Corrosion of five corundum-mullite aggregates with the same chemical composition and the different pore characteristics and phase compositions by the blast furnace slag were conducted using the static crucible test. Effects of pore characteristics and phase compositions on the slag resistance of the aggregates were investigated through X-ray diffractometer (XRD), scanning electron microscopy (SEM), mercury porosimetry measurement and FactSage® software, etc. It is found that the pore characteristics and phase compositions strongly affect the slag resistance of the aggregates. With an increase in apparent porosities (1.4-41.6%), the slag penetration and corrosion resistances of aggregates decrease evidently. When the apparent porosities are in the range of 41.6-44.8%, the pore size plays more important role in the penetration resistance than the viscosity of the slag penetrated; the pore size of 2.74 μm can greatly inhibit the slag penetration. Under the conditions of large difference in the apparent porosities, the phase compositions have little effect on the corrosion resistance; whereas, when the apparent porosities are similar, the higher the corundum content, the higher the corrosion resistance is.

Keywords: Lightweight refractories, Porous corundum-mullite aggregates, Slag resistance, Pore characteristics, Phase compositions.