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.
Bibliographical noteFunding Information:
This work was supported by the Ministry of Science and ICT (MSIT) through the National Research Foundation of Korea (NRF) grant (2018R1A2B2006609). The computation was performed on the Niagara supercomputer at the SciNet HPC Consortium in the Compute/Calcul Canada national computing platform, which is funded by the Canada Foundation for Innovation under the auspices of Compute Canada, the Government of Ontario, Ontario Research Fund - Research Excellence, and the University of Toronto. The computational resource provided by Prof. Mansoor Barati at University of Toronto and the discussion with Dr Achraf Atila at University of Erlangen-Nuremberg on RINGS code are highly acknowledged.
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All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys