Effects of oxygen partial pressure on the thermodynamics of CaO–SiO 2 –VO x system at 1873 K
Effects of oxygen partial pressure on the thermodynamics of CaO–SiO 2 –VO x system at 1873 K
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DOI：
10.1111/jace.16833
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发表时间：
2019-10
影响因子：
3.9
通讯作者：
B. Yan;Daya Wang;T. Deng;Liusun Wu;Yuan-chi Dong
中科院分区：
文献类型：
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作者：
B. Yan;Daya Wang;T. Deng;Liusun Wu;Yuan-chi Dong
本论文主要研究了CaO-SiO_2-VOX体系的热力学问题。一方面研究了氧分压对CaO-SiO_2-VOx体系在1873 K时相关系的影响，另一方面测定了钒化合物的标准生成吉布斯自由能。在第一个方面，测定了CaO-SiO2-VOx体系在1873 K、1.7 × 10−9atm氧分压下的相关系，并绘制了等温截面图。通过与6.9 × 10− 11 atm下的相图比较，阐明了氧分压对该体系的影响。随着氧分压的增加，在6.9 × 10− 11 atm下稳定存在的化合物CaV 2 O 4被氧化成V2 O3和CaVO 3。V_2O_3在液相中的溶解度极限也显著增加，导致单液相面积增大。在第二方面中，测量了1873 K下的CaV 2 O 4、CaVO 3、V2 O3和Ca 2Si 1-δVδ O 4（0 <δ< 0.1）的标准生成吉布斯能。CaV 2 O 4和CaVO 3的测定值分别为−1 259 468.9 ± 5090.5 J/mol和−963 479.8 ± 3298.6 J/mol。在此基础上，确定了CaV 2 O 4在1873 K下稳定存在的氧分压极限为4.4 × 10−10atm。
In this study, two aspects concerning with the thermodynamics of CaO–SiO2–VOxsystem were investigated. One aspect is about the effects of oxygen partial pressure on the phase relationships in CaO–SiO2–VOxsystem at 1873 K, and the other is the measurement of the standard Gibbs energy of formation of the vanadium compounds. In the first aspect, the phase relationships in CaO–SiO2–VOxsystem at 1873 K under oxygen partial pressure of 1.7 × 10−9atm were determined, and the isothermal section diagram was constructed. Furthermore, by comparing this diagram with that under 6.9 × 10−11atm, the effects caused by oxygen partial pressure on this system were elucidated. With the increase in oxygen partial pressure, the compound CaV2O4that exists stably under 6.9 × 10−11atm is oxidized to V2O3and CaVO3. The solubility limit of V2O3in liquid phase also increases remarkably, which results in the enlargement of the single liquid area. In the second aspect, the standard Gibbs energy of formation of CaV2O4, CaVO3, V2O3, and Ca2Si1−δVδO4(0 <δ< 0.1) at 1873 K were measured. The determined values for CaV2O4and CaVO3are −1 259 468.9 ± 5090.5 J/mol and −963 479.8 ± 3298.6 J/mol, respectively. Then, the limit of oxygen partial pressure for CaV2O4existing stably at 1873 K is determined to be 4.4 × 10−10atm.