Phase equilibria studies for CaO–SiO2-5wt.%MgO–Al2O3–TiO2 system in high Al2O3 content area with w(CaO)/w(SiO2) ratio of 1.50

Abstract

With the purpose of providing fundamental understanding of equilibrium phase relations with the addition of Al2O3 to CaO–SiO2-5wt%MgO–Al2O3–TiO2 system, the equilibria phase relations were experimental determined from 1300 °C to 1450 °C at constant w(CaO)/w(SiO2) ratio of 1.50 using high temperature equilibrium and quenching method followed by XRD (X-Ray diffraction) and SEM-EDX (Scanning Electron Microscope and Energy Dispersive X-ray Fluorescence scope) analysis. The results showed that with the increase of Al2O3 content up to 30 wt%, the coexisting equilibria solid phases gradually changed from perovskite of CaO·TiO2 and melilite solid solution of (2CaO·Al2O3·SiO2, 2CaO·MgO·2SiO2)ss to spinel of MgO·Al2O3. Comparisons with the predictions by Factsage revealed that the simulated results were only well agreed when Al2O3 content lower than 20 wt%, while significant discrepancies existed with Al2O3 content higher than 30 wt%. Finally, the 1400 °C and 1450 °C isotherms, as well as the predicted primary phase boundary lines were projected on the pseudo-ternary phase diagram of CaO–SiO2-5wt.%MgO–Al2O3–TiO2 system within specific composition range.