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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3 resultados
Resultados da Pesquisa
Item Effects of glass wool residue recycled admixtures on the properties of portland cement-based composites.(2022) Silva, Keoma Defáveri do Carmo e; Cotta, Jéssica Fernandes; Elói, Fernanda Pereira da Fonseca; Carvalho, José Maria Franco de; Peixoto, Ricardo André Fiorotti; Silva, Guilherme Jorge BrigoliniIn this study, the effects of a recycled mineral admixture based on glass wool residue (GWR) in microstructural and mechanical properties of ordinary portland cement (OPC)-based composites are examined. The GWR was dried and milled into a fine powder, whereby it was physicochemically characterized. Physicomechanical tests, quantitative X-ray diffraction, and scanning electron microscope observation were performed in pastes and mortars at 28, 56, and 90 days of age. Moreover, the potential application of the GWR was evaluated by determining the pozzolanic activity and the fiber reinforcement effect. The results showed that the partial replacement of cement by 25% by weight of GWR presented no reductions in flexural strength at 28 and 56 days of curing, whereas the long-term flexural strength increased by 17%. This replacement also increased the long-term compressive strength of the composites—reaching a strength activity index of 1.06. The results also showed that GWR presented some fiber reinforcement effect—depending on the particle size. Promising properties were observed for samples blended with GWR, yielding technical, environmental, and economic benefits.Item Ultra-fast dehydration and reduction of iron oxides by infrared pulsed radiation.(2002) Costa, Adilson Rodrigues daLaser irradiation of iron oxides (goethite and hematite) is studied in order to understand their interaction with short duration pulses. Results have shown that Nd:YAG laser provides enough energy to induce fast chemical transformation of goethite and hematite.Item Phase transitions in Nb rich coating produced by laser alloying : a synchrotron radiation diffraction study.(2001) Costa, Adilson Rodrigues da; Craievich, Aldo; Vilar, RuiA great variety of studies have been performed in order to develop new materials with high performance in many adverse conditions such as wear and corrosive environment coupled with high temperatures and high stress levels. A strong scientific and technical effort is currently dedicated to develop wear and corrosion resistant surfaces to provide components having good behavior in such extreme working conditions, we have chosen laser alloying and prepared Nb rich coatings upon a nodular cast iron microstructure. The new tailored material is in fact a composite having a very hard coating covering a traditional iron base material. If the material is submitted for thermal cycling, it is imperative to know the phase transformations during heating/cooling cycles, as well as, during long periods of permanence at high temperatures. According to these guidelines, we performed an X-ray diffraction (XRD) study using the XRD beam line of the National Synchrotron Light Laboratory (LNLS, Brazil). The analysis of the XRD pattern indicates the presence of niobium and niobium carbides (Nb, NbC, Nb2C) from room temperature up to 750°C.