Surface Tension of Liquid Iron as Functions of Oxygen Activity and Temperature
Surface Tension of Liquid Iron as Functions of Oxygen Activity and Temperature
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DOI：
10.2355/isijinternational.51.1580
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发表时间：
2011-01-01
影响因子：
1.8
通讯作者：
Fukuyama, Hiroyuki
中科院分区：
文献类型：
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作者：
Morohoshi, Keisuke;Uchikoshi, Masahito;Fukuyama, Hiroyuki
铁液的表面张力是评价熔体中Marangoni流动的过程模拟的重要性质。在本研究中，我们成功地测量了不同氧活度和温度下的铁液表面张力，克服了实验困难，通过以下尝试：（1）为了防止样品的化学污染，采用了使用电磁悬浮器的振荡液滴法。考虑到样品旋转，确定表面振荡频率。(2)为了控制铁液的氧活度，采用了使用含CO/CO2的气体混合物的气液平衡方法。该方法能够在保持低的碳活性的同时精确地控制氧活性，因此，表面张力的氧活性依赖性是明确的，而没有碳效应。(3)为了测量高氧活性直至Fe/Fe平衡的表面张力，使用高纯铁（99.9972质量%）。否则，熔体中的少量活性杂质（如铝）会被氧化，从而影响表面张力测量。根据实验数据，采用Szyszkowski模型，将铁液表面张力表示为氧活度和温度的函数。此外，还讨论了熔体表面氧吸附反应的热力学性质和吸附氧层的结构。
Surface tension of liquid iron is an important property for process simulations evaluating Marangoni flow in the melt. In this study, we succeeded to measure accurate surface tension of liquid iron under various oxygen activities and temperatures with overcoming experimental difficulties through the following attempts: (1) To prevent chemical contamination of sample, an oscillating droplet method using an electromagnetic levitator was employed. Surface oscillation frequencies were determined with taking into account sample rotation. (2) To control the oxygen activity of liquid iron, a gas-liquid equilibrium method using CO/CO2 containing gas mixtures was employed. This method enables precise control of oxygen activity with keeping carbon activity low, and therefore, oxygen activity dependence of surface tension was clarified without carbon effect. (3) To measure the surface tension for higher oxygen activities up to the Fe/Fe equilibrium, high-purity iron (99.9972 mass%) was used. Otherwise, minor reactive impurities in the melt such as aluminum are oxidized, which affects the surface tension measurement. Based on the experimental data, the surface tension of liquid iron was expressed as functions of oxygen activity and temperature using the Szyszkowski model. In addition, thermodynamic properties on the oxygen adsorption reaction and structure of the adsorbed oxygen layer on the melt surface were also discussed.