Enthalpic analysis of melts in the CaO center dot SiO2(CS)-2CaO center dotSiO2(C2S)-2CaO center dot Al2O3 center dot SiO2(C(2)AS) system

The heats of solution of gamma-C2S and beta-C2S at temperature 298 K have b een measured to reach the consistency of the values of relative enthalpy of melts in the CS-C2S-C(2)AS system determined by two different methods: com bination of measurements with the drop and solution calorimeters and the me thod of inverse drop calorimetry. Assuming that the athermic solutions are formed on the connecting line CS-C2S, the temperature-composition dependenc e of relative enthalpy in the CS-C2S-C(2)AS system has been determined by r egressive analysis. On the basis of this dependence the enthalpies of mixin g on formation of melts in part of the CS-C2S-C(2)AS system, i.e. the C3S2- CS-C(2)AS subsystem, from the melts of CS, C2S, and C(2)AS at temperature 1 873 K were calculated. The obtained values point to exothermic character of reactions on formation of the melts of this subsystem from the CS, C2S, an d C(2)AS melts.