Induced Electro-Deposition of High Melting-Point Phases on MgO–C Refractory in CaO–Al2O3–SiO2 – (MgO) Slag at 1773 K

MgO–C refractory was polarized across the slag-refractory interface at a voltage of 8 V in a synthetic CaO–Al –SiO – (MgO) Slag at 1773 K. A deposition layer mainly composed of dicalciumsilicate (2CaO.SiO ) or spinel (MgO.Al ) with several hundred microns thick was achieved by cathodic polarization. However, the anodic decay was accelerated in comparison to the cathodic refractories and nonpolarized reference MgO–C refractories. The electrodeposition layer was mainly caused by the reduction of silicate anions, in which a shift of slag composition to the dicalciumsilicate (C S) or spinel (MA) primary phase field was induced. Furthermore, the rapid migration of mobile Ca and Mg ions can also lead to the enrichment of CaO and MgO at the slag/refractory interface. The present voltage level (8 V) is acceptable for the economic considerations and the slag component also need a careful section for the corrosion protection of MgO–C refractories.