Mullite development on firing in porcelain stoneware bodies

By Jorge Martín-Márquez, J. Rincón, M. Romero. 2010

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Abstract Microstructural evolution on heating was investigated in a reference industrial composition (50% kaolinitic clay, 40% feldspar and 10% quartz) of porcelain stoneware, fast fired at different temperatures (500–1400 °C). The evolution of mullite crystals, regarding shape and size progress, was examined by scanning electron microscopy (SEM). The proportion of Type I mullite crystals decreases with firing temperature and simultaneously, the size of crystals increases, reaching the maximum value of aspect ratio (3:1) at 1400 °C. Type II and Type III secondary mullite needles increase with temperature in both number and length, which leads to an increase in the aspect ratio from 5:1 to ∼20:1 in Type II crystals and from ∼33:1 to 50:1 in Type III mullite needles. Finally, clusters of Type III mullite fibres are observed in porcelain stoneware samples fast fired in the 1250–1280 °C interval.

Subfields: Building and Construction, Ceramics and Composites, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/21c6a18f8ff65f22ee4a92bf4b9c1b0e64c24031