Phase Equilibria in Water–Salt Systems Containing Sodium and Calcium Chlorides and Urea at Temperatures below 0°C

Abstract

Phase equilibria are studied in sections of the systems NaCl–CO(NH₂)₂–H₂O, CaCl₂–CO(NH₂)₂–H₂O, and NaCl–CaCl₂–CO(NH₂)₂–H₂O at temperatures from 0 to –57°C. The features of the mutual influence of the components on the temperatures of the eutectics in the systems and on the deicing ability of urea–salt mixtures are determined. It is found that the introduction of urea into the systems CaCl₂–H₂O and NaCl–CaCl₂–H₂O gives rise to low-temperature eutectics with crystallization temperatures of –54 and –57°C, which are promising for the development of low-temperature deicing agents on their basis.