Research On Composition And Properties Of Float Glass With High Al₂O₃

With the development of modern high-rise building, automobile, information and optoelectronic industry, high-performance flat glass are applied widely. However, ordinary sodium calcium silicon flat glass as a window, windscreen and substrate glass, its hardness and mechanical performance is not high, the surface resistance to anti-damage and impact resistance are not very good, besides, flat glass's weathering has largely endangers the usability of glass. Therefore, it has more far-reaching meaning on studying a kind of high hardness, mechanical properties and good chemical stability glass material.In general composition of sodium calcium silicon system flat glass, Al2O3 makes glass's crystallization tendency and crystallization speed and thermal expansion coefficients effectively reduced, while improving the glass viscosity, softening temperature, surface tension, thermal stability, the chemical stability and mechanical properties, makes glass more stable. But with the improvement of Al2O3 glass viscosity increases, the corresponding melting, molding, soften and annealing temperatures have increased, and the improvement of Al2O3 makes the melting molten glass slowed, clarification longer, hardening speed accelerated, and produces easily wave muscle and stripe in glass surface, increased the glass defect, also makes it very disadvantageous to the molten glass polishing, spreading thin and peace exhibition in tin slot.So in view of the above problems, this topic to ordinary Na2O-CaO-SiO2 system float flat glass as the research object, improve it on the basis of the existing composition,using digital microscope, and density tester, Fourier transform infrared spectrometer, horizontal dual-rod dilatometer, high temperature rotating crucible viscometer, electric anti-flexural meter, scanning electron microscope means to study the effect of Al2O3/SiO2 on glass melting system effect, structure, thermal performance, high viscosity, mechanical properties, chemical stability and resistance to weathering performance. Through the experimental observation and theory analysis we found:With the applied amount of Al2O3 raised, the glass viscosity increased, the clarification effect is reduced, the number of bubbles in glass increased, volume largen, the glass of melting system effect becomes poor; But after the introduction of B2O3, high viscosity of glass decreased, the melting rate of batch mixture is faster, the number of bubbles in glass decreased, volume is decrescent, the glass of melting system effect meliorate.In sodium calcium silicon flat glass, Al3+ions existence in form of [AlO4]. With the increase of Al2O3/SiO2, in glass network, the number of non-bridging oxygen decreased, which makes the glass network structure more closely and intact. So with the increase of Al2O3/SiO2, glass density and flexural strength improved, its thermal expansion coefficient decreased.Along with the increase of Al2O3/SiO2 in glass, glass network enhanced, the ability of resisting the ion exchange of H+ in water and R+ in glass improved, and which can effectively improve the water resistance and alkaline resistance of glass. Meanwhile the increased amount of Al2O3 (1%-8%) can effectively reduce the mutual diffusion of Na+ in glass with H+ in glass surface absorption water (or H3O+), which brings stronger resistance to weathering performance.