Study Of Crystallization Behavior In Blast Furnace Slag Glass-Ceramics

As a new type of inorganic polycrystalline solid material,glass-ceramics are widely used in mechanical manufacturing,architecture,biomedicine,electronics,aerospace and military fields because of its good thermal stability,wear resistance,corrosion resistance,toughness and high hardness,mechanical strength.Blast furnace slag is a by-product of the steel smelting process,now most of the methods to use blast furnace slag have a lower level.Unutilized blast furnace slag will be disposed of in idle accumulation mode,which is not only occupying land but also polluting the environment.In this paper,blast furnace slag is used to prepare the excellent performance of glass-ceramics,while widening the utilization of blast furnace slag also relieved the environmental pressure.The main conclusions of the dissertation are as follows:(1)CaO,MgO,Al2O3 and SiO2 were taken as the main raw materials to simulate blast furnace slag.The effects of the ratio of four main raw materials on the crystallization behavior,microstructure,crystalline phase composition and mechanical properties of glass-ceramics were studied systematically by orthogonal test.The crystallization kinetics of the basic glass was analyzed by DTA;The microstructure and the crystal phase composition of the glass ceramics were studied by SEM and XRD;Mechanical properties of the glass ceramics were determined by flexural strength,density,acid and alkaline corroosion.As a new idea,I look the average crystal growth index as the research target.The test showed that the optimal proportion of the raw materials are CaO:32%;MgO:13%;Al2O3:8%;SiO2:47%.The average crystal growth index of sample prepared under the optimal condition is 2.46;and flexural strength is 147.4 Mpa,volume density is 2.71 g·cm-3,mass loss after acid and alkaline corrosion were 0.37%and 0.081%.All properties are in the excellent level.(2)According to the obtained optimal proportion of basic glass components,blast furnace slag was used to prepare glass-ceramics.The effect of heat treatment on the microstructure,crystal phase composition and mechanical properties of glass-ceramics were studied Systematically.The average crystal growth index of blast furnace slag basic glass is 2.46;The optimal heat treatment process of blast furnace slag glass-ceramic is 790℃ nucleation 90 min,then raised to 900℃ crystallization 90 min at 4℃/min heating rate.The glass-ceramic samples prepared according to the heat treatment have a flexural strength of 121 MPa and a density of 2.56 g·cm-3,the mass loss rates after acid and alkaline corrosion are 0.47%and 0.109%.