| Low-temperature sealing glass has been widely used in microelectronics,electrovacuum and aerospace field and so on bu virtue of its excellent chemicalstability,anti-aging performance and electrical insulting performance.As with therequirements for sealing improving and people’s environmental awarenessincreasing,there are three development directions at present for sealing glass:lead-freefor composition,lower sealing temperature,micro-crystallization for sealing glass.Weselected Bi2O3-ZnO-B2O3lead-free low-temperature sealing glass which is one of themost prospective glasses as study object in this subject.Through the design of formulaand some testing instruments for structure and properties,we studied its vitrificationproperty,low-temperature performance,structure and spectral absorption performanceeffect to the structure with coloring agent added and the adjustment to the thermalexpansivity of the glass.The results prove that Bi2O3-ZnO-B2O3glass has a wide vitrification range.Withthe increase of Bi2O3,the glass transition point and devitrification temperaturedecreased.With the increase of ZnO,the transition temperature changed little at about400℃but the devitrification temperature of the glass droppedmuch.The study foundthat,there are structure units such as [BO3]、[BO4]、[BiO3]、[BiO6]in the glass,and[BiO6] is the most important factor that affect the glass transition point.With theincrease of Bi2O3,[BiO6] increased and the structure of the glass became loose.Withthe increase of ZnO,the content of [BiO6] changed little.With the increase of B2O3,thecontent of [BiO6] decreased.Therefore,when we fine-tune the formula of theBi2O3-ZnO-B2O3low-temperature sealing glass,we shall first assure a high content ofBi2O3,and then adjust the proportion of Bi2O3to ZnO to assure that the glass has lowtransition temperature with high devitrification temperature,and then the glass will notcrystallize when sealing.In the study,we got a formula of which the glass transitiontemperature was low at about359℃and the devitrification temperature was relativelyhigh at513℃.We also studied the effect caused by the coloring ions to the spectral absorptionperformance of the glass.The result found that the absorption edge of the glass movedtowards long wave to visible light area compared with silicate glass,and the spectralabsorption rate in the visible-infrared area of Bi2O3-ZnO-B2O3glass increasedgreatly after adding colorant.The study showed that there were less bridge oxygens in Bi2O3-ZnO-B2O3glass than in the silicate glass,the binding energy of O1s ofBi2O3-ZnO-B2O3glass was also smaller than silicate glass,and the electron cloud ofO2+Bi2O3-ZnO-B2O3glass was dense and the structure of the glass becamelooser,which is the most important cause for the change of the spectral absorptionperformance.According to the special spectral absorption performance ofBi2O3-ZnO-B2O3glass with colorant added,we greatly improved the heatingefficiency by ray radiation heating technology,which can be used to prepare temperedvacuum glass.In addition,in order to achieve the goal of matched sealing with flat glass,weadded some cordierite to adjust the expansion coefficient of the glass.The resultshowed that cordierite can well adjust the expansion coefficient,the sealing glass with5%cordierite added matched well with flat glass for BBZ-14sample.Glass transitiontemperature and softening temperature increased after adding cordierite.We foundthrough SEM that cordierite distributed equally in the glass and did not melt downbecause cordierite in the glass was angular.The glass was compact and had lowporosity after sintering and the pore diameter is under50μm. |
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