Papers by Sylma Maestrelli
Materials Research, Nov 13, 2017
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Cerâmica, 2018
Resumo O porcelanato é um tipo de placa cerâmica de revestimento que vem se destacando atualmente... more Resumo O porcelanato é um tipo de placa cerâmica de revestimento que vem se destacando atualmente por apresentar boas propriedades estéticas, como a superfície decorada, e mecânicas, como a baixa absorção de água e elevada resistência mecânica e ao ataque químico. As matérias-primas utilizadas para a produção de porcelanato são principalmente a argila e o feldspato. O feldspato é uma das matérias-primas responsáveis pela sinterização durante a queima e auxilia no desenvolvimento de baixa porosidade e elevada resistência ao desgaste da peça cerâmica. Porém, o Brasil apresenta reservas de feldspato em regiões distantes dos centros produtores, fato que encarece a produção deste produto. Dessa forma surge como alternativa a utilização de nefelina para substituir o feldspato, total ou parcialmente, pois este mineral apresenta características bastante similares. Para verificar a influência de tal substituição nas propriedades do porcelanato, inicialmente foi necessário realizar o estudo d...
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Environmental Technology, 2019
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Trends in Civil Engineering and its Architecture, 2018
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Materials Science Forum, 2015
Concrete mixing technology has spread with the development of water-reducing additives, enabling ... more Concrete mixing technology has spread with the development of water-reducing additives, enabling production of high quality products. Despite the discoveries and important technological advances, occurrences concerning the incompatibility between sealers and additives have been reported. The main incompatibilities occur between additive and cement of different brands, or different batches. This study investigated the influence of a superplasticizer on the properties of two cements of the same class (type CP II E 32), but different manufacturers. Two cements (without the presence of the additive) were characterized by physical, chemical and mechanical tests. The setting times for pastes made from cement, water and superplasticizer mixtures were determined. The results showed a significant difference in physical, chemical and mechanical properties of cements, as well as those related to the hydration process thereof.
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Materials Science Forum, 2014
For a Soderberg Technology, paste production process consists of four basic steps: raw material h... more For a Soderberg Technology, paste production process consists of four basic steps: raw material handling; dry aggregate preparation; mixing; and briquettes loading at electrolytic cells for aluminum production. Dry aggregate is prepared from calcined petroleum coke, where the grains are crushed and separated between 3 different fractions of pre-determined sizing and a dust component. Petroleum pitch blended with the finest particles from dry aggregate forms the binder used for wetting, lubricating and filling open pores of larger coke grains, resulting into a higher anode paste quality with adequate mechanical properties, higher density, oxidation resistance and lower electrical resistivity. Raw materials recent trends showed significant quality degradation and cost raise, pushing up industry to look forward for untraditional suppliers, in addition to process optimization. This paper describes enablers chosen to improve paste properties, through dry aggregate particle size distribut...
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Meio Ambiente em Foco - Volume 11, 2020
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Educação, meio ambiente e território 2, Feb 21, 2019
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Cerâmica, 2013
Poços de Caldas é um importante centro hidrotermomineral do Brasil, o qual apresenta depósitos de... more Poços de Caldas é um importante centro hidrotermomineral do Brasil, o qual apresenta depósitos de argilas não plásticas para as quais não há registros significativos a respeito da caracterização direcionada destes materiais, o que prejudica estudos de aplicação industrial. Estas argilas não plásticas, não aproveitadas, vêm sendo armazenadas em galpões ou a céu aberto, o que gera um elevado custo para a indústria, além de transformar-se em um passivo ambiental. No presente trabalho realizou-se o estudo químico-mineralógico de seis amostras de argilas de baixa plasticidade, além da caracterização preliminar destas amostras quanto à granulometria, plasticidade e propriedades cerâmicas básicas, visando ampliar os horizontes das investigações destes materiais. Este estudo preliminar mostrou que, de maneira geral, as amostras são compostas por minerais refratários como caulinita e gibbsita, apresentando teores menos significativos de outras fases, como quartzo, vermiculita e illita. Junta...
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Materials science …, 2005
One possible route for the production of nanometric powders is the reactive high-energy milling. ... more One possible route for the production of nanometric powders is the reactive high-energy milling. For a variety of systems of highly exothermic reactions, the milling can lead to self-sustaining reactions, with the reaction being observed after an induction or ignition ...
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Materials Research
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Materials Science Forum
Statistical techniques are particularly useful in the engineering, objecting the optimization of ... more Statistical techniques are particularly useful in the engineering, objecting the optimization of fabrication processes. This paper had the purpose of evaluating if the variables such as mechanical resistance, linear shrinkage, apparent porosity, density and water absorption are influenced by the amount of peat added to refractory clay, to ensure the porosity on the production of porous ceramics used as ceramic filters. In order to treat the data it was used the technique of variance analysis, with the regression analysis and the Scott-Knott test. According to the variance analysis, there were some differences between the treatments for all properties analyzed and, by the regression analysis, optimum peat levels were found for all properties analyzed, for some properties these levels were considered inadequate for being superior to the limit stablished.
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Materials Research
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Research, Society and Development
This work evaluates how the High Energy Ball Milling (HEBM) in a shaker mill influences the optic... more This work evaluates how the High Energy Ball Milling (HEBM) in a shaker mill influences the optical, physical, and microstructural properties of ZnO. The procedure also combines Fe inclusion from the grinding medium with particle size reduction. ZnO powder was milled by 1, 2, 3, 4, and 5 h, which resulted in a particle size reduction to the nanometric scale with a mean size of around 50 nm and a crystallite size reduction by three times when processed from 4 h. Milling has proven to be an efficient process for obtaining nanoparticles with an incredibly short processing time and changed the morphology of the particles from random to spherical shapes. Results also indicate the processing progressively expanded the ZnO hexagonal structure due to the imposed strain and Fe inclusion, which can help to decrease the bandgap and slow down the recombination rate of the electron-hole pairs, improving the photocatalysis activity. The optical results showed no additional band appeared due to mi...
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Journal of the European Ceramic Society
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DESALINATION AND WATER TREATMENT
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Ceramics International
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Papers by Sylma Maestrelli