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
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
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 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
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
In order to investigate corrosive phenomena of fused-cast Al_2O_3-ZrO_2-SiO_2(AZS) refractory materials by molten glass,two types of fused-cast AZS refractory bricks were taken as the interests of the research to stud...In order to investigate corrosive phenomena of fused-cast Al_2O_3-ZrO_2-SiO_2(AZS) refractory materials by molten glass,two types of fused-cast AZS refractory bricks were taken as the interests of the research to study static corrosion rates(mm/d) of the two type materials by molten soda-lime-silica glass at different temperatures(1400,1450 and 1500 *C) and for different isothermal periods(0.5,1.0 and 1.5 d).It was shown that static corrosion rate of each AZS material by molten glass at the triple point developed with raising temperature but slightly decreased with enhancing isothermal period.Based on chemical compositions,microstructures,and corrosive morphologies of AZS refractory materials,the relation between them and static corrosion rates of AZS refractory materials by molten glass was analyzed.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.
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
Low carbon Al2O3- C refractory materials were prepared by ＂Al/Si metal incorporated, insitu formed non-oxides＂ method using corundum, Al powder, Si powder and flake graphite as starting materials. High temperature s...Low carbon Al2O3- C refractory materials were prepared by ＂Al/Si metal incorporated, insitu formed non-oxides＂ method using corundum, Al powder, Si powder and flake graphite as starting materials. High temperature strength, stress -strain relationship and thermal shock resistance of these composites were investigated. The results show that these composites possess improved high temperature strength and good thermal shock resistance. When A1 addition increases from 0 to 8 mass%, correspondingly, Si addition decreases from 8 mass% to O, hot modulus of rupture at 1 400 ℃ increases significantly from 10. 4 MPa to 32. 4 MPa; the maximum strain under 6.5 MPa stress at 1400 ℃ decreases from 215 t.tm to 90 μm; residual strength ratio after 3 thermal shock cycles （1 100 ℃ , air quenching） decreases from 80% to 65%. This may be attributed to in-situ formation of nonoxides because Al and Si react with C, CO and N, to form Al4C3 , AlN and SiC creating strengthening and toughening effects.展开更多
This review summarized the recent advances in the utilization of nonmetallic minerals and their applications for fabrication of unfired refractories.The preparation of refractory powder utilizing cheap nonmetallic min...This review summarized the recent advances in the utilization of nonmetallic minerals and their applications for fabrication of unfired refractories.The preparation of refractory powder utilizing cheap nonmetallic minerals of zircon,low-grade bauxite and quartz was discussed,respectively.The preparation of three unfired SiC-based refractories：SiC-SiAlON-ZrN,Al2O3-SiC/β-SiAlON/Ti（C,N）-C,and Al2O3-SiC-Si3N4 using the as-prepared refractory powders was introduced.展开更多
Powders of aluminum nitride can be prepared by self-sustain high-temperature synthesis (SHS) between aluminum and nitrogen but its high exothermic effect causes melting and evaporation of aluminum and low efficiency o...Powders of aluminum nitride can be prepared by self-sustain high-temperature synthesis (SHS) between aluminum and nitrogen but its high exothermic effect causes melting and evaporation of aluminum and low efficiency of such reaction. A presence of inorganic salt in the starting powder mixture can decrease a heat evolved in the SHS reaction, hinders melting and coalescence of aluminum, and facilitates penetration of nitrogen into interior of a powder bed. Mixtures of alumina powders with different grain sizes and different amounts of aluminum carbonate were subjected to the SHS reaction under 0.05, 0.1 or 1 MPa nitrogen. The powders were composed of aluminum nitride, unreacted aluminum, aluminum oxynitride and in some cases corundum and aluminum oxycarbonate. The finale effects are strongly dependent on the amount of the salt, a grain size of aluminum and a nitrogen pressure.展开更多
China has long been recpgnised as an important source of refractory raw materials far refractory markets world-wide. Bauxite, magnesia, fused a-lumina , and refractory clays in particular, have maintained China s stro...China has long been recpgnised as an important source of refractory raw materials far refractory markets world-wide. Bauxite, magnesia, fused a-lumina , and refractory clays in particular, have maintained China s strong position as the world ' s leading supplier of these minerals. However , important changes have taken place in the structure of Chinese and global supply of these minerals. More-over, the world refractory market and the minerals trading sector have also undergone a radical transformation that has influenced mineral supply, and shifted end product manufacture to China. This paper highlights these changes and sees hour they have, impacted on China as a world source of refractory minerals.展开更多
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.
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 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.
基金financial support by National Natural Science Foundation of China(51172221,51472227)Major Program of Scientific Instrument and Equipment Development of China(2011YQ140145)+1 种基金National High Technology Research and Development Program of China(863 Program,2015AA034204)Project of Science and Technology Department of Guangdong Province(2015B010919007)
文摘In order to investigate corrosive phenomena of fused-cast Al_2O_3-ZrO_2-SiO_2(AZS) refractory materials by molten glass,two types of fused-cast AZS refractory bricks were taken as the interests of the research to study static corrosion rates(mm/d) of the two type materials by molten soda-lime-silica glass at different temperatures(1400,1450 and 1500 *C) and for different isothermal periods(0.5,1.0 and 1.5 d).It was shown that static corrosion rate of each AZS material by molten glass at the triple point developed with raising temperature but slightly decreased with enhancing isothermal period.Based on chemical compositions,microstructures,and corrosive morphologies of AZS refractory materials,the relation between them and static corrosion rates of AZS refractory materials by molten glass was analyzed.
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.
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.
基金supported by Henan Scientific and Technological Research Projects(112102210095)the Education Department of Henan Province Natural Science Foundation(2011A430024)Science Fund for Distinguished Young Scholars of Henan Province (No.124100510019)
文摘Low carbon Al2O3- C refractory materials were prepared by ＂Al/Si metal incorporated, insitu formed non-oxides＂ method using corundum, Al powder, Si powder and flake graphite as starting materials. High temperature strength, stress -strain relationship and thermal shock resistance of these composites were investigated. The results show that these composites possess improved high temperature strength and good thermal shock resistance. When A1 addition increases from 0 to 8 mass%, correspondingly, Si addition decreases from 8 mass% to O, hot modulus of rupture at 1 400 ℃ increases significantly from 10. 4 MPa to 32. 4 MPa; the maximum strain under 6.5 MPa stress at 1400 ℃ decreases from 215 t.tm to 90 μm; residual strength ratio after 3 thermal shock cycles （1 100 ℃ , air quenching） decreases from 80% to 65%. This may be attributed to in-situ formation of nonoxides because Al and Si react with C, CO and N, to form Al4C3 , AlN and SiC creating strengthening and toughening effects.
基金supported by the National Natural Science Foundations of China ( 51032007,51372232,and 51472222 )the Research Fund for the Doctoral Program of Higher Education of China ( 20130022110006 )the Beijing Higher Education Young Elite Teacher Project ( YETP0636)
文摘This review summarized the recent advances in the utilization of nonmetallic minerals and their applications for fabrication of unfired refractories.The preparation of refractory powder utilizing cheap nonmetallic minerals of zircon,low-grade bauxite and quartz was discussed,respectively.The preparation of three unfired SiC-based refractories：SiC-SiAlON-ZrN,Al2O3-SiC/β-SiAlON/Ti（C,N）-C,and Al2O3-SiC-Si3N4 using the as-prepared refractory powders was introduced.
基金The work was financially supported by the Polish State National Centre for Research and Development under Program INNOTECH-K2/IN2/16/181920/NCBR/13.
文摘Powders of aluminum nitride can be prepared by self-sustain high-temperature synthesis (SHS) between aluminum and nitrogen but its high exothermic effect causes melting and evaporation of aluminum and low efficiency of such reaction. A presence of inorganic salt in the starting powder mixture can decrease a heat evolved in the SHS reaction, hinders melting and coalescence of aluminum, and facilitates penetration of nitrogen into interior of a powder bed. Mixtures of alumina powders with different grain sizes and different amounts of aluminum carbonate were subjected to the SHS reaction under 0.05, 0.1 or 1 MPa nitrogen. The powders were composed of aluminum nitride, unreacted aluminum, aluminum oxynitride and in some cases corundum and aluminum oxycarbonate. The finale effects are strongly dependent on the amount of the salt, a grain size of aluminum and a nitrogen pressure.
文摘China has long been recpgnised as an important source of refractory raw materials far refractory markets world-wide. Bauxite, magnesia, fused a-lumina , and refractory clays in particular, have maintained China s strong position as the world ' s leading supplier of these minerals. However , important changes have taken place in the structure of Chinese and global supply of these minerals. More-over, the world refractory market and the minerals trading sector have also undergone a radical transformation that has influenced mineral supply, and shifted end product manufacture to China. This paper highlights these changes and sees hour they have, impacted on China as a world source of refractory minerals.
