Effect of MgO on corrosion mechanism under LF refining slag for MgAlON-MgO composites synthesized from spent MgO-C brick: Wetting behaviour, reaction process and infiltration mechanism

The Ladle Furnace (LF) refining slag resistance of MgAlON-MgO composites synthesized from spent MgO-C brick was investigated using the sessile drop technique, manifesting that MgAlON with slag corrosion thickness of 780 & mu;m exhibits the best slag resistance than other composites. MgAlON-MgO composites react with the slag to generate calcium aluminate, spinel, and TiN. Furthermore, MgAlON-MgO composites with different MgO content show different corrosion process. The corrosion process of MgAlON and MgAlON-4.2 wt%MgO proceeds with wetting, reaction, and infiltration processes, while that of MgAlON-10.5 wt%MgO and MgAlON-15.7 wt% MgO only proceeds with wetting and infiltration processes. Compared with MgAlON-10.5 wt%MgO and MgAlON-15.7 wt%MgO, MgAlON and MgAlON-4.2 wt%MgO show low contact angle, presenting good slag wettability. Nevertheless, the viscosity of molten slag decreases with increasing MgO content, and MgAlON-MgO composites with high MgO content (MgAlON-10.5 wt%MgO and MgAlON-15.7 wt%MgO) show high porosity, thus aggravating the infiltration of molten slag. Compared with the wetting behaviour between molten slag and MgAlON-MgO composites, the infiltration of slag plays a decisive role in the slag corrosion process. Therefore, MgAlON and MgAlON-4.2 wt%MgO exhibit better slag resistance, showing the potential application in the ladle furnace.