Navegando por Assunto "Sintering"

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Acesso aberto (Open Access)
Confecção de discos de desbaste a partir de AI2O3 e pó de vidro
(Universidade Federal do Pará, 2009) OLIVEIRA, Rosane Felice de; DIAS, Carmen Gilda Barroso Tavares; http://lattes.cnpq.br/2113791118142177
This article describes the development of abrasive and cutting disks made of alumina and waste glass powder to apply in cutting tools. These disk mills are used to micromize rigid post-consumed thermoplastics and let its use in a lot of recycling process, as rotomolding. This cutting disk uses glass powder as a fluxing agent and poly(ethylene terephthalate) post-consumed to give a plastic behavior to the powder, making it easier to fill in the mold. The amounts of glass powder were analyzed from previous studies with different minerals, as diopside and feldspar, since the studies with waste glass powder substituting natural minerals are recent. The development of the disks occurs in two steps. The first one is the homogeneization of the compounds with the calculated amounts. Afterwards it's pressed and taken to the mufla to get the percolation of the resin and its complete degradation up to a temperature of 900oC, pre-sintering and soften the silicates. After getting these green composites, it happens the second and final step, when the disks are sintered to decrease the porosity and improve its strength, followed by a superficial finish and cutting tests.
Acesso aberto (Open Access)
Estudo da reciclagem de cinza volante para produção de agregado sintético utilizando reator de leito fixo
(Universidade Federal do Pará, 2016-02-16) PEREIRA, Luiz Felipe Silva; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
The use of such industrial waste boiler fly ash for recycling and reuse, has intensified in recent years much for its physico-chemical characteristics that may result after the processing, in a material with good mechanical strength and can be designed for use in several areas such as construction. In this paper we obtain synthetic aggregates, after sintering process in a fixed bed reactor. For the production of aggregates pellet sewed up mixer from a mixing wheel boiler ash, clay and charcoal. After the process of ceramic sintering were measured material properties such that: porosity, density and water absorption. For the characterization of phases and mineralogical structures of the sintered material, we used the techniques of X-ray diffraction and scanning electron microscopy. Thus the contribution of this work is aimed at reducing environmental impacts, due to the possibility that the material produced has to replace natural aggregates.
Acesso aberto (Open Access)
Estudo da sinterização em reator vertical de leito fixo: desenvolvimento de processo para produção de agregado sintético a partir de cinza volante e biomassa
(Universidade Federal do Pará, 2016-05-19) QUARESMA, Danielly da Silva; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
The synthetic aggregates have been employed in civil construction as a measure for the reduction of mineral extraction. Within this context, the recycling of industrial waste configured today as the basis of the majority of processes to reduce the exploitation of mineral resources. This paper presents the formulation of a process of environmental character and self-sustaining from an energy point of view parameters to develop a process for the production of synthetic aggregate from fly ash and biomass fixed bed reactor. Thus, for the production of aggregate pellets were made from a mixture of clay, fly ash and charcoal in fixed proportions. The reactor is filled with 20% pellets (6.35 mm > pellet ≥ 4 mm) and 80% charcoal (3.36 mm > carbon ≥ 1.70 mm) rated for promoting the efficiency of combustion reactions and subsequent sintering process at different air velocities (Darcy at 20 °C) of 0.0059 m.s-1 (1º Experiment), 0.0098 m.s-1 (2º Experiment) and 0.017 m.s-1 (3º Experiment). By means of X-ray diffraction and scanning electron microscopy was identified the presence of mullite in synthetic aggregate. This material is characterized as lightweight aggregate, in accordance with current standards. With synthetic aggregates manufactured to lightweight concrete, according to the established standard, without structural function in civil construction, but with applications of moderate resistance and may be used in the counterfloor. The process if showed interesting for the sintering of aggregates with good adhesion to the matrix of cement, and can easily be controlled by composition, granulometry, temperature gradient and gaseous flow, reducing environmental impacts, to the extent that the material produced implies in not extraction of natural aggregates.
Acesso aberto (Open Access)
Modelos matemáticos de transferência de calor e massa: extração de metais por membranas poliméricas e sinterização de materiais cerâmicos
(Universidade Federal do Pará, 2024-07-16) VILHENA, Mailson Batista de; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
The overall objective of this work was to present a mathematical study of multicomponent mass transfer in a metal ion extraction cell through a flat polymeric membrane and to conduct an experimental and kinetic study focused on the production of synthetic aggregate from bauxite residue. In the first part of the work, a mass transfer model for the recovery of metal ions using flat polymeric membranes was developed. Unlike most existing models, which are limited to studying a single component and do not consider the selectivity and effects of multiple components on reaction kinetics, a model capable of simulating the simultaneous extraction of various metals is proposed. This model is based on the mass conservation equation and was solved using the Coupled Integral Equations Approach (CIEA), and validated with experimental measurements and previous simulations. In the second part, an experimental and theoretical study was conducted using a kinetic model for the production of coarse synthetic aggregates from bauxite residue, silica, and clay. The experimental study included the production and characterization of the aggregates in different compositions. To analyze the sintering process of a full-sized pellet, a small electric furnace with an attached balance was built, allowing the monitoring of mass loss measurements as a function of temperature and time. Additionally, a kinetic study was carried out using mathematical models to evaluate the main solid-state reactions and their phase transformations during the sintering process, using experimental data from thermal analysis.