Browsing by Author "Liu, Changsheng"
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Item The effect of 15 wt%Al2O3 addition on the equilibrium phase relations of CaO–SiO2–TiO2 system at 1400 °C in air(Elsevier Limited, 2021-09-01) Wan, Xingbang; Shi, Junjie; Qiu, Yuchao; Chen, Min; Li, Jianzhong; Liu, Changsheng; Taskinen, Pekka; Jokilaakso, Ari; Department of Chemical and Metallurgical Engineering; Metallurgy (MTG); Northeastern University ChinaThe combined processing of industrial wastes of titania-bearing slags with coal fly ash is an important part of the circular economy. In the present work, the effect of Al2O3 on the 1400 °C liquidus isotherms of the perovskite, rutile and tridymite primary phase fields in the CaO–SiO2–TiO2–Al2O3 system has been determined by employing a high-temperature equilibration-quenching technique, followed by X-ray Photoelectron Spectroscopy and Scanning Electron Microscopy-Energy Dispersive X-ray Spectrometry. Titanium was confirmed to be stable as TiO2 in the present equilibria. The equilibrium solid phases of perovskite CaO·TiO2, rutile TiO2 and tridymite SiO2 were confirmed to be coexisting with the liquid oxide phase. The comparison of the addition of 0–15 wt% Al2O3 was beneficial for expanding the primary phase field of perovskite to lower TiO2 concentrations. Comparisons of the experimental 1400 °C isotherm with the predictions using FactSage and MTDATA databases confirmed some differences to the present experimental data, thus demonstrating the direction for updating the present thermodynamic titania-bearing oxide databases.Item Influence of manganese oxide on the liquid-perovskite equilibrium in the CaO–SiO2–TiO2 system at 1400 °C in air(Elsevier Limited, 2021-04-15) Wan, Xingbang; Chen, Min; Qiu, Yuchao; Shi, Junjie; Li, Jianzhong; Liu, Changsheng; Taskinen, Pekka; Jokilaakso, Ari; Department of Chemical and Metallurgical Engineering; Metallurgy (MTG); Northeastern University ChinaIn the Selective Crystallization and Phase Separation (SCPS) process, manganese oxide is used as an additive to promote the precipitation of perovskite. However, the influence of manganese oxide on the liquid domain of the perovskite primary phase field is still unclear. In the present work, the liquid-perovskite equilibrium with the addition of 0–15 wt% Mn3O4 was experimentally determined using a high-temperature isothermal equilibration-quenching technique, combined with X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS). It was confirmed that manganese was mainly existed as Mn2+ and Mn3+ in the molten phase, whereas titanium existed as Ti4+. Within the composition range of the present study, the 1400 °C liquid compositions varying from 0 wt% to 15 wt% Mn3O4 overlapped significantly, mainly located at w (CaO)/w (SiO2) ratios between 0.9 and 1.1. The isotherms simulated by FactSage, as well as the data from the literature, generally agreed well with the present experimental results. The calculated 1400 °C isotherms at different Mn3O4 levels indicated that perovskite precipitation by manganese oxide was mainly promoted by increasing the Mn3O4 concentration to expand the primary phase field of perovskite toward both higher and lower TiO2 content areas.