Thermodynamic Simulation of the Phase Diagram of the Cu2O–Na2O–K2O System

Resumo

Thermodynamic simulation of phase equilibria is carried out, allowing us to calculate the liquidus lines for the phase diagrams of the Cu₂O–Na₂O, Cu₂O–K₂O, and K₂O–Na₂O oxide binary systems, and also the liquidus surface of the Cu₂O–Na₂O–K₂O ternary system. In the course of the work, the values of the model parameters used to calculate the activity of the oxide melts of the investigated systems are determined. The values of the activity of copper oxide and sodium oxide in the Cu₂O–Na₂O system for a temperature of 1250°C are calculated. The activity data are characterized by negative deviations from Raoult’s law. During the simulation, the enthalpy and entropy of the formation of a KNaO compound from the liquid components are estimated. According to the calculations, the liquidus surface of the phase diagram of the Cu₂O–Na₂O–K₂O ternary system has two points of invariant equilibria.