Abstract: The changes of two-phase compositions in the phase separation process of Na₂O-CaO-Al₂O₃-B₂O₃-SiO₂-TiO₂ system was studied.Samples treated under different temperatures were tested by using SEM examination,energy spectrum analysis,and X-ray diffraction etc..Results showed that after the phase separation,the system was separated into boron/alkali-rich phase and silicon-rich phase;the chemical compositions of the two phases had a definite relation with the changes of phase separation temperatures. When the heat treatment rising from 700 ℃ to 850 ℃,the amount of boron/alkali-rich phase rised,and the degree of phase separation increased.When phase separation temperature was lower,there was only net adjustment oxide CaO in boron/alkali-rich phase,while net adjustment oxide Na₂O concentrated in silicon-rich phase.With the phase separation temperature rising,CaO retained in boron/alkali-rich phase, whereas Na₂O took place phase transfer from silicon-rich phase to boron/alkali-rich phase gradually.In the phase separation process,TiO₂ concentrated and crystallized on the phase separation interface.

Key words: glass phase separation, boron/alkali-rich phase, change of composition