Viscosity and structure evolution of bearing‐BaO slag melt with the low CaO/SiO2 mass ratio of 0.7

• Published in: Journal of the American Ceramic Society 2022-02, Vol.105 (2), p.842-852
• Main Authors: Liu, Wenguo, Chen, Yanbiao, Chen, Jiansheng, Wang, Jingsong, Zuo, Haibin
• Format: Article
• Language: English
• Subjects: Aluminum; BaO; Barium oxides; blast furnace slag; Calcium oxide; corrected optical basicity; Evolution; Fourier transforms; Infrared analysis; Infrared spectroscopy; NMR; NMR spectroscopy; Nuclear magnetic resonance; Oxygen; Photoelectrons; Rotating cylinders; Silicon dioxide; Slag; Spectrum analysis; Structural analysis; structure; Viscosity; Viscous flow; X ray photoelectron spectroscopy
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.18110

The effect of BaO on the viscosity of experimental slag with the CaO/SiO2 ratio of 0.7 was studied based on the rotating cylinder method, and the structure evolution analysis was performed using Fourier transform infrared (FT‐IR), X‐ray photoelectron spectroscopy (XPS) and 27Al MAS‐NMR spectra. The results indicated that the viscosity of molten slag decreased gradually with BaO content rising from 0 wt.% and 5 wt.% due to the dominant effect of free O2‐ rather than Ba2+. The viscous flow activation energy (Eη) of molten slag was calculated, presenting a similar change trend with that of viscosity. The structure analysis demonstrated that, with the increasing BaO content, the [SiO4]‐tetrahedral structures and Si‐O‐Al bonds were destroyed due to an increase in the relative fraction of free oxygen (O2‐). For the Al‐related structural units, the 27Al magic angles spinning nuclear magnetic resonance (27Al MAS NMR) spectra analysis illustrated that the concentration of [AlO4] units reduced, whereas that of [AlO5] and [AlO6] units increased because of the increase of free oxygen and nonbridged oxygen (O0). The results of structure analysis agreed well with the viscosity variations of experimental slag.