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1734301 
Journal Article 
Phase composition of alumina-mullite-zirconia refractory materials 
Zanelli, C; Dondi, M; Raimondo, M; Guarini, G 
2010 
Yes 
Journal of the European Ceramic Society
ISSN: 0955-2219 
30 
1 
29-35 
WOS:000271540900004 
Refractories in the Al(2)O(3)-SiO(2)-ZrO(2) system are widely used in many applications, for ceramic rollers in particular, and are characterized by high mechanical strength, excellent thermal shock resistance, resistance to corrosion by alkaline compounds and low creep at high temperature. Their performances greatly depend on the amount and chemical composition of crystalline and glassy phases, which were investigated by quantitative XRPD (RIR-Rietveld) and XRF in order to assess the effect of various Al(2)O(3)/SiO(2) ratios of starting batches and different alumina particle size distributions. Refractories consist of mullite, corundum, zirconia polymorphs and a vitreous phase in largely variable amounts. The mullite percentage, unit cell parameters and composition vary with sintering temperature, being mostly influenced by the Al(2)O(3)/SiO(2) ratio of the batch. Its orthorhombic unit cell increased its volume from 1400 to 1500 degrees C, while its stoichiometry became more aluminous. The corundum stability during firing is strongly affected by the Al(2)O(3)/SiO(2) ratio, but not by the particle size distribution of alumina raw materials. Zirconia raw materials are involved in the high temperature reactions and about one-third of the available ZrO(2) is dissolved in the glassy phase, ensuring excellent resistance to alkali corrosion, mainly depending on the fraction of coarse alumina. The phase composition of the vitreous phase increased with sintering temperature, being over 20% when the fractions of coarse alumina in the starting batch are between 0.2 and 0.5. (C) 2009 Elsevier Ltd. All fights reserved. 
Mullite; Al(2)O(3)-SiO(2)-ZrO(2); Corundum; Glassy phase; Refractory; XRD; Zirconia