Study On The Glasses With Low Sealing Temperature

With excellent thermotolerance, chemical stability and high mechanical properties, sealing glasses are widely used in the sealing applications of vacuum engineering, electronics, space navigation and motor vehicle. Thereby to lower sealing temperature becomes the most focus on the research of sealing glasses. When the sealing temperature is low, tradition lead sealing glasses are in high-lead content, or they would be with toxic metal oxide such as Cd, Hg, Tl which would polluted the environment. Nowadays, lead reduction and exploitation of lead free glasses are the social requirement which is much more concerned than before.In this paper both lead borate sealing glasses and lead free phosphate sealing glasses are studied. The sealing glasses were prepared by trandition melting-quenching method. The relationship between composition, structure and properties was investigated by DSC, IR, XRD,DILL. And then the effects of compositions on the mechanical performance, characteristic temperatures, thermal expansion and chemical stability of the glass were discussed.Researches on lead borate sealing glasses show that PbO/B2O3 ratio exerts the most important effect on glass network. ZnO is beneficial to stabilize the glass against devitrification . Bi2O3 has little effects on the sealing temperature, while it helps to adjust the thermal expansion coefficient of lead borate glasses in a definitive range. When 0.5～4 mol% GeO2 is introduced, the glass possesses the highest stability and lowest sealing temperature (400 ?C), which is desirable for low-temperature sealing. Lead free phosphate sealing glasses was investigated on the base of ZnO- B2O3- P2O5 thernary system glasses. The glass-forming range of this thernary system can be obtained, and the results show that ZnO-B2O3-P2O5 system sealing glasses are amorphous material with sealing temperature between 400～600℃. Both B2O3 and P2O5 are the former of glass network, and ZnO can enter the glass network when it is in relative low content so as to improve the glass stability. But the glass network would be broken when ZnO is in relative high content. All of the Tg, Tm, Ts and Td are increased with the decrease of P2O5/B2O3 ratio. Meanwhile Tm goes up, Tg, Ts, Td, increase start but decrease later with increasing of B2O3/ZnO ratio. It has much to do with ZnO in glass network. B2O3/ZnO ratio is not the dominating factor effecting on thermal expansion coefficientα, whereas ZnO has obvious influence on the thermal expansion coefficient of the glass,αwould mount up with the increase of content.