This journal is©the Owner Societies 2020 Phys. Chem. Chem. Phys.Citethis:DOI:10.1039/d0cp00382dEf f ects of temperature on the thermalconductivity of amorphous CaO–SiO 2 –Al 2 O 3slags: a computational insightZhe Wang, * ab Shuheng Huang, c Guanghua Wen,* ab Wenbo Jiang, abFuhang Chen ab and Ping Tang abAmorphous CaO–SiO 2 –Al 2 O 3 (CSA) slags are widely used in the glass, ceramic, cement and metallurgyindustries. Temperature, as an external condition, plays an important role in the thermal conductivity ofsilicates. Herein, the effects of temperature on the thermal conductivity of CSA slags were systematicallyinvestigated by using equilibrium molecular dynamics (EMD) simulations. Moreover, the effects of thecomposition and the structural unit on the thermal conductivity of CSA slags were examined. The resultsshowed that the thermal conductivity of amorphous CSA slags significantly increases with an increase intemperature in the range of 1273 to 1973 K. Furthermore regression analysis based on a machine learningmethod showed that the temperature is the most crucial factor that affects the thermal conductivityof amorphous CSA slags, and high CaO/Al 2 O 3 and CaO/SiO 2 molar ratios can lead to high thermalconductivity.1. IntroductionThe CaO–SiO 2 –Al 2 O 3 (CSA) ternary system is one of the moststudied silicate systems due to its broad range of advantagessuch as versatility, high stability and corrosion resistance, 1,2and is widely used in the glass, ceramic, cement and metallurgyindustries. 3 Thus, accurate measurements of the structure andproperties of the CSA system play an important role in manyindustrial processes. Thermal conductivity is a fundamentalproperty and parameter that quantitatively describes the intrinsicability of CSA systems to transfer or conduct heat. However, fewstudieshavebeenperformedformeasuringthethermalconductivityof silicate systems at high temperatures (above 1273 K), which isan essential reaction condition in metallurgical, ceramic andglass industrial processes. At present, the thermal conductivityof silicates at high temperatures is mainly determined byexperimental techniques, such as the transient hot-wire method(THW), 4–6 laser pulse method (LP) 7,8 and front-heating front-detection laser flash technique (FHFDLF). 9,10 Nevertheless, thelack of measurement standards of thermal conductivity resultsin a large divergence of the measured values among differentmeasurement methods. 11To date, comparatively little work has been done to explorethe ef f ect of temperature on the thermal conductivity of silicatesystems. Susa et al. 12 measured the thermal conductivity ofalkali silicate slags by the THW method in the temperaturerange of 1050–1550 K. The thermal conductivities of thesilicates decreased with increasing temperature. By using theLP method, Nelson et al. 13 analyzed the thermophysical propertiesof borosilicate glass-ceramic waste in the temperature range of298–1273 K. The results suggested that the thermal conductivityof the sample first increased with increasing temperature to themelt point. Subsequently, the thermal conductivity decreasedsignificantly before slowly increasing again at 1273 K. Hasegawaet al. 14 investigated the thermal conductivities of CSA slags by theFHFDLF method. The results showed that the temperatures andcompositions of CSA slags have little influence on their thermalconductivities. However, the mechanism of these phenomena isstill unclear. Despite these exploratory studies, it is difficultto explore the intricate relationship between temperature andthermal conductivity by relying solely on experimental methods.With the development of molecular simulation techniques,molecular dynamics (MD) simulations have been successfullyapplied to the estimation of the temperature-dependent thermalconductionofmaterials.Basedonequilibriummoleculardynamics(EMD) simulations, Dasmahapatra et al. 15 predicted the thermalconductivity of amorphous silicon boron nitride (a-SiBN) andexplored the relationships between the thermal conductivity,temperature and composition. The results showed that thethermal conductivity of a-SiBN decreased with increasinga College of Materials Science and Engineering, Chongqing University,Chongqing 400044, China. E-mail: zhewang@cqu.edu.cn, wengh@cqu.edu.cnb State Key Laboratory of Mechanical Transmissions, Chongqing University,Chongqing 40044, Chinac College of Bioengineering, Chongqing University, Chongqing 400044, ChinaReceived 23rd January 2020,Accepted 26th March 2020DOI: 10.1039/d0cp00382drsc.li/pccpPCCPPAPERPublished on 26 March 2020. Downloaded by TONGJI UNIVERSITY LIBRARY on 4/24/2020 6:45:18 PM. View Article OnlineView Journal
