Effect of Al2O3/SiO2 and CaO/Al2O3 ratios on wettability and structure of CaO-SiO2-Al2O3-based mold flux system

The effect of Al2O3/SiO2 and CaO/Al2O3 ratios on the molten structure of CaO-SiO2-Al2O3-based mold flux system was analyzed by Fourier transform infrared spectroscopy,Raman spectroscopy,and X-ray photoelectron spectroscopy.Also,the variation in the wettability between the mold flux system and an interstitial free(IF)steel substrate was investigated using the sessile drop method.The results indicate that the contact angle and interfacial tension between the molten slag and solid steel increase slightly with the increase in the Al2O3/SiO2 ratio,while they decrease with the increase in the CaO/Al2O3 ratio.The network structure for the designed mold flux system changes gradually from silicate to aluminosilicate and aluminate with the increase in the Al2O3/SiO2 ratio,and the network is simplified with the increase in the CaO/Al2O3 ratio.Besides,combining the results of sessile drop method and melt structure analyses,it suggests that the variation in interfacial properties of mold flux/IF steel substrate is mainly caused by the change in melt structure,especially the variation in free oxygen ions(O^2-)and non-bridged oxygen(O^-)at the interface.