Thermal conductivity of alumino-borosilicate melts and establishment of its prediction method through the local structure evaluation

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01680
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 26060:Metals production and resources production-related
• Research Institution: The University of Tokyo
• Principal Investigator: Morita Kazuki 東京大学, 大学院工学系研究科(工学部), 教授 (00210170)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 熱伝導度 / アルミノホウケイ酸 / 溶融酸化物 / 局所構造 / 予測モデル

Outline of Final Research Achievements

Thermal conductivity of the aluminoborosilicate (CaO-B2O3-Al2O3-SiO2) system, which is a component of mold flux for continuous casting of steel, was measured and the local structure of its vitrified sample was analyzed. From the obtained results, quantitative evaluation of the covalent bonding between unit atoms was performed.
The followings were confirmed. Thermal conductivity decreases with increasing temperature in all melts, showing a clear negative correlation between CaO concentration, optical basicity and thermal conductivity, indicating that heat conduction in the molten oxide is due to phonon transfer.
An attempt was also made to construct a predictive model by evaluating the local structure and the average position of the electron distribution of each bond obtained by first-principles calculations as covalent bonding, and examining the correlation with thermal conductivity values.

Free Research Field

金属生産工学

Academic Significance and Societal Importance of the Research Achievements

融体の局所構造と熱物性や熱力学的性質との関係を明らかにすることにより、諸特性の発現機構を体系的に理解することにより、複雑組成の物性予測手法を確立することができれば、現状では試行錯誤の域を出ないプロセス設計に対して、目的の特性から組成を決定する革新的なツール開発への発展が期待される。また、構造と各成分の熱力学的性質の相関についてはほとんど情報がなく、本研究で得られるデータは新たな学理構築に資する可能性を有している。
本研究成果は、特に本研究で念頭にある鋼の連続鋳造プロセスにおいて、モールドフラックスの高温における熱伝導度の厳密な制御への指針となる。