As curvas limite de conformação (CLC) são utilizadas há mais de 50 anos. Propostas inicialmente para o desenvolvimento de produtos provenientes da indústria automobilista em função das necessidades apresentadas pela área, são atualmente aplicadas de maneira geral para a indústria da estampagem na produção de inúmeros tipos de peças, oferecendo previsões de possíveis falhas e/ou defeitos durante as etapas do processo de estampagem. As CLC´s permitem prever o afinamento excessivo, enrugamento, estiramento e é claro, a fratura da peça. As diferenças metalúrgicas existentes entre os dois processos iniciais - fundição contínua (F.C.) e fundição semicontínua (F.S.C.) - resultam em diferenças nas propriedades finais obtidas para uma mesma rota de laminação a frio e recozimentos intermediários do material especificado. Desta forma, torna-se indispensável um estudo sobre a influência dos processos de fabricação iniciais F.C. e F.S.C. com relação à estampabilidade da liga, sendo esta avaliação efetuada através das CLC´s obtidas por ensaios de tração uniaxiais, propostos pelo IRSID (\"Institut de Recherches de La Sidérurgie\"), (lado esquerdo da curva ?2 < 0) e ensaio Erichsen (lado direito da curva ?2 > 0) e do ensaio de Nakazima reduzido em 60%, ou seja, todo o ferramental e os corpos de prova utilizados nos ensaios foram reduzidos em 60% das dimensões mencionadas pela norma ISSO 12004-2. A diferença microestrutural apresentada entre as etapas de fabricação dos dois processos avaliada através de ensaios de determinação do tamanho de grão, limites de resistência à tração, escoamento (0,2%), alongamento (em 50,80 mm), coeficientes de encruamento n, resistência K, ensaios de \"orelha\", levantamento da CLC0, Erichsen e textura, auxiliaram nas conclusões finais do levantamento das CLC´s para os dois processos do material acabado e metodologias. O processo de fundição semicontínua nas condições processadas apresentou melhores combinações entre as propriedades, exceto na formação de \"orelha\" apresentada na etapa intermediaria de processamento do material. Principalmente o parâmetro CLC0 no plano da chapa, resultou em uma deformação ?1 19% (?2 = 0), superior à apresentada pelo processo F.C., deformação muito importante para a fabricação de peças estampadas. Evidenciou-se também uma diferença de aproximadamente 37% entre as metodologias IRSID x Nakazima reduzido na obtenção da deformação plana para o processo F.C. e 31% para o processo de F.S.C.. Nas condições de deformação; estiramento biaxial, tração uniaxial e embutimento profundo, a chapa produzida pelo processo de fundição contínua apresenta melhor desempenho. / Forming limits curves (FLC) are used for more than 50 years. Initially proposed for the development of products from the automobile industry in terms of the needs of the area. It is currently being applied in general to the metal forming industry in the production of numerous types of parts, providing predictions of possible faults and / or defects during the stages of the stamping process. The FLC\'s can predict excessive thinning, wrinkling, stretching and of course, the fracture of the part. The existing metallurgical differences between the two initial processes - continuous casting (C.C.) and semi-continuous casting (S.C.C.) - result in differences in the final properties obtained for the same route of cold rolling and intermediate annealing of the specified material. Thus, it is essential to study the influence of the initial manufacturing processes CC and SCC with respect to the formability of the sheets. This investigation is based on the, assessment of the FLC\'s obtained by uniaxial tensile tests proposed by IRSID (\"Institut de Recherches de Sidérurgie\"), (?2 < 0, left side of the curve) and Erichsen test (right side of curve. ?2> 0) and the Nakazima test reduced by 60%. The difference between the sheets obtained in both processing routes was evaluated by the following parameters: grain size, tensile strength limits, yield strength (0.2%), elongation (at 50.80 mm), strain hardening coefficient n, resistance K, \"earing\" test, lifting of the CLC0, Erichsen test and texture where discussed in view of the obtained FLC\'s for both the two processes of the finished material. The semi-continuous casting process in processed conditions showed better combinations of properties except the formation of \"earing\" presented at the intermediate stage of processing of the material. Particularly the evaluation of the FLC0 parameter resulted in a strain in the plate plane ?1 19% (?2 = 0) superior to the sheet obtained by the continuous casting process. A difference of approximately 37% between the IRSID x Nakazima methodologies was also reduced in obtaining the flat deformation for the F.C. process and 31% for the F.S.C. process. However, for other deformation paths; biaxial stretching, uniaxial traction and deep drawing of the results for the continuous casting sheet were superior.

Orientador: Gelson Luis Adabo / Banca: Renata Garcia Fonseca / Banca: Ricardo Faria Ribeiro / Resumo: A aplicação do titânio e ligas de titânio para implantes dentários e próteses têm crescido nos últimos anos devido às suas excelentes propriedades físicas e mecânicas. No entanto, o titânio tem alto ponto de fusão (1668ºC) e sob elevadas temperaturas, reage com elementos do ar atmosférico (oxigênio, nitrogênio, hidrogênio) e com componentes de diversos revestimentos. As reações entre o metal fundido e alguns elementos de revestimentos, principalmente fosfatados ou à base de sílica, resultam na formação de uma zona de contaminação superficial denominada "α-case". Para minimizar este problema, revestimentos contendo óxidos menos reativos, tais como Al2O3, MgO, ZrO2 e CaO, têm sido desenvolvidos. Os revestimentos especiais para fundição de titânio à base de sílica, de MgO, alumina e espinélio apresentam um tempo de processamento bastante longo (8 a 10 horas). Recentemente, foi desenvolvido um revestimento à base espinélio com processamento acelerado (Trinell - Dentaurum, Ispringen, Germany) que permite a utilização de uma técnica de secagem em forno de microondas e temperatura de aquecimento inicial do forno de 400 ºC, diminuindo o tempo de processamento para cerca de 5 horas. No entanto, não existem estudos que comprovem a eficiência deste novo revestimento. O propósito deste estudo foi avaliar o efeito do novo material Trinell (TR) na camada de reação, porosidade interna, fluidez, rugosidade superficial e adaptação marginal de estruturas fundidas em titânio, quando comparado a dois revestimentos convencionais para fundição de titânio: um revestimento fosfatado, Rematitan Plus (RP) - controle negativo e outro à base de espinélio Rematitan Ultra (RU) - controle positivo. A camada de reação foi avaliada por meio de ensaio dureza Vickers; a medida da porosidade interna foi determinada por exame radiográfico; a rugosidade superficial... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The use of titanium and titanium alloys in dental implant and prosthesis has increased in the past few years because of their excellent physical and mechanical properties. However, titanium has a high melting point (1668 ºC) and inherent reactivity with elements of atmospheric air (oxygen, nitrogen, hydrogen) and with components of several investment materials under high temperatures. The reactions between molten metal and some of the elements of phosphate-bonded and other silica-based investment materials result in the development of a surface contamination zone called "α-case". To minimize this problem, new investment materials containing less reactive oxides, such as Al2O3, MgO, ZrO2 and CaO have been developed. The commercial silica-, MgO-, Al2O3 - and spinel-based investments especially formulated to titanium casting demand a processing time in a range of 8 to 10 hours. Recently, a new short-cycle spinel-based investment (Trinell - Dentaurum, Ispringen, Germany) was developed. It has a reduced processing time - 5 hours in the furnace- because of an investment drying technique into microwaves oven followed by an initial heating in furnace at 400 °C. However, there are not studies which verify the efficiency of this new investment. The aim of this study was to evaluate the reaction layer, the internal porosity, the surface roughness, the castability and the marginal misfit of titanium castings performed with the new material, Trinell (TR), in comparison to two conventional investments for titanium castings: phosphate-bonded Rematitan Plus (RP) - negative control, and the spinel-based Rematitan Ultra (RU) - positive control. The reaction layer was evaluated by Vickers hardness; the measure of the internal porosity was determined by radiographic test; the surface roughness was measured with a surface-test analyzer, the castability was determined by the percentage of completely... (Complete abstract click electronic access below) / Mestre

A tecnologia de impressão para incorporação do princípio ativo tem se mostrado promissora para o desenvolvimento de filmes para liberação oral. Estudos mostram que esta técnica foi eficiente na incorporação de fármacos sintéticos, entretanto pode ser interessante avaliar a possibilidade do uso desta técnica para incorporação de extratos naturais, devido as diversas atividades farmacológicas que eles podem apresentar. Dentre as fontes naturais, a romã (Punica granatum L.) tem se destacado pelo seu potencial antioxidante, anti-inflamatório e antimicrobiano. Este trabalho teve como objetivo avaliar as diferentes partes da Punica granatum L. como fonte de compostos ativos e analisar a possibilidade do uso da técnica de impressão para incorporação destes compostos em substratos para liberação oral. A extração dos compostos ativos foi avaliada para as diferentes partes da romã (casca, folha, mesocarpo e semente) em relação ao rendimento de sólidos solúveis totais, concentração de compostos fenólicos e flavonoides. O melhor extrato foi concentrado em rotaevaporador e avaliado em relação aos parâmetros importantes para uma solução de impressão (tensão superficial e viscosidade). Para utilização como substrato foram avaliados filmes à base de carboximetilcelulose (CMC), hidroxipropilmetilcelulose (HPMC) e blenda (CMC:HPMC - 1:1) produzidos pela técnica de tape-casting e papel comestível comercial. O extrato foi impresso utilizando uma impressora jato de tinta (L375, EPSON). Os substratos foram impressos com diferentes números de camada (1 à 4 camadas de impressão) e caracterizados em relação ao conteúdo de água, cor, pH de superfície, microscopia eletrônica de varredura e de força atômica, tempo de desintegração, concentração de compostos fenólicos, liberação in vitro, cinética de liberação, espectroscopia de infravermelho, difração de raio-X e estabilidade dos compostos fenólicos. A melhor extração foi obtida do mesocarpo, utilizando-se a temperatura de 70 ºC, tempo de 30 min e solução hidroalcoólica com 70% de álcool. Observou-se que os extratos obtidos do mesorcarpo (sem e com concentração) apresentaram intervalos de valores de tensão superficial e viscosidade dentro dos valores observados na literatura para impressora, entretato o extrato obtido do mesocarpo com remoção de 40% de solvente apresentou maior concentração de compostos fenólicos e por isso foi utilizado como solução de impressão. Analisando os substratos, observou-se que os filmes obtidos por tape-casting apresentaram maior tensão na ruptura, elongação e módulo elástico que o papel comestível comercial. Adicionalmente, os extratos apresentaram boa afinidade com os substratos testados. Os filmes à base de HPMC e blenda de CMC:HPMC não foram utilizados para impressão por curvarem rapidamente após serem retirados da placa, visto que essa deformação impediu que passassem pela cabeça de impressão sem serem danificados. Em relação aos filmes impressos, observou-se que o aumento do número de camadas aumentou a concentração de compostos fenólicos, possibilitando a produção sob demanda, de acordo com a necessidade individual. Não houve variação do pH de superfície e o tempo de desintegração do papel comestível comercial foi superior aos filmes à base de carboximetilcelulose. A liberação dos compostos foi influenciada pelo substrato utilizado e o lado de exposição (lado sem impressão e lado impresso). Os compostos fenólicos foram estáveis nos filmes no intervalo de 196 dias. Desta forma, pode-se concluir que a técnica de impressão pode ser utilizada para incorporação dos compostos fenólicos extraídos do mesocarpo da romã. / Printing technology for incorporation of the active compounds has shown promise for the development of oral release films. Studies show that this technique was efficient in the incorporation of synthetic drugs, however it may be interesting to evaluate the possibility of using this technique to incorporate natural extracts, due to the various pharmacological activities that they can present. Among the natural sources, pomegranate (Punica granatum L.) has been highlighted by its antioxidant, anti-inflammatory and antimicrobial potential. This work aimed to evaluate the different parts of Punica granatum L. as a source of active compounds and to analyze the possibility of using the printing technique to incorporate these compounds into substrates for oral release. The extraction of the active compounds was evaluated for different parts of the pomegranate (bark, leaf, mesocarp and seed) in relation to the yield of total soluble solids, concentration of phenolic compounds and flavonoids. The best extract was concentrated in a rotavaporator and evaluated in relation to the parameters important for a printing solution (surface tension and viscosity). Films based on carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC) and blend (CMC: HPMC - 1: 1) produced by the tape-casting technique and commercial edible paper were evaluated for use as substrate. The extract was printed using a piezoelectric inkjet printer (L375, EPSON). The substrates were printed with different numbers of layers (1 to 4 printing layers) and characterized in relation to water content, color, surface pH, scanning and atomic force electron microscopy, disintegration time, phenolic compound concentration, release in vitro, release kinetics, infrared spectroscopy, X-ray diffraction and stability of phenolic compounds. The best extract was obtaind from the mesocarp, using the extraction temperature of 70ºC, time of 30 min and hydroalcoholic solution with 70% ethyl alcohol. It was observed that the extracts obtained from the mesorcarp (without concentration and with different percentages of concentration) presented ranges of values of surface tension and viscosity within the values observed in the literature for printer, and the extract with removal of 40 % of solvent present hither concentration of phenolic compounds and therefore was used as print solution. By analyzing the substrates, it was observed that the films obtained by tape-casting had a higher tension in the rupture, elongation and elastic modulus than commercial edible paper. In addition, the extracts showed good affinity with the substrates tested. HPMC-based films and blends (HPMC:CMC) were not used for printing by bending rapidly after being removed from the plate as this deformation prevented them from passing through the print head without being damaged. In relation to the printed films, it was observed that the increase in the number of layers also increased the concentration of phenolic compounds, allowing the production on demand, according to the individual needs. There was no variation of the surface pH and the disintegration time of the commercial edible paper was higher than the carboxymethylcellulose based films. The release of the compounds was influenced by the substrate used and the exposure side (unprinted side and printed side). The phenolic compounds were stable in the films within the 196 day. In this way, it can be concluded that the printing technique can be used to incorporate the phenolic compounds extracted from the mesocarp of the pomegranate.

Aliado ao fato dos biomateriais ainda serem pouco explorados pelas indústrias alimentícias, este trabalho propôs o desenvolvimento de embalagens que sejam, além de biodegradáveis, também ativas através do uso de um agente antimicrobiano natural capaz de inibir a proliferação de fungos correntes em produtos de panificação (Penicillium commune e Eurotium amstelodami). Primeiramente, filmes biodegradáveis a base de fécula de mandioca foram elaborados pela técnica de casting, usando açúcares e glicerol como plastificantes. O aumento do conteúdo de glicerol causou diminuição da resistência máxima à tração e elevação dos valores de propriedades de barreira. Numa segunda etapa do trabalho, a introdução de nanopartículas de argila esmectita influenciou positivamente as propriedades de barreira dos filmes, devido à diminuição observada nos valores de permeabilidade ao vapor de água e coeficiente de permeabilidade ao oxigênio. Nesta fase, a variação do conteúdo de glicerol também afetou significativamente as propriedades mecânicas e de barreira dos filmes biodegradáveis. As concentrações inibitórias mínimas dos óleos essenciais de cravo e de canela contra os fungos estudados foram definidas e o óleo essencial de canela foi selecionado, para ser incorporado aos filmes biodegradáveis, em três conteúdos distintos, pois foi o composto que mostrou uma inibição mais eficiente. A atividade antimicrobiana dos filmes biodegradáveis com incorporação de óleo essencial de canela foi testada sobre os micro-organismos escolhidos através de testes de difusão em halo, cujos resultados foram suficientes para demonstrar o potencial ativo da embalagem desenvolvida. Como método alternativo de incorporação do agente antimicrobiano, gás carbônico (CO2) em estado supercrítico foi utilizado como solvente. Os resultados obtidos foram promissores, uma vez que se observou incorporação de agente antimicrobiano dentro da matriz polimérica em quantidade suficiente para inibir a proliferação dos fungos testados. / This work concerned the development of biodegradable and active packaging based on cassava starch and natural antimicrobial agents that efficiently inhibit growth of fungi commonly found in bread products (Penicillium commune and Eurotium amstelodami). Biodegradable films were prepared by the casting technique, using sugars and glycerol as plasticizers. An increase in glycerol content caused a decrease in tensile strength and an elevation on barrier properties results. In a second phase of the work, incorporation of nanoclays diminished water vapor and oxygen permeability thus improving film packaging properties. Two antimicrobial agents were tested (cinnamon and clove essential oils) and cinnamon essential oil was chosen to be incorporated in biodegradable films based on cassava starch because it was more efficient against Penicillium commune and Eurotium amstelodami. Antimicrobial activity of biodegradable films with cinnamon essential oil was evaluated by means of a halo diffusion test in which an inhibition zone around a sample of the biodegradable and active film was analysed. As alternative method of antimicrobial agent incorporation, carbon dioxide (CO2) in supercritical state was used as solvent. Promising results were obtained since the amount of antimicrobial agent incorporated inside the polymeric matrix was sufficient to inhibit proliferation of fungi.

In dieser Arbeit wird ein chemisches Abgussverfahren für selbstorganisierte Strukturen in Lösung verwendet, das es ermöglicht definierte poröse Materialien mit Strukturierung auf der Nanometerskala herzustellen. Ähnlich wie beim Gussverfahren von Werkstücken wird die Vorlage durch ein geeignetes Material abgebildet. Durch Entfernen dieser Vorlage erhält man ein poröses (mit Hohlräumen durchsetztes) Negativ derselben. Die auf diese Weise erhaltenen Materialien sind in mehrerer Hinsicht interessant:<br> So lassen sich aus ihrer Morphologie Rückschlüsse über die Natur der selbstorganisierten Strukturen erhalten, da der hier verwendete Abbildungsprozess selbst kleinste strukturelle Details erfasst. Die Hohlräume der synthetisierten porösen Stoffe hingegen können als winzige Reaktionsgefäße, sogenannte &quot;Nano-Reaktoren&quot; verwendet werden. Dies ermöglicht sowohl die Synthese von Nano-Partikeln, die auf anderem Wege nicht zugänglich sind, als auch die Möglichkeit Einflüsse der räumlichen Restriktion auf die Reaktion zu untersuchen. Besonders räumlich ausgedehnte Strukturen sollten hierbei Auffälligkeiten zeigen.<br> Somit ist die Gliederung der Arbeit vorgegeben:<br> - Die Herstellung und Charakterisierung von porösen Stoffen und selbstorganisierten Strukturen<br> - Ihre Verwendung als &quot;Nano-Reaktor&quot; / This work employs a chemical casting technique, which allows the synthesis of mesoporous materials with definite morphology and pore-size distribution. The structure is thereby determined by a self-assembled template on a nanometer length scale. By removing the template, the final mesoporous materials are formed. The materials are interesting from several points of view: <br> First, one can learn about the nature of self-organized structures by casting, since the process is known to map even the smallest details. Second, the porous materials can be used as &quot;nano-reactors&quot;, both for the synthesis of nano-particles, which are not otherwise accessible, and for the investigation of the reaction itself, since reactions in very small volumes often show differences when compared with their bulk counterparts. For the synthesis of geometrically extended structures this confinement could be especially interesting.<br> The work therefore divides into two parts:<br> - The synthesis and characterisation of porous matter and self-organized structures<br> - Their usage as &quot;nano-reactors&quot;

The central goal of this research is to quantitatively characterize the relationships between processing, microstructure, and mechanical properties of important high-pressure die-cast (HPDC) Mg-alloys. For this purpose, a new digital image processing technique for automatic detection and segmentation of gas and shrinkage pores in the cast microstructure is developed and it is applied to quantitatively characterize the effects of HPDC process parameters on the size distribution and spatial arrangement of porosity. To get better insights into detailed geometry and distribution of porosity and other microstructural features, an efficient and unbiased montage based serial sectioning technique is applied for reconstruction of three-dimensional microstructures. The quantitative microstructural data have been correlated to the HPDC process parameters and the mechanical properties. The analysis has led to hypothesis of formation of new type of shrinkage porosity called, gas induced shrinkage porosity that has been substantiated via simple heat transfer simulations. The presence of inverse surface macrosegregation has been also shown for the first time in the HPDC Mg-alloys. An image analysis based technique has been proposed for simulations of realistic virtual microstructures that have realistic complex pore morphologies. These virtual microstructures can be implemented in the object oriented finite elements framework to model the variability in the fracture sensitive mechanical properties of the HPDC alloys.

Underwater excavations of a Late Bronze Age shipwreck at Uluburun, Turkey recovered a combined 475 oxhide and plano-convex discoid copper ingots. While the hoard of ingots excavated at Uluburun brings the total number of copper ingots from the Late Bronze Age to over 1000, interestingly, only one ingot mold from the that period has been identified. Scholars have speculated over the means behind the creation of these ingots for decades, but with a relative absence of archaeological molds the most promising method of reaching any conclusions as to the types of molds used in antiquity seems to be experimentation. Experimental archaeology, has, in recent years been responsible for many breakthroughs in how the past is viewed. In the face of an overwhelming disparity of copper ingot molds from the Late Bronze Age, trials designed around testing different mold materials and casting techniques have the potential to determine, with relative certainty, how copper ingots were cast over 3000 years ago. This thesis examines the possible materials used to create copper ingot molds through a study of their prevalence in antiquity and also details experiments in which these materials were used, in concert with different casting techniques, to create copper ingots. The results of these experiments are combined with analyses of the Uluburun ingots in an effort to bring some closure to the debate surrounding copper ingot molds in the Late Bronze Age.

The aim of this study was to produce partially reinforced aluminum metal matrix composite components by insertion casting technique and to determine the effects of silicon content, fiber vol% and infiltration temperature on the mechanical properties of inserts, which were the local reinforcement parts of the components. Silicon content of alloys was selected as 7 wt% and 10 wt%. The reinforcement material, i.e. Saffil fiber preforms, had three different fiber vol% of 20, 25 and 30 vol% respectively. The infiltration temperatures of composite specimens were fixed as 750 &deg / C and 800 &deg / C. In the first part of the thesis, physical and mechanical properties of composite specimens were determined according to the parameters of silicon content of the matrix alloy, infiltration temperature and vol% of the reinforcement phase. X-ray diffraction examination of fibers resulted as the fibers mainly composed of deltaalumina fibers and scanning electron microscopy analyses showed that fibers had planar isotropic condition for infiltration. Microstructural examination of composite specimens showed that appropriate fiber/matrix interface was created together with small amount of micro-porosities. Bending tests of the composites showed that as fiber vol% increases flexural strength of the composite increases. The highest strength obtained was 880.52 MPa from AlSi10Mg0.8 matrix alloy reinforced with 30 vol% Saffil fibers and infiltrated at 750 &deg / C. Hardness values were also increased by addition of Saffil fibers and the highest value was obtained as 191 HB from vertical to the fiber orientation of AlSi10Mg0.8 matrix alloy reinforced with 30 vol% Saffil fibers. Density measurement revealed that microporosities existed in the microstructure and the highest difference between the theoretical values and experimental values were observed in the composites of 30 vol% Saffil fiber reinforced ones for both AlSi7Mg0.8 and AlSi10Mg0.8 matrix alloys. In the second part of the experiments, insertion casting operation was performed. At casting temperature of 750 &deg / C, a good interface/component interface was obtained. Image analyses were also showed that there had been no significant fiber damage between the insert and the component.

This study is on the production and testing of an aluminum metal matrix composite. Metal Matrix Composites can be produced in several different ways. In this study, an aluminum matrix composite is produced by direct addition of the reinforcement ceramic into the liquid metal. The ceramic reinforcement for this process was a mixture of TiB2 and Al2O3 which was produced by means of a thermite reaction of reactants Al, B2O3 and TiO2 all in powder form with their respective stoichiometric amounts. This ceramic mixture was ground to fine powder size and then added to liquid aluminum in small percentages. After casting and taking samples of unreinforced alloy and reinforced alloys, their tensile strength and hardness as material properties were measured and compared. Another issue is the wetting of ceramic particles by molten Aluminum. The aim of the experiments in general is to find a better way to produce a composite material with desired mechanical properties.

Thesis (M.S.)--University of Michigan, 1988.