Engenharia de Materiais
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/17
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3 resultados
Resultados da Pesquisa
- Production of cellular ceramics by gel casting ceramic emulsions Produção de cerâmicas celulares por emulsão seguida de gelifi cacao(2011) DE SOUSA, E.; DELLU JUNIOR, M.; PANDOLFELLI, V. C.; SA, F.Cellular ceramics have been produced by several methods, resulting in a wide range of structures and properties. This work describes a novel route to produce cellular ceramics based on the gel casting of emulsions consisting of an aqueous ceramic suspension containing water-soluble organic monomers and an emulsifi ed insoluble liquid phase (kerosene). The effects of solids loading and kerosene content on the rheological properties of emulsions were evaluated. SEM of the cellular structure revealed isolated pores for samples with low porosity, which changed to an interconnected network of pores as the porosity increased. Diametrical compression was used to evaluate the strength of sintered samples, which varied in the range of 2.0 and 48 MPa, depending on the porosity.
- Alumina foam coated with strontium oxide as a heterogeneous catalyst(2012) Bassetti F.B.; Innocentini M.D.M.; Pereira G.J.; Ortega F.S.The most common method to produce biodiesel is the transesterification of oils in the presence of methanol and a catalyst. Catalysts may be either homogeneous or heterogeneous, whereas the heterogeneous consume fewer resources, energy and are reusable, being considered an environmentally attractive approach. This research presents the production of a heterogeneous catalysis system for biodiesel synthesis, consisting of alumina foam with a thin coating of SrO. The support, obtained by direct foaming of suspensions, presented approximately 90% vol. of highly connected pores. The SrO film was obtained by soaking the ceramic foam into either a Pechini resin with SrO precursors or an aqueous solution of strontium nitrate, followed by heating to 1400°C for 2 hours. The density and permeability of samples were evaluated and microstructure was characterized by EDS and SEM. The results show that the use of ceramic foams as catalyst support is feasible using the proposed route. © (2012) Trans Tech Publications, Switzerland.
- Evaluation of mechanochemical and hydrothermal transformations in a wet-milled alumina by transmission electron microscopy and thermal analysis(2017) Yoshimura H.N.; de Lima M.B.; Santos S.F.; Ortega F.S.© 2017 Trans Tech Publications, Switzerland.Milling and hydrothermal treatment of alumina powders in aqueous medium can result in surface transformations generating aluminum hydroxides. The aim of this work was to advance the understanding on these transformations. A α-alumina powder was ball milled in water at different pHs for 10 h, and then autoclaved (150 °C, 3 atm, 3 h). The powders were analyzed by transmission electron microscopy, differential scanning calorimetry simultaneously with thermogravimetry, Xray diffraction, and infrared spectroscopy. It was observed that milling in basic medium caused the formation of doyleite [Al(OH3)] nanoparticles, which were fully converted to boehmite (AlOOH) by hydrothermal treatment. The boehmite fraction determined by thermal analysis was 1.7 wt%. The powder milled in acid medium had no mechanochemical and hydrothermal transformations.