Comprehensive Understanding of the Role of Carbon Black in the Sintering and Melting Behavior of Mold Flux

Carbon materials play an important role in controlling the sintering and melting behaviors of mold flux. However, the reactions between carbon and mold fluxes and corresponding effects on the properties of mold fluxes are ignored in previous studies. The effects of carbon black on the sintering and melting behavior of mold flux during the heating process were systematically investigated by TG-FTIR, DSC, XRD, TEM, SEM, XPS, Raman spectroscopy, and viscosity measurement. The results showed that: carbon black between the mineral particles was visualized by TEM, and Ca4Si2O7F2 as sintering phase was not formed until 1300°C in CaO–SiO2–CaF2–Na2O slag on account of the insulation of carbon black. Residual carbon black absorbed on the surface of slag droplets suppressed the melting by preventing the aggregation of droplets. Besides, SiC as production of the carbon-slag reaction significantly increased the slag viscosity by improving the polymerization degree of molten slag.