Solubilities of α ‐ Fe2 O 3 and Fe3 O 4 in Fused Na2 SO 4 at 1200 K
Solubilities of α ‐ Fe2 O 3 and Fe3 O 4 in Fused Na2 SO 4 at 1200 K
复制标题
1200 K 下 α-Fe2 O 3 和 Fe3 O 4 在熔融 Na2 SO 4 中的溶解度
DOI：
10.1149/1.2113608
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
R. Rapp
中科院分区：
文献类型：
--
作者：
Yunshu Zhang;R. Rapp
在1200 K温度下，测定了a- fe203和Fe304的溶解度随熔体碱度的变化规律。在较低的Pox下，在不同的碱度范围内，以Fe304或FeS为稳定相，测定了这些化合物在Na2SO4中的溶解度。通过对溶解度的测定，计算出NaxSO4中NaFeO~、FeS和FeSO4的活度系数分别为430、180和0.83。在此基础上，计算了氧化铁a-Fe203和Fe304的溶解度以及主要的酸性溶质和碱性溶质的溶解度，这些溶质在NaxSO4中是稳定的。热腐蚀发生在高温氧化环境中，当熔盐沉积接触金属表面时。熔融Na2SO4的热腐蚀会对燃气轮机和其他燃烧产物环境造成重大损害。金属氧化物通常是与熔融氧化钠接触的稳定相。因此，了解金属氧化物在熔融Na~ SO4中的溶解度行为有助于理解热腐蚀过程，特别是热腐蚀的开始。近年来报道了NiO（1,2）、Co~ O~（1,2）、A]=、O~(3)和Y. 20:~(4)在NaxSO4中的溶解度。a-Fe的溶解度。在熔合Na2SO4(5)中，O3在1atm02和1200k下作为熔体碱度（定义为log anaxo）的函数进行了测量。然而，a- fe ~ O:~仅在高Po2和一定碱度下稳定。当Na2SO4熔体中的Pox降低时，F% O4变得稳定。从图1所示的Na-Fe-SO体系的热力学相稳定性图来看，两种氧化铁的溶质种类和溶解度预计取决于熔体碱度和熔体中的Pox。显然，需要在低氧压力下进行溶解度测量，以提供对Na2SO4中铁-氧-硫体系溶解行为的概述，并为扩展到其他体系提供见解。
The solubility of mixed a-Fe203 and Fe304 in fused NaxSO4 was measured at 1200 K as a function of the melt basicity at 2.14• 10-7 atm 02. At lower Pox, in separate ranges of basicity where either Fe304 or else FeS is the stable phase, the solubilities of these compounds in Na2SO4 were determined. From these solubility measurements, the activity coefficients of NaFeO~, FeS, and FeSO4 in fused NaxSO4 were calculated to be 430, 180, and 0.83, respectively. On this basis, the solubilities of the iron oxides a-Fe203 and Fe304 and the dominant acidic and basic solutes were calculated for the entire regimes of Pox and melt basicity in which these phases are stable in NaxSO4.Hot corrosion occurs at high temperatures in oxidizing environments when a molten salt deposit contacts a metal surface. Hot corrosion by molten Na2SO4 can cause significant damage in gas turbine and other combustionproduct environments. Metal oxides are often the stable phases in contact with fused NaxSO4. Therefore, a knowledge of the solubility behavior of metal oxides in molten Na~ SO4 should assist in understanding hot corrosion processes, especially the initiation of hot corrosion. The solubilities of NiO (1, 2), Co~ O~(1, 2), A]=, O~(3), and Y. 20:~(4) in NaxSO4 have been reported recently. The solubility of a-Fe,., O3 in fused Na2SO4 (5) has been previously measured at 1 atm 02 and 1200 K as a function of the melt basicity, defined as log aNaxo-However, a-Fe~ O:~ is stable only at high Po2 and in a certain basicity regime. As the Pox in a Na2SO4 melt is reduced, F% O4 becomes stable. From the thermodynamic phase stability diagram for the Na-Fe-SO system shown as Fig. 1, the solute species and solubilities of the two iron oxides would be expected to depend upon both the melt basicity and the Pox in the melt. Obviously, solubility measurements at reduced oxygen pressures are needed to provide an overview of the dissolution behavior in the iron-oxygensulfur system in Na2SO4, and to provide insight for extension to other systems.