Catalytic Mullitization of Kaolinite by Metallic Oxide*

“…These changes are very important when clays are used in ceramic production, being necessary to decrease the kiln heating to avoid possible fissures. Finally, Mg 2+ and Fe 3+ contribute to mullite formation, Ca 2+ has a less significant role, and Na + , K + and Ti 4+ delay these processes [62].…”

Section: Dilatometrymentioning

confidence: 99%

Mineralogical and Thermal Characterization of Kaolinitic Clays from Terra Alta (Catalonia, Spain)

2020

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This research characterizes the kaolinitic clays from Cretaceous–Paleocene lateritic deposits of Terra Alta (south Catalonia) to evaluate their possible applications. The outcrops and quarries belong to the Horta de Sant Joan and Pinell de Brai areas. The chemical composition, mineralogy, rheological behavior, particle size distribution and plasticity are determined. The Fe and Ti4+ contents prevent them from being directly used as raw material for white ceramics. The mineralogy consists of kaolinite with quartz, illite, hematite, and minor K-feldspar and calcite. Most of the area comprises medium plastic clays that are classified as fired clays and can be used as ceramic and construction materials. In Horta de Sant Joan, a kaolinitic-rich level, up to 75 wt % of kaolinite, is highly crystalline with low plasticity and can be classified as flint clay, useful as a refractory clay. The evaluated kaolinitic clays can also be used to obtain a triaxial ceramic when they are mixed with feldspar to act as a fluxing agent and chamotte.

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“…This fact may be related to the higher content of calcium in the material. This element apparently favors the formation of the vitreous phase, which would limit recrystallization kinetics (25,26). The reflection planes of the cristobalite in M3 also present smaller number of counts compared with the information of M1 and M2, which could also be associated with the effect of calcium present in the ceramic paste.…”

Section: Structural and Morphological Characterization Of The Materiamentioning

confidence: 99%

Influencia de las materias primas y de la técnica de moldeo en la fabricación de productos cerámicos tipo gres

2017

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ResumenSe empleó material arcilloso y caliza proveniente de minas cercanas a la zona metropolitana de Cúcuta, así como el material de rotura después del proceso de cocción de productos cerámicos (chamota) para la conformación de probetas de baldosas cerámicas mediante las técnicas de extrusión y prensado. Una vez realizado el proceso cerámico (con temperaturas de cocción entre 1050°C y 1250°C), se evaluó el efecto de las diferentes mezclas preparadas sobre las propiedades tecnológicas de resistencia mecánica a la flexión, abrasión profunda y porcentaje de absorción de agua de acuerdo a la norma técnica colombiana. Los productos cocidos fueron caracterizados mediante difracción de rayos X, fluorescencia de rayos X y microscopía electrónica de barrido a fin de evidenciar efectos causados por las materias primas y el tipo de moldeo empleado. Los resultados obtenidos dejan ver la existencia de un efecto de la composición mineralógica de las muestras y de la técnica de conformado sobre la propiedades tecnológicas analizadas al momento de elaborar cerámicos gresificados. Se evidenció que para las mezclas de materias primas utilizadas, la técnica de extrusión permite una más rápida formación de fase vítrea y contribuye a una recristalización más rápida en altas temperaturas. Los mejores valores para las propiedades tecnológicas analizadas fueron encontrados en la temperatura de 1150°C. Palabras clave: Caracterización, cerámica roja, chamota, extrusión, gres, prensado.Abstract Clay-rich materials and limestone from mines close to the metropolitan area of Cucuta together with materials obtained after firing process of ceramic products (chamotte) were used to form samples of ceramic tiles using extrusion and pressing. Once the ceramic process was finished (with firing temperatures between 1050 °C and 1250 °C), the effect of different ceramic pastes on technological characteristics, such as mechanical resistance to flexion, deep abrasion and percentage of water absorption, was evaluated according to the Colombian technical standard. Samples were characterized using X-ray diffraction, X-ray fluorescence and scanning electron microscopy to identify effects caused by presence of raw materials and the type of molding used. The results show that mineralogical composition and forming technique have an impact on the technological properties of the resulting material. Also it can be seen that for mixtures of raw materials employed in the study, the extrusion technique allows faster glassy phase formation, however this molding technique could be one of the reason for faster recrystallization at high temperatures. The best values for the technological properties were found at temperature of 1150 °C.

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Catalytic Mullitization of Kaolinite by Metallic Oxide*

Cited by 35 publications

References 8 publications

Mullite Phase

Mullite Phase

Mineralogical and Thermal Characterization of Kaolinitic Clays from Terra Alta (Catalonia, Spain)

Influencia de las materias primas y de la técnica de moldeo en la fabricación de productos cerámicos tipo gres

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