties (white and purple) were used in the experiments and the results showed the same optimal pH of 8,5 for both varieties and different temperatures of 30ºC for the white one, and 10ºC, 20ºC and 35ºC for the purple one.

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The aim of this work was to evaluate the effect of the addition of different surfactants in physical and chemical properties of spray solutions, droplets spectra and drift potential on agricultural spraying. The surfactants and concentrations (v v-1) were: Haiten (0.1%), Antideriva and Intec (0.05% and 0.1%). The following characteristics were analyzed: surface tension, viscosity, density and electric conductivity. The droplet size spectrum was determined by a laser particle analyzer (Mastersizer S®, version 2.15) including measurements of volume medium diameter (VMD), the percent of droplets below 50 and 100 μm (V50 e V100) and index span. In order to estimate the drift potential, a series of wind tunnel tests were performed with a Teejet XR 8003 flat fan nozzle at 200 kPa (medium droplets) used to apply the spray solutions containing water, the adjuvants and a food color dye (Brilliant blue FD & C no 1) at 0,6% m v-1. The drift was collected on nylon strips transversally fixed along the tunnel at different distances from the nozzle and different high from the bottom part of the tunnel. Drift deposits were evaluated by spectrophotometry. The results showed that the addition of adjuvants changed physical and chemical properties of spray solutions in different magnitudes according to the surfactant. Surfactants changed the droplet spectrum and drift potential, indicating that higher VMD and smaller V100 induced higher percentage of drift.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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In this work, the project of a new experimental facility to be installed at the Aerodynamics Division of the Institute of Aeronautics and Space is presented. This new facility will provide means to perform experimental campaigns to analyze the flow behavior at different rocket nozzle concepts using cold gas that will be obtained from a modification of the Pilot Transonic Wind Tunnel air system. The new installation will enable less expensive experiments in a more secure environment, since the cold gas experimental procedures do not demand fuel storage and burn and security procedures are much less severe. Furthermore, experiments can be carried with different types of sensors, commonly used in wind tunnel tests. Also, the optical access is facilitated enabling the use of optical techniques for the characterization of flow properties inside the nozzles, such as pressure and temperature sensitive painting. The full project design and the operation conditions will be showed, as also some technical considerations about the flor behavior in the facility

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With advances in health care, has been na increase of demand for material that could replace the functions of the human body parts, thus evolved biomedic prosthesis which today are responsible for the constant improvement of the quality of life. The Titanium alloys are widely used as implants due to its properties, like high mechanical resistance, biocompatibility and corrosion resistance, and the addition alloying elements like Zirconium, may improve some of those properties. Such properties are related to the microstructure and consequently to the type of processing performed. The purpose of this dissertation was to characterize the experimental alloy Ti15Zr after route of processsing and heat treatment in order to extend the knowledge about this alloy. The latter has been abtained by fusion of pure metals in a arc melting furnace with an inert argon atmosphere. The material has been homogenized in a tube furnace at 950ºC for 24h and cold worked by swaging, after that, bars with 10 mm of diameter were obtained by the process of rotary forging. The samples were solubilized at 900º C for 2 hours and quenched in water. After that, 4 samples were submitted to the aging, at 400º C, 450º C, 500º C and 550º C. The microstructure and phase analysis was done by optical microscopy and X-rays diffraction (XRD), the mechanical characterization was carried out by microhardness test and finally, evaluation of corrosion resistance of the alloy by electrochemical tests. The XRD and the optical microscopy made it possible to analyze that the heat treatment influenced the phase shifting from α to α', and probably affected the alloy hardness, at the first aged sample at 500º Chas been a sudden increase in the value of hardness, probably by appearance of omega phase, unwanted phase to the medical application duo to great fragility, and finally ... (Complete abstract click electronic access below)