To prevent the shrinkages by the densification during the application of unfired Al2O3-C
refractories or Al2O3 castables in steel making conditions, MgO was added as aggregate or matrix powder
and the expansion caused by spinel formation was studied. Because the spinel was formed at the
contacting areas between Al2O3 and MgO particles and the volume of in-situ formed spinel increased
more abnormally at the side of Al2O3 particles than MgO, the addition of MgO aggregates was not
recommendable due to the formation of large voids around the MgO aggregates. Nevertheless, corrosion
resistance was increased with the amount of fine MgO added, and the finer MgO powder added, the better
residual expansion and minute structure formation was observed. In the contrary, in case of castables
volume expansion due to spinel formation was not obvious because the degree of densification was less
than high-pressure formed refractories. But CA6 phase would not form around alumina aggregates during
corrosion so the corrosion resistance was much more enhanced.
Technological approaches to directed structure formation of construction nanocomposites with increased corrosion resistance
