This study aims to provide the basic knowledge for furnace refractory design by investigating refractory property changes occurred in a hydrogen atmosphere.Since refractory bricks are thermodynamically stable in a hyd...This study aims to provide the basic knowledge for furnace refractory design by investigating refractory property changes occurred in a hydrogen atmosphere.Since refractory bricks are thermodynamically stable in a hydrogen atmosphere at 1100°C,we tried to find out the minute changes.In this experiment,a refractory brick was prepared by andalusite,mullite chamotte,and clay as raw materials and heated to 1100°C in a 100%hydrogen atmosphere for 72 h.It was found that the strength of the brick was decreased and the color was changed to black by the reduction of impurities.And in addition,this study covered research on the slaking risk of MgO raw materials because the minimum temperature is expected to 400°C in fluidized reduction furnaces unlike shaft furnaces.展开更多
Refractory materials,as the crucial foundational materials in high-temperature industrial processes such as metallurgy and construction,are inevitably subjected to corrosion and penetration from high-temperature media...Refractory materials,as the crucial foundational materials in high-temperature industrial processes such as metallurgy and construction,are inevitably subjected to corrosion and penetration from high-temperature media during their service.Traditionally,observing the in-situ degradation process of refractory materials in complex high-temperature environments has presented challenges.Post-corrosion analysis are commonly employed to assess the slag resistance of refractory materials and understand the corrosion mechanisms.However,these methods often lack information on the process under the conditions of thermal-chemical-mechanical coupling,leading to potential biases in the analysis results.In this work,we developed a non-contact high-temperature machine vision technology by the integrating Digital Image Correlation(DIC)with a high-temperature visualization system to explore the corrosion behavior of Al2O3-SiO2 refractories against molten glass and Al2O3-MgO dry ramming refractories against molten slag at different temperatures.This technology enables realtime monitoring of the 2D or 3D overall strain and average strain curves of the refractory materials and provides continuous feedback on the progressive corrosion of the materials under the coupling conditions of thermal,chemical,and mechanical factors.Therefore,it is an innovative approach for evaluating the service behavior and performance of refractory materials,and is expected to promote the digitization and intelligence of the refractory industry,contributing to the optimization and upgrading of product performance.展开更多
To optimize their Al_(2)O_(3)-SiO_(2) raw materials,anorthite based insulation refractories were prepared by the in-situ sintering process combined with the foaming method after sintering at 1350℃for 3 h,using green ...To optimize their Al_(2)O_(3)-SiO_(2) raw materials,anorthite based insulation refractories were prepared by the in-situ sintering process combined with the foaming method after sintering at 1350℃for 3 h,using green and pollution-free kaolin,kyanite,andalusite and sillimanite as Al_(2)O_(3)-SiO_(2) raw materials,respectively,and industrial CaCO_(3) as the CaO source.Effects of Al_(2)O_(3)-SiO_(2) raw material types on the physical properties,phase composition and microstructure were investigated.The results are as follows.All samples prepared by different Al_(2)O_(3)-SiO_(2) raw materials have hexagonal flake anorthite and a small amount of mullite and corundum.Their bulk density and thermal conductivity decrease in the order of using kaolin,andalusite,kyanite and sillimanite as the Al_(2)O_(3)-SiO_(2) raw material,but their apparent porosity increases.Moreover,in the sample with kaolin,the bonding between anorthite crystals on the pore walls is closer than that of the other samples,which is conducive to increasing the cold crushing strength.The bonding between anorthite crystals on pore walls gradually decreases in the order of using kyanite,andalusite and sillimanite as the Al_(2)O_(3)-SiO_(2) raw material,thus their cold crushing strength decreases accordingly.In comprehensive consideration,the properties of the sample from kyanite are the optimal.Its apparent porosity,thermal conductivity and cold crushing strength are 84.6%,0.141 W·m^(-1)·K^(-1) and 1.89 MPa,respectively.展开更多
Magnesia（MgO） is widely used in the production of refractory materials due to its high melting point,high thermal shock,and excellent slag resistance.The properties of refractory materials depend upon magnesia sourc...Magnesia（MgO） is widely used in the production of refractory materials due to its high melting point,high thermal shock,and excellent slag resistance.The properties of refractory materials depend upon magnesia sources and processing parameters.In this work,three different magnesium sources,namely,magnesium hydroxide concentrate,magnesium carbonate concentrate,and intermediate flotation concentrate,were obtained from the Zinelbulak talc-magnesite,Uzbekistan,by causticization-hydration and flotation processes,respectively.A series of refractory materials were prepared on the basis of these magnesium sources,and their effects on physico-mechanical properties and microstructures were investigated as a function of sintering temperature,molding pressure,and the particle size of magnesium sources.The experimental results showed that a refractory material obtained from the magnesium hydroxide concentrate at 1600℃ for 4 h demonstrated favorable parameters due mainly to a higher degree of contact among fine particles.The results obtained from X-ray diffraction and optical microscopy confirmed the presence of periclase and forsterite as the predominant phases in refractory specimens.The prepared refractory materials meet the requirements of the State Standards（Nos.4689-94 and 14832-96） for magnesia and forsterite refractories,respectively.It is,therefore,suggested herein that the use of different magnesium sources derived from the Zinelbulak talc-magnesite will offer the potential to provide economic benefits in the refractory industry.展开更多
Three different castables were prepared as steel-ladle purging-plug refractory materials： corundum-based low-cement castable （C-LCC）, corundum-spinel-based low-cement castable （C-S-LCC）, and no-cement corundum-sp...Three different castables were prepared as steel-ladle purging-plug refractory materials： corundum-based low-cement castable （C-LCC）, corundum-spinel-based low-cement castable （C-S-LCC）, and no-cement corundum-spinel castable （C-S-NCC） （hydratable alu- mina p-A1203 bonded）. The properties of these castables were characterized with regard to water demand/flow ability, cold crushing strength （CCS）, cold modulus of rupture （CMoR）, permanent linear change （PLC）, apparent porosity, and hot modulus of rupture （HMoR）. The re- sults show the CCS/CMoR and HMoR of C-LCC and C-S-LCC are greater than those of the castable C-S-NCC. According to the micro- structure analysis, the sintering effect and the bonding type of the matrix material differ among the three castables. The calcium hexaluminate （CA6） phase in the matrix of C-LCC enhances the cold and hot mechanical strengths. In the case of C-S-LCC, the CA6 and 2CaO·2MgO·14A12O3（C2MEA14） ternary phases generated from the matrix can greatly increase the cold and hot mechanical strengths. In the case of the no-cement castable, sintering becomes difficult, resulting in a lower mechanical strength.展开更多
The research progress and industrial application of chrome-free refractories for RH degasser were introduced in the paper.It is proved that unburned magnesia-spinel refractories used for RH throat and snorkel in Baost...The research progress and industrial application of chrome-free refractories for RH degasser were introduced in the paper.It is proved that unburned magnesia-spinel refractories used for RH throat and snorkel in Baosteel have longer service life compared with traditional direct bonded fused magnesia-chrome materials.The new developed chrome-free unburned magnesia-spinel composite can fully meet the present demand for RH operation and can be applied extensively for RH processing.At present,instead of chrome-containing materials,chrome-free refractories have been applied widely for RH in Baosteel.Super low carbon MgO-C material with high mechanical properties at mild and high temperatures can be an alternative chrome-free material for RH.展开更多
The distribution of refractory raw material resources , its throughput capacity, product varieties and quality as well as market situation in China were investigated.
To solve the problem of over-high density of lightweight insulation refractory bricks prepared with fly ash, new lightweight insulation refractory materials with density 〈 0. 89 g · cm^-3 were .synthesized using...To solve the problem of over-high density of lightweight insulation refractory bricks prepared with fly ash, new lightweight insulation refractory materials with density 〈 0. 89 g · cm^-3 were .synthesized using pyrophyl-lite, .fly ash, and Suzhou clay as the main starting materials and saw dast as the pore forming substance, and controlling the addition of the pyrophyllite （20%, 30% , and 40% by mass ） and the treating temperature （1 250, 1 300, 1 350, and 1 400 ℃ ）. The synthesized materials were characterized by the XRD, SEM and the thermal conductivity measuring in.strument. The results show at pyrophyllite addition of 30% and treat temperature of l 400 ℃ , the material can achieve linear shrinkage of 6. 6%, apparent porosity of 57%, bulk density of 0. 75 g · cm^-3, compressive strength of 2.7 MPa, and thermal conductivity at 350 ℃ of 0. 152 -0. 216 W·（ m·K）^-1.This indicates that the pyrophyllite decomposition at high temperatures forms mullite and amorphous quartz introducing volume expansion, which counteracts some shrinkage at high temperatures. So it is feasible to use pyrophyllite, fly ash waste and clay to prepare lightweight insulation refractory materials.展开更多
New apparatus for the determination of torsion strength of refractory materials at elevated temperatures has been developed in this work. With the employment of heating wire and induction heating unit,this device can ...New apparatus for the determination of torsion strength of refractory materials at elevated temperatures has been developed in this work. With the employment of heating wire and induction heating unit,this device can carry out torsion strength test at high temperatures at the heating rate ranging from 10 ℃/min to 200 ℃/min.Torsion strength of high alumina brick,magnesia brick and Si3 N4 bonded SiC brick has been tested at different heating rates of 10 ℃/min,100 ℃/min and 200℃/min,separately. Results indicate that,for high alumina brick,the tested torsion strength at the heating rate of 10 ℃/min is very close to that at 100 ℃/min,but very different from that at 200 ℃/min. The tested torsion strength of magnesia brick at different heating rates differs greatly,while that of Si3 N4 bonded SiC brick is similar. This suggests that the structure of refractory materials with poor thermal shock resistance might be damaged when the heating rate of 200 ℃/min was applied,but the heating rate of 100 ℃/min is possible for a lot of refractory products. At fast heating rates,it takes only1 h to finish a test at elevated temperatures,thus saving a lot of time and energy.展开更多
The article describes the experiences of alternative materials for the manufacturing of the refractory materi- als in the company P-D Refractories CZ a. s. The atten- tion is focused on energy by-products （EBP）. Ene...The article describes the experiences of alternative materials for the manufacturing of the refractory materi- als in the company P-D Refractories CZ a. s. The atten- tion is focused on energy by-products （EBP）. Energy by-products are generated during burning and desul- phurization in thermal power plants. Classical high-tem- perature -fly ash （class F.fly ash according to ASTM C618） is the most important and .fly ash from .fluidized technology （ class C-fly ash） is the second group. In the Czech Republic, power plants produce about 14 million tons of energy by-products every year. Utilization of these products in ceramic technology means a reduction of raw material costs and also it helps to reduce adverse environ- mental impact. Class F-fly ash （ FFA ） and cinder from high temperature combustion （CD） were used in light- weight insulation fireclay bricks. We can use these mate- rials as a grog and a lightening agent for materials with bulk density over 900 kg · m-3 and classification tem- perature up to 1 150 ℃. Class C.fly ash （CFA） is be- ing tested in a wide range of the refractory materials. For example, it can be used in lightweight fireclay bricks, fireclay bricks for stoves, acid-resistant fireclay bricks or refractory castables. The range of potential products, where EBP could be used, is very wide and energy by-products have become an important raw mate- rial source.展开更多
1 Scope This standard specifies the definition, classification, technical requirements, test methods, quality appraisal procedure, packing, marking, transportation, storage, and quality certificate of abrasion resist...1 Scope This standard specifies the definition, classification, technical requirements, test methods, quality appraisal procedure, packing, marking, transportation, storage, and quality certificate of abrasion resistant refractory materials.展开更多
The refractory raw materials used in recent years were introduced,including metal and intermetallic compounds（ aluminum,silicon,ferrosilicon,etc.）,nonoxide raw materials（ Si3N4 and ferrosilicon nitride）.The develo...The refractory raw materials used in recent years were introduced,including metal and intermetallic compounds（ aluminum,silicon,ferrosilicon,etc.）,nonoxide raw materials（ Si3N4 and ferrosilicon nitride）.The developmental tendency of China＇s raw refractories in the future was also discussed.展开更多
基金supported by the Korea Planning & Evaluation Institute of Industrial Technology (KEIT)the Ministry of Trade, Industry & Energy (MOTIE, Korea) of the Republic of Korea (No. RS2023-00262421)
文摘This study aims to provide the basic knowledge for furnace refractory design by investigating refractory property changes occurred in a hydrogen atmosphere.Since refractory bricks are thermodynamically stable in a hydrogen atmosphere at 1100°C,we tried to find out the minute changes.In this experiment,a refractory brick was prepared by andalusite,mullite chamotte,and clay as raw materials and heated to 1100°C in a 100%hydrogen atmosphere for 72 h.It was found that the strength of the brick was decreased and the color was changed to black by the reduction of impurities.And in addition,this study covered research on the slaking risk of MgO raw materials because the minimum temperature is expected to 400°C in fluidized reduction furnaces unlike shaft furnaces.
基金supported by the National Natural Science Foundation of China(52272022)Key Program of Natural Science Foundation of Hubei Province(2021CFA071).
文摘Refractory materials,as the crucial foundational materials in high-temperature industrial processes such as metallurgy and construction,are inevitably subjected to corrosion and penetration from high-temperature media during their service.Traditionally,observing the in-situ degradation process of refractory materials in complex high-temperature environments has presented challenges.Post-corrosion analysis are commonly employed to assess the slag resistance of refractory materials and understand the corrosion mechanisms.However,these methods often lack information on the process under the conditions of thermal-chemical-mechanical coupling,leading to potential biases in the analysis results.In this work,we developed a non-contact high-temperature machine vision technology by the integrating Digital Image Correlation(DIC)with a high-temperature visualization system to explore the corrosion behavior of Al2O3-SiO2 refractories against molten glass and Al2O3-MgO dry ramming refractories against molten slag at different temperatures.This technology enables realtime monitoring of the 2D or 3D overall strain and average strain curves of the refractory materials and provides continuous feedback on the progressive corrosion of the materials under the coupling conditions of thermal,chemical,and mechanical factors.Therefore,it is an innovative approach for evaluating the service behavior and performance of refractory materials,and is expected to promote the digitization and intelligence of the refractory industry,contributing to the optimization and upgrading of product performance.
基金This work was supported by the National Natural Science Foundation of China(5180021223)Henan Provice Science&Technology Programs(232102231046 and 232102231051)Cultivation Programme for Yong Backbone Teachers in Henan University to Technology(2142121).
文摘To optimize their Al_(2)O_(3)-SiO_(2) raw materials,anorthite based insulation refractories were prepared by the in-situ sintering process combined with the foaming method after sintering at 1350℃for 3 h,using green and pollution-free kaolin,kyanite,andalusite and sillimanite as Al_(2)O_(3)-SiO_(2) raw materials,respectively,and industrial CaCO_(3) as the CaO source.Effects of Al_(2)O_(3)-SiO_(2) raw material types on the physical properties,phase composition and microstructure were investigated.The results are as follows.All samples prepared by different Al_(2)O_(3)-SiO_(2) raw materials have hexagonal flake anorthite and a small amount of mullite and corundum.Their bulk density and thermal conductivity decrease in the order of using kaolin,andalusite,kyanite and sillimanite as the Al_(2)O_(3)-SiO_(2) raw material,but their apparent porosity increases.Moreover,in the sample with kaolin,the bonding between anorthite crystals on the pore walls is closer than that of the other samples,which is conducive to increasing the cold crushing strength.The bonding between anorthite crystals on pore walls gradually decreases in the order of using kyanite,andalusite and sillimanite as the Al_(2)O_(3)-SiO_(2) raw material,thus their cold crushing strength decreases accordingly.In comprehensive consideration,the properties of the sample from kyanite are the optimal.Its apparent porosity,thermal conductivity and cold crushing strength are 84.6%,0.141 W·m^(-1)·K^(-1) and 1.89 MPa,respectively.
基金the Fulbright Program for the award of a research fellowship
文摘Magnesia（MgO） is widely used in the production of refractory materials due to its high melting point,high thermal shock,and excellent slag resistance.The properties of refractory materials depend upon magnesia sources and processing parameters.In this work,three different magnesium sources,namely,magnesium hydroxide concentrate,magnesium carbonate concentrate,and intermediate flotation concentrate,were obtained from the Zinelbulak talc-magnesite,Uzbekistan,by causticization-hydration and flotation processes,respectively.A series of refractory materials were prepared on the basis of these magnesium sources,and their effects on physico-mechanical properties and microstructures were investigated as a function of sintering temperature,molding pressure,and the particle size of magnesium sources.The experimental results showed that a refractory material obtained from the magnesium hydroxide concentrate at 1600℃ for 4 h demonstrated favorable parameters due mainly to a higher degree of contact among fine particles.The results obtained from X-ray diffraction and optical microscopy confirmed the presence of periclase and forsterite as the predominant phases in refractory specimens.The prepared refractory materials meet the requirements of the State Standards（Nos.4689-94 and 14832-96） for magnesia and forsterite refractories,respectively.It is,therefore,suggested herein that the use of different magnesium sources derived from the Zinelbulak talc-magnesite will offer the potential to provide economic benefits in the refractory industry.
文摘Three different castables were prepared as steel-ladle purging-plug refractory materials： corundum-based low-cement castable （C-LCC）, corundum-spinel-based low-cement castable （C-S-LCC）, and no-cement corundum-spinel castable （C-S-NCC） （hydratable alu- mina p-A1203 bonded）. The properties of these castables were characterized with regard to water demand/flow ability, cold crushing strength （CCS）, cold modulus of rupture （CMoR）, permanent linear change （PLC）, apparent porosity, and hot modulus of rupture （HMoR）. The re- sults show the CCS/CMoR and HMoR of C-LCC and C-S-LCC are greater than those of the castable C-S-NCC. According to the micro- structure analysis, the sintering effect and the bonding type of the matrix material differ among the three castables. The calcium hexaluminate （CA6） phase in the matrix of C-LCC enhances the cold and hot mechanical strengths. In the case of C-S-LCC, the CA6 and 2CaO·2MgO·14A12O3（C2MEA14） ternary phases generated from the matrix can greatly increase the cold and hot mechanical strengths. In the case of the no-cement castable, sintering becomes difficult, resulting in a lower mechanical strength.
文摘The research progress and industrial application of chrome-free refractories for RH degasser were introduced in the paper.It is proved that unburned magnesia-spinel refractories used for RH throat and snorkel in Baosteel have longer service life compared with traditional direct bonded fused magnesia-chrome materials.The new developed chrome-free unburned magnesia-spinel composite can fully meet the present demand for RH operation and can be applied extensively for RH processing.At present,instead of chrome-containing materials,chrome-free refractories have been applied widely for RH in Baosteel.Super low carbon MgO-C material with high mechanical properties at mild and high temperatures can be an alternative chrome-free material for RH.
基金The text of this paper was translated from Chinese into English by Mr. Peng Xigao revised by Mrs.Zhang Yongfang, Luoyang Institute of Refractories Research.
文摘The distribution of refractory raw material resources , its throughput capacity, product varieties and quality as well as market situation in China were investigated.
基金financial support from the National Nature Science Foundation of China(51502213)
文摘To solve the problem of over-high density of lightweight insulation refractory bricks prepared with fly ash, new lightweight insulation refractory materials with density 〈 0. 89 g · cm^-3 were .synthesized using pyrophyl-lite, .fly ash, and Suzhou clay as the main starting materials and saw dast as the pore forming substance, and controlling the addition of the pyrophyllite （20%, 30% , and 40% by mass ） and the treating temperature （1 250, 1 300, 1 350, and 1 400 ℃ ）. The synthesized materials were characterized by the XRD, SEM and the thermal conductivity measuring in.strument. The results show at pyrophyllite addition of 30% and treat temperature of l 400 ℃ , the material can achieve linear shrinkage of 6. 6%, apparent porosity of 57%, bulk density of 0. 75 g · cm^-3, compressive strength of 2.7 MPa, and thermal conductivity at 350 ℃ of 0. 152 -0. 216 W·（ m·K）^-1.This indicates that the pyrophyllite decomposition at high temperatures forms mullite and amorphous quartz introducing volume expansion, which counteracts some shrinkage at high temperatures. So it is feasible to use pyrophyllite, fly ash waste and clay to prepare lightweight insulation refractory materials.
文摘New apparatus for the determination of torsion strength of refractory materials at elevated temperatures has been developed in this work. With the employment of heating wire and induction heating unit,this device can carry out torsion strength test at high temperatures at the heating rate ranging from 10 ℃/min to 200 ℃/min.Torsion strength of high alumina brick,magnesia brick and Si3 N4 bonded SiC brick has been tested at different heating rates of 10 ℃/min,100 ℃/min and 200℃/min,separately. Results indicate that,for high alumina brick,the tested torsion strength at the heating rate of 10 ℃/min is very close to that at 100 ℃/min,but very different from that at 200 ℃/min. The tested torsion strength of magnesia brick at different heating rates differs greatly,while that of Si3 N4 bonded SiC brick is similar. This suggests that the structure of refractory materials with poor thermal shock resistance might be damaged when the heating rate of 200 ℃/min was applied,but the heating rate of 100 ℃/min is possible for a lot of refractory products. At fast heating rates,it takes only1 h to finish a test at elevated temperatures,thus saving a lot of time and energy.
文摘The article describes the experiences of alternative materials for the manufacturing of the refractory materi- als in the company P-D Refractories CZ a. s. The atten- tion is focused on energy by-products （EBP）. Energy by-products are generated during burning and desul- phurization in thermal power plants. Classical high-tem- perature -fly ash （class F.fly ash according to ASTM C618） is the most important and .fly ash from .fluidized technology （ class C-fly ash） is the second group. In the Czech Republic, power plants produce about 14 million tons of energy by-products every year. Utilization of these products in ceramic technology means a reduction of raw material costs and also it helps to reduce adverse environ- mental impact. Class F-fly ash （ FFA ） and cinder from high temperature combustion （CD） were used in light- weight insulation fireclay bricks. We can use these mate- rials as a grog and a lightening agent for materials with bulk density over 900 kg · m-3 and classification tem- perature up to 1 150 ℃. Class C.fly ash （CFA） is be- ing tested in a wide range of the refractory materials. For example, it can be used in lightweight fireclay bricks, fireclay bricks for stoves, acid-resistant fireclay bricks or refractory castables. The range of potential products, where EBP could be used, is very wide and energy by-products have become an important raw mate- rial source.
文摘1 Scope This standard specifies the definition, classification, technical requirements, test methods, quality appraisal procedure, packing, marking, transportation, storage, and quality certificate of abrasion resistant refractory materials.
文摘The refractory raw materials used in recent years were introduced,including metal and intermetallic compounds（ aluminum,silicon,ferrosilicon,etc.）,nonoxide raw materials（ Si3N4 and ferrosilicon nitride）.The developmental tendency of China＇s raw refractories in the future was also discussed.
