424 resultados para Aço Corrosão
Resumo:
The resistance of aluminum and their alloys, to the corrosion phenomenon, in aqueous solutions, is a result of the oxide layer formed. However, the corrosion process in the aluminum alloy is associated with the presence a second phase of particles or the presence of chloride ions which promote the disruption of the oxide layer located producing the corrosion process. On the other hand, the term water produced is used to describe the water after the separation of the oil and gas in API separators. The volumes of produced water arrive around 5 more times to the volume of oil produced. The greatest feature of the water is the presence of numerous pollutants. Due to the increased volume of waste around the world in the current decade, the outcome and the effect of the discharge of produced water on the environment has recently become an important issue of environmental concern where numerous treatments are aimed at reducing these contaminants before disposal. Then, this study aims to investigate the electrochemical corrosion behavior of aluminum alloy 6060 in presence of water produced and the influence of organic components as well as chloride ions, by using the electrochemical techniques of linear polarization. The modification of the passive layer and the likely breakpoints were observed by atomic force microscopy (AFM). In the pit formation potential around -0.4 to -0.8 V/EAg/AgCl was observed that the diffusion of chloride ions occurs via the layer formed with the probable formation of pits. Whereas, at temperatures above 65 C, it was observed that the range of potential for thepit formation was -0.4 to -0.5 V/EAg/AgCl. In all reactions, the concentration of Al(OH)3 in the form of a gel was observed
Resumo:
The human activities responsible for the ambient degradation in the modern world are diverse. The industrial activities are preponderant in the question of the impact consequences for brazilian ecosystems. Amongst the human activities, the petroliferous industry in operation in Potiguar Petroliferous Basin (PPB) displays the constant risk of ambient impacts in the integrant cities, not only for the human populations and the environment, but also it reaches the native microorganisms of Caatinga ground and in the mangrove sediment. Not hindering, the elaboration of strategies of bioremediation for impacted areas pass through the knowledge of microbiota and its relations with the environment. Moreover, in the microorganism groups associated to oil, are emphasized the sulfate-reducing prokaryotes (SRP) that, in its anaerobic metabolism, these organisms participate of the sulfate reduction, discharging H2S, causing ambient risks and causing the corrosion of surfaces, as pipelines and tanks, resulting in damages for the industry. Some ancestries of PRS integrate the Archaea domain, group of microorganisms whose sequenced genomes present predominance of extremophilic adaptations, including surrounding with oil presence. This work has two correlated objectives: i) the detection and monitoring of the gene dsrB, gift in sulfate-reducing prokaryotes, through DGGE analysis in samples of mDNA of a mangrove sediment and semiarid soil, both in the BPP; ii) to relate genomic characteristics to the ecological aspects of Archaea through in silico studies, standing out the importance to the oil and gas industry. The results of the first work suggest that the petrodegraders communities of SRP persist after the contamination with oil in mangrove sediment and in semiarid soil. Comparing the populations of both sites, it reveals that there are variations in the size and composition during one year of experiments. In the second work, functional and structural factors are the probable cause to the pressure in maintenance of the conservation of the sequences in the multiple copies of the 16S rDNA gene. Is verified also the discrepancy established between total content GC and content GC of the same gene. Such results relating ribosomal genes and the ambient factors are important for metagenomic evaluations using PCR-DGGE. The knowledge of microbiota associated to the oil can contribute for a better destination of resources by the petroliferous industry and the development of bioremediation strategies. Likewise, search to lead to the best agreement of the performance of native microbiota in biogeochemical cycles in Potiguar Petroliferous Basin ecosystem
Resumo:
A Endodontia uma rea em constante evoluo. Considerveis desenvolvimentos nos materiais e tcnicas tm sido essenciais para o melhoramento dos resultados nos tratamentos realizados. exemplo disso mesmo a constituio dos instrumentos Endodnticos primordiais, construdos em cordas de piano, com evoluo para aço de carbono, material este que sofria corrosão provocado pelo cloro presente no hipoclorito de sdio. O aço de carbono evoluiu para aço inoxidvel e deste as limas endodnticas passaram a ser feitas em nquel-titnio, conferindo-lhes melhor flexibilidade e efeito de memria de forma. Mesmo com todas estas melhorias significativas, fraturas de instrumentos e erros durante a instrumentao continuam a acontecer e com eles veio a necessidade da pesquisa de possveis melhorias da constituio das limas em NiTi. Como resultado surgiram ligas como o M-wire, fase-R e CM-wire, criadas a partir de tratamentos trmicos, que trouxeram s limas Endodnticas maior flexibilidade e resistncia fratura que os instrumentos feitos em NiTi convencional. A mais recente evoluo das limas Ni-Ti, desenvolvida pela Coltene Whaldent (Allsttten, Suia), so as limas Hyflex EDM, limas para canais radiculares de 5 gerao. O seu processo de fabrico por eletroeroso cria uma superfcie nica fazendo com que estas limas sejam mais duras e resistam mais quebra, aliado sua alta flexibilidade. possvel assim reduzir o nmero de limas para a limpeza e modelagem dos canais durante os tratamentos endodnticos sem comprometer a preservao da anatomia dos canais. As limas Hyflex EDM possuem, tal como as limas Hyflex CM, o efeito de controle de memria (CM), o que confere propriedades muito similares entre os dois sistemas.
Resumo:
This archaeovitreological study deals with artefacts of Miranduolo site, Tuscany region (Italy), dated 1250-1350 AD. The Miranduolo site is a medieval hill-village dated from 7th to 14th century. The information obtained reveal that Miranduolo was under control of noble families, which displayed the social, economic and political power. It is marked by controlling the farmers and metal workers on the site, as well as having control over agricultural surpluses. No in situ glass workshop has been recovered, implying that the glass artefacts were imported. One aim of this work is application of SEM-EDS to visualize textural characteristics and thickness of the pristine glass and corrosion layers. Preliminary qualification and semi-quantification of major and minor chemical elements will provide the data on the glass group present and fluxes employed. The data obtained will be integrated with the one obtained by more sensitive techniques such as PIXE/PIGE and LA-ICP-MS. Twenty cross-sections of transparent glasses (colorless, azure, and different hues of yellow and) have been analyzed by VP-SEM. All the analyzed glasses display a homogenous matrix. Only four samples (MD 24, MD 139, MD 143, MD 259) show corrosion layers of various thickness with 2.25m, 136-500 m, 26.8 m and 17.01 m. EDS linescan analyses indicate strong depletion in the corrosion layers of Na and K, while Ca depletes to a minor extent. In general, both glass composition and the burial conditions were favorable for preservation. Samples can be classified as mainly plant ash Na-Ca-Si glasses made with both unpurified and purified Levantine ash. Only sample MD 243 is made from Barilla plant ash. Sample MD 139 cannot be classified into main compositional groups as K2O is 1.33 wt% and MgO 5.92 wt%. In 8 samples MnO content is lower than 0.8 wt%, meaning that in these samples MnO is naturally present. In other 12 samples, MnO above 0.8 wt% indicates deliberate addition as a decolorant agent to intentionally obtain different hues or the amount added was not successful in making the glass transparent. The results considering fluxes are compatible with archaeovitreological study from contemporary primary glass workshops in Tuscany. For determining the provenance of silica sources, further analysis with more sensitive techniques has to be carried out; Resumo: Este estudo arqueovitreologia lida com artefatos do local Miranduolo, regio da Toscana (Itlia), datados de 1250-1350 AD. O sitio de Miranduolo uma colina vila medieval datada do sc.VII ao sc.XIV. As informaes obtidas revelam que Miranduolo estava sob o controle de famlias nobres, que exibiu o poder social, econmico e poltico. marcado por controlar os agricultores e trabalhadores do metal no sitio, bem como ter controlo sobre os excedentes agrcolas. No h na oficina de vidro in situ foi recuperado, o que implica que os artefactos de vidro foram importados. Um dos objetivos deste trabalho a aplicao de SEM-EDS para visualizar caractersticas de textura e espessura das camadas de corrosão do vidro tambm como da reas originais. qualificao preliminar e semi-quantificao de maiores e menores elementos qumicos ir fornecer os dados sobre o grupo presente vidro e fluxos empregado. Os dados obtidos so integrados com os dados obtidos por meio de tcnicas mais sensveis, como PIXE / PIGE e LA-ICP-MS. Vinte seces transversais de vidros transparentes (incolor, azul celeste, e diferentes tons de amarelo) foram analisados por VP-SEM. Todos os vidros analisados exibir uma matriz homognea. Apenas quatro amostras (MD 24, MD 139, MD 143, MD 259) mostram camadas de corrosão de vrias espessuras com 2.25m, 136-500m, 26,8m e 17,01m. Anlises Linescan EDS indicam forte esgotamento nas camadas de corrosão de Na e K, enquanto Ca esgota, em menor grau. Em geral, tanto a composio de vidro e as condies de depsito foram favorveis para a preservao. As amostras podem ser classificados como vidros principalmente Na-Ca-Si feitas com cinzas de plantas do tipo levantino, no purificada e purificada. Apenas a amostra MD 243 feita a partir de cinzas vegetais tipo Barilla. A amostra MD 139 no pode ser classificada em grupos principais de composio porque K2O 1,33% em peso e MgO 5,92% em peso. Em 8 amostras, o teor de MnO menor do que 0,8% em peso, o que significa que nestas amostras MnO est naturalmente presente. Em outras 12 amostras, MnO acima de 0,8% em peso indica adio intencional como um agente de colorante para obter intencionalmente diferentes matizes ou o valor acrescentado no foi bem sucedido em fazer o vidro transparente. Os resultados, considerando os fluxos so compatveis com o estudo arqueovitreologico com as principais oficinas de vidro contemporneos na Toscana. Para determinar a origem das fontes de slica, uma anlise mais aprofundada com tcnicas mais sensveis tem de ser levada a cabo.
