Study On The Component, Structure And Properties Of Borosilicate Float Glass

The properties of borosilicate glass have an obvious advantage contrasted with normal silicate glass. But this system glass is still mainly used in non-flat fields, such as instrument glass and vessel glass. Its application can be expanded into fire-resistant glass, LCD and solar battery if the borosilicate glass be produced by float technics in larger scale.But there is some problem in the melting and molding of borosilicate glass, such as high melting temperature, larger viscosity and easy phase separation, etc, which make it's hard to be yielded by float technics, and then limited its large-scale application. Therefore, this paper expects to systematically study the component, structure and properties of borosilicate glass, look after the appropriate component of borosilicate float glass, which is satisfied with float technics, not easy to be of phase separation and crystallization, and with excellent and steady properties.This paper firstly discussed the influence of different factors on the boron volatilization and glass clarification, on which the melting and molding process system was established. Referenced the point of float technics of normal silicate glass, discussed the point and request of float technics of borosilicate glass from the glass melting and molding temperature, viscosity-temperature curve and upper limit of crystallization temperature, etc. The result shows that setting rate of borosilicate glass is slower than that of normal silicate glass.This paper studied the effect of basic component on the structure and properties of borosilicate glass from four aspects, B₂O₃/SiO₂, Al₂O₃/SiO₂, mixed alkali oxide and mixed alkaline earth oxide. The structure of glass was analyzed by XRD, SEM, IR spectrum, the effect of chemical component on the thermal expansion, viscosity and phase separation of borosilicate glass was mainly studied. The results show that:When SiO₂ is substituted by B₂O₃, with the increasing of B₂O₃/SiO₂, thermal expansion coefficient of glass exists a minimum, transition temperature (T_g) and thermal expansion temperature (T_f ) both decrease, [BO₃] increase gradually, which aggravate the phase separation of glass, the setting rate become more rapid.When SiO₂ is substituted by Al₂O₃, find that the effect of Al₂O₃ on the glass contains B₂O₃ and glass not contains B₂O₃ is quite more different. With the increasing of Al₂O₃/SiO₂, thermal expansion coefficient of glass increases, the T_g and T_f both increase, the addition of Al₂O₃ into borosilicate glass has not obvious improvement on the phase separation of glass, the viscosity of glass increases and the setting rate become more slow.With the increasing of Li₂O, the phase separation of glass aggravates gradually, thermal expansion coefficient decreases linearly; T_f increases firstly and then decreases for the severe phase separation. With the increasing of K₂O,αand T_f of glass both increase, K₂O has not obvious effect on the phase separation of glass. There are not "mixed alkali effect" onαand T_f of binary and ternary borosilicate glass, but T_f of glass related with ion diffusion increase obviously for the "mutual block of ions".When Na₂O is substituted by alkaline earth oxide, T_f of glass increase obviously for the "mixed effect". But the effect of alkaline earth ions aggravated phase separation of glass is more severe than that of alkali ions, because the field intensity of alkaline earth ions is larger than that of alkali ions.Finally, on the basis of the effect of chemical component on the structure and properties, designed four borosilicate float glass component with different thermal expansion, not easy to be of phase separation and crystallization, and basically satisfied with float technics.