Improvement of Resistance to Slag Penetration in Magnesia-Based Refractory with Colloidal Alumina Addition II by Means of a Proper Particle Size Distribution of MgO

By addition of colloidal alumina, three different particle sizes of dead burnt MgO were employed as raw materials to prepare MgO-based spinel substrates at 1773 K (1500 A degrees C). It was found that the particle size of MgO, as well as its size distribution, had substantial impact on the resistance of the refractory to the slag penetration at 1873 K (1600 A degrees C). Using relatively small particles of MgO (< 0.5 mm) can efficiently limit the slag penetration, due to the formation of solid phases (CaO center dot Al2O3 and CaO-MgO-Al2O3) at the grain boundaries. A particularly significant improvement against the slag penetration was found on MgO substrates with a proper particle size distribution in a size range of 0-1 mm. The improvement could be mainly related to the higher density and distribution of spinel phase in the MgO matrix, which is mostly located at the borders of large MgO particles. (C) The Minerals, Metals & Materials Society and ASM International 2016