Thermodynamic assessment of the Na2O-Al2O3-SiO2-B2O3 pseudo-binary and -ternary systems. (January 2019)

• Record Type: Journal Article
• Authors: Utlak, Stephen A.; Besmann, Theodore M.
• Is Part Of: Journal of chemical thermodynamics. Volume 130(2019)
• Page Start: 251
• Page End: 268
• Publication Date: 2019-01
• Subjects: Oxide materials -- Thermochemistry -- Thermodynamic properties -- Thermodynamic modeling -- Phase diagrams -- Phase transitions; Thermodynamics -- Periodicals; Thermochemistry -- Periodicals; Thermodynamique -- Périodiques; Thermochimie -- Périodiques; Thermochemistry; Thermodynamics; Periodicals; 541.369
• DOI: 10.1016/j.jct.2018.09.001
• Languages: English
• ISSNs: 0021-9614

Abstract

Highlights: Na2 O-Al2 O3 -SiO2 -B2 O3 thermodynamic database was developed. Na2 O-B2 O3 -SiO2 system assessment included a novel modeling of malinkoite phase. New assessment of the Na2 O-B2 O3 -Al2 O3 system that included the Na2 Al2 B2 O7 compound. Abstract: Thermodynamic assessments of the pseudo-binary and -ternary systems formed by B2 O3 with Na2 O, Al2 O3, and SiO2 were conducted according to the CALPHAD methodology. The compound energy formalism and two-sublattice partially ionic liquid models were used to thermodynamically represent the solid solutions malinkoite and mullite and the liquid phase of each system, respectively. A comprehensive literature review of available phase equilibria and thermodynamic experimental data as well as a detailed discussion of the modeling approaches implemented to optimize each system is provided. Assessment results are then presented and discussed, and the future path forward is outlined. The addition of B2 O3 to the Na2 O-Al2 O3 -SiO2 system contributes to the development of a thermodynamic database that will ultimately predict the equilibrium behavior of nepheline formation in high-level radioactive waste glass.