Chem. J. Chinese Universities ›› 2019, Vol. 40 ›› Issue (6): 1242.doi: 10.7503/cjcu20180795

• Physical Chemistry • Previous Articles     Next Articles

In-situ Studies of Microstructure of CaF2-Al2O3-MgO Electroslag by Raman Spectroscopy and 27Al MAS NMR

CAO Peiming1, YOU Jinglin1(), ZHOU Candong2, LU Liming3, WANG Jian1, WANG Min1, DING Yani1, XU Yandong1   

  1. 1. State Key Laboratory of Advanced Special Steel, Shanghai Key Laboratory of AdvancedFerrometallurgy, School of Materials Science and Engineering, Shanghai University,Shanghai 200444, China
    2. Central Research Institute of Baosteel, Shanghai 200940, China
    3. CSIRO Mineral Resources, Technology Court, Pullenvale, Queensland 4069, Australia
  • Received:2018-11-26 Online:2019-06-10 Published:2019-03-27
  • Supported by:
    † Supported by the National Natural Science Foundation of China(No.21773152), the Shanghai Committee of Science and Technology Fund, China(No.12520709200), the National “111” Project(the Programme of Introducing Talents of Discipline to Universities) of China(No.D17002), the Open Project of State Key Laboratory of Advanced Special Steel, Shanghai University, China(Nos.SKLASS2015-01, SKLASS2017-02) and the Special Fund Project of Shanghai Municipality for Science and Technology Development, China(No.YDZX20173100001316).

Abstract:

The microstructure and Al coordination of crystalline, glassy and molten states of CaF2-Al2O3-MgO electroslag remelting slag were investigated by in-situ Raman spectroscopy and 27Al magic angle spinning nuclear magnetic resonance(MAS NMR). X-Ray diffraction was used to analyze phase of the crystal sample. Raman vibrational wavenumber and scattering activity of S-6530 crystal and melt were calculated based on density functional theory(DFT) and ab initio quantum chemical studies, respectively, and the major vibrational modes were assigned. The results showed that six-fold coordinated aluminum mainly exists in the S-6530 crystal, supplemented by a small amount of four or five-fold coordinated aluminum. During the heating process, the Al—O polyhedron of MgAl2O4 phase is transformed from [AlO6] to [AlO4] or [AlO5]. Al is present predominantly in [AlO4] tetrahedron in both S-6530 glass and melt, the proportion of [AlO4] is as high as 71.1%, compared with its crystalline state, the proportion of [AlO5] also increases to 28.6%. Based on quantum chemistry ab-initio calculation of the constructed molten cluster models, the [AlO4] configuration tends to be layered and frame structure dominated by Q3 and Q4 connections, and [AlO5] configuration remains isolated.

Key words: CaF2-Al2O3-MgO electroslag remelting slag, In-situ Raman spectroscopy, 27Al MAS NMR, Density fuctional theory(DFT), Al coordination

CLC Number: 

TrendMD: