Research On High-temperature Viscosity And Properties Of Li₂O-Al₂O₃-SiO₂ Glass-ceramics

Li2O-Al2O3-SiO2(LAS) glass-ceramics containingβ-spodumene and/orβ-quartz solid solution, own low thermal expansion coefficient, good thermal and chemical stability, and so have been applied in many fields.β-spodumene containing glass-ceramics also have the potential to meet the dielectric constant and thermal expansion requirements for integrated circuit substrates.However, due to their high melting temperatures and viscosity in LAS glasses, it makes them difficulty to be prepared, so additions of fluxes such asNa2O, Li2O,K.2O,ZnO, P2O5have been used in LAS glass-ceramics to decrease the viscosity and melting temperature.But it would induce some problems like high thermal expansion coefficient and/or loss of transparency, and/or low mechanical properties at the same time. The low thermal expansion was 0.701×10-7 K-1 and the temperature was 1570℃when Na2O contents 2%。In the present research the effects of basic composition on the microstructure and properties of LAS glass-ceramics without dopants were investigated by XRD, SEM, DTA, and Raman.Do some research on high temperature viscosity and the thermal expansion.The results show that respectively.The time of crystallization was more important in heat-treatment than other factors.The viscosity and melting temperature of LAS glass-ceramics decrease with the increase of Na2O addition. The viscosity temperature between 1555℃and 1600℃.and the crystallization temperature and crystallizing activation energy of the resulting glass decreased. And the kinetic and phase structure analysis indicated that the main phase wasβ-spodumene and/orβ-quartz solid solution.the crystalline and the radius of crystal grain if specimens were decreased.the expansion of glass-ceramics was increased,and between -2.3970×10-7 and 5.3000×10-7.Mixed alkali effect was used in LAS glass and LAS glass-ceramics. The viscosity, melting temperature the expansion of LAS glass-ceramics decrease at first and then increase with the increase of K2O addition.the melting temperature was 1500℃when (Li2O,K2O)wt% were(5,2)wt% and(4,3)wt%. The viscosity and melting temperature of LAS glass-ceramics increase with the increase of Na2O decrease.and the ZnO increase. The melting temperature could decrease to 1550℃.The thermal expansion of LAS glass-ceramics was decreased.and the crystalline and the radius of crystal grain if specimens were increased当ZnO3.5%,Na2O1%时,The low thermal expansion was -0.536×10-7K-1 and the temperature was about 1600℃when (ZnO, Na2O) content (3.5%,1%)。The viscosity, melting temperature the expansion of LAS glass-ceramics decrease at first and then increase with the increase of P2O5 addition.the temperature between 1550℃and 1600℃The main phase of glass-ceramics changedβ-spodumene toβ-quartz solid solution,but the processing was not good. the low thermal expansion was 5.840×10-7 K-1 when (P2O5, ZrO2)wt% were(2.5,0.5)wt%.