Studies on the system lime-ferric oxide-silica

The equilibrium diagram of a part of the ternary system lime-ferric oxidesilica is presented. A comparison with the diagram of the lime-alumina-silica system shows that the presence of ferric oxide results in extension of the stability fields of the calcium silicates and the lowering of the liquidus and eutectic temperatures in much of the area investigated. Evidence from thermal analyses is offered of a limited solid-solution series between dicalcium silicate and ferric oxide, substantiated by an X-ray investigation. The amount of reduction of ferric oxide a t the liquidus temperature of representative t ernary mixtures is recorded. The applications to iron-rich cements are discussed.