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Falcao V.D.,Instituto Federal Of Educacao Ciencia E Tecnologia Of Minas Gerais | Miranda D.O.,Rede Tematica em Engineering de Materiais REDEMAT | Miranda D.O.,Fundacao Centro Tecnologico Of Minas Gerais Cetec | Sabino M.E.L.,Rede Tematica em Engineering de Materiais REDEMAT | And 7 more authors.
Progress in Photovoltaics: Research and Applications | Year: 2011

Undoped zinc oxide thin films were grown at room temperature using two techniques: plasma deposition (PD) and electron beam evaporation in an argon atmosphere. PD offers some advantages, such as low ion damage and low deposition temperature. The optical transmittance of the films deposited by both methods was higher than 80% in the near UV-VIS range; the energy band gap and index of refraction agree with values reported in the literature. The resistivity of films grown by PD was 3.1 × 10 -2 ωcm, lower than the value of 1.2 × 10 -1 ωcm found for plasma assisted e-beam evaporated films. © 2010 John Wiley & Sons, Ltd.

Nakamura Filho A.,Rede Tematica em Engineering de Materiais REDEMAT | De Almeida A.C.,Rede Tematica em Engineering de Materiais REDEMAT | Riera H.E.,Rede Tematica em Engineering de Materiais REDEMAT | Gouveia V.J.P.,Fundacao Centro Tecnologico Of Minas Gerais Cetec | And 3 more authors.
Materials Research | Year: 2014

Applying the theories of Materials Science and Engineering to describe the composition and hierarchy of microstructures that comprise biological systems could help the search for new materials and results in a deeper insight into evolutionary processes. The layered microstructure that makes up the freshwater bivalve Limnoperna fortunei shell, an invasive specie in Brazil, was investigated utilizing SEM and AFM for the determination of the morphology and organization of the layers; and XRD was used to determine the crystalline phases of the calcium carbonate (CaCO3) present in the shell. The presence of the polymorphs calcite and aragonite were confirmed and the calcite is present only on the external side of the shell. The shell of L. fortunei is composed of two layers of aragonite with distinct microstructures (the aragonite prismatic layer and the aragonite sheet nacreous layer) and the periostracum (a protein layer that covers and protects the ceramic part of the shell). A new morphology of the calcite layer was found, below the periostracum, without defined form, albeit crystalline.

Da Silva G.L.R.,Rede Tematica em Engineering de Materiais REDEMAT | Da Silva G.L.R.,Federal University of Ouro Preto | Dias Silva R.,Rede Tematica em Engineering de Materiais REDEMAT | Cheloni L.,Federal University of Ouro Preto | And 4 more authors.
Materials Research | Year: 2016

The use of scrap tires in the coal blends is an alternative to reduction of coke production costs as well as mitigates the impact caused by tire accumulation in the environment. Tests were carried out on a pilot scale, with coal blends and waste tire in 4 levels and 3 particle sizes, in order to assess the impact on the produced coke quality, especially on the Strength after Reaction with CO2-CSR and Drum Index (DI150-15). In addition, it evaluated the mechanical resistance to compression, punctual chemical composition by Energy Dispersive Spectroscopy (EDS) analysis beyond the carbonaceous matrix-tire interface by SEM microscopy. The results from the coking tests showed that addition of up to 3% of the average ground tire (20-30mm) with steel mesh, raised either as CSR DI150-15, making feasible added also from a technical point of view.

Junqueira R.M.R.,Instituto Senai Of Inovacao Em Engineering Of Superficies | De Andrade Manfridini A.P.,Rede Tematica em Engineering de Materiais REDEMAT | De Oliveira Loureiro C.R.,Instituto Senai Of Inovacao Em Engineering Of Superficies | De Mendonca R.,Rede Tematica em Engineering de Materiais REDEMAT | And 2 more authors.
Surface Engineering | Year: 2013

Anodic interference films were grown on stainless steel by an electrochemical process in a 70 g L-1 CrO3+500 g L -1 H2SO4 solution at temperatures of 25-75°C. The aim of this research was to assess the influence of temperature on characteristics of this coating. The morphology of the films was assessed through atomic force microscopy, the chemical composition was assessed by X-ray photoelectron spectroscopy, while the mechanical characteristics were assessed by resistance to abrasion wear and nanohardness. The roughness of the films grown at 25°C is less than that of the other temperatures. No significant difference regarding the porosity of the films was detected. A chromium hydroxide was observed on the top of the oxide layer grown on stainless steel. The steel coloured at 75°C presented a lesser hardness compared to the samples grown at 25, 35 and 55°C. The wear resistance increased as the temperature of the film's growth rose, which was inversely proportional to the hardness. © 2013 Institute of Materials, Minerals and Mining.

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