The Investigation Of Viscosity And Crystallization Of Glass Frit In Different Temperature

The objective of this work is to study the influence of fluorine on physical chemistry properties of silicate glass, including the rheology, thermodynamics, crystallization and as well the relationship between the rheology and the thermodynamics.On the basis of the original formula of non alkali glass, CaO-Al2O3-SiO2- AlF3( series A)and CaO-Al2O3-SiO2-CaF2( series C) glasses were prepared by means of conventional melt quenching technology. Bringing the low viscosity which was measured by means of the concentric cylinder method and the glass transition temperature (Tg) and the heatcapacity (Cp) which were determined by using DSC output data together,then the VFT,AG,AV and Mauro equations were used for description of the viscosity-temperature relationship. The results showed that:(1) The Mauro Formula has the same number of three-parameters as VFT,AV and AG formulas and describes the viscosity–temperature relationship better than others,However,VFT,AV and AG formula still have some practical significance.(2) With the increase of fluorine, the activation energy for viscous flow in high temperature,ΔCp and configurational entropy is larger at the same time, glass transformation temperature and fragility becomes small in both series A and series C. Besides, there is no direct relationship betweenΔCp and fragility. While the activation energy for viscous flow of series A is less than series C, in other words, the viscosity is reduced obviously by AlF3 at the same temperature.(3) Configurational entropy not only has a link with temperature but also with fragility and glass transformation temperature. The ratio of the Eeq(T)/Eis(oT)which is derived from VFT, AV , AG and Mauro Formula respectively is proportionalto the fragility of a liquid near Tg.(4) We got value of the volume of [AlO3F] tetrahedron of CaO-Al2O3-SiO2-F glass using Doweidar Density Model which can regard as a constant. Furthermore, a satisfactory agreement between the calculated of densities of glasses and the measured densities of ones was got. Based on above conclusions, measuring the density is a way of controling production'quality.(5) From the research of the crystallization of glass, we found that A2, A4, C4, C6 all can be as the original formulas of the non alkali glass. When the samples were treated from high temperature to 700K at the rate of 1K/min. only does A4 devitrify in form of surface crystalline and the crystalline solid is CaF2, Therefor the EM Rabinovich'polarization mechanism of formation of oxyhalide groupings is applicable to CaO-Al2O3-SiO2-F glass.From what has been discussed above, we got a theoretical foundation to steer the production of non alkali glass.