Study On The Structures And Properties Of Lead-free And Fusible Glasses

Low melting point glass has good chemical stability, low service temperature and a widerange of expansion coefficient, which can be widely used in ceramics, enamel, glass, glaze,enamel film electronic devices, plasma flat-panel plasma TV wall, sealing agent fields.Currently on the market most widely used glass glaze contains lead, cadmium and other toxicheavy metals, the structure of divalent lead easily polarized, and have high refractive indexand resistivity.Plarization can formed the best shieding of the positive charge, greatly reducedthe glass melting temperature, viscosity decreases, softening point reduction, material ofvariable length, while giving the expansion coefficient of glass lower than alkali metal oxidesand the gloss and water resistance superior to alkali metal oxides.Therefore, lead-silicate glassare widely used. With the constant progress of technology and the enhanced awareness ofenvironmental protection, lead result in poisoning and the pollution of the environment,causing more and more attention in all aspects.The project is to study without the lead ofSiO₂-B₂O₃-ZnO-BaO-Na₂O-K₂O-Li₂O system composed of glass, changing the B₂O₃, ZnOand BaO contents, to determine optimal composition of the glass components.Through the measurement of chromaticity and light transmission of glass samples shows:B₂O₃, ZnO and BaO has effect on the transmission rate of glass, which more B₂O₃lead to thehigher transmission rate; through chemical experimental stability study the influence ofdifferent components on the glass stability, among which the ZnO content has a great effect,with the ZnO content increased,chemical stability of glass enhanced;whith also tested thethermal expansion coefficient,softening temperature,hardness, refraction rate of glass samplesand research the several different composition range of SiO₂45%, B₂O₃10%¹5%, ZnO15%²0%,Na₂O10%,K₂O9.5%,Li₂O0.5%, BaO5%¹0%have effect on these performance.The results show that: When the melting temperature is1280℃and annealingtemperature is500℃,this glass system has no crystallization,light transmittance is62%to97%,the refractive index is in the range of1.4406¹.5594,the haedness is between317⁴00，the expansion coefficient is95×10^-7K^-1101×10^-7K^-1,the softening temperature is between530℃⁵65℃and have a good water resistance.