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Effect of Alumina and Silica on the Hydration Behavior of Magnesia-Based Refractory Castables
Article first published online: 31 AUG 2011
© 2011 The American Ceramic Society
Journal of the American Ceramic Society
Volume 94, Issue 12, pages 4218–4225, December 2011
How to Cite
Silva, W. M., Aneziris, C. G., Brito, M. A. M. (2011), Effect of Alumina and Silica on the Hydration Behavior of Magnesia-Based Refractory Castables. Journal of the American Ceramic Society, 94: 4218–4225. doi: 10.1111/j.1551-2916.2011.04788.x
- Issue published online: 2 DEC 2011
- Article first published online: 31 AUG 2011
- Manuscript Accepted: 14 JUL 2011
- Manuscript Received: 7 MAR 2011
Samples taken from the core of real-sized castable pieces were studied under TGA, DTA, SEM, and XRD techniques after hydration during normal dry-out process. The TGA was also performed at bulk samples, and the effect of volume on the hydration process was evaluated. The castables consisted of dead-burned magnesia with additions of calcined and/or tabular aluminas, or microsilica to the matrix. The addition of alumina in combination with magnesia increased the hydration rate during the drying of the castable due to a lower permeability of the casted piece. Addition of microsilica, on the other hand, reduced damage due to hydration. The microsilica promotes the formation of a low crystallinity chrysotile precursor, due to its reaction with the magnesium hydroxide formed after the hydration of the surface of magnesia grains. This phase alleviates the stress generally associated to hydroxide formation, which otherwise leads to structural spalling.