Experimental determination of phase equilibria in the CaO‐BaO‐SiO₂‐12 mol pct. Al₂O₃‐13 mol pct. MgO system at 1573 K and 1623 K

Abstract

Phase equilibria of the CaO‐BaO‐SiO2‐12mol pct. Al2O3‐13mol pct. MgO system with a wide substitution range of CaO with BaO have been experimentally determined at 1623 K (1350°C) and 1573 K (1300°C) using high‐temperature equilibration followed by X‐ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA) analysis. The (Ca,Ba)3MgSi2O8, BaAl2O4, BaAl2Si2O8 and Ca2(Al0.46Mg0.54)(Al0.46Si1.54)O7 phases have been designated within the phase diagram. The liquidus temperature initially decreased and then increased for the samples substituting CaO with BaO at a constant (C + B)/S ratio between 1.50 and 1.86. For samples with a constant BaO/CaO ratio, the liquidus temperature showed similar trends with a lower (C + B)/S ratio from 1.22 to 0.67. The volume fraction of crystal phases of the samples as‐quenched from 1573 K (1300°C) correlated well with the variation of liquidus and the primary phases. In addition, the change in the Gibbs free energy of the reactions and the bond parameter (Xp × Z/Rk) of the cations were analyzed, where the maximum change in the Gibbs free energy was found for the formation of Ca3MgSi2O8; furthermore, the stronger basic tendency of Ba2+ than Ca2+ facilitates Ba2+ substitution for Ca2+ and bonding with acidic tendency cations to form Ba‐containing phases.

Selective elemental concentration during the solidification of stainless steel slags for increased Cr recovery with MnO addition

“…The composition of the different phases in the quenched sample was quantified by spot analysis, where the average of three distinct locations was used. The EPMA data were refined using ZAF correction to better quantify the elemental contents based on the relative peak intensities 23,24 …”

“…The EPMA data were refined using ZAF correction to better quantify the elemental contents based on the relative peak intensities. 23,24 3 | RESULTS AND DISCUSSION…”

Review on the High-Temperature Thermophysical Properties of Continuous Casting Mold Fluxes for Highly Alloyed Steels

“…As BaO gradually replaces CaO, there is also a significant increase in the viscosity of the mold flux, which should also be considered, and the optimal amount of BaO used to inhibit crystallization must be balanced with the combined effect of higher flux viscosities. 55,58,90) In addition, Fig. 3(b) also shows that lower CaF 2 contents can promote crystallization by decreasing the incubation time and accelerating the formation of gehlenite with a higher nucleation temperature.…”

“…94,104) Although the substitution of CaO with BaO can inhibit crystallization, the barium calcium aluminate (BaCa 2 Al 8 O 15 ) primary phase has been known to precipitate during continuous cooling in CaO-Al 2 O 3 -based fluxes. 105) However, according to Wang and Sohn, 55,90) although the substitution of CaO with equimolar amounts of BaO can reduce the liquidus temperature of CaO-Al 2 O 3 -based mold flux to inhibit crystallization, the substitution of CaO with BaO cannot occur without restrictions. As BaO gradually replaces CaO, there is also a significant increase in the viscosity of the mold flux, which should also be considered, and the optimal amount of BaO used to inhibit crystallization must be balanced with the combined effect of higher flux viscosities.…”

Immobilizing chromium in stainless steel slags with MnO addition

“…The equilibrated slags were rapidly removed from the furnace and quenched in liquid nitrogen. The details of the sample preparation have been provided elsewhere 22,23 . The XRD and SEM were used for phase analysis and morphological observations, respectively, where the detailed operational parameters of the analytical equipment have been provided in a previous publication 23 …”