Orientadores: Julio Cesar Hadler Neto e Pedro Jose Iunes / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-11T13:08:17Z (GMT). No. of bitstreams: 1 Vellame_IgorAlencar_M.pdf: 65129238 bytes, checksum: 6de747c41ecd760b5c0222e6d9b5b065 (MD5) Previous issue date: 2008 / Resumo: Este trabalho desenvolveu o estudo da evolução geométrica de traços da fissão induzida do isótopo 235U em um vidro da categoria soda-lime. Para isto foi necessário conhecer o modelo geométrico para a evolução de traços de fissão em materiais isotrópicos. Este modelo tem como base a competição entre duas taxas de ataque químico: uma no material ( VB); e outra nas trajetórias dos fragmentos no material ( VT). Este ataque químico é utilizado para alargar os traços com a finalidade de observá-los em um microscópio óptico. As técnicas de Microscopia Eletrônica de Varredura e de Microscopia de Força Atômica foram utilizadas para realizar medidas com maior resolução e durante os primeiros estáagios do ataque químico. Filmes de urânio foram produzidos para serem acoplados a uma montagem que também contém um colimador e um vidro. Esta montagem foi bombardeada por nêutrons térmicos em um reator nuclear. Cálculos da perda de energia dos fragmentos nas montagens foram simulados por um software. Medidas dos diâmetros e dos ângulos das paredes dos traços foram feitas. Recobrir parte da superfície do vidro com um material que não é corroído durante o ataque permitiu medir a taxa de ataque no material, VB= (0,113 ± 0,003) µm/s. Dois valores foram obtidos para a razão entre as taxas: Vdiametro= 1,66 ± 0,07; e Vprofundidade= 1,31 ± 0,09. O primeiro valor foi calculado pelo modelo utilizando as medidas dos diâmetros. Já o segundo valor foi calculado pelas profundidades obtidas indiretamente com o Microscópio de Força Atômica. Com estes valores constantes, chegou-se à conclusão de que o efeito causado pela passagem de um fragmento de fissão no vidro é a formação de um cilindro contínuo de danos. O resultado deste trabalho tem grande importância para modelos de annealing que supoem esta estrutura para os traços latentes / Abstract: A study on the geometric evolution of 235U induced fission tracks in a soda-lime glass was made. It was necessary to know about the geometric model for structure evolution of fission tracks in isotropic materials. This model is based on the competition of two chemical etching rates: one in the bulk material (VB) and another in each fragment trajectory (VT). This etching is generally used for track observation in an optical micro-scope. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were used because of the better resolution and for measurements at short etching times. Uranium films were produced and coupled to each glass trough an acrylic piece (collimator). Irradiated by thermal neutrons the film emits fragments. Energy loss calculations were simulated by SRIM software. Track diameters and wall angles were measured. The rate VB= (0,113 ± 0,003) µm/s were measured by recovering part of the glass surface with a non-etching material. Two values were obtained for the ratio between the etching rates: Vdiam= 1,66 ± 0,07 and Vdepth= 1,31 ± 0,09. The model was used to calculate the first value with the diameters measurements. The second one was obtained by indirect depth measurements with AFM. Thus, with all these constant values we can consider that the effect produced by fission fragments traversing a soda-lime glass is the production of a homogeneus cylinder of damage. This result is very important for annealing models / Mestrado / Física Nuclear / Mestre em Física

In the production of glass, the addition of more cullet to the batch of glass and the reduction of the thickness of glass are means to reduce energy consumption and raw material usage. This contributes towards improved energy efficiency targets of the European Union. This thesis investigated the energy consumed for the process of strengthening thinner glass as well the environmental implications of thinner and stronger compared to conventional glass across the life cycle of glass. The life cycle phases also included a recycling phase where 70% of the used glass was recycled with the remaining 30% being landfilled. The functional unit selected for this study was 1m2 of SLS glass, 4mm thick, with an average light transmittance of 91%. This corresponds to 10kg of clear float glass as per general rule. The findings of this thesis showed that one of the major contributing factors to high energy consumption in the melting phase of SLS glass is low efficiency of the furnace; this led to significant energy losses in the production of SLS glass. Recycling of flat glass, at a 70% rate, led to a 12% reduction in total global warming potential, a 10% reduction in the Acidification Potential, a 13% reduction in the Eutrophication Potential in marine environs, and a 7% reduction in the Eutrophication Potential in terrestrial habitats. The chemical and thermal strengthening process consumed 2.24 and 2.37 kWh/m2 respectively. The consequential impact of this is dependent on the source of the electricity for the strengthening processes. It was concluded that the energy used for the strengthening of the thinner glass is considerably less than the energy used in the production of a conventional glass that satisfies the same strength parameters.

No description available.

The present thesis deals with optimization of the formation of thin layers of metallic materials. In the theoretical part was elaborated overview of the implementation of the formation of thin- film structures, particularly using vacuum techniques. Chemical and physical vapor deposition. They were described methods of pretreatment of thin layers. The findings were discussed methods of controlling the pre-treated surface, quality control and mutual adhesion of coating layers. In the experimental part of the pre-treatment methods were selected and applied to selected substrates. Pretreatments were evaluated using a control surface by wetting angles and by atomic force microscopy. Then, the metal structure formed of copper on the pretreated substrates. Implementation by means of magnetron sputtering. Adhesion layers was checked by testing the surface lattice method. The quality was observed by scanning electron microscopy. The results were used to design the technological process of making metal layers.