Reoptimization of the CaO–FeO–Fe ₂ O ₃ –SiO ₂ system integrated with EPMA studies (part I—experimental results)

Abstract New experimental measurements have been obtained for phase equilibria in the CaO–FeO–Fe 2 O 3 –SiO 2 system at 1250–1740°C for a wide range of oxygen partial pressures ( p (O 2 ) = 1, 0.21, 10 −5 , 10 −6 , 10 −7 , 10 −8 , 10 −9 atm) as well as in equilibrium with metallic iron ( p (O 2 ) down to 10 −12 atm). The investigation was undertaken using equilibration/quenching technique and electron probe X‐ray microanalysis (EPMA) which allow to measure the elemental compositions of the liquid and solid phases in equilibrium. The current work is a continuation of an extensive earlier work by the coauthors and fills in the gaps concerning mostly low‐SiO 2 areas of the phase diagram in the primary fields of dicalcium and tricalcium silicates. This work is part of a bigger combined experimental/modeling study of the Ca–Fe–Si–O system and its subsystems. The current experimental work a first part of a two‐part manuscript describing the new experimental data in the Ca–Fe–Si–O system and its thermodynamic modeling (part II).