Análise de dissipadores de calor com filmes de diamante CVD

Dissipadores de calor recobertos com filmes de diamante CVD foram desenvolvidos para acoplar a semicondutores, utilizando-se do Laboratório de Deposição de Filmes de Diamante CVD, na UNESP - Campus de Guaratinguetá e o Laboratório de Diamantes da Universidade São Francisco, em Itatiba, SP. Analisou-se o filme de diamante CVD sobre o silício, para emprego como dissipador de calor, porque o filme de diamante CVD pode ter o valor da condutividade térmica até cinco vezes superior ao do cobre e de dez vezes a do alumínio. Os filmes foram obtidos via deposição através de reator de filamento quente, trabalhando-se com vários filamentos retilíneos em paralelo, resultando assim em um processo que visou obter um filme mais uniforme e com grande área de deposição. Os dados para análises da composição química superficial dos filmes foram obtidos por Difração de Raios-X, Dispersão de Energia de Raios-X e para a verificação da morfologia e espessura do filme foi utilizada a Microscopia Eletrônica de Varredura. Para a verificação do comportamento da temperatura sobre o dissipador com o filme de diamante CVD foi utilizada uma câmera de imagem termográfica, marca Fluke, modelo Ti 40 FT. Foram obtidos filmes de 2 e 10 ?m sobre o silício. Estas espessuras ainda não oferecem um desempenho mecânico que o torne autosustentado. Do ponto de vista de desempenho térmico as análises mostraram que, mesmo com pequena espessura, o filme de diamante CVD apresentou bom resultado experimental. Os principais desafios de construção para esse dissipador de calor são a obtenção do filme com espessura acima de um mm e a garantia da qualidade do filme com a repetitividade do processo em cujo caso torna-se necessário definir as dimensões do dissipador antes da deposição do filme.

Avaliação da eficácia de primers para metal na resistência ao cisalhamento da união entre cimentos resinosos e metais não nobres. Efeito do armazenamento em água

O sucesso das restaurações metálicas indiretas depende, dentre outros fatores, de uma união eficaz entre a estrutura metálica e o cimento dentário empregados. Sabe-se que os primers para metal atuam com comprovada eficácia na resistência adesiva dos cimentos resinosos às ligas nobres. Entretanto, pouco foi estudado sobre o efeito de tais materiais em ligas não nobres. O propósito deste estudo foi avaliar a eficácia de primers para metal na resistência ao cisalhamento da união entre cimentos resinosos e metais não nobres. Discos (9 mm de diâmetro e 3 mm de altura) foram fundidos em liga de NiCr (n=80) e em titânio comercialmente puro (Ti c.p.) (n=80) e foram incluídos em anel de PVC com resina acrílica quimicamente ativada. As superfícies dos discos foram regularizadas com lixas de carbeto de silício de granulação 320, 400 e 600 e jateadas com partículas de óxido de alumínio de 50 µm. Espécimes de cada metal foram divididos em quatro grupos (n=20). Uma matriz metálica bi-partida (5 mm de diâmetro interno e 2 mm de altura) foi posicionada na superfície do espécime. As áreas adesivas receberam um dos seguintes tratamentos: 1) Panavia F; 2) Alloy Primer e Panavia F; 3) Bistite DC e 4) Metaltite e Bistite DC. Para evitar a exposição dos cimentos à luz, estes foram espatulados e inseridos na matriz dentro de uma câmara de revelação radiográfica. Quarenta minutos após a confecção, os espécimes foram armazenados em água destilada a 37ºC por 24 horas e então termociclados (1.000 ciclos, 5ºC e 55ºC, 30 segundos cada banho). Após a termociclagem, os espécimes foram armazenados novamente nas mesmas condições descritas anteriormente por um período de 24 horas (n=10) ou de 6 meses (n=10) antes do ensaio de cisalhamento em uma máquina de ensaios mecânicos (Material Test System 810).

Análise química, citotoxicidade e biocompatibilidade de cimentos de ionômero de vidro

Objetivo: O presente trabalho, dividido em três estudos, teve como objetivo geral identificar e quantificar a liberação de componentes e avaliar a citotoxicidade e a biocompatibilidade de cimentos de ionômero de vidro (CIVs). Método: Para o estudo 1, extratos dos CIVs Vitrebond (VB), Fuji Lining LC (FL), Vitremer (VM), Fuji II LC (FII), Ketac Fil Plus (KF) e Ketac Molar Easymix (KM) foram obtidos pela imersão de corpos-de-prova em meio de cultura celular (DMEM). Esses extratos (n=9 por grupo) foram analisados por eletrodo específico quanto à presença de flúor e por espectrometria de absorção atômica quanto à presença de alumínio e zinco. HEMA e iodobenzeno foram identificados por CG/EM (n=6). Para o estudo 2, células MDPC-23 foram colocadas em contato com os extratos dos CIVs por 24 horas. Em seguida, foram avaliadas a atividade da desidrogenase succínica (SDH) (n=8), a produção de proteína total (PT) (n=8), a atividade da fosfatase alcalina (FAL) (n=8) e a morfologia celular (n=2). Para o estudo 3, tubos de polietileno (n=24 por grupo) foram preenchidos com os CIVs e implantados no tecido subcutâneo de 42 ratos. Como grupo controle foi utilizada a guta-percha. Após 7 ou 15 dias de pós-operatório, metade dos espécimes de cada grupo e período (n=6) foi preparada para análise histológica, e os demais (n=6) para análise da expressão de genes que codificam para IL-1? e TNF-?. Resultados: Os extratos de todos os CIVs apresentaram uma concentração de flúor significativamente maior do que o meio de cultura DMEM (controle), tendo o VB liberado maior quantidade, estatisticamente significante, do que os demais CIVs. O VB foi, também, o único material que liberou quantidades relativamente altas de alumínio e de zinco. O HEMA foi identificado nos extratos de todos os CIVs modificados por resina (VB, FL, VM e FII), e o iodobenzeno... (Resumo completo, clicar acesso eletrônico abaixo)

Estudo da viabilidade técnica, econômica e ambiental da substituição de um banco de resistências elétricas de aquecedores por uma caldeira alimentada por biomassa de paletes residuais na indústria de laminação

Given the increasing demand for fossil fuels to power the engines of the global economy, and also the slow process of synthesis of oil, it becomes necessary to develop new sources of renewable energy in addition to improve promising sources that already exist, turning them competitive. Based on this, biomass is shown very promising between the most popular energy sources due to its availability, applicability, and above all, the fact of not emitting green house gases when analyzing the whole carbon cycle. In this sense, this work presents, through an environmental, technical and economic analysis, the impact in an aluminum mill of replacing the use of electricity, in one process, by a boiler fueled with biomass from waste process of packaging the finished product with pallets. Thus, besides the reduction of CO2 emissions, financial gains are targeted, since the main goal of the corporations that require such power is to maximize its profits

Caracterização geológica do perfil laterítico no município de Rondon do Pará, bloco sul do projeto Alumina Rondon

This completion of course work has as its object of study the Bauxite Province of Paragominas regarded as the richest Amazon bauxite province and whose genesis is related to laterization processes responsible for the formation of mineral deposits of the Rondon Alumina Project, designed to assess areas in the southeast of Pará State, for mineral resources exploration of bauxite, which is the main source of aluminum in the country. Located in the region of Rondon do Pará - PA, the study area is geologically inserted in Lithostratigraphic Unit called Cobertura Laterítica Matura (Mature Lateritic Cover), formed by alteration of paleotropics Cretaceous siliciclastic rocks, and its geomorphology corresponds to a broad plateau with displays of representative profiles of the processes that acted in the region. In this context, the present research aims to characterize the geological evolution of the laterite profile, with detailed studies in the area, geological description of the formations from the bauxite surfaces, and mineralogical composition litochemical of different horizons that were correlated and deployed in an evolutionary model compatible with its traits. The data collected during the analysis subsidized metalogenetic understanding of the processes that acted in the enrichment of aluminum and iron as well as the redistribution of the latter modified profile. The results and information were embodied in the form of geological characterization of the different constituents of mineral associations of bauxite horizons, similarities or differences in both textural and structural aspects, in order to propose a evolutionary model with retaken of gibbsitization processes

A cor do citrino: efeito de irradiação e tratamento térmico

Quartz crystals under natural or artificial irradiation can acquire dark shades and variations btween smoky, black and brown but when submitted at heat-treatment they can become greenish, yellowish or brownish, called citrine at gem shops. In this work a lot of samples was collected from different places in Brazil (Corinto - MG, Diamantina - MG, Sento Sé - BA and Santana do Araguaia – PA) and at first they were submitted at artificial irradiation resulting in dark colours. After that they were submitted at heat-treatment in differents temperatures and time of exposure to record when color change happened to light colours. It variated according to each origin, temperature, time of expousure and different aluminiun and other chemical elements content. Its was possible to define the ideal conditions to results better colours and related it with geology and chemical quartz composition.

Estudo do envelhecimento da liga AA 7075 encruada

Aluminum alloys are widely used in industry, because they combine different mechanical properties according to the alloying elements used in addition to thermal and mechanical treatments performed, resulting in materials with good weight/resistance relation. The 7XXX series alloys are worked heat treatable alloys commonly used in the aerospace industry, especially due to their high mechanical properties obtained after aging heat treatment, which increases the interest around 7075 alloy. Some studies with alloys which can be aged show that it is possible that cold word processes affect the results of aging. Thus, this study was intended to verify the influence of the aging process of AA 7075 alloy. There were three routes of aging with specimens previously treated thermally. In the first route T6 treatment was performed with a annealed specimen and other in solid solution. The second was the natural aging in a annealed specimen. In the last route was done aging by steps with a annealed specimen and other in solid solution with the intention to reduce the effects of natural aging. The results show that the routes 1 and 3 had similar hardness for all the samples, showing that the validity of Route 3 as an alternative and also the hardening did not affect the hardness at the end of the process, significantly reducing the time required for the highest hardness. Finally, natural aging was less effective in increasing hardness

Potencial de reciclagem dos resíduos sólidos urbanos do Município de Salto-SP

O excessivo consumo de recursos naturais renováveis e não renováveis combinado com a ineficiência e o desperdício de seu uso geram uma problemática muito atual nos centros urbanos: a grande produção de resíduos sólidos urbanos (RSU) e sua destinação inadequada. O presente trabalho caracterizou o RSU da cidade de Salto – SP a fim de quantificar os materiais recicláveis presentes nestes sólidos, bem como mapear sua origem e o perfil social de sua fonte geradora. Foram utilizadas quinze (15) classes de recicláveis, além do lixo orgânico e rejeitos. Dentre as classes estão: latas de aço; sucatas ferrosas; papel misto; papelão ondulado; embalagens longa vida; polietileno de alta densindade – PEAD; polipropileno – PP; poliestireno (PS); PET óleo; PET refrigerante; vidro; outros plásticos – PVC, materiais compostos de mais de um tipo de plástico e PS expandido; aparas plásticas; latinhas de alumínio e outros alumínios,. Os resultados apontam para uma grande geração de materias recicláveis no RSU em bairros de maior poder aquisitivo. O porcentual total de recicláveis na cidade foi de 38,38%

Avaliação do uso de fantomas antropomórficos na análise experimental dos fatores que afetam o contraste de imagens radiográficas

This experimental study aimed the evaluation of the use of anthropomorphic phantoms in the analysis of the influence of the acquisition parameters in the contrast of radiographic images. The analyzed factors were the variation of the peak kilovoltage (kVp) and the product of the filament circuit by the time of exposition (mAs). The influence of these factors was verified for different anthropomorphic phantoms: foot, knee and chest. The image contrast behavior with the simulators was compared to values obtained with the use of an aluminum ladder being the behavior of this reference for analysis and discussion. To assure the reproducibility of images, quality control tests were made and evaluation of procedure conditions before the experiments. The results obtained are shown in a scale of images where it was possible to evaluate the impact in the darkness of images. Regions with different compositions were analyzed which were different in image, this way the values of optical density and contrast are represented as charts and graphics. We conclude that the use of anthropomorphic phantoms in the evaluation of the influence of tension of the tube and time of exposition in the contrast of the radiographic images is not indicated for a quantitative analysis through optical density, once they present incompatible results with the data as reference as the aluminum ladder even so these simulators present a great property in qualitative analysis regarding the differentiation of structures and subjective evaluations

Estudo e modelagem 3D de um cabeçote para um motor monocilíndrico, 400cc, 4 T

The cylinder head contains the combustion chamber for the air-fuel mixture and the intake and exhaust valves, the valve guide and the valve seat. The cylinder head also is a support for the camshaft and valve rocker. The holes where the spark plugs are connected are designed to fit the better place in the combustion chamber. The cylinder heads often are manufactured using materials such as aluminum and cast iron. The cooling fins located in the outside of the cylinder head are designed for a good heat transfer and therefore their dimensions and positioning are important. This work aims the calculation for a cylinder head to be installed in a 400 cc displacement, gasoline powered, four stroke, single cylinder engine. According to the displacement it will be analyzed the combustion chamber, the intake and exhaust valves, as well as the camshaft and rocker arms. This also a work to help to accomplish the design of a single cylinder engine, where the alternatives parts, cylinder block and crankcase are all already machined and assembled in this campus

Indução de morte celular por apoptose decorrente da irradiação com Raios-X: um ensaio com células mamárias humanas tumorais

Apoptosis is a form of programmed cell death selectively removes abnormal cells, and thus contributes to maintaining the balance of the dynamics of cell reproduction. Therefore the verification of the occurrence of apoptotic cell death after a pathological stimulus is crucial for the analysis of the maintenance of normal cell cycle of a given tissue or organ. In this experiment were used cells lines human mammary tumor MDAMB231, T47, MCF7, which were irradiated with X-rays at a dose of 5 Gy in a time interval of 15 seconds, and filtration of 1mm aluminum. Samples containing the cells were grown in a specific culture medium, containing fetal bovine serum and growth factor, and two samples were prepared with each of the cell lines, one to be irradiated, and another that has not been irradiated, which denoted by negative control of the irradiation. The primary goal of the experiment was to verify and compare the rates of apoptosis in each cell lines, in which were irradiated and that were not irradiated, using flow cytometry as a method for detecting apoptotic cell death in together with specific markers annexin V and propidium iodide. Data from the readings made by flow cytometry were analyzed and interpreted using the software WinMDI statistical graph. By comparing the indices relating to the readings of positive and negative for specific markers of apoptosis, based on differences in the statistical data presented lectures regarding the cellular irradiated and not irradiated, collude cells in question once... (Complete abstract click electronic access below)

Tratamento de modificação de eutético da liga AA356

Alloy Al-7%Si-0,3Mg (AA356), having an excellent combination of properties such as low solidification shrinkage and good fluidity, good weldability, high wear resistance, high strength to weight particularly in the automotive and aerospace engineering. The refinement of the structure aluminum silicon eutectic alloy is a fairly common practice in the casting, through the treatment knows as modification. You can get the modification for the addition of chemicals and rare earths, these have the ability to modify the structure of the eutectic, but only sodium and strontium produce a strong action modifier when used in low concentrations. The modifying effect of silicon grain turns into a fibrous form branched and enveloped by the metal matrix in the form of a composite structure that has the highest limit of tensile strength, ductility and machinability. This work will be obtained AA356 alloy ingots using two different types of molds: metal mold and sand mold. Macrographs will be made in ingots obtained for observation of the macrostructures obtained in both types of ingots. Will be sampled at strategic locations of the ingots to correlate microstructure and cooling rate. The results showed that the material of the ingot has a strong influence on the resulting micro-andmacrostructure

Estudo da propagação de trinca por fadiga sob carregamento de amplitude variável

For engineering projects that require high reliability levels, is often not enough know only physical and chemical material properties. It’s necessary understand the failure mode of these materials in operation to ensure security level in the project and establish more stringent criteria in the analysis of structural integrity. Due to this need, aircraft industry has been using aluminum alloys in their designs and projects. “Currently more than 70% of aircraft structures are built of high strength aluminum alloys among which stand out 7075-T6 and 2024-T3 alloys, which are considered basics for being used in the new alloys development.” (PASTOUKHOV & VOORWALD, 1995). Some years ago ALCOA develops Al 2524 alloy that has emerged as refinement of Al 2024 (Al, Cu. Mg) alloy, with purpose of improve fracture toughness and fatigue resistance on structural components. The present research addresses testing of fatigue crack propagation under variable amplitude loading for Al 2024 alloy, observing the interaction effects from application of overhead blocks and plastic zone at the crack tip and makes an analysis of fracture surface images

Metodologia de determinação das curvas de probabilidade de falha S-N-P para uma liga de aluminio submetida a diferentes tratamentos termicos de solubilização e precipitação

The approach of the subject matter in this work relies on the fact that the reliability of methods for performance analysis of materials proves critical for the result. This work focused on the development and presentation of the methodology for lifting probability curves for fatigue test (SN) according to standard E739, this focus is justified by the fact that the results in fatigue test show considerable dispersion making it difficult to reading and interpretation of data, this dispersion arises because the phenomenon of rupture is strongly influenced by internal characteristics of the material, we can then have much data ranging from test to test. Thus we set out originally for a brief study of aluminum alloys in question, as well as the treatments to which they were subjected. We also studied the behavior of materials when subjected to cyclic loading, which configures process of fatigue failure, and even fatigue test method in question. This statistical analysis is based on the ASTM E739 standard, so its contents was studied in detail so that we could present in detail the methodology and raise SN curves for different aluminum alloy 7012 subjected to fatigue test. Data were collected from tests conducted in the department of materials from two samples of aluminum alloy 7012 solubilized and precipitated by different time intervals and assayed temperature fatigue-type traction-compression, these data were then analyzed and used to survey curves using the base as E739. After lifting the curve analyzed the characteristics of the test samples and their correlation with the test results. We confirmed the effectiveness of the method of statistical analysis by ASME E739, which allowed the reading of data without this method would be very difficult to have a reading and comparison of the results for the two types... (Complete abstract click electronic access below)

Um estudo sobre a preparação metalográfica da liga de aluminio AA7075-T6

The increasing technological innovation and demand for materials with better properties boosts research into new materials and new alloys. To do so, aluminum alloys are being developed, among them the AA7075-T6, having many applications in aerospace and military industries, machinery and equipment, molds for plastic injection and structures. To study and understand the properties, characteristics and especially the microstructure of the material, the metallographic preparation is essential. This paper presents new methodologies to achieve the metallography of samples of scrap alloy AA7075-T6, with emphasis on methods of polishing. For the five samples, the best results were those with specific grinding, the samples only going down on the sander. For polishing, the most effective method so far has been using the polishing cloth 16.3, of ATM enterprise, solution of diamond 3 μm, solution of diamond 1 μm, and colloidal solution of OP-S. For the etching, the reactive agent used was phosphoric acid (H3PO4) 85% P.A., as 90% in the proportion of distilled water to 10% acid. The best results were obtained in the attacks of 300 and 240 seconds, revealing the grain boundaries in most areas. Methodologies need more studies and more tests, but the results have proved to be satisfactory