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Search Results: 1 - 10 of 672064 matches for " A. S. A.;Chinelatto "
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Post mortem analysis of burned magnesia-chromite brick used in short rotary furnace of secondary lead smelting
Prestes, E.;Chinelatto, A. S. A.;Resende, W. S.;
Ceramica , 2009, DOI: 10.1590/S0366-69132009000100008
Abstract: burned magnesia-chromite bricks are the standard product for the lining of furnaces in lead industry, where the short service life is a great problem. used sintered magnesia-chromite brick sample from short rotary furnace lining, sent by a secondary lead manufacturer, showed parallel cracks to the hot face due to structural spalling damage. the refractory infiltrated region and slag interface were analyzed using a scanning electron microscope with an energy dispersive spectroscopy analyzer, and x-ray diffraction powder analysis. crucible corrosion test was performed to evaluate the influence of slag attack. the results showed that the structural spalling was due to strong pb-infiltration of the refractory microstructure by bath components of the furnace (metallic lead and lead sulphite) during the reduction process and that the slag infiltration had little contribution due to the good resistance of the magnesia-chromite bricks to feo rich slag attack.
Alumina ceramics obtained by chemical synthesis using conventional and microwave sintering
Thomazini, D.;Gelfuso, M. V.;Chinelatto, A. S. A.;Chinelatto, A. L.;Sanson, F. K.;Teixeira Neto, F.;
Ceramica , 2011, DOI: 10.1590/S0366-69132011000100006
Abstract: it is well known that the heating mechanism and powder precursor define the microstructural characteristics of ceramics. especially abnormal grain growth of pure alumina ceramics developed during conventional sintering method suggests that this material is a potential candidate to be treated in microwave sintering process. alumina ceramics produced with commercial (a1k) and chemically synthesized powders were sintered in conventional and microwave furnaces. two methods were employed to prepare the chemically synthesized nanosized powders: pechini method and emulsification with oleic acid. the microwave sintered samples were characterized by apparent density and scanning electron microscopy and compared with the samples sintered in a conventional furnace. alumina ceramics sintered in the microwave furnace had fine grained microstructure, not related with the starting powders. this characteristic was achieved in a sintering time shorter than those produced in the conventional furnace. however, satisfactory densification was observed only to a1k ceramics (3.95 g/cm3) sintered during one hour in microwave furnace.
Characterization of high-energy milled alumina powders
Tomasi, Roberto;Rabelo, Adriano A.;Chinelatto, Adriana S. A.;Reis, Laudo;Botta Fo, Walter J.;
Ceramica , 1998, DOI: 10.1590/S0366-69131998000500003
Abstract: the utilization of reactive high-energy milling has been reported for the synthesis of ceramic powders namely, metal oxides, carbides, borides, nitrides or mixtures of ceramics or ceramic and metal compounds. in this work, high-energy milling was used for reduction of alumina powders to nanometric particle size. the ceramic characteristics of the powders were analyzed in terms of the behavior during deagglomeration, compaction curves, sintering and microstructure characterization. it was observed that the high energy milling has strong effect in producing agglomeration of the nanosized powders. this effect is explained by the high-energy impact of the balls, which may fracture particles or just cause the particles compacting. in this case, strong agglomerates are produced. as the powder surface area increases, stronger agglomerates are produced.
Characterization of high-energy milled alumina powders
Tomasi Roberto,Rabelo Adriano A.,Chinelatto Adriana S. A.,Reis Laudo
Ceramica , 1998,
Abstract: The utilization of reactive high-energy milling has been reported for the synthesis of ceramic powders namely, metal oxides, carbides, borides, nitrides or mixtures of ceramics or ceramic and metal compounds. In this work, high-energy milling was used for reduction of alumina powders to nanometric particle size. The ceramic characteristics of the powders were analyzed in terms of the behavior during deagglomeration, compaction curves, sintering and microstructure characterization. It was observed that the high energy milling has strong effect in producing agglomeration of the nanosized powders. This effect is explained by the high-energy impact of the balls, which may fracture particles or just cause the particles compacting. In this case, strong agglomerates are produced. As the powder surface area increases, stronger agglomerates are produced.
Sor??o e persistência da sorgoleona em um Latossolo Vermelho-Amarelo
Demuner, Antonio J.;Barbosa, Luiz C. A.;Chinelatto Jr., Luiz S.;Reis, César;Silva, Antonio A.;
Química Nova , 2005, DOI: 10.1590/S0100-40422005000300016
Abstract: the root exudates produced by sorghum contain a biologically active constituent known as sorgoleone. the behavior of sorgoleone in a red-yellow latosol was studied. the sorption model of sorgoleone in soil was better adjusted to the freundlich equation, through the coefficients kf (capacity of sorption) and 1/n (linearity of the isotherm). the persistence of sorgoleone in soil and its possible degradation were also evaluated by monitoring their residues in the soil along the time. recovery rate of sorgoleone from the soil reached 93% after 24h. it was verified that sorgoleone is strongly sorbed in the soil and its half-life is 10 days, under the experimental conditions. the presence of sorgoleone or its metabolites was not detected in the soil after 60 days.
Porcelanas elétricas aluminosas: Parte I - Revis?o da literatura
Chinelatto, A. L.;Souza, D. P. F. de;
Ceramica , 2004, DOI: 10.1590/S0366-69132004000100010
Abstract: porcelains are multiphase ceramics produced from natural raw materials. the microstructural development of these ceramics depends on their composition, on the characteristics of the raw materials, and on the ceramic processing. due to the complexity of porcelains, several aspects of the microstructural evolution and its effects on the properties of porcelains are as yet little understood, despite the large number of reports published on the subject. part i of this article is a literature review on aluminous porcelains, focusing on the effect of their compositions on their electrical and mechanical properties, as well as the influence of some additives on their microstructural development.
Porcelanas elétricas aluminosas: parte II - desenvolvimento da microestrutura e sua influência no módulo de ruptura
Chinelatto, A. L.;Souza, D. P. F. de;
Ceramica , 2004, DOI: 10.1590/S0366-69132004000300002
Abstract: the microstructure and bending strength of aluminous porcelains were analyzed at rising sintering temperatures. it was found that, in the presence of high alumina content, the particle rearrangement process during sintering is inhibited by the formation of a skeleton of alumina particles that are insoluble in the liquid phase. the bending strength increases along with the amount of crystalline phase, with the alumina particles contributing more effectively to this increase than the mullite crystals.
A Comparative Investigation of Lead Sulfate and Lead Oxide Sulfate Study of Morphology and Thermal Decomposition  [PDF]
S. A. A. Sajadi
American Journal of Analytical Chemistry (AJAC) , 2011, DOI: 10.4236/ajac.2011.22024
Abstract: The compound lead oxide sulfate PbSO4.PbO was prepared in our laboratory. The Thermal behavior of PbSO4 was studied using techniques of Thermogravimetry under air atmosphere from 25 to 1200°C. The identity of both compounds was confirmed by XRD technique. Results obtained using both techniques support same decomposition stages for this compound. The electron microscopic investigations are made by SEM and TEM. The compound is characterized by XRD and the purity was determined by analytical Methods. Also a series of thermogravimetric analysis is made and the ideal condition is determined to convert this compound to pure lead oxide.
Metal ion-binding properties of L-glutamic acid and L-aspartic acid, a comparative investigation  [PDF]
S. A. A. Sajadi
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.22013
Abstract: A comparative research has been developed for acidity and stability constants of M(Glu)1, M(Asp)2 and M(Ttr)3 complexes, which have been determined by potentiometric pH titration. Depending on metal ion-binding properties, vital differences in building complex were observed. The present study indicates that in M(Ttr) com-plexes, metal ions are arranged to the carboxyl groups, but in M(Glu) and M(Asp), some metal ions are able to build chelate over amine groups. The results mentioned-above demonstrate that for some M(Glu) and M(Asp) complexes, the stability constants are also largely determined by the affinity of metal ions for amine group. This leads to a kind of selectivity of metal ions, and transfers them through building complexes accompanied with glutamate and aspartate. For heavy metal ions, this building complex helps the absorption and filtration of the blood plasma, and consequently, the excursion of heavy metal ions takes place. This is an important method in micro-dialysis. In this study the different as-pects of stabilization of metal ion complexes regarding to Irving-Williams sequence have been investigated.
Equilibria and Stability in Glycine, Tartrate and Tryptophan Complexes, Investigation on Interactions in Cu(II) Binary and Ternary Systems in Aqueous Solution  [PDF]
S. A. A. Sajadi
Open Journal of Inorganic Non-metallic Materials (OJINM) , 2014, DOI: 10.4236/ojinm.2014.41001
Abstract:

The acidity and stability constants of M(Gly)1, M(Ttr)1, and M(Trp)1 M: Cu2+, Cu(Bpy2)2+, and Cu(Phen3)2+ complexes, were determined by potentiometric pH titration. It is shown that the stability of the binary Cu(L), (L: Gly, Ttr, and Trp) complex is determined by the basicity of the carboxylate group on one side and amino group on the other side. It is demonstrated that the equilibrium, Cu(Ha4)2+ + Cu(L) \"\"Cu(Har)(L) + Cu2+, is displacement due to the well known experience that mixed ligand complexes formed by a divalent 3d ion, a heteroaromatic N base and an O donor ligand possess increased stability. The stability constants of the 1:1 complexes formed between Cu2+, Cu(Bpy)2+ or Cu(Phen)2+

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