Preliminary study on the production of functionally graded materials by friction stir processing

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia MecânicaAn investigation was carried out to evaluate the potential application of Friction Stir Processing (FSP) to produce Functionally Graded Materials (FGM‟s). Friction stir processed materials can be considered as FGM‟s since the localized microstructural modification results in a gradual property modification. Therefore, to enhance hardness and ductility at specific superficial levels, surface layers of processed material were produced by multiple-pass FSP with an overlap ratio of 0.5. Overlapping was done on the advancing (AS) and retreating sides (RS) to study potential differences on the resulting mechanical properties. It was observed that processing in these two conditions led to different surface topography, since overlapping by the advancing side resulted in a wave-like surface profile. The mechanisms involved in FSP also led to its exploitation for the production of particle-reinforced Metal Matrix Composite (MMC) materials, as the severe plastic deformation produced during the process promotes the dispersion of the particles within the matrix. An investigation was conducted in order to produce aluminium based functionally graded MMCs reinforced by SiC ceramic particles with median size of 118.8, 37.4 and 12.3 micron. AA5083 aluminium alloy plates in the H111 and partially annealed conditions were processed. Several strategies for reinforcement were investigated and its influence on the particle distribution and homogeneity. The most promising results were achieved when the pin fully overlapped the groove. SiC fraction area analysis revealed two orthogonal gradients. Since FSP was used as a surface processing technique, the magnitude of the microstructural effects generated by the tool gradually decreases along the depth of the processed material. A second gradient was generated parallel to the bead surface due to the asymmetric nature of material flow around the tool. The use of smaller sized particles led to more homogeneous composite layers and smother gradients. Tool wear was very significant, proving that SiC reinforcement is not the most suitable method to produce FGM‟s

Cotistas nas Universidades Federais brasileiras: uma análise sobre a evasão das Universidades Federais

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A família na Constituição brasileira

- Divulgação dos SUMÁRIOS das obras recentemente incorporadas ao acervo da Biblioteca Ministro Oscar Saraiva do STJ. Em respeito à Lei de Direitos Autorais, não disponibilizamos a obra na íntegra.- Localização na estante: 347.6(81) F198nf- Coordenado por: Ives Gandra da Silva Martins, Paulo de Barros Carvalho, Luiz Gonzaga Bertelli e João Carlos Biagin

Liberdade religiosa e liberdade de expressão

- Divulgação dos SUMÁRIOS das obras recentemente incorporadas ao acervo da Biblioteca Ministro Oscar Saraiva do STJ. Em respeito à Lei de Direitos Autorais, não disponibilizamos a obra na íntegra.- Localização na estante: 342.731’727 L695r- Coordenado por: Ives Gandra da Silva Martins, Paulo Barros Carvalho, Luiz Gonzaga Bertelli e João Carlos Biagini

Manejo orgânico de pastagens com uso de termopotássio e termofosfato na região do Cerrado

The objective of this work was to evaluate the performance of the thermopotassium and thermophosphate agrominerals, as sources of P and K, in an organic pasture consortium of 'Marandu' Urochloa brizantha + Stylosanthes spp. in the Brazilian Cerrado. The organic management was compared with conventional farming using chemical fertilizers, during three years, in two adjacent experiments, one with and the other without previous growth of green manure (Crotalaria juncea). The management treatments were: conventional, with the application of 200 kg ha-1 potassium chloride, 260 kg ha-1 triple superphosphate, and 217 kg ha-1 urea; organic, with the application of 1.0 Mg ha-1 thermophosphate, 2.0 Mg ha-1 termopotassium, and 7.0 Mg ha-1 chicken manure; and control, without fertilizers. Soil fertility, dry mass production, and legume content in the pasture were evaluated. The experiment with green manure resulted in a significant increase in the soil-extractable contents of P and K and in pasture productivity. In the organic treatment, due to the slow release of agromineral nutrients, long-term effects are observed on the soil-extractable contents of P and K.O objetivo deste trabalho foi avaliar o desempenho dos agrominerais termopotássio e termofosfato, como fontes de P e K, em consórcio de pastagem orgânica de Urochloa brizantha 'Marandu' + Stylosanthes spp. no Cerrado brasileiro. O manejo orgânico foi comparado ao convencional com uso de fertilizantes químicos, durante três anos, em dois experimentos adjacentes, um com e outro sem cultivo prévio de adubo verde (Crotalaria juncea). Os tratamentos de manejo foram: convencional, com aplicação de 200 kg ha-1 de cloreto de potássio, 260 kg ha-1 de superfosfato triplo e 217 kg ha-1 de ureia; orgânico, com aplicação de 1,0 Mg ha-1 termopotássio, 2,0 Mg ha-1 termofosfato e 7,0 Mg ha-1 cama de frango; e controle, sem adubação. Foram avaliadas fertilidade do solo, produção de matéria seca e contribuição da leguminosa na pastagem. O experimento com adubação verde proporcionou aumento significativo nos teores de P e K extraíveis do solo e na produtividade da pastagem. No tratamento orgânico, devido à liberação lenta dos nutrientes dos agrominerais, são observados efeitos de longo prazo nos teores extraíveis de P e K do solo