Effects of the amphoteric behavior of Al2O3 on the structure and properties of CaO–SiO2–Al2O3 melts by molecular dynamics

• Published in: Journal of non-crystalline solids 2021-01, Vol.552, p.120435, Article 120435
• Main Authors: Chen, Yang, Pan, Weijie, Jia, Boran, Wang, Qiangqiang, Zhang, Xubin, Wang, Qian, He, Shengping
• Format: Article
• Language: English
• Subjects: Amphoteric oxide; CaO–SiO2–Al2O3 melt; Molecular dynamics simulation; Slag structure
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2020.120435

•The characteristics of Al2O3 in different environments and its mechanism of action on the melt were investigated.•As the content of Al2O3 increased, the polymerization degree of the system increased, and the disorder of the Al–O structure increased.•With the further increase of Al2O3, the tri-coordinate oxygen and five-coordinate aluminum increase significantly, and the structure tends to be unstable.•The acid-base change of Al2O3 depends on the melt components, especially the content of alkaline cations. Amphoteric oxide Al2O3 is generally considered to be acidic or alkaline in different environment. The effects of Al2O3 on the structure and dynamic property of CaO–SiO2–Al2O3 melt were investigated by MD simulation in this work. The results showed that as the content of Al2O3 increased, the contents of the tri-coordinate O and high-coordinate Al increased to balancing charge. When the basicity reaches 1, the viscosity of the melt increases with the addition of Al2O3 and reaches a maximum at 26 mol% of Al2O3. The higher concentration of Al2O3 leads to the relative deficiency of Ca atoms and the increase of tri-coordinate O and five-coordinate Al content, instability of the structure, and increase in DAl and DO. Al2O3 is considered to be acidic and forms network structures in the environment with sufficient alkaline cation. In contrast, Al2O3 becomes alkaline with insufficient basic cations environment, thus providing Oxygen atoms and balancing charge.