155 resultados para Colloidal Pbse
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Química - IQ
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Pós-graduação em Ciência e Tecnologia de Materiais - FC
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Biotecnologia Animal - FMVZ
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Pós-graduação em Nanotecnologia Farmacêutica - FCFAR
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The glassy carbon is a material with a huge technological evolution. Due to its lightness, biocompatibility and their thermal and electrical properties this material finds applications in several industrial fields such as electronics, medical, aerospace and chemical. In order to explore the conductive properties of glassy carbon for use as modified electrodes, the present work aims the processing of monolithic and reticulated glassy carbon with colloidal copper for use in electrochemical applications. First, the best parameters for the cure of furfuryl alcohol resin doped were established through viscosimetry measurements and pressurized differential scanning calorimetry. The analysis of the micrographs of the cured resins show that copper concentrations above 3% weight, generate higher porosity in the material. The characterizations of the monolithic and reticulated glassy carbon resulting from carbonization were performed by scanning electron microscopy (SEM), Raman and Electrochemical impedance spectroscopy, and although it was not possible to detect the presence of copper by SEM, the influence of these particles have been observed by Raman and FT-IR spectra and electrochemical behavior of the material. The decrease in conductivity of monolithic and reticulated glassy carbon in the presence of copper may be related to the defects caused by the presence of copper in the structure of the material.
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The increasing technological innovation and demand for materials with better properties boosts research into new materials and new alloys. To do so, aluminum alloys are being developed, among them the AA7075-T6, having many applications in aerospace and military industries, machinery and equipment, molds for plastic injection and structures. To study and understand the properties, characteristics and especially the microstructure of the material, the metallographic preparation is essential. This paper presents new methodologies to achieve the metallography of samples of scrap alloy AA7075-T6, with emphasis on methods of polishing. For the five samples, the best results were those with specific grinding, the samples only going down on the sander. For polishing, the most effective method so far has been using the polishing cloth 16.3, of ATM enterprise, solution of diamond 3 μm, solution of diamond 1 μm, and colloidal solution of OP-S. For the etching, the reactive agent used was phosphoric acid (H3PO4) 85% P.A., as 90% in the proportion of distilled water to 10% acid. The best results were obtained in the attacks of 300 and 240 seconds, revealing the grain boundaries in most areas. Methodologies need more studies and more tests, but the results have proved to be satisfactory
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In the present work the thermal characteristics of gels and xerogels of Silica/organic hybrids derived from different concentrations of GPTS-TEOS were investigated by thermal analysis (TG, DTA, and DSC). The preparation of gels of the Silica/organic hybrid matrix was held through the sol-gel process, consisting by the hydrolysis of alkoxides GPTS and TEOS in proportion (1:1) and (1:2) that was promoted in acidic conditions under reflux and stirring at 80oC/2h, producing the matrix in the colloidal state (sol). Gels were prepared by addition of NH4OH to the sol, promoting gelation of sol in sealed plastics containers. Part of the gels samples was analyzed by TG, DTS and DSC techniques in order to characterize water loss and degradation of the polymeric “epoxy” groups present in the structure of the silica derived from the GPTS alkoxide. Another set of samples was dried at 80oC/48h to obtain xerogels (dried gels) and analyzed by the same techniques. We obtained the characteristics temperatures of the matrix by the techniques DTA, DSC and TG, under measurements of thermal analysis until 800oC and 600oC in case of DSC. By thermal analysis (TG, DTA, and DSC) the main endothermic events (loss of water, melting, pyrolysis) and exothermic events (burning of the polymer) of the GPTS-TEOS matrix were determined