As core and foundational materials for high-temperature processes in industries such as iron and steel,nonferrous metals,cement,glass,ceramics,chemicals,machinery,electric power,and national defense,refractories are d...As core and foundational materials for high-temperature processes in industries such as iron and steel,nonferrous metals,cement,glass,ceramics,chemicals,machinery,electric power,and national defense,refractories are directly pivotal to the operational stability and technological innovation of these sectors.However,the industry currently confronts multiple challenges,including constraints on raw material resources,bottlenecks in process technology,and a lag in intelligent transformation.To break through this development impasse from a scientific and technological innovation perspective,it is proposed to focus on diversified market demands,fully leverage the advantageous properties of raw mineral resources,accelerate integration and transformation through the“Artificial Intelligence+Refractories”model,and strengthen the development of original innovation capabilities.Through theoretical research and practical exploration,preliminary laboratory-scale results have been achieved,providing a new pathway and reference for the high-quality development of the refractory industry.展开更多
To develop specific lining materials for rare earth steel nozzles,LaAlO_(3)powder was first synthesized by high-temperature solid-phase synthesis at 1400℃for 3 h using La_(2)O_(3)and Al_(2)O_(3)powders as raw materia...To develop specific lining materials for rare earth steel nozzles,LaAlO_(3)powder was first synthesized by high-temperature solid-phase synthesis at 1400℃for 3 h using La_(2)O_(3)and Al_(2)O_(3)powders as raw materials.Then BN,AlN,Si_(3)N_(4)and TiN powders were pressed intoφ30 mm×7 mm substrate samples under 120 MPa with PVA as the binder.Equal amounts of La_(2)O_(3)and LaAlO_(3)powders were placed on their surfaces,reacting at 1550℃for 3 h in different atmospheres(reducing and argon conditions).The interfacial reactions of the four nitride(BN,Si_(3)N_(4),AlN,and TiN)substrate samples with La_(2)O_(3)and LaAlO_(3)in different atmospheres were studied,respectively.The results show that in reducing and argon atmospheres,the intensity order of the reactions between the four nitrides and La_(2)O_(3)is Si_(3)N_(4)>BN>AlN>TiN.In the reducing atmosphere,the reaction intensity order of the four nitrides with LaAlO_(3)is Si_(3)N_(4)>AlN≈TiN>BN.However,in the argon atmosphere,the order is Si_(3)N_(4)>BN>AlN≈TiN.TiN has good structural stability in both reducing and argon atmospheres,and shows weak reactivity with La_(2)O_(3)and LaAlO_(3).It is a relatively good anti-clogging lining material for rare earth steel nozzles.展开更多
To resolve severe slag penetration and erosion in Al_(2)O_(3)-SiC-C refractories during high scrap ratio iron ladle operation,a novel strategy utilizing exogenous MgAl_(2)O_(4) spinel as a sacrificial FeO_(x) scavenge...To resolve severe slag penetration and erosion in Al_(2)O_(3)-SiC-C refractories during high scrap ratio iron ladle operation,a novel strategy utilizing exogenous MgAl_(2)O_(4) spinel as a sacrificial FeO_(x) scavenger was proposed.Al_(2)O_(3)-SiC-C refractories produced with plate-like corundum,silicon carbide,and flake graphite incorporating MgAl_(2)O_(4) additives were cured at 1400℃ in the condition of carbon embedding.The impacts of additives on phase composition,microscopic morphology,and performance of materials were studied.The results indicated that Al_(2)O_(3)-SiC-C refractories with the addition of 2 wt.%MgAl_(2)O_(4) exhibited a smaller oxidation area after oxidation tests compared to samples without MgAl_(2)O_(4),resulting in 28%improvement in oxidation resistance compared to blank samples.In the erosion test,the results informed that adding 4 wt.%MgAl_(2)O_(4) induced significant interfacial slag modification:MgAl_(2)O_(4) dynamically dissolved FeO_(x) to form protective Mg(Fe,Al)_(2)O_(4) solid solution on the slag-refractory interface.This sacrificial dissolution effectively immobilized FeO_(x),elevated local slag viscosity,and fundamentally inhibited slag penetration and matrix dissolution.The erosion index decreased from 50%in the blank group to 27.4%.展开更多
Henan refractories industry is a major refractory production base in China,which is also an advantage industry in Henan province.Recently,Henan provincial government has formulated relevant industrial and environmenta...Henan refractories industry is a major refractory production base in China,which is also an advantage industry in Henan province.Recently,Henan provincial government has formulated relevant industrial and environmental protection policies,and approved the construction of“Henan Province New Refractory Industry Cluster”.Henan’s main refractory enterprises have developed a series of green technologies,processes and products,and carried out automation and intelligent transformation,equipment upgrading,and the deep integration of information technology and refractory manufacturing through interconnection and digital empowerment.To promote the high-quality development of refractory industry,The Association of Henan Refractory Industry has established a series of standards and evaluation systems of refractories including air pollutant emission,energy consumption limits,carbon emission limits,green products,etc.The Association of Henan Refractory Industry also organized exchanges and mutual cooperation between enterprises inside and outside the region,and guided the development of specialization,refinement and innovation.This paper summarized the relevant works of refractories in Henan,and put forward some suggestions for solving the existing problems of refractories in Henan.展开更多
Nitrogen gas pressure sintering was successfully employed to achieve the in-situ formation of Si_(3)N_(4)-bonded MgO-C refractories.The primary objective was to investigate the influence of different gas pressures on ...Nitrogen gas pressure sintering was successfully employed to achieve the in-situ formation of Si_(3)N_(4)-bonded MgO-C refractories.The primary objective was to investigate the influence of different gas pressures on the mechanical properties and microstructure of MgO-C refractories.The results indicate that higher nitrogen pressure promotes the transformation of silicon nitride from theαphase to theβphase.This phase transition positively impacts the mechanical properties of Si_(3)N_(4)-bonded MgO-C refractories,leading to an enhancement in their overall strength.Notably,when the nitrogen pressure was set at 3 MPa,exceptional compressive strength of 109.7 MPa and an elastic modulus of 142.4 GPa were achieved by these prepared refractories.These findings highlight the great potential for utilizing gas pressure sintered Si_(3)N_(4)-MgO-C refractories.展开更多
The microstructure and phase composition of high-alumina,chromic oxide,and AZS/Cr refractories containing 30%and 60%(by mass)Cr_(2)O_(3) after exposure to aluminaboronsilicate glasses and basalt melts depending on the...The microstructure and phase composition of high-alumina,chromic oxide,and AZS/Cr refractories containing 30%and 60%(by mass)Cr_(2)O_(3) after exposure to aluminaboronsilicate glasses and basalt melts depending on the type of melts and temperature have been studied.The mechanisms of refractory corrosion by the used melts and the factors contributing to the inhibition of corrosion development have been investigated by the method of petrographic analysis.On the basis of obtained results,the use of high-alumina,chromic oxide,and AZS/Cr refractories in the sections of glass furnace linings,experiencing the intensive impact of aluminaboronsilicate glasses and basalt melts,has been confirmed and scientifically substantiated.展开更多
Traditional magnesia-based refractories face challenges such as high thermal conductivity and poor slag penetration resistance,which contradict the energy efficiency requirements of modern metallurgy.In this study,mic...Traditional magnesia-based refractories face challenges such as high thermal conductivity and poor slag penetration resistance,which contradict the energy efficiency requirements of modern metallurgy.In this study,microporous magnesia was prepared using low-grade magnesite via the one-step sintering method.The microstructure and properties of microporous magnesia prepared by high-silicon and high-calcium magnesites calcined at various temperatures were compared.The pore structure and phase evolution were analyzed,the effect of which on the properties of lightweight magnesia-based dry vibration mix was discussed.The results indicated that within high-silicon magnesite,SiO_(2) initially reacted with Mgo to form Mg_(2)Si0_(4),which gradually reacted with Cao impurities as the temperature increased transforming into a Mgo-Cao-SiO_(2) ternary liquid phase and uniformly permeated along the grain boundaries.Due to the bridging effect of strip-like Cao in high-calcium magnesite,the reorganization and sintering of Mgo grains at high temperatures were inhibited,resulting in the presence of a significant number of elongated pores within the magnesia after calcination at various temperatures,which was detrimental to the mechanical properties and slag resistance.The microporous Mg0 prepared by high-silicon magnesite at 1700°C exhibited the superior physical properties.The microporous Mgo aggregates had a stronger interlocking force with the matrix,resulting in a greater bonding strength.Moreover,the micropores not only effectively reduced the thermal conductivity but also facilitated the supersaturated precipitation of molten slag,hindering further penetration.Compared to the dry vibration mix prepared by fused Mgo,the lightweight magnesia-based dry vibration mix prepared with the high-silicon magnesite exhibited higher mechanical strength(~40%increase)and thermal insulation performance(0.870 W·(m·K)at 1000 C),and improved slag resistance.展开更多
development of refractories with low reactivity to rare earth inclusions is an important direction to solve the problem of the nozzle clogging of rare earth steel.La_(2)Ce_(2)O_(7),La_(2)Zr_(2)O_(7),and LaAlO_(3)powde...development of refractories with low reactivity to rare earth inclusions is an important direction to solve the problem of the nozzle clogging of rare earth steel.La_(2)Ce_(2)O_(7),La_(2)Zr_(2)O_(7),and LaAlO_(3)powders were synthesized using the high-temperature solid-state method with La_(2)O_(3),CeO_(2),ZrO_(2),and Al2O_(3)(particle sizes of 5-10μm)as raw materials,firing at 1400℃for 2 h.Subsequently,La_(2)Ce_(2)O_(7),La_(2)Zr_(2)O_(7),and Y_(2)O_(3)powders were pressed intoφ30 mm×7 mm substrate samples with PVA as a binder;and equal amounts of La_(2)O_(3),La_(2)S_(3),and LaAlO_(3)powders were placed on their surfaces.The samples were then fired at 1550℃for 3 h with carbon embedded.The interfacial reaction of the three rare earth oxide refractories(La_(2)Ce_(2)O_(7),La_(2)Zr_(2)O_(7),and Y_(2)O_(3))with the main rare earth inclusions(La_(2)O_(3),La_(2)S_(3),and LaAlO_(3))in molten rare earth steel was studied.The results show that the La_(2)Ce_(2)O_(7)sample has poor structural stability and readily reacts with La_(2)S_(3),leading to cracking.The La_(2)Zr_(2)O_(7)sample reacts with La_(2)O_(3)and LaAlO_(3)weakly,but performs poor La_(2)S_(3)corrosion resistance.The Y_(2)O_(3)sample demonstrates the weakest interaction with the three rare earth inclusions as well as the most stable structure,indicating significant potential as a specialized anti-clogging lining material for rare earth steel.展开更多
β-Sialon has emerged as a promising material for enhancing the service life of Al_(2)O_(3)-C refractories due to its excellent physicochemical properties.The impact of varying concentrations of nanometer Al/Si alloy ...β-Sialon has emerged as a promising material for enhancing the service life of Al_(2)O_(3)-C refractories due to its excellent physicochemical properties.The impact of varying concentrations of nanometer Al/Si alloy on the in-situ synthesis of β-Sialon within Al_(2)O_(3)-C refractory materials,as well as its oxidation behavior,was investigated.The findings indicate that the presence of Al/Si alloy promotes the formation of AlN and SiC whiskers at 1300℃,which subsequently facilitate the production of plate-like β-Sialon at 1500℃.Density functional theory analysis reveals that the(020)crystal plane of β-Sialon exhibits the lowest adsorption energy for Al2O and AlO molecules under the influence of iron atoms,suggesting a solid-liquid-vapor growth mechanism for β-Sialon formation.The introduction of these ceramic phases significantly enhances the mechanical properties of Al_(2)O_(3)-C refractories.Specifically,the addition of 6 wt.%Al/Si alloy yielded specimens with the highest cold modulus of rupture and cold crushing strength at 1500℃,achieving values of 35.2 and 127.5 MPa,respectively--representing increases of 40.1%and 37.4%.Furthermore,during high-temperature oxidation,the formation of plate-like β-Sialon leads to the development of a dense protective layer on the surface.This impedes the diffusion pathways of oxygen and consequently enhances the oxidation resistance of the refractory.展开更多
An experiment was conducted to assess the impact of fused calcia-stabilized zirconia micro-powder on the thermal shock behavior of magnesia–spinel refractories.The effects of calcia-stabilized zirconia on the microst...An experiment was conducted to assess the impact of fused calcia-stabilized zirconia micro-powder on the thermal shock behavior of magnesia–spinel refractories.The effects of calcia-stabilized zirconia on the microstructure evolution and properties of magnesia–spinel refractories were characterized by the high-temperature elastic modulus,thermal shock damage resistance parameters,retainment of elastic modulus after thermal shock,and scanning electron microscopy.The results indicated that the incorporation of calcia-stabilized zirconia improved the thermomechanical properties and thermal shock behavior of magnesia–spinel specimens.The hot modulus of rupture of magnesia–spinel specimens increased by 2.5-fold due to the incorporation of calcia-stabilized zirconia micro-powder.The presence of a martensitic phase transformation in partially unstable ZrO2 and thermal mismatches among various phases contributed to a controlled formation of microcracks.And the pinning effect caused by the calcia-stabilized zirconia particles surrounding the grain boundaries played a crucial role in preventing the propagation of microcracks.This phenomenon significantly bolstered the thermal shock stability of magnesia–spinel refractories,consequently prolonging their service life.展开更多
MgO–CaO refractories have attracted much attention in the field of clean steel due to the ability of their internal CaO to adsorb elements such as S and P in molten steel.However,there are still some problems such as...MgO–CaO refractories have attracted much attention in the field of clean steel due to the ability of their internal CaO to adsorb elements such as S and P in molten steel.However,there are still some problems such as difficult sintering and insufficient corrosion resistance existing in this system.Different contents of Y_(2)O_(3) were introduced into MgO–CaO system to prepare MgO–CaO–Y_(2)O_(3) ternary refractories via traditional and induction sintering methods.The influence of microstructural regulation on the slag-resistant properties of the refractories was investigated.The results show that the introduction of Y_(2)O_(3) in the MgO–CaO refractories prepared via the two sintering methods leads to the grain boundary reconstruction effect.Under the condition of traditional sintering,when a smaller amount of Y_(2)O_(3) is introduced into the MgO–CaO refractories,Y_(2)O_(3) is able to activate the lattice,promote sintering,and improve the densification of the refractories.However,when more Y_(2)O_(3) is introduced,the excess Y_(2)O_(3) hinders the sintering densification process.Combined with lamellar intergranular phase generated in the refractories,Y_(2)O_(3)-based solid solution can react with the slag,increase the slag viscosity and inhibit the penetration of the slag into the refractories.Under the condition of induction sintering,the solid solution of yttrium ions in CaO is increased by using the coupling of electromagnetic and thermal fields.Compared with the MgO–CaO refractories with high Y_(2)O_(3) content prepared by traditional sintering,the induction sintered refractories have higher densification,which further increases the corrosion resistance.The results provide a new path for developing long-life MgO–CaO based refractories.展开更多
The low cost and high efficient clean steels metallur- gy has been focused much attention in China. Among the factors affecting the cleanliness and consequent quali- ty of steel products, refractories are one of the k...The low cost and high efficient clean steels metallur- gy has been focused much attention in China. Among the factors affecting the cleanliness and consequent quali- ty of steel products, refractories are one of the key fac- tors. Meanwhile the restriction of resource, energy and environment is getting stronger, thus the improvement of refractories becontes much more important. In this paper, refractories selection principle Jbr clean steel production according to their thermodynamic features was ex- plained; refractories for tundLsh and flow control in con- tinuous casting, which play important roles in prohibi- ring secondary contamination of molten steel, were intro- duced. Moreover, new development of low-carbon and carbon-free refractory materials was also described.展开更多
Based on the relevant phase diagrams of ternary system in MgO - CaO - ZrO2 - SiO2 quarternary systems, the phase diagram of Fe - O system and the condensed phase stability area diagram of iron oxides, the corrosion re...Based on the relevant phase diagrams of ternary system in MgO - CaO - ZrO2 - SiO2 quarternary systems, the phase diagram of Fe - O system and the condensed phase stability area diagram of iron oxides, the corrosion resistance of MgO - CaO - ZrO2 refractories to silicate cement, and the forming conditions and prepar- ing measures of hercynite are analyzed.展开更多
Three kinds of composite alumina refractories were prepared with tabular alumina （3-1 and 1-0 mm） as aggregates,tabular alumina powder,α-Al2 O3 micropowder,and Si powder as matrix,adding 3 mass％ hexagonal boron ni...Three kinds of composite alumina refractories were prepared with tabular alumina （3-1 and 1-0 mm） as aggregates,tabular alumina powder,α-Al2 O3 micropowder,and Si powder as matrix,adding 3 mass％ hexagonal boron nitride （h-BN）,3 mass％ flake graphite and 10 mass％ flake graphite,respectively.Cold physical properties,hot modulus of rupture,oxidation resistance,thermal shock resistance and slag corrosion resistance of the specimens were compared.The results show that：（1） physical properties and hot modulus of rupture of Al2 O3-h-BN refractories are slightly different from those of low carbon Al2 O3-C refractories,but better than those of traditional Al2 O3-C refractories with 10 mass％ graphite ; （2） Al2 O3-h-BN refractories have better thermal shock resistance and oxidation resistance than the carbon containing refractories,while similar slag resistance with low carbon Al2 O3-C refractories ; （3） h-BN can replace flake graphite as a starting material for the preparation of composite alumina refractories,considering the overall properties of the material.展开更多
Al2O3-C refractories are widely used as functional elements like nozzles, well blocks, sliding gate plates and stoppers in the continuous casting process of steel production. Application of silicon as a metallic agent...Al2O3-C refractories are widely used as functional elements like nozzles, well blocks, sliding gate plates and stoppers in the continuous casting process of steel production. Application of silicon as a metallic agent in Al2O3-C slide gate plate production is usual. In fact, a non-oxide bond can be generated due to the reaction between silicon and carbon under reducing atmosphere in the plate matrix. This non-oxide bond can enhance the mechanical strength and abrasion resistance. In order to improve the mechanical and thermo-mechanical properties, functional additives can be aimed to lower the sinte- ring temperature and tailor the microstructure. For this reason, the effect of a special solid state sintering aid addition on the microstructure and thermo-mechanical properties of Al2O3-C slide gate plates in the presence of Si as a metallic component has been investigated. Two types of specimens were pressed at 150 MPa, tempered at 200 ℃ and fired in coke bed at 1 400 ℃ , respectively. Physical （ BD and AP ） , mechanical （ CCS and MOR ） and thermo-mechanical （ HMOR ） properties were determined; in addition, phase composition was characterized by X-ray diffraction analysis （ XRD ） and microstructure of specimens was investigated by field emission scanning electron microscopy （FESEM）. Results have shown that the addition of sintering aid increased the generation of cation vacancy in Al2O3 structure which enhanced the cation diffusion and densification process ; consequently, CCS, MOR and HMOR of specimens increased drasticallywhile bulk density and apparent porosity remained un- changed.展开更多
Optical microscopes with polishing equipment possess high performance/cost ratio for refractories industry. Here, the preparation of polishing sections of refractory materials and products and their observation under ...Optical microscopes with polishing equipment possess high performance/cost ratio for refractories industry. Here, the preparation of polishing sections of refractory materials and products and their observation under microscopes were introduced in detail. The observation of microstructures helps to improve and optimize production process. Optical microscopes can observe （1） homogenous or inhomogeneous composition distribution to improve mixing intensity; （2） coarse grains contact or not and contacted grain edges broken or intact to adjust the pressing parameters to avoid overpressure ; （ 3 ） the filling degree of components to optimize the particle size distribution; （4） the sintering necks and bridges and matrix shrinkage status to adjust sintering intensity or sintering atmosphere; （5） the crack edge in round or sharp to know when the cracks formed （ before or after entering sintering zone） and take countermeasures ; （6） used refractories to find the wear mechanism.展开更多
Refractory materials have been widely used in high-temperature industries,in which the boron content has a great influence on the performance.To control the detection quality and satisfy the requirement of production ...Refractory materials have been widely used in high-temperature industries,in which the boron content has a great influence on the performance.To control the detection quality and satisfy the requirement of production and scientific research of refractories,conditional tests involving three methods for the boron determination(alkali titrimetry,inductively coupled plasma atomic emission spectrometry(ICP-AES),and curcumin absorption spectrophotometry)were carried out in this work.The affecting factors on the determination of boron were analyzed and discussed by performing the experiment.The results show that compared with curcumin absorption spectrophotometry,alkali titrimetry and ICP-AES have the advantages of simple operation,quick analysis and high precision(relative standard deviation<5%),which are more appropriate for boron determination in refractories.展开更多
This paper attempts to clarify the systematic works of the refractories for the RH degassers and the ways of improving their lining life. It includes ： （ 1 ） types of RH degassers ; （2） the operating conditions o...This paper attempts to clarify the systematic works of the refractories for the RH degassers and the ways of improving their lining life. It includes ： （ 1 ） types of RH degassers ; （2） the operating conditions of refining and the severely damaged areas in RH degassers ; （3） the reasons why side wall and bottom of lower vessel, throat and snorkels become the severe wear areas are analyzed, such as erosion and abrasion caused by the high circula- tion rate of treated molten steel, thermal and structural spalling by the violent temperature change, high corrosion by the Fe-oxides containing siliceous slag and CaF：riched desulfurization powders attack, degradation of texture by the vaporization of refractory components in vacuum and in oxygen blowing; besides the above men- tioned factors, what other reasons to make the snorkels become the most quick wear elements are also explained; （4） the studies of resistance to refining slags attack and slag penetration and its prevention ; the evaluation of va- rious refractory materials to withstand the attack of slags is based on the experimental results of rotating cylinder method, rotary drum test and induction furnace test, and the phase diagrams analyses; the measures to reduce the slag penetration are discussed, for example the deep of slag penetration can be decreased by reducing the size of brick pores ; （5） suitable refractory materials selection and recent developments for the different severe wear areas in RH, and lining maintenance; （6） refractories for RH to refine silicon steel; （7） the ways of improving RH lining life.展开更多
Carbon nanotubes （CNTs） have been extensively studied over the last two decades since they possess excellent properties.CNTs have been considered as new promising reinforcements for carbon containing refractories （...Carbon nanotubes （CNTs） have been extensively studied over the last two decades since they possess excellent properties.CNTs have been considered as new promising reinforcements for carbon containing refractories （CCRs）.Current research progress of the CNT-reinforced MgO-C and Al2O3-C refractories was summarized in this mini-review,and the CNT-reinforced CCRs possess remarkable mechanical properties and superior thermal shock resistance compared to CCRs without CNTs.展开更多
This paper presents a general survey of roles and progress of fundamental and fitnctional refractories applied in seco Mal：y steelmaking, tundish and mold tnetallurgy along with the evolution of clean steel technolog...This paper presents a general survey of roles and progress of fundamental and fitnctional refractories applied in seco Mal：y steelmaking, tundish and mold tnetallurgy along with the evolution of clean steel technology, focusing on refractories that are to create clean environments, benefit cleanliness and productive efficiency for the clean steal production, in particular, reducing the total oxygen content and inclusion defects in steel. All that arguments have revealed in abundant that the interaction between the clean steel technology and inno vation of refractories is so intimate that the philosophy of clean steel technology would not be accomplished without functioning of the innovated state of the arts refractories in it.展开更多
基金the National Natural Science Foundation of China(51474165 and 51772222)the relevant enterprises for their financial support.
文摘As core and foundational materials for high-temperature processes in industries such as iron and steel,nonferrous metals,cement,glass,ceramics,chemicals,machinery,electric power,and national defense,refractories are directly pivotal to the operational stability and technological innovation of these sectors.However,the industry currently confronts multiple challenges,including constraints on raw material resources,bottlenecks in process technology,and a lag in intelligent transformation.To break through this development impasse from a scientific and technological innovation perspective,it is proposed to focus on diversified market demands,fully leverage the advantageous properties of raw mineral resources,accelerate integration and transformation through the“Artificial Intelligence+Refractories”model,and strengthen the development of original innovation capabilities.Through theoretical research and practical exploration,preliminary laboratory-scale results have been achieved,providing a new pathway and reference for the high-quality development of the refractory industry.
文摘To develop specific lining materials for rare earth steel nozzles,LaAlO_(3)powder was first synthesized by high-temperature solid-phase synthesis at 1400℃for 3 h using La_(2)O_(3)and Al_(2)O_(3)powders as raw materials.Then BN,AlN,Si_(3)N_(4)and TiN powders were pressed intoφ30 mm×7 mm substrate samples under 120 MPa with PVA as the binder.Equal amounts of La_(2)O_(3)and LaAlO_(3)powders were placed on their surfaces,reacting at 1550℃for 3 h in different atmospheres(reducing and argon conditions).The interfacial reactions of the four nitride(BN,Si_(3)N_(4),AlN,and TiN)substrate samples with La_(2)O_(3)and LaAlO_(3)in different atmospheres were studied,respectively.The results show that in reducing and argon atmospheres,the intensity order of the reactions between the four nitrides and La_(2)O_(3)is Si_(3)N_(4)>BN>AlN>TiN.In the reducing atmosphere,the reaction intensity order of the four nitrides with LaAlO_(3)is Si_(3)N_(4)>AlN≈TiN>BN.However,in the argon atmosphere,the order is Si_(3)N_(4)>BN>AlN≈TiN.TiN has good structural stability in both reducing and argon atmospheres,and shows weak reactivity with La_(2)O_(3)and LaAlO_(3).It is a relatively good anti-clogging lining material for rare earth steel nozzles.
基金support from the project supported by the National Natural Science Foundation of China(Grant No.52402034)the Science and Technology Innovation Team Foundation of Hubei Province(Grant No.T2023001)+1 种基金the Natural Science Foundation of Hubei Province(Grant No.2023BAB106)the Natural Science Foundation of Wuhan(Grant No.2024040701010051).
文摘To resolve severe slag penetration and erosion in Al_(2)O_(3)-SiC-C refractories during high scrap ratio iron ladle operation,a novel strategy utilizing exogenous MgAl_(2)O_(4) spinel as a sacrificial FeO_(x) scavenger was proposed.Al_(2)O_(3)-SiC-C refractories produced with plate-like corundum,silicon carbide,and flake graphite incorporating MgAl_(2)O_(4) additives were cured at 1400℃ in the condition of carbon embedding.The impacts of additives on phase composition,microscopic morphology,and performance of materials were studied.The results indicated that Al_(2)O_(3)-SiC-C refractories with the addition of 2 wt.%MgAl_(2)O_(4) exhibited a smaller oxidation area after oxidation tests compared to samples without MgAl_(2)O_(4),resulting in 28%improvement in oxidation resistance compared to blank samples.In the erosion test,the results informed that adding 4 wt.%MgAl_(2)O_(4) induced significant interfacial slag modification:MgAl_(2)O_(4) dynamically dissolved FeO_(x) to form protective Mg(Fe,Al)_(2)O_(4) solid solution on the slag-refractory interface.This sacrificial dissolution effectively immobilized FeO_(x),elevated local slag viscosity,and fundamentally inhibited slag penetration and matrix dissolution.The erosion index decreased from 50%in the blank group to 27.4%.
文摘Henan refractories industry is a major refractory production base in China,which is also an advantage industry in Henan province.Recently,Henan provincial government has formulated relevant industrial and environmental protection policies,and approved the construction of“Henan Province New Refractory Industry Cluster”.Henan’s main refractory enterprises have developed a series of green technologies,processes and products,and carried out automation and intelligent transformation,equipment upgrading,and the deep integration of information technology and refractory manufacturing through interconnection and digital empowerment.To promote the high-quality development of refractory industry,The Association of Henan Refractory Industry has established a series of standards and evaluation systems of refractories including air pollutant emission,energy consumption limits,carbon emission limits,green products,etc.The Association of Henan Refractory Industry also organized exchanges and mutual cooperation between enterprises inside and outside the region,and guided the development of specialization,refinement and innovation.This paper summarized the relevant works of refractories in Henan,and put forward some suggestions for solving the existing problems of refractories in Henan.
基金the financial support from the National Natural Science Foundation of China(U21A2057 and 52402034)the Key Research and Development Program of Hubei Province(2023BAB106).
文摘Nitrogen gas pressure sintering was successfully employed to achieve the in-situ formation of Si_(3)N_(4)-bonded MgO-C refractories.The primary objective was to investigate the influence of different gas pressures on the mechanical properties and microstructure of MgO-C refractories.The results indicate that higher nitrogen pressure promotes the transformation of silicon nitride from theαphase to theβphase.This phase transition positively impacts the mechanical properties of Si_(3)N_(4)-bonded MgO-C refractories,leading to an enhancement in their overall strength.Notably,when the nitrogen pressure was set at 3 MPa,exceptional compressive strength of 109.7 MPa and an elastic modulus of 142.4 GPa were achieved by these prepared refractories.These findings highlight the great potential for utilizing gas pressure sintered Si_(3)N_(4)-MgO-C refractories.
文摘The microstructure and phase composition of high-alumina,chromic oxide,and AZS/Cr refractories containing 30%and 60%(by mass)Cr_(2)O_(3) after exposure to aluminaboronsilicate glasses and basalt melts depending on the type of melts and temperature have been studied.The mechanisms of refractory corrosion by the used melts and the factors contributing to the inhibition of corrosion development have been investigated by the method of petrographic analysis.On the basis of obtained results,the use of high-alumina,chromic oxide,and AZS/Cr refractories in the sections of glass furnace linings,experiencing the intensive impact of aluminaboronsilicate glasses and basalt melts,has been confirmed and scientifically substantiated.
基金National Natural Science Foundation of China(52302027,52272022 and 52472032).
文摘Traditional magnesia-based refractories face challenges such as high thermal conductivity and poor slag penetration resistance,which contradict the energy efficiency requirements of modern metallurgy.In this study,microporous magnesia was prepared using low-grade magnesite via the one-step sintering method.The microstructure and properties of microporous magnesia prepared by high-silicon and high-calcium magnesites calcined at various temperatures were compared.The pore structure and phase evolution were analyzed,the effect of which on the properties of lightweight magnesia-based dry vibration mix was discussed.The results indicated that within high-silicon magnesite,SiO_(2) initially reacted with Mgo to form Mg_(2)Si0_(4),which gradually reacted with Cao impurities as the temperature increased transforming into a Mgo-Cao-SiO_(2) ternary liquid phase and uniformly permeated along the grain boundaries.Due to the bridging effect of strip-like Cao in high-calcium magnesite,the reorganization and sintering of Mgo grains at high temperatures were inhibited,resulting in the presence of a significant number of elongated pores within the magnesia after calcination at various temperatures,which was detrimental to the mechanical properties and slag resistance.The microporous Mg0 prepared by high-silicon magnesite at 1700°C exhibited the superior physical properties.The microporous Mgo aggregates had a stronger interlocking force with the matrix,resulting in a greater bonding strength.Moreover,the micropores not only effectively reduced the thermal conductivity but also facilitated the supersaturated precipitation of molten slag,hindering further penetration.Compared to the dry vibration mix prepared by fused Mgo,the lightweight magnesia-based dry vibration mix prepared with the high-silicon magnesite exhibited higher mechanical strength(~40%increase)and thermal insulation performance(0.870 W·(m·K)at 1000 C),and improved slag resistance.
文摘development of refractories with low reactivity to rare earth inclusions is an important direction to solve the problem of the nozzle clogging of rare earth steel.La_(2)Ce_(2)O_(7),La_(2)Zr_(2)O_(7),and LaAlO_(3)powders were synthesized using the high-temperature solid-state method with La_(2)O_(3),CeO_(2),ZrO_(2),and Al2O_(3)(particle sizes of 5-10μm)as raw materials,firing at 1400℃for 2 h.Subsequently,La_(2)Ce_(2)O_(7),La_(2)Zr_(2)O_(7),and Y_(2)O_(3)powders were pressed intoφ30 mm×7 mm substrate samples with PVA as a binder;and equal amounts of La_(2)O_(3),La_(2)S_(3),and LaAlO_(3)powders were placed on their surfaces.The samples were then fired at 1550℃for 3 h with carbon embedded.The interfacial reaction of the three rare earth oxide refractories(La_(2)Ce_(2)O_(7),La_(2)Zr_(2)O_(7),and Y_(2)O_(3))with the main rare earth inclusions(La_(2)O_(3),La_(2)S_(3),and LaAlO_(3))in molten rare earth steel was studied.The results show that the La_(2)Ce_(2)O_(7)sample has poor structural stability and readily reacts with La_(2)S_(3),leading to cracking.The La_(2)Zr_(2)O_(7)sample reacts with La_(2)O_(3)and LaAlO_(3)weakly,but performs poor La_(2)S_(3)corrosion resistance.The Y_(2)O_(3)sample demonstrates the weakest interaction with the three rare earth inclusions as well as the most stable structure,indicating significant potential as a specialized anti-clogging lining material for rare earth steel.
基金supported by the Natural Science Foundation of Henan Province(No.232300420329)Key Scientific Research Project of Colleges and Universities in Henan Province(Nos.23B430012,22A430028,and 25B430022)+2 种基金Henan Provincial Science and Technology Research Project(No.242102231064)National Natural Science Foundation of China(No.52202064)Luoyang Major Science and Technology Innovation Project(No.2301009A).
文摘β-Sialon has emerged as a promising material for enhancing the service life of Al_(2)O_(3)-C refractories due to its excellent physicochemical properties.The impact of varying concentrations of nanometer Al/Si alloy on the in-situ synthesis of β-Sialon within Al_(2)O_(3)-C refractory materials,as well as its oxidation behavior,was investigated.The findings indicate that the presence of Al/Si alloy promotes the formation of AlN and SiC whiskers at 1300℃,which subsequently facilitate the production of plate-like β-Sialon at 1500℃.Density functional theory analysis reveals that the(020)crystal plane of β-Sialon exhibits the lowest adsorption energy for Al2O and AlO molecules under the influence of iron atoms,suggesting a solid-liquid-vapor growth mechanism for β-Sialon formation.The introduction of these ceramic phases significantly enhances the mechanical properties of Al_(2)O_(3)-C refractories.Specifically,the addition of 6 wt.%Al/Si alloy yielded specimens with the highest cold modulus of rupture and cold crushing strength at 1500℃,achieving values of 35.2 and 127.5 MPa,respectively--representing increases of 40.1%and 37.4%.Furthermore,during high-temperature oxidation,the formation of plate-like β-Sialon leads to the development of a dense protective layer on the surface.This impedes the diffusion pathways of oxygen and consequently enhances the oxidation resistance of the refractory.
基金supported by the Key Project of the National Natural Science Foundation of China(Grant No.U21A2058)the Hebei Guoliang New Materials Co.,Ltd.(Grant No.22150239J).
文摘An experiment was conducted to assess the impact of fused calcia-stabilized zirconia micro-powder on the thermal shock behavior of magnesia–spinel refractories.The effects of calcia-stabilized zirconia on the microstructure evolution and properties of magnesia–spinel refractories were characterized by the high-temperature elastic modulus,thermal shock damage resistance parameters,retainment of elastic modulus after thermal shock,and scanning electron microscopy.The results indicated that the incorporation of calcia-stabilized zirconia improved the thermomechanical properties and thermal shock behavior of magnesia–spinel specimens.The hot modulus of rupture of magnesia–spinel specimens increased by 2.5-fold due to the incorporation of calcia-stabilized zirconia micro-powder.The presence of a martensitic phase transformation in partially unstable ZrO2 and thermal mismatches among various phases contributed to a controlled formation of microcracks.And the pinning effect caused by the calcia-stabilized zirconia particles surrounding the grain boundaries played a crucial role in preventing the propagation of microcracks.This phenomenon significantly bolstered the thermal shock stability of magnesia–spinel refractories,consequently prolonging their service life.
基金financially supported by the National Natural Science Foundation of China(Nos.U20A20239 and U21A2057)the Key Research and Development Project of Hubei Province,China(No.2023BEB017)2023 Longzhong Talent Support Plan(23).
文摘MgO–CaO refractories have attracted much attention in the field of clean steel due to the ability of their internal CaO to adsorb elements such as S and P in molten steel.However,there are still some problems such as difficult sintering and insufficient corrosion resistance existing in this system.Different contents of Y_(2)O_(3) were introduced into MgO–CaO system to prepare MgO–CaO–Y_(2)O_(3) ternary refractories via traditional and induction sintering methods.The influence of microstructural regulation on the slag-resistant properties of the refractories was investigated.The results show that the introduction of Y_(2)O_(3) in the MgO–CaO refractories prepared via the two sintering methods leads to the grain boundary reconstruction effect.Under the condition of traditional sintering,when a smaller amount of Y_(2)O_(3) is introduced into the MgO–CaO refractories,Y_(2)O_(3) is able to activate the lattice,promote sintering,and improve the densification of the refractories.However,when more Y_(2)O_(3) is introduced,the excess Y_(2)O_(3) hinders the sintering densification process.Combined with lamellar intergranular phase generated in the refractories,Y_(2)O_(3)-based solid solution can react with the slag,increase the slag viscosity and inhibit the penetration of the slag into the refractories.Under the condition of induction sintering,the solid solution of yttrium ions in CaO is increased by using the coupling of electromagnetic and thermal fields.Compared with the MgO–CaO refractories with high Y_(2)O_(3) content prepared by traditional sintering,the induction sintered refractories have higher densification,which further increases the corrosion resistance.The results provide a new path for developing long-life MgO–CaO based refractories.
文摘The low cost and high efficient clean steels metallur- gy has been focused much attention in China. Among the factors affecting the cleanliness and consequent quali- ty of steel products, refractories are one of the key fac- tors. Meanwhile the restriction of resource, energy and environment is getting stronger, thus the improvement of refractories becontes much more important. In this paper, refractories selection principle Jbr clean steel production according to their thermodynamic features was ex- plained; refractories for tundLsh and flow control in con- tinuous casting, which play important roles in prohibi- ring secondary contamination of molten steel, were intro- duced. Moreover, new development of low-carbon and carbon-free refractory materials was also described.
文摘Based on the relevant phase diagrams of ternary system in MgO - CaO - ZrO2 - SiO2 quarternary systems, the phase diagram of Fe - O system and the condensed phase stability area diagram of iron oxides, the corrosion resistance of MgO - CaO - ZrO2 refractories to silicate cement, and the forming conditions and prepar- ing measures of hercynite are analyzed.
文摘Three kinds of composite alumina refractories were prepared with tabular alumina （3-1 and 1-0 mm） as aggregates,tabular alumina powder,α-Al2 O3 micropowder,and Si powder as matrix,adding 3 mass％ hexagonal boron nitride （h-BN）,3 mass％ flake graphite and 10 mass％ flake graphite,respectively.Cold physical properties,hot modulus of rupture,oxidation resistance,thermal shock resistance and slag corrosion resistance of the specimens were compared.The results show that：（1） physical properties and hot modulus of rupture of Al2 O3-h-BN refractories are slightly different from those of low carbon Al2 O3-C refractories,but better than those of traditional Al2 O3-C refractories with 10 mass％ graphite ; （2） Al2 O3-h-BN refractories have better thermal shock resistance and oxidation resistance than the carbon containing refractories,while similar slag resistance with low carbon Al2 O3-C refractories ; （3） h-BN can replace flake graphite as a starting material for the preparation of composite alumina refractories,considering the overall properties of the material.
文摘Al2O3-C refractories are widely used as functional elements like nozzles, well blocks, sliding gate plates and stoppers in the continuous casting process of steel production. Application of silicon as a metallic agent in Al2O3-C slide gate plate production is usual. In fact, a non-oxide bond can be generated due to the reaction between silicon and carbon under reducing atmosphere in the plate matrix. This non-oxide bond can enhance the mechanical strength and abrasion resistance. In order to improve the mechanical and thermo-mechanical properties, functional additives can be aimed to lower the sinte- ring temperature and tailor the microstructure. For this reason, the effect of a special solid state sintering aid addition on the microstructure and thermo-mechanical properties of Al2O3-C slide gate plates in the presence of Si as a metallic component has been investigated. Two types of specimens were pressed at 150 MPa, tempered at 200 ℃ and fired in coke bed at 1 400 ℃ , respectively. Physical （ BD and AP ） , mechanical （ CCS and MOR ） and thermo-mechanical （ HMOR ） properties were determined; in addition, phase composition was characterized by X-ray diffraction analysis （ XRD ） and microstructure of specimens was investigated by field emission scanning electron microscopy （FESEM）. Results have shown that the addition of sintering aid increased the generation of cation vacancy in Al2O3 structure which enhanced the cation diffusion and densification process ; consequently, CCS, MOR and HMOR of specimens increased drasticallywhile bulk density and apparent porosity remained un- changed.
文摘Optical microscopes with polishing equipment possess high performance/cost ratio for refractories industry. Here, the preparation of polishing sections of refractory materials and products and their observation under microscopes were introduced in detail. The observation of microstructures helps to improve and optimize production process. Optical microscopes can observe （1） homogenous or inhomogeneous composition distribution to improve mixing intensity; （2） coarse grains contact or not and contacted grain edges broken or intact to adjust the pressing parameters to avoid overpressure ; （ 3 ） the filling degree of components to optimize the particle size distribution; （4） the sintering necks and bridges and matrix shrinkage status to adjust sintering intensity or sintering atmosphere; （5） the crack edge in round or sharp to know when the cracks formed （ before or after entering sintering zone） and take countermeasures ; （6） used refractories to find the wear mechanism.
文摘Refractory materials have been widely used in high-temperature industries,in which the boron content has a great influence on the performance.To control the detection quality and satisfy the requirement of production and scientific research of refractories,conditional tests involving three methods for the boron determination(alkali titrimetry,inductively coupled plasma atomic emission spectrometry(ICP-AES),and curcumin absorption spectrophotometry)were carried out in this work.The affecting factors on the determination of boron were analyzed and discussed by performing the experiment.The results show that compared with curcumin absorption spectrophotometry,alkali titrimetry and ICP-AES have the advantages of simple operation,quick analysis and high precision(relative standard deviation<5%),which are more appropriate for boron determination in refractories.
文摘This paper attempts to clarify the systematic works of the refractories for the RH degassers and the ways of improving their lining life. It includes ： （ 1 ） types of RH degassers ; （2） the operating conditions of refining and the severely damaged areas in RH degassers ; （3） the reasons why side wall and bottom of lower vessel, throat and snorkels become the severe wear areas are analyzed, such as erosion and abrasion caused by the high circula- tion rate of treated molten steel, thermal and structural spalling by the violent temperature change, high corrosion by the Fe-oxides containing siliceous slag and CaF：riched desulfurization powders attack, degradation of texture by the vaporization of refractory components in vacuum and in oxygen blowing; besides the above men- tioned factors, what other reasons to make the snorkels become the most quick wear elements are also explained; （4） the studies of resistance to refining slags attack and slag penetration and its prevention ; the evaluation of va- rious refractory materials to withstand the attack of slags is based on the experimental results of rotating cylinder method, rotary drum test and induction furnace test, and the phase diagrams analyses; the measures to reduce the slag penetration are discussed, for example the deep of slag penetration can be decreased by reducing the size of brick pores ; （5） suitable refractory materials selection and recent developments for the different severe wear areas in RH, and lining maintenance; （6） refractories for RH to refine silicon steel; （7） the ways of improving RH lining life.
基金financially supported by the National Natural Science Foundation of China ( General program,51272188, 51472184 and 51472185 )the Natural Science Foundation of Hubei Province,China ( Contract No. 2013CFA086 )Foreign Cooperation Projects in Science and Technology of Hubei Province,China ( Contract No. 2013BHE002)
文摘Carbon nanotubes （CNTs） have been extensively studied over the last two decades since they possess excellent properties.CNTs have been considered as new promising reinforcements for carbon containing refractories （CCRs）.Current research progress of the CNT-reinforced MgO-C and Al2O3-C refractories was summarized in this mini-review,and the CNT-reinforced CCRs possess remarkable mechanical properties and superior thermal shock resistance compared to CCRs without CNTs.
文摘This paper presents a general survey of roles and progress of fundamental and fitnctional refractories applied in seco Mal：y steelmaking, tundish and mold tnetallurgy along with the evolution of clean steel technology, focusing on refractories that are to create clean environments, benefit cleanliness and productive efficiency for the clean steal production, in particular, reducing the total oxygen content and inclusion defects in steel. All that arguments have revealed in abundant that the interaction between the clean steel technology and inno vation of refractories is so intimate that the philosophy of clean steel technology would not be accomplished without functioning of the innovated state of the arts refractories in it.
