Solubility of Calcium and Oxygen in Molten Iron Equilibrated with Slag in CaO, Al2O3 or CaO-stabilized ZrO2 Crucible at 1873 K

Abstract

The solubility of calcium and oxygen in molten iron equilibrated with CaO-Al2O3-ZrO2 molten slag in CaO, Al2O3 or 5.5 mass% CaO-stabilized ZrO2 crucible at 1 873 K was measured by means of the slagmetal equilibrium partition method under Ar gas atmosphere. From the results by XRD and the phase diagram of CaO-Al2O3-ZrO2 system, the slag in a CaO crucible was in equilibrium with CaO·ZrO2 and CaO and the slag composition was 57.36 mass% CaO-34.86% Al2O3-7.78% ZrO2. The slag in a Al2O3 crucible was in equilibrium with CaO·2Al2O3 and ZrO2-CaO solid solution (Css) and the slag composition was 27.08 mass% CaO-53.42% Al2O3-19.50% ZrO2. The slag in a CaO-stabilized ZrO2 crucible was in equilibrium with ZrO2-CaO solid solution (Css) and CaO·ZrO2 and the slag composition was 30.38 mass% CaO-51.56% Al2O3-18.06% ZrO2. The average concentrations of oxygen and calcium in molten iron in equilibrium with slag and compounds were 251 ppm and 3 ppm in a CaO crucible, 33 ppm and 4 ppm in an Al2O3 crucible and 21 ppm and 5 ppm in a CaO-stabilized ZrO2 crucible, respectively. The logarithm of equilibrium constant, logK, for the reaction of CaO(s) = Ca + O is -4.38 and the interaction parameter of eCa O is 31.8. The value is satisfied the thermodynamic phase stability.

Determination of Equilibrium Constant of Calcium Oxidation by Slag-Metal Equilibrium Distribution Method

“…However, because the oxygen partial pressure and temperature seem to reach the stationary state, this problem should not influence the following thermodynamic investigation. Analytical concentrations of the solved elements for the experiments using the molten iron and titanium alloy are listed in our previous papers, 31,36) and are also summarized in Table 1 with the measured oxygen partial pressure and the experimental conditions.…”

“…31,35) The experiment at 1873 K was performed using a molten iron with CaOAl 2 O 3 ZrO 2 melts in CaO crucible. 36) For both experiments, the oxygen partial pressure in the furnace was experimentally measured using an oxygen sensor. Details of the experiments, analytical methods and its inspections have been thoroughly described in the literature.…”

Composition Changes of Inclusions by Reaction with Slag and Refractory: A Review

“…[15][16][17][18][19][20] Todoroki et al 15) Various values of the equilibrium constant of reaction (11), published by different researchers and recommended by JSPS, are listed in Table 5. 28,30,[65][66][67][68][69][70][71][72][73] By ref. [40], the calculated relationship between [%Ca] and [%O] using an interaction coefficient sometimes reveals an oval shape, as shown in Fig.…”

Suppression of Crystallization in Ti-Based Alloys by Fluxing

“…Weight of the alloys was 5 to 19 g, and that of the mixtures of flux was 2 to 5 g. The melted alloys and mixtures were kept at various experimental temperatures for 1800 s. Continuously, calcium-block of 0.05 to 0.5 g as deoxidant was added into the melts. Since the equilibrating time exceeded 3600 s in the previous study, 25) the melts were kept for various times of 5400 to 7200 s. The melts were quenched into a water-pool which was located in bottom place. Cooling rate of the melts could be estimated at about 20-30 Ks À1 by visual observation of an emission color change from 1473 to 773 K. The quenched alloys were cut to several parts as shown in Fig.…”

“…Detailed descriptions were given in a previous paper. 25) An atmosphere in the furnace was kept with an Ar gas flow of 2 Nml/s. When the experimental temperature was kept at 1473 K, the oxygen partial pressure in the atmosphere gas was 3:3 Â 10 À36 atom at measuring temperature of 843 K which was located above the crucible as shown in Fig.…”