Teses
URI Permanente desta comunidade
Navegar
Navegando Teses por Orientador "Florêncio, Odila"
Agora exibindo 1 - 3 de 3
Resultados por página
Opções de Ordenação
- DissertaçãoCaracterização dos vidros metálicos CuZrAl e CuZrAlErLustosa, Cicero Junior Rodrigues (2018-12-11)
Escola de Engenharia Mackenzie (EE)
Vidros metálicos têm atraído o interesse de muitas pesquisas desde sua primeira fabricação, e tem se mostrado promissores para a ciência e a engenharia. Esse tipo de material apresenta propriedades superiores comparado a ligas policristalinas com composição semelhante, com alta resistência específica e elevada dureza. Com estrutura ordenada em pequenas distâncias, apresentando relação de primeira vizinhança, e o estado metaestável fornecem propriedade estrutural incomum e mecanismos de deformação não convencionais. Entretanto, o entendimento físico de sua estrutura amorfa e como ela afeta as propriedades dos vidros metálicos ainda é considerado um grande desafio na física da matéria condensada e ciência dos materiais. Nesse trabalho, foram realizadas caracterização morfológica, térmica e mecânica de dois tipos de amostras de vidros metálicos de grande volume com as composições Cu47,5Zr45,5Al5Er2 e Cu47,75Zr47,75Al4,5. As técnicas utilizadas foram: difração de raios X (DRX), microscopia óptica, microscopia eletrônica de varredura, espectroscopia por dispersão de raios X, ensaio de ultramicrodureza, calorimetria de diferencial de varredura e análise dinâmico-mecânica (DMA). Além disso, três modos de operação da microscopia de varredura por sonda foram empregados: microscopia de força atômica, mapeamento nanomecânico quantitativo e microscopia de força Kelvin. Os experimentos feitos complementaram-se mutuamente e produziram algumas informações interessantes provenientes das composições estudadas. Os resultados de DRX identificaram estruturas cristalinas somente em uma das amostras. Já as investigações morfológicas, em todas as técnicas, permitiram a comparação entre as composições. A amostra sem érbio apresentou formação de dendritas e superfície mais irregular. Através do DMA a temperatura que relaciona a temperatura de transição vítrea (Tg) com o aumento do atrito interno foi observada para as duas amostras. Além disso, a relaxação estrutural β, característica em composições vítreas de CuZrAl com 1 Hz de frequência na amplitude de oscilação foram observadas. As análises de ultramicrodureza sugerem que a amostra que possui érbio em sua constituição e apresenta menor variação dos resultados para a dureza e módulo de elasticidade. - TeseCaracterização microestrutural e interpretações genéticas de texturas em astromateriaisGonçalves, Augusto Nobre (2020-01-30)
Escola de Engenharia Mackenzie (EE)
This work sought to contribute to the scientific knowledge on astromaterials in three ways: (i) advocating the need for uniformity in the terminologies employed with respect to the classification and interpretation of meteoric material textures, since there are some imprecise terms traditionally used in their description, causing noise in communication; (ii) proposing and describing the use of more geologically rigorous terminology, as a way to reach the advocated uniformization; and (iii) producing a micrography atlas for a systematic mineralogical and microstructural characterization of those materials according to the prescribed terminology. From the organization of the collection of samples, those which would be the most representative pieces of their taxonomic groups to go to preparation of laminas for microscopy were defined. The laminas with the selected samples were characterized by petrographic microscopy – a traditional technique for mineralogy and petrology studies that uses two light polarizing filters in its optical system to allow microstructure identification and its highlighting. The result was the creation of a photomicrography catalogue that allowed interpretation of identified textures in terms of igneous, metamorphic and sedimentary phenomena, employing the astromaterial classification terminology proposed in this thesis. Part of the micrography atlas was used in a project of culture and extension that will become a themed artistic-scientific exposition for scientific propagation and popularization of the importance of studying meteoritic materials. - TeseUtilização de resíduos de construção e demolição na fabricação de blocos de concreto estrutural com adição de óxido de grafenoRamos, Elizabeth das Chagas (2020-12-18)
Escola de Engenharia Mackenzie (EE)
The increased demand for obtaining and improving materials that are more durable and efficient in the construction industry, presents an opportunity invaluable for the development of new materials with the application of nanomaterials and the use of construction and demolition waste (CDW) generated within the construction industry. Graphene oxide (GO) stands out for being a two-dimensional nanomaterial based on carbon that when added to concrete in low proportions modifies the hydration mechanism of Portland cement and its microstructure, improving its compressive strength. The dispersed GO water was purchased at the Technology Center for Nanomaterials and Grafene (CTNANO) for use in this work. For the manufacture of blocks structural construction waste was used, being reusable or recyclable waste such as aggregates and demolition, renovation and pavement repair waste, including soil from earthworks, ceramic components (bricks, blocks, tiles, cladding plates, mortar and concrete, pieces pre-molded in sthe crushing of Class A Type materials, according to CONAMA RESOLUTION number 307/2002 and number 469/2015, and were made available as aggregates (Grit and Gravel 0). For the execution of the concrete used in the manufacture of the structural blocks, the following were added: Portland cement of high initial strength - CP V ARI, aggregates recycled materials, stone powder and water, subsequently received addition of graphene oxide in aqueous dispersion, in order to improve your it`s strenghth. The structural block obtained was characterized through mechanical and microstructural tests. To evaluate properties of the materials used to make the materials used to make the blocks and the final product obtained, until now, tests have been made on the specific mass of the aggregates, moisture content of the aggregates test, unit mass test, determination of the granulometric composition of aggregates, dimensional analysis and determination of compressive strength, determination of water absorption and liquid area, determination of shrinkage by drying, resistance to hollow prism compression, x-ray fluorescence and microscopy optics. The results showed that the addition of graphene oxide in dispersion water,in concentrations between 0,015% and 0,08%, caused a 112% increase in resistance to compression and decreased the water absorption of the structural block. Key words: nanomaterials, graphene oxide, concrete, construction waste (CDW)