Structural evolution of calcia during calcium deoxidation in Fe-O-Ca melt
Structural evolution of calcia during calcium deoxidation in Fe-O-Ca melt
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Fe-O-Ca熔体中钙脱氧过程中氧化钙的结构演化
DOI：
10.1039/c9cp02212k
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发表时间：
2019
影响因子：
3.3
通讯作者：
Jin Wei
中科院分区：
文献类型：
--
作者：
Xiao Yuanyou;Lei Hong;Zhang Hongwei;Wang Guocheng;Wang Qi;Jin Wei
CaO在铁液中的结晶过程是从形核开始的，形核决定了CaO夹杂物的结构和尺寸，因此研究钙处理对夹杂物的变质机理具有重要意义。本文采用两步形核法研究了CaO夹杂物结晶初期的行为。采用第一性原理方法计算了CaO晶体和CaO团簇的结构和性质。探讨了CaO在Fe-O-Ca熔体中的形核机理。计算结果表明，CaO团簇具有立方结构和适当的变化是最低的能量结构，比其他异构体更稳定。立方（CaO）n团簇的稳定性随团簇尺寸的增大而增大，并逐渐接近CaO晶体的稳定性。CaO团簇在Fe-O-Ca熔体中可以自发形成，而CaO团簇在Fe-O-Ca熔体中的转化反应在很大程度上取决于[Ca]和[O]的过饱和比。CaO团簇在铁液中可能以悬浮CaO夹杂物的形式长期存在，这些CaO团簇的悬浮物是铁液中过剩氧的来源。
The crystallization process of CaO in iron melt begins with nucleation, which determines the structure and size of the CaO inclusions; thus, it is important to investigate the mechanism of inclusion modification by calcium treatment. In this study, a two-step nucleation method was used to investigate the behavior during the early stages of CaO inclusion crystallization. The first principles method was applied to calculate the structures and properties of CaO crystals and CaO clusters. Then, the nucleation mechanism of CaO in the Fe–O–Ca melt has been discussed. The numerical results show that CaO clusters with cubic structures and appropriate variations are the lowest energy structures and are more stable than other isomers. The stability of the cubic (CaO)n clusters increases with the increase in size and gradually approaches that of the CaO crystal. CaO clusters can form spontaneously in the Fe–O–Ca melt, while the transformation reaction of the CaO clusters in the Fe–O–Ca melt deeply depends on the supersaturation ratio of [Ca] and [O]. CaO clusters may remain as suspended CaO inclusions in the iron melt for a long time, and these suspensions of CaO clusters are the source of excess oxygen in the iron melt.