Preparation And Properties Of Glazed Glass-ceramics Sintered From Granite Waste

China’s granite industry has grown up rapidly with the economic development.The annual increasing production of granite waste cause the environmental pollution and health hazard.Therefore,the reutilization of granite waste becomes an urgent issue.Granite waste contains a large amount of feldspars,and could be used as a cheap feedstock to prepare glazed glass-ceramics with excellent performance in the construction tiles.In this thesis,granite waste was used as the main raw material,and pretreated by the physical and physicochemical methods to significantly reduce the iron content in granite waste.The glazed glass-ceramics were prepared by the sintering process.The mechanical properties of glazed glass-ceramics were strengthened by adding small amounts of sintering additive and the glossiness of glazed glass-ceramics further improved by two-step sintering.The relationship among sintering system,microstructure and properties was systematically studied to facilitate the resource utilization of granite wastes.The iron content of granite wastes using physical iron removal and Physicochemical iron removal decreased from 5.7%to 1.2%and 0.12%,respectively.Physicochemical iron removal is more effective than physical iron removal,and the calcium content drops significantly.The glazed glass-ceramics were prepared from the granite wastes with iron removal.With the increase of the sintering temperature,the bending strength and bulk density of the glazed glass-ceramics increased first and then decreased,while the water absorption is the opposite trend.The content of quartz and anorthite decreased continuously,and the glossiness of glass-ceramics increased first and then decreased.When the sintering temperature is more than 1200℃,anorthite almost melts in the glass phase.As the heating rate increases,the glossiness of glass-ceramics increases first and then decreases.The optimal sintering temperature is 1175℃,the heating rate is 10℃/min,the glossiness is 78.6 GU,the bending strength is 96.8 MPa,and the water absorption is0.14%,the bulk density is 2.24 g/cm~3.The sintered glazed glass-ceramics for granite wastes with physical iron removal consist of Anorthite,albite and quartz.The sintering temperature was 1060℃,and the strip-shaped anorthite phase and short bar-shaped albite phase appeared.The sintering process belongs to liquid phase sintering,the mass transfer method is viscous flow,and the sintering activation energy is 287 kJ/mol.with the heating rate increases,the bending strength,bulk density and the content of each crystal phase increase first and then decrease.With the extension of sintering time,the bending strength and bulk density of the glass-ceramics increase first and then decrease,the crystal phase content continuously decreases,and the glossiness increases.The maximum bending strength and the highest surface glossiness of glass-ceramics are 135.3 MPa and 79.5 GU,respectively,which have a good glaze decoration effect.Addition of fly ash glass-ceramics appeared two kinds of large-scale lump and strip-shaped anorthite,the bending strength and bulk density of glass-ceramics is up to 2.50 g/cm~3 and 161.0 MPa,respectively.The results of two step sintering studies show that the sintering the first step sintering temperature is 1100℃,holding for 2 h,the second step sintering temperature is 1200℃,holding for 20 minutes.The glossiness of the prepared glazed glass-ceramics is up to 82GU,and the bending strength is 108.4 MPa.the glazed glass-ceramics with good architectural decoration effect can be prepared by two-step sintering.