| The main components of water-quenched slag of Baotou Iron and Steel Company No.6BF are CaO,SiO2,Al2O3 and MgO.These four components basically meet the requirements of CAMS glass-ceramics.The titanium dioxide,Fe2O3 and fluoride contained in the slag can also promote the crystallization of glass-ceramics.Considering the above two points,the slag of Baotou Iron and Steel Company is suitable for preparing silicate glass-ceramics.Silicate glass-ceramics are superior to natural stone materials such as marble and granite in mechanical properties,physical and chemical properties and corrosion resistance to a certain extent.Therefore,they are widely used in construction and have broad prospects for development in the future.In this study,CaO-MgO-Al2O3-SiO2 glass-ceramics with pyroxene as the main crystalline phase were prepared by melting method with Baotou Iron and Steel Company blast furnace slag as the main raw material.Reasonable values of basic glass components were determined by calculation with Factsage 7.1 thermodynamic software.On the basis of the previous research on the amount of blast furnace slag and the selection and proportion of nucleating agent in the preparation of glass-ceramics,this paper mainly studies the effect of heat treatment system on the crystallization behavior and physical and chemical properties of glass-ceramics with large proportion of molten blast furnace slag.DTA method and scanning electron microscopy?SEM?method are used to analyze the effect of heat treatment on the crystallization behavior of glass-ceramics with large proportion of molten blast furnace slag.The bending strength of the samples after heat treatment was tested,and the bending strength was taken as a measure index.Through orthogonal test,the heat treatment system was optimized,and the optimum heat treatment system and the corresponding physical and chemical properties of glass-ceramics prepared from blast furnace slag of Baotou Iron and Steel Company.were obtained.The results are as follows:1.According to the calculation of Factsage 7.1 thermodynamic software,the composition of glass-ceramics is determined as"30%CaO+51%SiO2+11%Al2O3+8%MgO".The content of magnesia-alumina Diopside is 43.9-44.1wt%,wollastonite is26.9-28.6wt%,feldspar is 25.9-28.4 wt%,and there is no yellowstone.2.According to the previous research on the amount of blast furnace slag and the ratio of nucleating agent,the optimum content of blast furnace slag in basic glass is 70%,and the optimum ratio of nucleating agent is 1%Cr2O3 and 4%TiO2.The glass-ceramics prepared on this basis have the best properties.3.The corresponding heat treatment system was obtained by DTA analysis,and the heat treatment system for preparing glass-ceramics was optimized by orthogonal test with the flexural strength as the index.The results show that crystallization temperature is the most important factor affecting the flexural strength of glass-ceramics,followed by nucleation time,and nucleation temperature and crystallization time have the least effect on the flexural strength of glass-ceramics.4.Through orthogonal test,the optimum heat treatment system for preparing glass-ceramics from large proportion of molten blast furnace slag at Baotou Steel is determined as follows:nucleation temperature 750°C heat preservation for 2.5 h,crystallization temperature 930°C heat preservation for 1 h,and its flexural strength can reach 102.2 MPa.Under this system,the properties of glass-ceramics are obviously better than those of other groups in orthogonal test.In the current research,the properties of the prepared glass-ceramics are in the middle and upper level. |
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