Article ID: ISIJINT-2019-793
To clarify the mechanism of CaS formation on the oxide inclusion of the CaO–Al2O3 system, the sulfide capacities of solid oxides was measured in the present study. The results show that the sulfide capacity of (12CaO·7Al2O3; C12A7) was much larger than of other compounds, and increased with temperature. The value for C12A7 was larger than that measured for the liquid oxide of the same composition. Furthermore, the diffusion behavior of sulfur in solid steel to the inclusion of the CaO–Al2O3 system, was investigated using a diffusion couple. After heating at 1473 K for 72 h, in the case of C12A7, the intensity of sulfur in the oxide was high, but the formation of CaS was not detected. This suggests that the formation of CaS was suppressed around the C12A7 particles by the diffusion of sulfur in the solid oxide.