Degradation of MgO-C refractories corroded by SiO2-Fe2O3-V2O5-TiO2-MnO-MgO slag

The properties and degradation of resin bonded MgO-C bricks corroded by SiO2-Fe2O3-V2O5-TiO2-MnO-MgO slag were investigated by dynamic induction slag test. Carbon oxidation by oxygen and/or reducing slag and corrosion of MgO grains attacked by corrosive vanadium containing slag are the main degradation mechanism. High temperature and long exposure time lead to more serious corrosion. Marangoni convection at the three phase boundary steel-slag-refractory is observed. Oxidation of carbon is observed which affords pores, cracks and voids for the vanadium containing slag corrosion and penetration. Periclase grains are seriously infiltrated by the slag, leading to the disintegration and the removal of MgO subgrains into the slag. Complex forsterite and spinel solid solution with FeO and MnO, sometimes V2O5 are confirmed by EDS. EDS also confirms the presence of corrosive low melting point species vanadate in the slag or as the result of reaction of slag and refractory components, which is deleterious to the slag resistance of the brick. Furthermore, diffused FeO content in periclase gradually decreases when going deeper into the refractory. However MnO is found difficult to diffuse into periclase.