Estruturas celulares de mulita sintetizadas a partir da cinza da casca de arroz
The rice husk does not present nutritional and commercial values, so it ends up being consumed by the rice producers as energy source for internal processes, culminating in the generation of a harmful residue to the environment, the rice husks ash. Due to high silica content and small amounts of oth...
| Autor principal: | Oliveira, João Victor Marcondes de |
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| Formato: | Trabalho de Conclusão de Curso (Graduação) |
| Idioma: | Português |
| Publicado em: |
Universidade Tecnológica Federal do Paraná
2020
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| Assuntos: | |
| Acesso em linha: |
http://repositorio.utfpr.edu.br/jspui/handle/1/12247 |
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| Resumo: |
The rice husk does not present nutritional and commercial values, so it ends up being consumed by the rice producers as energy source for internal processes, culminating in the generation of a harmful residue to the environment, the rice husks ash. Due to high silica content and small amounts of other alkali oxides, the rice husk ash has been shown with great potential for reuse. Numerous studies are conducted to explore the possible applications of this residue as a precursor material for synthesis of mullite, the only stable phase of the system Al2O3-SiO2 under atmospheric conditions and that, due to its illustrious thermal properties, ends up being of great technological and industrial interest. Therefore, the purpose of this study was to report the use of rice husk ash as a precursor material for the fabrication of mullite cellular structures, widely used as filters, catalysts and refractory materials in applications that demand high working temperatures. The cell structures were made using the replica method and, for this purpose, suspensions with 55% by weight precursor solids content was prepared. Also, the precursor suspensions had pH of 4,9, 7,2 and 9,8 to verify the influence of particle agglomeration on mullite formation. As materials for preparing the precursor suspensions, were the rice husk ash, alumina and carboxymethylcellulose (CMC). The results indicated that it was possible to obtain mullite cellular structures by reactive sintering at 1600ºC for two hours, using the rice husk ash together with alumina. However, some residual phases were observer in the final cell structures, possibly because the sintering time was not sufficient to lead to the total mulitization or even due to the loss of silica reactivity related to the crystallization processes. It was not possible to perform a verification of the influence of the pH on the formation of agglomerates and, consequently, on the formation of mullite, since the rheological behavior was not as expected and due uncertainty to behavior of zeta potential of the silica, lead to inaccuracy in the interactions of the solid precursors. |
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