The present work focuses on the mineralogical analysis of sedimentary clay material samples collected from deposits located in the Campos dos Goytacazes-RJ (Brazil) region. These samples are representative and widely used by the ceramic plants in production of bricks and roofing tiles. The samples were selected with the objective of analyzing their characteristics regarding chemical composition, loss on ignition, X-ray diffraction, morphology, particle size, plasticity and thermal analysis. The sedimentary red clays have low amount of SiO 2 , high amount of Al 2 O 3 , and high loss on ignition. In addition, it was found that the character of the clays is typically kaolinitic.
ResumoO presente trabalho é focado sobre a análise mineralógica de amostras de argilas sedimentares coletadas de depósitos localizados na região de Campos dos Goytacazes-RJ (Brasil). Estas amostras são representativas e largamente usadas na produção de blocos cerâmicos e telhas. As amostras foram selecionadas com o intuito de analisar suas características com respeito à composição química, perda ao fogo, difração de raios X, morfologia, análise de tamanho de partícula, plasticidade e análise térmica. As argilas vermelhas sedimentares têm baixa quantidade de SiO 2 , alta quantidade de Al 2 O 3 e alta perda ao fogo. Além disso, foi determinado que o caráter das argilas é tipicamente caulinítico. Palavras-chave: argilas sedimentares, mineralogia, minerais industriais.Cerâmica 51 (2005) ) 381-386
In this work the use of "thin" red clay from south-eastern Brazil (Campos dos Goytacazes, RJ) as raw material for the manufacture of wall tile was investigated. A wide range of characterization techniques was employed, including X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), grain-size analysis, and thermogravimetric analysis. The wall tile body was prepared by the dry process. The tile pieces were uniaxially pressed and fired between 1080 -1180 ºC using a fast-firing cycle. The following technological properties were determined: linear shrinkage, water absorption, apparent density, and flexural strength. The development of the microstructure was followed by SEM and XRD analyses. It was found that the "thin" red clay is kaolinitic type containing a substantial amount of quartz. The results also showed that the "thin" red clay could be used in the manufacture of wall tiles, as they present properties compatible with those specified for class BIII of ISO 13006 standard.
In ceramic wall tile processing, fast single-firing cycles have been widely used. In this investigation a fast single-firing porous wall tile mixture was prepared using raw materials from the North Fluminense region. Specimens were obtained by uniaxial pressing and sintered in air at various temperatures (1080 -1200 °C) using a fast-firing cycle (60 minutes). Evolution of the microstructure was followed by XRD and SEM. The results revealed that the main phases formed during the sintering step are anorthite, gehlenite and hematite. It appears that the sintering process is characterized by the presence of a small amount of a liquid phase below 1140 °C. As a result, the microstructure of the ceramic bodies showed a network of small dense zones interconnected with a porous phase. In addition, the strength of the material below 1140 °C appeared to be related to the type and quantity of crystalline phases in the sintered bodies.
O presente trabalho teve por objetivo estudar as propriedades físico-mecânicas de uma massa para revestimento cerâmico poroso base vermelha a partir de matérias-primas da região Norte Fluminense. A massa cerâmica preparada pelo processo via seca foi caracterizada quanto a composição química, análise de tamanho de partícula, difração de raios X e comportamento térmico. Os corpos cerâmicos foram prensados sob 35 MPa e sinterizados entre 1080 e 1200 ºC usando um ciclo de queima rápido. A microestrutura sinterizada foi avaliada por microscopia eletrônica de varredura. Os corpos cerâmicos sinterizados exibiram baixos valores de retração linear, resultando em boa estabilidade dimensional. A microestrutura é caracterizada por alta porosidade. Além disso, foram atingidas as especificações para revestimento poroso (NBR 13818) em termos da tensão de ruptura à flexão e da absorção de água dos corpos cerâmicos sinterizados, indicando o potencial das matérias-primas cerâmicas do Norte Fluminense para este tipo de aplicação.
ResumoNo presente trabalho foi feita uma análise comparativa das propriedades tecnológicas de uma massa cerâmica vermelha para revestimento poroso queimada em dois distintos ciclos de queima, sendo um ciclo de queima lento tradicional e um ciclo de queima rápido. Os corpos cerâmicos foram queimados entre 1080 e 1160 ºC. As seguintes propriedades tecnológicas foram determinadas: retração linear, absorção de água, massa específica aparente e tensão de ruptura à flexão. Análise microestrutural foi realizada por meio de difração de raios X e microscopia eletrônica de varredura. Os resultados experimentais mostraram claramente que o emprego de um ciclo de queima lento resultou em melhores propriedades dos corpos cerâmicos sinterizados. Palavras-chave: revestimento poroso, ciclo de queima, propriedades.
Abstract
In this work was done a comparative analysis of the technological properties of a red wall tile ceramic paste fired in two different
Large quantities of eggshell waste are discarded in the food processing industry. This work investigates the incorporation of eggshell waste as a raw material into a wall tile body, replacing natural carbonate material by up to 15 wt%. Formulations containing eggshell were uniaxially dry pressed and fired at 1150°C using a fast-firing cycle. Physico-mechanical properties of the fired tiles (e.g. linear shrinkage, water absorption, apparent density, flexural strength) were then determined. Development of the microstructure was followed by scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses. The results showed that eggshell waste could be used in wall tiles, in the range 5–10 wt%, as a partial replacement for traditional carbonate-based materials with only a slight decrease in the end product properties.
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