The in-situ formation mechanism of MgAl_(2)O_(4) was introduced,focusing on the formation process by solid phase reaction and gas phase reaction as well as the phenomenon of secondary spinelization.The influencing fac...The in-situ formation mechanism of MgAl_(2)O_(4) was introduced,focusing on the formation process by solid phase reaction and gas phase reaction as well as the phenomenon of secondary spinelization.The influencing factors of the in-situ MgAl_(2)O_(4) formation and its effect on the microstructure and the properties of materials were systematically summarized for the Al2O3-MgO-MgAl_(2)O_(4) system and the carbon-containing refractories systems.It was pointed out that the in-situ formation of MgAl_(2)O_(4),including secondary spinelization,can regulate the microstructure and the service performance of materials.Its expansion effect can not only offset the shrinkage caused by sintering to improve the corrosion resistance of refractories,but also seriously restrict the reliability of functional refractories.The composition,the particle size,the atmosphere,and the temperature are important factors affecting the in-situ formation of MgAl_(2)O_(4).In the carbon-containing materials systems,the solid-solid reaction and the gas-solid reaction coexist to produce MgAl_(2)O_(4),which provides an effective way to further regulate the microstructure and the properties of materials through the reaction process.展开更多
Four-hole submerged entry nozzles （SEN） with dif- ferent structures were researched using the water simula- tion test by particle image velocimetry （PIV） and DJSO0 hydraulic measurement system to get suitable SEN ...Four-hole submerged entry nozzles （SEN） with dif- ferent structures were researched using the water simula- tion test by particle image velocimetry （PIV） and DJSO0 hydraulic measurement system to get suitable SEN for high efficiency continuous casting. The influences of the exit area ratio （2： 1：2, 3：2： 3, 1： 1：1 and 1：2： 1）, upper guide island angle θ （20°, 40°, 60° and 80°） , and lower guide island angle α （60°, 80°, 100° and 120°） on the vortex position in the mold and fluctuations were researched. The results show that the exit area ratio and the upper and low guide island angles have ob- vious influence on the flow field; the flow field in the mold is suitable at 1：2：1 of the exit area ratio, 80° of upper guide island angle, and 100° of lower guide island angle.展开更多
In order to improve the properties of alumina-carbon refractories,specimens were prepared using white fused corundum,zirconia-mullite and flake graphite as the raw materials,phenolic resin as the binder,adding differe...In order to improve the properties of alumina-carbon refractories,specimens were prepared using white fused corundum,zirconia-mullite and flake graphite as the raw materials,phenolic resin as the binder,adding different mass fractions(1.5%,2.0%,and 2.5%,respectively)of glass dust,cold isostatic pressing by 120 MPa,drying and firing at 900℃for 3 h.Effects of the glass dust addition on the apparent porosity,bulk density,cold modulus of rupture,hot modulus of rupture and thermal shock resistance were studied.The results show that the cold modulus of rupture of the specimens is improved significantly as the results of glass dust accelerating sintering.However,the hot modulus of rupture decreases.As the glass phase buffers the strain produced by thermal shock,the thermal shock resistance of alumina-carbon specimens is improved,especially for low carbon alumina-carbon materials.展开更多
The long nozzle,stopper,and submerged entry nozzle play an important role in continuous casting. They are of the similar composition and are mainly damaged by liquid steel thermal shock which leads to immediate cracks...The long nozzle,stopper,and submerged entry nozzle play an important role in continuous casting. They are of the similar composition and are mainly damaged by liquid steel thermal shock which leads to immediate cracks or fracture in their combined area because of the thermal mechanical properties mismatch,or damaged by corrosion on their interface. The failure mechanisms are the thermal shock damage and continuous reaction corrosion. High efficiency and long life of the long nozzle,stopper,and submerged entry nozzle can be realized by optimizing the thermal mechanical properties,the key erosion step,and the combination match.展开更多
The causes, the formation process, and the prevention of submerged entry nozzle(SEN) clogging were introduced. The influence of electric field on the SEN clogging was focused on, including the basic theory and measure...The causes, the formation process, and the prevention of submerged entry nozzle(SEN) clogging were introduced. The influence of electric field on the SEN clogging was focused on, including the basic theory and measurement of SEN charging,the preliminary research on SEN charging, the influence of molten steel on the wetting behavior of refractory materials in electric field, and the influence of electric field on the oxide inclusions in molten steel. Based on the influence of the hydrodynamics, chemistry and other factors on refractory materials, structure, inclusion particle transfer and adhesion, many anti-clogging researches have been carried out, such as optimizing process conditions, compositing anti-clogging inner lining materials, innovating SEN structure and applying physical fields, which solve the problem of SEN clogging to a certain extent.However, the problems of weak adaptability and superficial study on clogging mechanism are still prominent. The electric field control is a new technology to prevent clogging. Although it has achieved certain results in on-site continuous casting trials,some problems such as the method of applying electric field, the electric field parameters and the equipment still need to be gradually improved, and the surface characteristics of inclusions and SEN materials at high temperatures need to be further studied. It was pointed out that the combination of materials and applied electric field will become an important direction for SEN anti-clogging technology.展开更多
基金supported by the National Key Research and Development Program of China(2021YFB3701400)the Natural Science Foundation of China(51932008)Central Plains Science and Technology Innovation Leader(204200510011).
文摘The in-situ formation mechanism of MgAl_(2)O_(4) was introduced,focusing on the formation process by solid phase reaction and gas phase reaction as well as the phenomenon of secondary spinelization.The influencing factors of the in-situ MgAl_(2)O_(4) formation and its effect on the microstructure and the properties of materials were systematically summarized for the Al2O3-MgO-MgAl_(2)O_(4) system and the carbon-containing refractories systems.It was pointed out that the in-situ formation of MgAl_(2)O_(4),including secondary spinelization,can regulate the microstructure and the service performance of materials.Its expansion effect can not only offset the shrinkage caused by sintering to improve the corrosion resistance of refractories,but also seriously restrict the reliability of functional refractories.The composition,the particle size,the atmosphere,and the temperature are important factors affecting the in-situ formation of MgAl_(2)O_(4).In the carbon-containing materials systems,the solid-solid reaction and the gas-solid reaction coexist to produce MgAl_(2)O_(4),which provides an effective way to further regulate the microstructure and the properties of materials through the reaction process.
基金The National Natrual Science Foundation of China(Grant No.51372231)
文摘Four-hole submerged entry nozzles （SEN） with dif- ferent structures were researched using the water simula- tion test by particle image velocimetry （PIV） and DJSO0 hydraulic measurement system to get suitable SEN for high efficiency continuous casting. The influences of the exit area ratio （2： 1：2, 3：2： 3, 1： 1：1 and 1：2： 1）, upper guide island angle θ （20°, 40°, 60° and 80°） , and lower guide island angle α （60°, 80°, 100° and 120°） on the vortex position in the mold and fluctuations were researched. The results show that the exit area ratio and the upper and low guide island angles have ob- vious influence on the flow field; the flow field in the mold is suitable at 1：2：1 of the exit area ratio, 80° of upper guide island angle, and 100° of lower guide island angle.
基金National Natural Science Foundation of China (51772277)the National Key R&D Program of China (2017YFB0304000)
文摘In order to improve the properties of alumina-carbon refractories,specimens were prepared using white fused corundum,zirconia-mullite and flake graphite as the raw materials,phenolic resin as the binder,adding different mass fractions(1.5%,2.0%,and 2.5%,respectively)of glass dust,cold isostatic pressing by 120 MPa,drying and firing at 900℃for 3 h.Effects of the glass dust addition on the apparent porosity,bulk density,cold modulus of rupture,hot modulus of rupture and thermal shock resistance were studied.The results show that the cold modulus of rupture of the specimens is improved significantly as the results of glass dust accelerating sintering.However,the hot modulus of rupture decreases.As the glass phase buffers the strain produced by thermal shock,the thermal shock resistance of alumina-carbon specimens is improved,especially for low carbon alumina-carbon materials.
文摘The long nozzle,stopper,and submerged entry nozzle play an important role in continuous casting. They are of the similar composition and are mainly damaged by liquid steel thermal shock which leads to immediate cracks or fracture in their combined area because of the thermal mechanical properties mismatch,or damaged by corrosion on their interface. The failure mechanisms are the thermal shock damage and continuous reaction corrosion. High efficiency and long life of the long nozzle,stopper,and submerged entry nozzle can be realized by optimizing the thermal mechanical properties,the key erosion step,and the combination match.
基金financially supported by the National Natural Science Foundation of China(51932008 and 51772277)Zhongyuan Science and Technology Innovation Leader(204200510011)
文摘The causes, the formation process, and the prevention of submerged entry nozzle(SEN) clogging were introduced. The influence of electric field on the SEN clogging was focused on, including the basic theory and measurement of SEN charging,the preliminary research on SEN charging, the influence of molten steel on the wetting behavior of refractory materials in electric field, and the influence of electric field on the oxide inclusions in molten steel. Based on the influence of the hydrodynamics, chemistry and other factors on refractory materials, structure, inclusion particle transfer and adhesion, many anti-clogging researches have been carried out, such as optimizing process conditions, compositing anti-clogging inner lining materials, innovating SEN structure and applying physical fields, which solve the problem of SEN clogging to a certain extent.However, the problems of weak adaptability and superficial study on clogging mechanism are still prominent. The electric field control is a new technology to prevent clogging. Although it has achieved certain results in on-site continuous casting trials,some problems such as the method of applying electric field, the electric field parameters and the equipment still need to be gradually improved, and the surface characteristics of inclusions and SEN materials at high temperatures need to be further studied. It was pointed out that the combination of materials and applied electric field will become an important direction for SEN anti-clogging technology.
