Thermodynamic modeling of ZrO2–CaO–TiO2 system

Abstract

The phase diagram of ZrO2–CaO–TiO2 system was essential for the development of photocatalytic materials and refractory materials. In this work, the ZrO2–CaO–TiO2 system was accessed by using the CALPHAD method. The substitutional solution models were used to describe liquid and solid solution phases, the sub-lattice models were used to describe ternary compounds, and then the thermodynamic parameters were obtained by the least square method combined with literature experiment results. The acquired thermodynamic parameters were used to calculate the isothermal sections of the ZrO2–CaO–TiO2 system at 1473 and 1673 K. There existed a good agreement between experimental and predicted phase relationships, the experimental points which were inconsistent with calculated results may be attributed to experimental errors and the sluggish kinetics of cations for ZrO2-based materials. In order to further verify the validity of the database, the thermodynamic parameters were also used to simulate the thermodynamic properties (specific heat capacity, enthalpy, and entropy) of CaZrTi2O7 within 5% errors. Good consistency demonstrated that the present thermodynamic database was self-consistent and credible.