Stability of Microstructure and Properties of Transparent Li_2O-Al_2O_3-SiO_2 Glass-ceramics

Transparent and low thermal expansion Li2O-Al2O3-SiO2 glass-ceramics were prepared by addition of TiO2 and ZrO2 as nucleation agents.The effects of heat-treatment temperature and time on the crystallization,and phase transition behavior were discussed and the stabilities of microstructure and properties were investigated by DTA,XRD and SEM.Isothermal transformation curve of the LAS glass was also measured.The results show that β-quartz solid solution is stable in the temperature range from 750℃ to 900℃ and in long annealing time.Further more,LAS glass-ceramics have excellent stability in high temperature,which is still transparent and low thermal expansion after heat-treated at 850℃ for 5h.The stability of structure and properties mainly attribute to the high nucleation efficiency of the TiO2 and ZrO2 mixed nucleation agents.