Experimental phase equilibria of the system Cu-O-CaO-Al2O3 in air

Phase equilibria of the system Cu-O-CaO-Al₂O₃ at Po₂ of 21278.25Pa was experimentally investigated for the first time using equilibration techniques. Composition of glassy molten phase and all solids in equilibrium were quantified using Electron Probe Micro-Analyzer (EPMA). Isothermal ternary sections of the 'Cu₂O'-CaO-Al₂O₃ system in the temperature range 1150-1400°C in steps of 50°C have been constructed based on three phase equilibria experimental data. From the triple points data obtained, large deviations exist among previously thermodynamically assessed diagrams and experimental results of this study. Especially triple points one (1), with halite and tricalcium aluminate as solid phases, and triple point four (4), with monocalcium aluminate and monocalcium dialuminate as solid phases, between 1350 and 1400°C, where the deviations in Al₂O₃, 'Cu₂O' and CaO contents of the liquid phase reach 40wt%. Thus there is a need for re-assessment with the new experimental data.