Influence of SO3 on the Phase Relationship in the System CaO–SiO2–Al2O3–Fe2O3

Abstract

The influence of the additive SO3 on the phase relationships in the quaternary system CaO‐SiO2‐Al2O3‐Fe2O3 was investigated by observing the change of volume ratio of 3CaOSiO2 (C3S) to 2CaOSiO2 (C2S) + CaO (C) in the sintered material with the increase of SO3 content. The primary phase volume of C3S in the quaternary phase diagram shrank with the increase of SO3 and disappeared when the SO3 content exceeded 2.6 wt% in the sintered material. Changes in the peritectic reaction relationship between CaO (C), 2CaOSiO2 (C2S), 3CaOSiO2 (C3S), 3CaOAl2O3 (C3A), 4CaOAl2O3Fe2O3 (C4AF), and liquid were also observed and discussed.