oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 158 )

2018 ( 326 )

2017 ( 348 )

2016 ( 370 )

Custom range...

Search Results: 1 - 10 of 192828 matches for " Ant?nio Pedro Novaes de; "
All listed articles are free for downloading (OA Articles)
Page 1 /192828
Display every page Item
Desenvolvimento de porcelana quartzosa para isoladores elétricos de alta tens o
Alan Neves Bonetti,Jony C. Tomelin,Orestes Estevam Alarcon,Antnio Pedro Novaes de Oliveira
Exacta , 2009,
Abstract: The fabrication technology of high-voltage ceramic insulators was traditionally developed by using quartz-based porcelain compositions. The objective of this work was to develop an IEC 672 C 110 quartz-based ceramic body for high-voltage insulators according to IEC 672 C 120. Thus, a reference industrial formulation was compared with two alternative formulations, which show higher alumina and lower free quartz contents. The milling step was also optimized related to time and residue. The raw materials were characterized by XRF and XRD. Ceramic bodies were characterized by laser diffraction and, after firing process, by XRD and SEM. The sintered samples show mechanical strength of about 70 MPa for the standard ceramic body and 100-110 MPa for the alternative ones. The quartz-based ceramic bodies (IEC 672 C 110) developed are in good agreement with the IEC 672 C 120 international standard.
Crystallization Mechanism and Kinetics of BaO-Li2O-ZrO2-SiO2 Glasses
Silveira, Cristian Berto da;Campos, Sílvia Denofre de;Campos, Elvio A. de;Oliveira, Antnio Pedro Novaes de;
Materials Research , 2002, DOI: 10.1590/S1516-14392002000100004
Abstract: differential thermal analysis and scanning electron microscopy were used to determine the influence of the addition of bao on the crystallization mechanism of li2o-zro2-sio2 systems. as the concentration of bao in the samples increased, a transition occurred in the predominant crystallization mechanism, which passed from superficial to volumetric. to determine the maximum nucleation rate, the crystallization kinetics of the sample containing 20 mole % bao, which showed the most uniform crystallization, was studied by counting the nuclei with an image analyzer. the first nuclei appeared at the first endothermic inflection point (at the start of tg, at 440 °c), while the maximum number of nuclei was counted at the midpoint of the glass transition region (446 °c). these results are similar to those observed for other materials that crystallize in volume, and confirm scanning electron microscopy data.
Crystallization Mechanism and Kinetics of BaO-Li2O-ZrO2-SiO2 Glasses
Silveira Cristian Berto da,Campos Sílvia Denofre de,Campos Elvio A. de,Oliveira Antnio Pedro Novaes de
Materials Research , 2002,
Abstract: Differential thermal analysis and scanning electron microscopy were used to determine the influence of the addition of BaO on the crystallization mechanism of Li2O-ZrO2-SiO2 systems. As the concentration of BaO in the samples increased, a transition occurred in the predominant crystallization mechanism, which passed from superficial to volumetric. To determine the maximum nucleation rate, the crystallization kinetics of the sample containing 20 mole % BaO, which showed the most uniform crystallization, was studied by counting the nuclei with an image analyzer. The first nuclei appeared at the first endothermic inflection point (at the start of Tg, at 440 °C), while the maximum number of nuclei was counted at the midpoint of the glass transition region (446 °C). These results are similar to those observed for other materials that crystallize in volume, and confirm scanning electron microscopy data.
Processing and Characterization of Yttria-Stabilized Zirconia Foams for High-Temperature Applications
Ana María Herrera,Amir Antnio Martins de Oliveira Jr.,Antonio Pedro Novaes de Oliveira,Dachamir Hotza
Journal of Ceramics , 2013, DOI: 10.1155/2013/785210
Abstract: In this work ceramic foams of 3 and 8 mol% yttria-stabilized zirconia (3YSZ and 8YSZ) were manufactured by the replication method using polystyrene-polyurethane foams with pore sizes in the 7–10 ppi range. A second coating was carried out on presintered foams in order to thicken struts and hinder microstructural defects. The produced ceramic foams were structurally and thermomechanically characterized. Samples recoated with 3YSZ presented the highest relative densities ( ) which contributed to a better mechanical and thermal behavior. 1. Introduction Porous radiant burners are devices used in applications benefit from radiant thermal heating. Numerous industries employ this technology for firing and drying, lower pollutant emission, and better product quality reached with these burners [1, 2]. Other functional advantages are a higher flame velocity within the porous structure when compared to a laminar free flame (due to the preheated of reagents), higher turn-down ration, higher efficiency in heat transfer by radiation, and the possibility of burning low calorific value fuels or very lean mixtures [3]. Ceramics foams for porous radiant burners are mainly produced by the replication method from polymeric templates. The method consists in the impregnation of a polymeric sponge with a ceramic slurry followed by a heat treatment which leads to the burning out of the organic body (sponge) and to the sintering of the ceramic skeleton [4]. Along the manufacture process, there are key parameters that must be taken into account to ensure the final product effectiveness. Among them, the most important are the linear expansion coefficient, maximum working temperature and thermal shock resistance of the ceramic material, thixotropy and pseudoplasticity of the ceramic slurry, and, finally, the heating rate of the thermal treatment. According to the above, the most reliable ceramic materials to work with are cordierite, mullite, silicon carbide, alumina, partially stabilized zirconia (YSZ), and some composite systems [5–13]. Cellular ceramics are already commercially available for a wide range of technological applications including filters, membranes, catalytic substrates, thermal insulation, gas burner media, refractory materials, and lightweight structural panels [5–7]. In these cases, reticulated porous ceramics are used because of their functional properties, such as low thermal expansion coefficient and thermal conductivity, high permeability, and chemical inertness [7]. Considering the particularities associated with each specific application, reticulated
Decomposi??o térmica de espumas de poliuretano para fabrica??o de vitroceramica celular de Li2O-ZrO2-SiO2-Al2O3 (LZSA)
Silveira, Cristian Berto da;Escobar, Jairo A.;Quintero, Miguel W.;Sousa, Eliandra de;Moraes, Elisangela Guzzi de;Oliveira, Antnio Pedro Novaes de;Rambo, Carlos Renato;Hotza, Dachamir;
Química Nova , 2007, DOI: 10.1590/S0100-40422007000500010
Abstract: characterization of the thermal decomposition of polyurethane (pur) foams was performed by fourier-transformed infrared (ft-ir) spectroscopy and thermogravimetric analysis (tga). three main weight loss paths were observed by tga, the residue being lower than 3 wt.% for 3 different pur foams analyzed. ft-ir spectra indicated co2, co, nh3 and isocyanides as main decomposition products. pur foams of different cell sizes were immersed in a slurry of the parent glass ceramic of composition li2o-zro2-sio2-al 2o3 (lzsa) and submitted to heat treatment. the lzsa cellular glass ceramics obtained after sintering and crystallization resembled the original morphology of the pur foams.
A Idéia de uma "Nova Ordem" ou o Remapeamento do Caos: Ensaio Sobre a Sistematiza o do "Mundo Vital"
Antnio Basílio Novaes Thomaz de Menezes
Princípios : Revista de Filosofia , 1995,
Abstract:
Habermas: Introdu o à Metacrítica da Raz o Instrumental
Antnio Basílio Novaes Thomaz de Menezes
Princípios : Revista de Filosofia , 1996,
Abstract:
Fragmentos de Arte e História: Benjamin Leitor de Baudelaire
Antnio Basílio Novaes Thomas de Menezes
Princípios : Revista de Filosofia , 2000,
Abstract:
Foucault e Kant: considera es em torno da ética e do Aufkl rung
Antnio Basílio Novaes Thomaz de Menezes
Princípios : Revista de Filosofia , 2005,
Abstract: This article has as subject the expected of an ethic connected the idea of modern in Michel Foucault. It broaches the reading that Foucault does of Kant’s text about the Aufkl rung. It examines the specific range of conditions of an individual’s ontology, trying to show the articulation between the present’s diagnosis and the criticism tradition’s reconstruction around the autonomy’s idea. It looks for showing, in the conception of modern’s attitude the historic power of Aufklarung’s inheritance that is in the criticism expected of a ethic’s problematic of the present, from an autonomy’s concept, shaped in the proposal of an “existence’s aesthetics”.
BIODIREITO, BIOéTICA, BIOPOLíTICA
Antnio Basílio Novaes Thomaz de Menezes
Fides : Revista de Filosofia do Direito, do Estado e da Sociedade , 2010,
Abstract:
Page 1 /192828
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.