Novel Engineered Routes for Advanced Al2O3-MgO Refractory Castables
1 Federal University of São Carlos, Materials Microstructural Engineering Group - GEMM, Brazil
2 Magnesita Refratários S.A., Research and Development Center, Brazil
3 Corus Research, Development & Technology, Ceramics Research Centre, The Netherlands
Volume 2, Issue 1, Pages 97 - 101
The use of ultra fine particles of alumina and magnesia in Al2O3-MgO refractory castables could lead to a well distributed in-situ spinel (MgAl2O4) formation and, then, a better corrosion resistance, a higher volumetric stability and a faster spinel generation. Consequently, adding Al2O3, MgO or Al2O3-MgO nanoscaled powders is a suitable alternative to attain the above mentioned effects. Nevertheless, although the trend in castables is the increasing use of nano-particles, drawbacks related to their high costs, agglomeration trend and the possibility of particles growth during sintering should not be disregarded. A further and cheaper alternative to speed up the spinel formation is the use of mineralizers, such as B2O3. However, the studies published up to now are mainly directed to the spinel powder synthesis instead of spinelforming castables design, which is also a promising technological route for attaining high-performance Al2O3-MgO castables, as long as the refractoriness drawbacks could be kept under control. As the reaction rates are commonly increased through liquid phase formation, thermo-mechanical properties coulddeteriorate. Therefore, this work addressed the evaluation of which one of these novel routes (nano x mineralizers) would be the most promising to be applied in the Al2O3-MgO castable design. A slight advantage was attained adding mineralizers, as they are cheaper, could speed up the aimed reactions, their expansion level can be designed and displayed outstanding hot properties, indicating a greater likelihood for a better general performance during the application in steel ladles.
spinel, castables, nanoparticles, mineralizers, engineered refractory castables
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