Research And Application Of Viscosity-Temperature Relationship Of CaO-Al₂O₃-MgO-SiO₂ Slag Glass-Ceramics

Slag glass ceramics prepared from waste residue such as tailings,slags discharged from industrial mining and fly ashes produced by power plant,is one of the most important branches of glass ceramics.Slags glass ceramics requires higher preparation technology,which signify a higher temperature during melting.Therefore,reducing the high temperature viscosity remains a momentous issue for the industrialization of slag glass ceramics.This paper studies the CaO-Al₂O₃-MgO-SiO₂?CAMS?quaternary slag glass ceramics prepared from Bayan Obo slags,fly ashes and chromium slags by conventional melt casting method,with external addition of Fe₂O₃,Cr₂O₃ and La₂O₃.The high temperature viscosity is measured by viscometer.The crystallization behavior and crystalline phases are detected by Differential Scanning Calorimeter?DSC?and X-Ray Diffraction?XRD?.Moreover,the microstructure and microzone composition are developed by Field Emission Scanning Electron Microscope?FESEM?.The physicochemical properties such as bending strength and corrosion resistance are measured as well.The effect of viscosity on production is studied in response to the effects of different high temperature viscosities on the various processes in the production site.The addition of different quantities of Fe₂O₃,Cr₂O₃ and La₂O₃ makes diverse difference on high temperature viscosity of slag glass ceramics during melting and physical and chemical properties of glass melts after heat treatment,which indicated that Fe₂O₃ and La₂O₃ play roles in decreasing the viscosity,while the addition of Cr₂O₃ leads to a promotion of melt viscosity.The change in the addition of the three components has different effects on the infrared spectrum of the base glass.Both the melting and crystallization temperature are reduced generally with the addition of Fe₂O₃ and Cr₂O₃,which implies a promotion of glass devitrification and increment of crystallization capacity,while La₂O₃ depresses the devitrification.There is no effect on the crystal structure of the glass-ceramic main phase,which is the diopside phase?Diopside?.Besides,the addiction of the three metallic oxides dose not have obvious effect on crystalline phases,density,corrosion resistance and Mohs hardness of slag glass ceramics samples,either.Notably,the bending strength varied because of the three metallic oxides,which shows a debasement trend settling in 200 MPa with the addition of Fe₂O₃.Besides,the addition of Cr₂O₃large impact of the flexural strength.Interestingly,the flexural strength of samples with La₂O₃decrease initially and then increase.According to the observation recording of the industrialization site,the viscosities of different high temperature melts may play a decisive role in setting the centrifuge parameters during centrifugal casting,such as the selection of centrifuge speed,centrifugation time and intersection position.When the viscosity of the glass liquid is too large,the viscosity is easy to adhere to the surface of the product or enter the inner part of the workpiece,resulting in the forming failure;When the viscosity is too small,segregation will be caused by centrifugal force,resulting in delamination after heat treatment.The high temperature melt viscosity will have an important impact on the performance and yield of subsequent products.