Study On Mechanism Of Reactive Crystallization And Preparation Of Glass Ceramics Using Waste Glass Powder

Sinter-reaction crystallization is a new route for the fabrication of glass-ceramics in recent years, which by directly adding a synthetic crystallization promoter into ordinary soda lime glass power, getting the crystalline phases by the chemical reaction between promoters and glass during sintering. This route does not require melting a base glass with a specific composition, but through directly sintering the mixture of crystallization powers and waste glass to fabricate the glass-ceramics, which not only has a wide scope but also requires a low sintering temperature, with great advantage in energy efficiency and environmental protection.This paper use calcium sodium window waste-glass as the main raw material, three types of crystallization promoter, including fluorphlogopite, gehlenite, enstatite are added to fabricate fluoramphibole glass-ceramic, wollastonite glass-ceramic and diopside glass-ceramic by sinter-reaction crystallization, respectively. The impact of crystallization promoter components, sintering temperature, holding time on the glass-ceramic microstructure, phase composition and mechanical properties is investigated, as well as the reaction crystallization method is explored by analysis elements changes by EDS.Gehlenite was used as crystallization promoter, the best addition of gehlenite is 20%, Wollastonite glass-ceramic achieves the best performance after sintered at 950℃ for 2h, with a Vickers hardness of 3.2GPa.Fluorphlogopite was used as crystallization promoter, the best dosage of fluorphlogopite is 30%, fluoramphibole glass-ceramic achieve the best performance after sintered at 950℃ for 2h. The different types of crystalline phases formed when the sample sintered at 900℃ for different holding time: during 0-2 hours, the glass reacted with fluorphlogopite to form fluoramphibole, after 3 hours, the glass reacted with fluorphlogopite to form diopside, after 4 hours, precipitated diopside reacted with residual glass phase to formed fluoramphibole.Enstatite was used as crystallization promoter; the best addition of enstatite is 30%. Diopside glass-ceramic achieve the best performance after sintered at 950℃ for 3 hours, when Vickers hardness value is 1.7GPa. During crystal isothermal process, enstatite first reacted with molten glass to form sanidine, and then formed diopside.