The mass transfer kinetics of niobium solution into liquid steel
The mass transfer kinetics of niobium solution into liquid steel
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DOI：
10.1007/bf02654280
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发表时间：
1991-08
期刊：
影响因子：
--
通讯作者：
S. Argyropoulos;Panagiotis Sismanis
中科院分区：
文献类型：
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作者：
S. Argyropoulos;Panagiotis Sismanis
在动态条件下，将Nb钢瓶浸入钢液中，测量其传质速率。将圆柱体悬挂在称重传感器上，在浸泡过程中连续测量圆柱体的表观重量以及浸泡样品中不同位置的温度，并用数据采集系统记录下来。根据质量测量结果，推算出传质速率。确定了一个钢壳期和自由溶出期。在钢壳阶段，冻结的钢壳在钢瓶最初浸泡后将其包裹起来。用低过热度的钢液浸入钢液中时，钢壳/Nb界面发生了化学反应。这种反应发生在钢壳时期的后期。确定了反应产物为金属间化合物Fe2Nb和Fe2Nb3。发现在自由溶解过程中发生的传质是放热的，速率控制步骤是通过质量边界层的液相扩散。表观活化能为172(±15)kJ/mol。这种异常高的表观活化能可以用Nb溶解到钢液中时发生的宏观放热反应来解释。
Niobium cylinders were immersed into liquid steel and their mass-transfer rates measured under dynamic conditions. The cylinders were suspended from a load cell, and the apparent weight of the cylinder as well as temperatures at various locations in the immersed specimens were measured continuously during immersion and recorded with a data acquisition system. From the weight measurements, the mass-transfer rate was deduced. A steel shell period and free dissolution period were identified. During the steel shell period, a shell of frozen steel wraps the cylinder following its initial immersion. When niobium cylinders were immersed into liquid steel with low superheat, a reaction was detected at the steel shell/niobium interface. This reaction took place during the later stages of the steel shell period. The intermetallic compounds Fe2Nb and Fe2Nb3were identified as reaction products. The mass transfer which takes place during the free dissolution period was found to be exothermic, and the rate-controlling step was found to be liquid phase diffusion through a mass-boundary layer. The apparent activation energy was estimated to be 172 (±15) kJ/mol. This uncommonly high value of apparent activation energy is best explained on the basis of the macroexothermic reaction which takes place as niobium dissolves into liquid steel.