Effect of BaO and MgO on structure and properties of aluminate slag with various CaO/Al2O3 ratios

To provide theoretical guidance for performance stability control of low-reactive mold fluxes, the effects of BaO and MgO on the structure and properties of aluminate slag with various CaO/Al 2 O 3 (C/A) ratios were investigated using the Fourier transform infrared spectrometer, Raman spectroscope, hemispherical melting point instrument, rotational viscometer and X-ray diffractometer. The results indicated that with BaO and MgO addition, the structure polymerization was first weakened and then enhanced at C/A of 1.1, and the transition contents corresponded to 8 wt.% BaO and 2 wt.% MgO, respectively, while the structure polymerization decreased continuously at C/A of 1.3. Since the viscosity change was well consistent with the structure evolution, the polymerization degree played a more prominent role in the slag viscosity than superheat degree when the melting temperature difference was within 40 °C. The break temperature decreased initially and then increased with augment of BaO and MgO at C/A of 1.1, while it manifested a decrease trend with BaO addition, and it decreased obviously but then turned to increase with MgO increment at C/A of 1.3. The crystallization phase and crystallization ratio kept stable with BaO increment, while the crystallization ratio rose greatly with MgO promoting LiAlO 2 precipitation at C/A of 1.1. The crystal types of all experimental slags were mainly Ca 12 Al 14 O 33 and CaF 2 at C/A of 1.3, and the precipitation of crystalline phase BaAl 2 O 4 demonstrated a rising trend, while that of Ca 12 Al 14 O 33 gradually declined with BaO augment.