Experimental Study on the Phase Equilibrium of the Ternary System Na_2CO_3-Na_2B_4O_7-H_2O at 273K

The solubilities and densities of equilibrium solutions were studied in the ternary system Na2CO3-Na2B4O7-H2O at 273K by isothermal evaporation method.The results show that the ternary system is a type of simple common saturation.No double salt or solid solution was formed.Na2CO3 has salting-in effect on Na2B4O7.Based on the solubility data,the phase diagram of the ternary system was plotted,which consists of two univariant curves.The phase equilibrium solids were Na2CO3·10H2O and Na2B4O7·10H2O.