Phase Equilibria Study of the ZnO-“FeO”-SiO₂-Al₂O₃ System at Po₂ 10⁻⁸ atm

Phase equilibria studies on ZnO-“FeO”-SiO₂-Al₂O₃ system have been carried out in the temperature range between 1523 K and 1573 K (1250 °C and 1300 °C) at Po₂ 10⁻⁸ atm. Experimental techniques applied in the present study include high temperature equilibration, quenching, and electron probe X-ray microanalysis (EPMA). The compositions of the phases present in the quenched samples were measured by EPMA and used to construct phase diagrams of the pseudo-ternary sections at fixed Al₂O₃ content. The experimental results show that, spinel, SiO₂, and willemite are the major primary phase fields in the composition range investigated. With 2 wt pct Al₂O₃ content in the liquid phase, the liquidus temperature can be increased by 35 K in the spinel primary phase in comparison with Al₂O₃-free system. The partitioning of ZnO and Al₂O₃ between the spinel and liquid phases is also discussed in the paper.