Papers by Author: Ledjane Silva Barreto

Abstract: Brazil has a large potential for energy generation and development of new materials from renewable resources through eco-friendly routes, which presents an alternative for construction of an eco-technological platform, where the entire lifecycle of the material or industrial product be sustainable. The proposal of the present work was synthesize carbon nanostructures from coconut coir dust and via template synthesis mediated by layered clays through hydrothermal process. The obtained materials were characterized by Raman Spectroscopy, Fourier Transform Infrared Spectroscopy and Scanning Electron Microscope (SEM). Carbon phase formation was indicated by infrared results with bands at 1444 cm^-1 and 1512 cm^-1 assigned to C=C of aromatic groups. Raman spectroscopy results showed presence of carbonaceous species by the appearance of D and G bands assigned to disordered and graphitic crystallites, respectively. SEM results showed overlapping sheets and plates formation. High Resolution Transmission Electron Microscopy measures are in progress.

Abstract: Ferritic stainless steels have been used to produce interconnects for intermediate temperature solid oxide fuel cells (ITSOFC) due to their appropriate properties. Ferritic stainless steel presents mechanical stability, much higher thermal and electronic conductivities; significantly lower cost, and mechanical resistance than austenitic steels. Besides, it presents a thermal expansion coefficient compatible with the other materials of the cell components. However, in the range of this device operating temperature (600 °C 800 °C) it can occur the formation of poorly conducting oxide (Cr₂O₃) reducing the fuel cell performance. The aim of this work was to obtain oxide coatings starting with La, Sr and Co nitrates applied by spray-pyrolysis technique on a stainless steel AISI 430 substrate. The coatings obtained were characterized by X-ray diffraction and scanning electron microscopy/energy dispersive spectroscopy. The oxidation resistance of the ferritic stainless steel, coated with a perovskite (La_0,6Sr_0,4CoO₃) film, was investigated by isothermal oxidation. The results showed that the coating obtained promoted the increase of the ferritic stainless steel oxidation resistance. However, after the oxidation test, it was observed a Cr enrichment and a very pronounced Sr enrichment, near to the alloy/coating interface, which can be associate to the decomposition of La_0,6Sr_0,4CoO₃ film.