Integrated Experimental and Thermodynamic Modelling Study of Phase Equilibria in the PbO-AlO1.5-SiO2 System in Air

The present study focused on phase equilibria in the PbO-AlO1.5 and PbO-AlO1.5-SiO2 systems. The equilibration and quenching technique followed by the electron probe X-ray microanalysis (EPMA) was used in the present study. The liquidus of the PbO-AlO1.5-SiO2 system in air, including corundum (Al2O3), cristobalite/tridymite/quartz (SiO2), feldspar (PbAl2Si2+xO8+2x), massicot (PbO), mullite (Al6+2xSi2-2xO13-x), PbAl12O19, PbAl2O4, Pb9Al8O21, Pb6Al2Si6O21, Pb4Al2Si2O11, Pb4Al4Si3O16, Pb3Al10SiO20 and Pb12Al2Si20O55 primary phase fields, has been characterised. New lead aluminosilicate compounds, Pb13Al4Si6O31, Pb12Al6Si10O31, Pb9Al4Si8O31, Pb7Al2Si8O26 and Pb7Al2Si10O30 were found to coexist with oxide liquid. The PbO-AlO1.5 binary and PbO-AlO1.5-SiO2 ternary systems in air were reoptimized based on the obtained experimental data. New experimental results together with phase equilibria and thermodynamic literature data were used to obtain a self-consistent set of parameters of the thermodynamic model for all phases of the PbO-AlO1.5-SiO2 system in air. The predicted liquidus projection of the PbO-AlO1.5-SiO2 system was presented for the first time in the full range of temperatures and compositions.