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 MgOC brick was investigated using the sessile drop technique, manifesting that MgAlON with slag corrosion thickness of 780 μm 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.