EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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2 resultados
Resultados da Pesquisa
Item Development and characterization of titanium dioxide ceramic substrates with high dielectric permittivities.(2020) Freitas, Antonio Evangelista de; Manhabosco, Taíse Matte; Batista, Ronaldo Junio Campos; Rêgo Segundo, Alan Kardek; Araujo, Humberto Xavier de; Araujo, Fernando Gabriel da Silva; Costa, Adilson Rodrigues daTitanium dioxide substrates have been synthesized by means of solid-state reactions with sintering temperatures varying from 1150 ◦C up to 1350 ◦C. X-ray diffraction and scanning electron microscopy (SEM) where employed to investigate the crystal structure, grain size and porosity of the resulting samples. The obtained ceramics are tetragonal (rutile phase) with average grain sizes varying from 2.94 µm up to 5.81 µm. The average grain size of samples increases with increasing temperature, while the porosity decreases. The effect of microstructure on the dielectric properties has been also studied. The reduction of porosity of samples significantly improves the dielectric parameters (relative dielectric permittivity and loss tangent) in comparison to those of commercial substrates, indicating that the obtained ceramic substrates could be useful in the miniaturization of telecommunication devices.Item A geometallurgical comparison between lump ore and pellets of manganese ore.(2015) Faria, Geraldo Lúcio de; Tenório, Jorge Alberto Soares; Jannotti Júnior, Nelson; Araujo, Fernando Gabriel da SilvaManganese lump ores are still the main rawmaterial used in the manufacture ofmanganese ferroalloys, but the processing of the ore to the beneficiation point generates fines. So an alternative to be studied is making pellets. Thiswork compares themain geometallurgical characteristics of the lump ore fromthe AzulMine and the pellets made from fines generated during beneficiation of this lump ore on a small scale. The characteristics assessed were: the chemical composition, mineralogical constitution, hot and cold particle disintegration, thermal decomposition and solid state reduction. It can be observed that the pellets contain a greater proportion of manganese oxides than the lump ore and they are also richer inMn. In the pellets the hot and cold particle disintegration phenomena are minimal when compared with those found in lump ore. Lump ore can be efficiently reduced in the solid state, while most of the manganese minerals in the pellets have already been reduced to MnO. The conclusion is that manufacturing pellets in order to take advantage of the manganese ore fines is a path that must be studied further, since the pellets can be used as a viable source of manganese and act as agents that contribute to the increase in permeability of the charge. But possible reductions in the temperature of the granular zone during solid state reduction need to be considered.