A Coupled Phase Diagram Experiment and the Thermodynamic Modeling of the ZnO-SnO2-SiO2 System

Abstract

The development of an accurate thermodynamic database to calculate the thermodynamic properties and phase equilibria in complex systems plays an important role in the development of many ceramic and metallurgical processes. Thermodynamic database is developed by the comprehensive critical evaluation and optimization of all the thermodynamic property and phase diagram data. As part of a large thermodynamic database development for glassmaking and metallurgical applications, the entire ZnO-SnO2-SiO2 system was critically evaluated and optimized. Due to the lack of phase diagram experiment data in the ZnO-SnO2, SnO2-SiO2, and the ternary ZnO-SnO2-SiO2 system, the phase equilibria in the binary and ternary systems were determined using the classical quenching experiments and differential thermal analysis (DTA) followed by X-ray diffraction (XRD) analysis and electron probe micro-analysis (EPMA). Sealed platinum capsules were employed for preventing the evaporation of ZnO and SnO2 in the experiments. In the course of the optimization, the melting temperature of SnO2 was re-evaluated. The phase diagrams of ZnO-SnO2, SnO2-SiO2, and ZnO-SnO2-SiO2 systems were constructed for the first time. By using the construct thermodynamic database containing the Gibbs energy functions of all phases in the ternary system, phase equilibria and the thermodynamic properties within the ternary system could be accurately calculated. All the thermodynamic calculations and optimization in the present study were carried out using the FactSageTM thermochemical software.