Análise da curva de resfriamento e refino de grão da liga de alumínio AA 356

The macrostructure of an alloy solidification in the raw state is of utmost importance due to its influence on mechanical properties. A structure showing columnar grains is generally undesirable in most applications of cast products and grain refining aims to suppress the formation of these grains and get a fine-grained equiaxed structure that improves the supply of liquid metal and the mechanical properties, as yield strength and tensile strength limit, as well as the tendency of formation of hot cracks. The type and size of grains formed are determined by chemical composition, cooling rate and the use of inoculum for grain refining. Titanium and boron are the major refiners in the aluminum industry and can be added to the molten metal in the form of alloys such as Al-Ti, Al-Ti-B or Al-B. In this paper we will discuss the information obtained from cooling curves and first derivative of the cooling curve to obtain the thermal parameters that influence the process of grain refining alloy AA 356.0

Planejamento, síntese e avaliação da capacidade de doação de óxido nítrico de novos derivados antiinflamatóios

A formação do trombo arterial, composto predominantemente por plaquetas, se dá sob condições de estresse de cisalhamento elevado, nos locais de lesão aterosclerótica vascular e fluxo sanguíneo perturbado e tem como consequência diminuição ou obstrução do calibre dos vasos dos diferentes órgãos podendo levar a eventos isquêmicos. As doenças cardiovasculares são consideradas as principais causas de morte no mundo. Nesse contexto, estima-se que a aterosclerose/aterotrombose seja a causa primária de doença arterial coronariana e acidente vascular cerebral representado mais de 50% das causas de mortes em países ocidentais . É sabido que a aterosclerose, primeiro evento que predispõe à aterotrombose, é considerada um processo inflamatório crônico, e que a utilização de antiinflamatórios não esteroidais (AINEs) COX-1, melhor estabilizam a estrutura da placa ateromatosa impedindo o rompimento e a consequente formação do trombo. Neste contexto, no presente trabalho foram obtidos de novos candidatos a fármacos com propriedades doadoras de NO e antiagregantes plaquetárias, através da estratégia de hibridação molecular dos AINEs contendo uma subunidade doadora de óxido nítrico, representada pelos furoxanos, e espaçada por uma subunidade N-acil hidrazônica. Dessa forma, a inibição da síntese de tromboxanos associada à doação de óxido nítrico permitiu atuação nas plaquetas através de um mecanismo múltiplo de ação com fins de diminuição da agregação plaquetária. Os produtos intermediários e finais apresentaram bons rendimentos e foram caracterizados por técnicas analíticas as quais predisseram que as estruturas propostas foram obtidas. Todos os compostos se como doadores de óxido nítrico. Os compostos 1a e 3a apresentaram atividade analgésica superior a dipirona, utilizada como controle. No ensaio de agregação plaquetária ―in vitro‖... (Resumo completo, clicar acesso eletrônico abaixo)

Tratamento da superfície do alumínio via eletrólise a plasma

This paper presents the study on the application of the electrolytic plasma for surface treatment of aluminum. A bibliographical study on the material of interest was preliminarily performed and later designed and built an electrolytic cell, including the excitation source. Unlike conventional electrolysis process, the plasma assisted carry on in the non-linear region of characteristic current/voltage curve. Therefore it requires for the on set of the process that the power supply operates on harder conditions than those on high current process. The plasma produced during the present investigation has temperatures in the range o 6,0.10 3 -7,0 .10 3 K, well above those found in conventional chemical process. It also shows a particular dynamic to promote changes on surface and to produce new materials. The plasma is generated by microdischarge in vapor or gas bubbles involved in physic-chemical processes in electrode regions of the electrolytic cell. The electrode material was the aluminum (7075). The Process Electrolytic Plasma Processing (EPP) is sensitive to various parameters such as operating voltage, current density, electrolyte, concentration of electrolyte, geometry of reactor, temperature of electrolytic solution and dynamic of the fluid in the cell. The experiments were carried on in order to find parameters for a stable abd steady operation. The choice for the electrolytic was silicate/alkali solution in various concentrations to operate in various voltage as well. Plasma was produced on negative (cathode) and positive (anode) electrode, in specific conditions. A stable operation on the cathode process was obtained with low concentration of the electrolytic in aqueous solution, current density around 250V effective voltage. For the evolution of plasma in anodic process it was required higher concentrations and higher... (Complete abstract click electronic access below)

Análise da eficiência do cobre, alumínio e PVC como condutores hidráulicos em aquecedores solares

One of society concerns are preserving the environment and the growing energy demand. These two issues are in conflict since most of the energy used today in some way harms the environment. Then is essential to develop and implement ways to clean and renewable energy. In this way, solar energy stands out as a source of clean energy, renewable, abundant and acessible. Solar energy can be harnessed by photovoltaic cells or by solar collectors. The aim of this article is analysethe yield of the solar heather assembled with hydraulic conductive and plastic bottles using three different materials for hydraulic conductors, in order to compare these efficiences and analyze material which has the best cost-benefit in this type of application. The materials analyzed in this study were copper, aluminum and PVC. For this analysis were assembled three alike solar heaters using each one of these materials, and were done several series of measurements of the temperature water output to each heat with flow between 10 and 30 liters per hour. With these data we can analyze the yield and the performance of copper, aluminum and PVC in this application. So we can conclude that aluminum has a higher efficiency, followed by PVC, and the copper had the lowest efficiency. This behavior kept for all values of flow rates examined

Estudo do efeito da classe de furação na resistência à fadiga em junta alumínio – fibra de carbono

This work performs a comparative study of fatigue life of riveted lap joints involving classes of drilling which adjustment is made with interference or clearance. For this study, representative specimens of this joints were manufactured with four rivets distributed in two rows. In this context, are presented the test matrix, the methodology employed in performing of the tests, the used mathematical modeling, and that methods that are the basis for the latter are described through the theoretical foundation. Next, are present the results obtained in fatigue tests and images of the region of failure of the specimens. Finally, are present some comments and conclusions related to the results obtained

Estudo da variação do limite de resistência à tração ao longo da bobina de vergalhão de alumínio 1350 AA

Therebar of aluminum 1350 AA produced by CBA are used inthe manufacture of wires and cables for electric power transmission, which marketshows increasingly favorableto aluminum due to itslow densityand high electrical conductivity, but to ensure that this materialmeets all specifications of projectsfor electricity transmission, it must have homogeneity in the chemicaland mechanicalproperties.One of the points of improvement in the process of rod production isreducing the high variation of the limitof tensile strengthalong the coils, therefore, this work seeks a better understanding of the factors that significantly influence the mechanical properties of rebar, specifically assessing the influence oftemperatureat the output of the coils, which can cause a recovery effect on the material andif thereare relevantdifferences between the two modes of rebar production: auto and manual.Samples of six coils have been specifically produced forthis study, which weresubsequently subjected to different annealing temperatures for one hour and ten minutes, similar to what occurs in the output of the coil from the machine. The tensile tests showed that aluminum 1350 AA is significantly influenced by temperature, whose behavior was very similar to that presented in the literature. It was found that the phenomenon of recovery occurred more significantly at high temperatures. Through the optical electron microscope Zeiss, 18 surface maps were made with 100x magnification for each sample in different conditions and the images were analyzed using entropy and fractal dimension, aiming to relate the condition of surface hardening on mechanical property of the samples in that condition. The results showed that these methods can be applied, provided they do not have any kind of imperfection on the surface, once they can influence the results. The study concluded that a more efficient cooling is required in ... (Complete abstract click electronic access below)

Estudo da influência da aplicação do fluido de corte no torneamento da liga de alumínio AA7075

One of the ways to minimize the effects of unproductive time caused by tool wear can be achieved by introducing an efficient system of lubrication and cooling in the process. However, in the last decade the research had the goal to restrict the maximum use of refrigerants and / or lubricants in metal-mechanical production. The important factors that justify this procedure include the operational costs of production, ecological issues, and the legal requirements of environmental conservation and preservation of human health. The purpose of the proposed work is the study of machining by turning with the focus on the influence caused by the application of cutting fluid in several ways of application (abundant and MQF) and also by comparing the results obtained by machining without the presence of fluid . For this purpose, the turning tests are conducted using an aluminum alloy (AA 7075). The response variables to be analyzed were obtained from the roughness (Ra and Ry), the stresses presented (VB) and their progression in relation to the cutting length achieved, the type of chip formed, in addition to changes in the degree of finish (roughness) presented by the turned parts. The results of this study should provide more detailed information about the actual influence of cutting fluids in turning this alloy, which are characterized by high rates of deformation when the formation of damaging your chip machining and also the quality of surface generated. Therefore, it is expected to provide subsidies to promote the optimization of machining this alloy making the most of the role of cutting fluid

Síntese e avaliação da capacidade de doação de óxido nítrico de novos compostos com atividade anti-agregante plaquetária úteis no tratamento de anemia falciforme

A anemia falciforme é uma doença genética caracterizada por uma anemia hemolítica crônica e fenômenos vaso-oclusivos, que levam a crises dolorosas e à lesão tecidual crônica e progressiva. Tem sido relatado que pacientes com anemia falciforme apresentam aumento dos níveis circulantes de citocinas, incluindo fator de necrose tumoral-α (TNF-α). O principal fármaco utilizado no tratamento dessa anemia é a hidroxiuréia (HU), fonte exógena de óxido nítrico (NO) e responsável pela inibição da agregação de plaquetas e aumento dos níveis de hemoglobina fetal (HbF). Trabalhos prévios têm demonstrado a importância da subunidade 1,2,5-oxadiazol-N-óxido como doadora de óxido nítrico. Nesse contexto, o presente trabalho tem como objetivo sintetizar um novo derivado híbrido do 1,2,5-oxadiol-N-óxido para a formação de um composto útil para o tratamento dos processos preventivos contra agregação plaquetária exacerbado em pacientes falciformes

Estudo do comportamento térmico e reológico de amidos na conformação cerâmica de compostos multicamada com alumina, titanato de alumínio e dióxido de titânio

The project aims to develop ceramic compounds with gradients of the mechanical properties, using the molding technique with commercial starches. To understand the process of interaction between starch and ceramic powders, the proposed methodology involves viscometry tests (up to 200 °C). Viscometric assays were carried out with slurries of alumina, titania and aluminum titanate with potato starch, cassava and corn. The specimens were tested for dilatometry, thermomechanical, thermal shock, mechanical and characterization by SEM. The ceramic powders and starches were analyzed using the optical microscope to measure the size of these. It was made of th kinetics of starch gelatinization and titania with the cornstarch in theoptical microscope to observe how the grains of starch behaved in welling

Efeitos ansiogênicos do óxido nítrico no córtex pre-frontal medial de camundongos

Medo e a ansiedade são emoções que têm origem nas reações de defesa que os animais exibem diante de ameaças que podem comprometer sua integridade física ou a própria sobrevivência, tais como confrontos com o predador ou com animais da mesma espécie. Em se tratando da espécie humana, estas respostas defensivas eliciadas representariam a ocorrência de transtornos de ansiedade e, a busca por sua compreensão, resultou no desenvolvimento de modelos animais de ansiedade, dentre os quais se destaca o labirinto em cruz elevado (LCE) que é baseado na aversão natural de roedores a espaços abertos. Com relação aos substratos neurais envolvidos nestas manifestações, cabe destacar a matéria cinzenta periaquedutal bem como estruturas prosencefálicas, como o córtex pré-frontal (CPFm), uma estrutura límbica que tem sido frequentemente descrita como relevante na neurobiologia da ansiedade. O óxido nítrico (NO) tem sido investigado em diferentes estruturas cerebrais de roedores nas quais foram evidenciadas respostas pró-aversivas. Sendo o CPFm uma estrutura que contém neurônios nitrérgicos, este estudo teve o objetivo de investigar o efeito da facilitação nitrérgica através da injeção intra-CPFm de um doador de NO, o NOC-9 [6-(Hidroxi-1-metil-2-nitrosohidrazino)-N-metil-1-hexanamina], sobre o comportamento de camundongos expostos ao labirinto em cruz elevado (LCE). Métodos e Resultados: Camundongos Suíços machos (25-35g, n = 53) receberam implante de cânula guia no CPFm. Cinco dias após, os animais receberam microinjeção de veículo ou NOC-9 nas doses de (1,875 nmol; 18,75 nmol; 37,5 nmol ou 75nmol) e, após cinco minutos, foram expostos... (Resumo completo, clicar acesso eletrônico abaixo)

Análise da curva de resfriamento da liga de alumínio AA 356

It is very important to study the macrostructure of a material in the crude state of solidification due to influence the mechanical properties, as well as the study of their cooling curve. In the present work was to study the alloy AA 356, its macrostructure and its cooling curve. The material was cast in two different molds, a sand and other metallic. In this paper we study the differences in its macrostructure and its cooling curves. In macrostructure can observe the absence of the three zones of solidification and the presence of large pores because of moisture in the sand. In the sample taken from the metal mold can observe the three zones of solidification: a coquilhada, columnar and equiaxed

Desenvolvimento de recobrimento submicrométrico de óxido de nióbio para aplicação em tubulações de prospecção de petróleo

Pós-graduação em Engenharia Mecânica - FEG

Interação silício e alumínio em plantas de arroz de terras altas e mamona

Pós-graduação em Agronomia (Agricultura) - FCA

Diagnóstico ambiental da bacia hidrográfica do córrego do Bugre em Alumínio - SP

Pós-graduação em Ciências Ambientais - Sorocaba

Análise comparativa entre os aquecedores solares industrial e os construídos com garrafas pet e canos de pvc, cobre e alumínio

Este trabalho apresenta o uso de energia solar, para o aquecimento de água, através da análise de aquecedores solares industrial e os construídos com garrafas PET com canos condutores de água de cobre, alumínio e PVC, instalados no Centro de Energias Renováveis - CER, do Campus de Engenharia Guaratinguetá. A análise foi realizada com a ajuda de sensores Termopar, software - Contemp View Simple, para obtenção de dados, software Teamviewer para acesso remoto. Sendo feitas as medições concluiu-se qual é o aquecedor mais eficiente a ser utilizado, sempre tendo como objetivo o aproveitamento da energia renovável usando a radiação solar