Journal
ACTA MATERIALIA
Volume 234, Issue -, Pages -Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2022.118014
Keywords
Blast furnace slag; Thermal conductivity; Topological order; Hot-wire method; Structural characterization; MD simulation
Funding
- Ministry of Science and ICT (MSIT) through the National Research Foundation of Korea (NRF) [2022R1A2C300322911]
- Canada Foundation for Innovation under the Compute Canada
- Government of Ontario, Ontario Research Fund-Research Excellence
- University of Toronto
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The thermal conductivity of CaO-SiO2-Al2O3-MgO melts was investigated, and it was found that the addition of a certain amount of Al2O3 can significantly enhance the thermal conductivity. The formation of polymerized aluminosilicate network is the reason for the increase in thermal conductivity.
Blast furnace slag stores a massive amount of thermal energy which commonly dissipates during cooling. To lay the foundation for the development of heat retrieval technique, it is vital to realize the thermophysical properties of the slags. In this work, thermal conductivity of CaO-SiO2-Al2O3-MgO melts with 0-15 mol% Al2O3 was investigated using the hot-wire method. The compositional dependence of thermal conductivity was discussed with respect to the structure characterized by Raman spectroscopy, MAS-NMR (magic angle spinning-nuclear magnetic resonance) and MD (molecular dynamics) simulation in short-and intermediate-range order. The additions of Al2O3 up to 9 mol% notably promote the thermal conductivity. The formation of Al-O-Si linkages is greatly enhanced, establishing a polymerized aluminosilicate network. The significant reduction of NBO/Treal contributes to a higher thermal conductivity. Further additions of Al2O3 up to 15 mol% do not significantly increase or reduce the thermal conductivity. Although NBO/Treal still decreases, the decremental rate becomes less rapid. The topological ring size of aluminosilicate network becomes smaller since the formation of Al-O-Al linkages is greatly facilitated at higher Al2O3 content, which reduces the mean free path of phonon vibrations. It may counteract the enhancement of thermal conductivity by the reduction of network modifying oxides. (C) 2022 Acta Materialia Inc. Published by Elsevier Ltd.
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