Reaction of Silicon Carbide Grains with Molten Iron Penetrating in Carbon-Based Refractories

The reaction of silicon carbide (SiC) particles with molten carbon-saturated iron was studied to find the optimum conditions for SiC application to refractories in the iron- and steel-making process. When compared with C brick, C-SiC brick dipped into carbon-saturated iron at 1500°C under 0.2-0.5MPa for 1h was less penetrated by iron. Optical microscope and scanning electron microscope observations showed morphological changes of SiC grains at the hot face of C-SiC brick as well as adhesion of Fe-Si metal to the SiC grains. The reaction mechanism was discussed using phase diagrams and thermodynamic data. In conclusion, the iron which penetrates the brick causes a breakdown of SiC in which Si dissolves into the iron. C of SiC and C in the iron precipitate on the surface of SiC grains. Moreover, the increase of Si in the iron raises its viscosity. This result shows that SiC grains act to inhibit iron penetration into carbon-based refractories.