Physical properties and geometrical morphologies of crushed air-cooled blast furnace slag (SCR) and crushed limestone (LCR) were comparatively investigated. The shape, angularity, surface texture and internal pore...Physical properties and geometrical morphologies of crushed air-cooled blast furnace slag (SCR) and crushed limestone (LCR) were comparatively investigated. The shape, angularity, surface texture and internal pore structure of aggregate particles for different size and gradation were numerically represented by sphericity (ψ) and shape index (SI), angularity number (AN), index of aggregate particle shape and texture (IAPST), porosity and pore size, respectively. The results show that SCR is a porous and rough aggregate. Apparent density, void, water absorption and smashing index of SCR are obviously higher than those of LCR with the same gradation, respectively. However, bulk density of SCR is lower than that of LCR with the same gradation. SI, AN, IAPST and porosity of SCR are obviously higher than those of LCR with the same gradation, respectively. The smaller particle size of SCR, the larger of its AN, IAPST and porosity.展开更多
Properties and mechanism were investigated on flexural fatigue of concrete containing polypropylene fibers and ground granulated blast furnace slag(GGBFS).Four polypropylene fibers’volume fractions and five slag pr...Properties and mechanism were investigated on flexural fatigue of concrete containing polypropylene fibers and ground granulated blast furnace slag(GGBFS).Four polypropylene fibers’volume fractions and five slag proportions were considered.An experiment was conducted to obtain the fatigue lives at three stress levels in 20 Hz frequency and at a constant stress level of 0.59 in four frequency respectively.Mechanism and evaluation were investigated based on the experimental data.Fatigue life span models were established.The results show that the addition of polypropylene fibers improves the flexural fatigue cumulative strength and fatigue life span.It is proposed that the slag particles and hydrated products improve Interfacial Transition Zone(ITZ)structure and benefit flexural fatigue performance.A composite reinforce effect is found with the incorporation of slag and polypropylene fibers.The optimum mixture contents 55%slag with 0.6%polypropylene fiber for the cumulative fatigue stress.Fatigue properties are decreased as the stress level increasing,the higher frequency reduces the fatigue strength more than lower frequency at a constant stress level.展开更多
The properties of the carbonated brick made of steel slag-slaked lime mixture such as strength, drying shrinkage, water absorption and soundness were mainly investigated. The experimental results indicate that, after ...The properties of the carbonated brick made of steel slag-slaked lime mixture such as strength, drying shrinkage, water absorption and soundness were mainly investigated. The experimental results indicate that, after carbonation, the strength of the brick increases, its drying shrinkage reduces, and its soundness becomes eligible. The optimal slaked lime/steel slag(SL/SS) ratio for the carbonated brick is 0.2 and the asprepared brick meets the requirements of the Chinese standard for MU20-grade building bricks, additionally, it also demonstrates prominent environmental benefits. The XRD and pore structure analyses indicate that the excellent properties of this carbonated brick are attributed to the formation of carbonate crystals and the dense structure due to the carbonation.展开更多
The microstructure and mechanical properties of as-cast A356(Al–Si) alloy castings were investigated. A356 alloy was cast into three different molds composed of sand, ferrochrome(Fe–Cr) slag, and a mixture of sa...The microstructure and mechanical properties of as-cast A356(Al–Si) alloy castings were investigated. A356 alloy was cast into three different molds composed of sand, ferrochrome(Fe–Cr) slag, and a mixture of sand and Fe–Cr. A sodium silicate–CO_2 process was used to make the necessary molds. Cylindrical-shaped castings were prepared. Cast products with no porosity and a good surface finish were achieved in all of the molds. These castings were evaluated for their metallography, secondary dendrite arm spacing(SDAS), and mechanical properties, including hardness, compression, tensile, and impact properties. Furthermore, the tensile and impact samples were analyzed by fractography. The results show that faster heat transfer in the Fe–Cr slag molds than in either the silica sand or mixed molds led to lower SDAS values with a refined microstructure in the products cast in Fe–Cr slag molds. Consistent and enhanced mechanical properties were observed in the slag mold products than in the castings obtained from either sand or mixed molds. The fracture surface of the slag mold castings shows a dimple fracture morphology with a transgranular fracture nature. However, the fracture surfaces of the sand mold castings display brittle fracture. In conclusion, products cast in Fe–Cr slag molds exhibit an improved surface finish and enhanced mechanical properties compared to those of products cast in sand and mixed molds.展开更多
The effects of MgO and TiO_2 on the viscosity, activation energy for viscous flow, and break-point temperature of titanium-bearing slag were studied. The correlation between viscosity and slag structure was analyzed b...The effects of MgO and TiO_2 on the viscosity, activation energy for viscous flow, and break-point temperature of titanium-bearing slag were studied. The correlation between viscosity and slag structure was analyzed by Fourier transform infrared(FTIR) spectroscopy. Subsequently, main phases in the slag and their content changes were investigated by X-ray diffraction and Factsage 6.4 software package. The results show that the viscosity decreases when the MgO content increases from 10.00wt% to 14.00wt%. Moreover, the break-point temperature increases, and the activation energy for viscous flow initially increases and subsequently decreases. In addition, with increasing TiO_2 content from 5.00wt% to 9.00wt%, the viscosity decreases, and the break-point temperature and activation energy for viscous flow initially decrease and subsequently increase. FTIR analyses reveal that the polymerization degree of complex viscous units in titanium-bearing slag decreases with increasing MgO and TiO_2 contents. The mechanism of viscosity variation was elucidated. The basic phase in experimental slags is melilite. Besides, as the MgO content increases, the amount of magnesia–alumina spinel in the slag increases. Similarly, the sum of pyroxene and perovskite phases in the slag increases with increasing TiO_2 content.展开更多
Na_(2)S,Na_(2)CO_(3),FeO,FeS and carbon were used to regulate the properties of slag or metal fractions,and their effects on metal growth and metal–slag separation behavior were investigated.The growth of ferronickel...Na_(2)S,Na_(2)CO_(3),FeO,FeS and carbon were used to regulate the properties of slag or metal fractions,and their effects on metal growth and metal–slag separation behavior were investigated.The growth of ferronickel grains can be enhanced by adding these additives,and Na_(2)S was the most effective.Na_(2)S,Na_(2)CO_(3) and FeO mainly affected the properties of slag,while carbon and FeS affected the metal fraction.The onset temperature of metal–slag separation was 1297℃ for the sample without additive,which was decreased to 1123 and 1101℃ after adding 3.30 wt.%Na_(2)S and 4.47 wt.%Na_(2)CO_(3),respectively.The onset temperature of metal–slag separation was mainly controlled by the slag fraction.The average apparent activation energy of metal grain growth was 125.32 kJ/mol without additive,and it decreased obviously after adding different additives.Na_(2)S also had the most remarkable effect on the decrease in activation energy.展开更多
Traditional processes for treating vanadium slag generate a huge volume of solid residue and a large amount of harmful gas,which cause serious environmental problems.In this study,a new process for the comprehensive u...Traditional processes for treating vanadium slag generate a huge volume of solid residue and a large amount of harmful gas,which cause serious environmental problems.In this study,a new process for the comprehensive utilization of vanadium slag was proposed,wherein zeolite A and a V2O5/TiO2 system were synthesized.The structural properties of the as-synthesized zeolite A and the V2O5/TiO2system were characterized using various experimental techniques,including X-ray diffraction,X-ray fluorescence,scanning electron microscopy,and infrared spectroscopy.The results reveal that zeolite A and the V2O5/TiO2 system are successfully obtained with high purity.The results of gas adsorption measurements indicate that the prepared zeolite A exhibits high selectivity for CO2 over N2 and is a candidate material for CO2 capture from flue-gas streams.展开更多
In this study, the key technologies of a 6-m long bearing steel ingot produced by electroslag remelting withdrawing(ESRW) process, including bifilar mode supply, slag system development, and design of mold, were studi...In this study, the key technologies of a 6-m long bearing steel ingot produced by electroslag remelting withdrawing(ESRW) process, including bifilar mode supply, slag system development, and design of mold, were studied based on the laboratory research achievements. The 6-m long ingot of bearing steel GGr15 with a cross-section of 300 mm × 340 mm was produced using the ESRW process with a bifilar mode and a multi-taper T-mold in a plant. The testing results show that the melting rate using the ESRW bifilar mode technology is three times faster than traditional electroslag remelting(ESR), and the power consumption is only 1,320 k Wh per ton steel. Through testing for the chemical composition, macrostructure and inclusions of remelted ingot, it can be concluded that the ESRW bifilar mode technology not only retains the characteristics of traditional ESR, but also improves the production efficiency and reduces the cost compared to traditional ESR.展开更多
In order to take data information from the slag property diagram in a ternarysystem automatically and actually, a picture recognition and drawing software has been developed byVisual Basic 6.0 based on the image codin...In order to take data information from the slag property diagram in a ternarysystem automatically and actually, a picture recognition and drawing software has been developed byVisual Basic 6.0 based on the image coding principle of computer system and the graphicsprogramming method of VB. This software can transform the ternary system isopleth diagram frombitmap format to data file and establish a corresponding database which can be applied to rapidlyretrieve a mass of data and make correlative thermodynamics or kinetics calculation. Besides, itstill has the function of drawing the ternary system diagram which can draw different kinds ofproperty parameters in the same diagram.展开更多
The magnesia based curable specimens with different Si3N4 contents were casted using sintered magnesite (w(MgO)=95%) as starting material, SiO2 micro-powder as binder, 0.3%, 4% and 5% β-Si3N4 powder replacing the...The magnesia based curable specimens with different Si3N4 contents were casted using sintered magnesite (w(MgO)=95%) as starting material, SiO2 micro-powder as binder, 0.3%, 4% and 5% β-Si3N4 powder replacing the equal addition of magnesia powder respectively. The slag resistance test was carried out at 1550℃ for 3h using Baosteel tundish slag and static crucible method. The result indicates that: introducing Si3N4 could obviously improve the slag resistance of MgO based castable, which increased with increasing Si3N4. Dense SiO2 sintered layer formed on the surface of magnesia based castable because of the oxidation of Si3N4 addition, which can prevent the further slag penetration. In the deep inner of castable, the partial-pressure of oxygen was very low, so Si3N4 can exist stably. Meanwhile in reducing atmosphere, Si3N4 was hard to be sintered, which resulted in the loose interior structure of MgO based castable.展开更多
基金Funded by the National Basic Research Program of China(No.2009CB623105)the Natural Science Foundation of Education Agency of Anhui Province(No.KJ2012A052)+1 种基金the Anhui Provincial Natural Science Foundation(No.1208085ME82)the Doctor Fund of Anhui University of Architecture(No.20123302)
文摘Physical properties and geometrical morphologies of crushed air-cooled blast furnace slag (SCR) and crushed limestone (LCR) were comparatively investigated. The shape, angularity, surface texture and internal pore structure of aggregate particles for different size and gradation were numerically represented by sphericity (ψ) and shape index (SI), angularity number (AN), index of aggregate particle shape and texture (IAPST), porosity and pore size, respectively. The results show that SCR is a porous and rough aggregate. Apparent density, void, water absorption and smashing index of SCR are obviously higher than those of LCR with the same gradation, respectively. However, bulk density of SCR is lower than that of LCR with the same gradation. SI, AN, IAPST and porosity of SCR are obviously higher than those of LCR with the same gradation, respectively. The smaller particle size of SCR, the larger of its AN, IAPST and porosity.
基金Funded by the National Science and Technology Support Plan (No.2006BAD11B03)Shaanxi Provincial Natural Science Foundation(No.SJ08E111)
文摘Properties and mechanism were investigated on flexural fatigue of concrete containing polypropylene fibers and ground granulated blast furnace slag(GGBFS).Four polypropylene fibers’volume fractions and five slag proportions were considered.An experiment was conducted to obtain the fatigue lives at three stress levels in 20 Hz frequency and at a constant stress level of 0.59 in four frequency respectively.Mechanism and evaluation were investigated based on the experimental data.Fatigue life span models were established.The results show that the addition of polypropylene fibers improves the flexural fatigue cumulative strength and fatigue life span.It is proposed that the slag particles and hydrated products improve Interfacial Transition Zone(ITZ)structure and benefit flexural fatigue performance.A composite reinforce effect is found with the incorporation of slag and polypropylene fibers.The optimum mixture contents 55%slag with 0.6%polypropylene fiber for the cumulative fatigue stress.Fatigue properties are decreased as the stress level increasing,the higher frequency reduces the fatigue strength more than lower frequency at a constant stress level.
基金Funded by the"Eleventh Five-year Plan"for Sci&Tech Research of China(NO.2006BAF02A24)
文摘The properties of the carbonated brick made of steel slag-slaked lime mixture such as strength, drying shrinkage, water absorption and soundness were mainly investigated. The experimental results indicate that, after carbonation, the strength of the brick increases, its drying shrinkage reduces, and its soundness becomes eligible. The optimal slaked lime/steel slag(SL/SS) ratio for the carbonated brick is 0.2 and the asprepared brick meets the requirements of the Chinese standard for MU20-grade building bricks, additionally, it also demonstrates prominent environmental benefits. The XRD and pore structure analyses indicate that the excellent properties of this carbonated brick are attributed to the formation of carbonate crystals and the dense structure due to the carbonation.
基金the DST–Fly Ash unit, New Delhi, India for their financial support (Grant Ref No.FAU/DST/600(52)/2012-13)Advance Analytical laboratory, Andhra University, India for the support in SEM–EDS studies
文摘The microstructure and mechanical properties of as-cast A356(Al–Si) alloy castings were investigated. A356 alloy was cast into three different molds composed of sand, ferrochrome(Fe–Cr) slag, and a mixture of sand and Fe–Cr. A sodium silicate–CO_2 process was used to make the necessary molds. Cylindrical-shaped castings were prepared. Cast products with no porosity and a good surface finish were achieved in all of the molds. These castings were evaluated for their metallography, secondary dendrite arm spacing(SDAS), and mechanical properties, including hardness, compression, tensile, and impact properties. Furthermore, the tensile and impact samples were analyzed by fractography. The results show that faster heat transfer in the Fe–Cr slag molds than in either the silica sand or mixed molds led to lower SDAS values with a refined microstructure in the products cast in Fe–Cr slag molds. Consistent and enhanced mechanical properties were observed in the slag mold products than in the castings obtained from either sand or mixed molds. The fracture surface of the slag mold castings shows a dimple fracture morphology with a transgranular fracture nature. However, the fracture surfaces of the sand mold castings display brittle fracture. In conclusion, products cast in Fe–Cr slag molds exhibit an improved surface finish and enhanced mechanical properties compared to those of products cast in sand and mixed molds.
基金financial support by the Fundamental Research Funds for the Central Universities (No. N130602003)National High Technology Research and Development Program of China (No. 2012AA062302)the National Natural Science Foundation of China (No. 51574067)
文摘The effects of MgO and TiO_2 on the viscosity, activation energy for viscous flow, and break-point temperature of titanium-bearing slag were studied. The correlation between viscosity and slag structure was analyzed by Fourier transform infrared(FTIR) spectroscopy. Subsequently, main phases in the slag and their content changes were investigated by X-ray diffraction and Factsage 6.4 software package. The results show that the viscosity decreases when the MgO content increases from 10.00wt% to 14.00wt%. Moreover, the break-point temperature increases, and the activation energy for viscous flow initially increases and subsequently decreases. In addition, with increasing TiO_2 content from 5.00wt% to 9.00wt%, the viscosity decreases, and the break-point temperature and activation energy for viscous flow initially decrease and subsequently increase. FTIR analyses reveal that the polymerization degree of complex viscous units in titanium-bearing slag decreases with increasing MgO and TiO_2 contents. The mechanism of viscosity variation was elucidated. The basic phase in experimental slags is melilite. Besides, as the MgO content increases, the amount of magnesia–alumina spinel in the slag increases. Similarly, the sum of pyroxene and perovskite phases in the slag increases with increasing TiO_2 content.
基金support from the National Natural Science Foundation of China(No.51904047)the Fundamental and Frontier Research Project of Chongqing,China(No.cstc2020jcyj-msxmX0515)the State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization,China.
文摘Na_(2)S,Na_(2)CO_(3),FeO,FeS and carbon were used to regulate the properties of slag or metal fractions,and their effects on metal growth and metal–slag separation behavior were investigated.The growth of ferronickel grains can be enhanced by adding these additives,and Na_(2)S was the most effective.Na_(2)S,Na_(2)CO_(3) and FeO mainly affected the properties of slag,while carbon and FeS affected the metal fraction.The onset temperature of metal–slag separation was 1297℃ for the sample without additive,which was decreased to 1123 and 1101℃ after adding 3.30 wt.%Na_(2)S and 4.47 wt.%Na_(2)CO_(3),respectively.The onset temperature of metal–slag separation was mainly controlled by the slag fraction.The average apparent activation energy of metal grain growth was 125.32 kJ/mol without additive,and it decreased obviously after adding different additives.Na_(2)S also had the most remarkable effect on the decrease in activation energy.
基金supported by the Natural Science Foundation of China (Nos. 51406029 and 51474067)the Key Laboratory Project of Liaoning Province of Education (No.LZ2015032)
文摘Traditional processes for treating vanadium slag generate a huge volume of solid residue and a large amount of harmful gas,which cause serious environmental problems.In this study,a new process for the comprehensive utilization of vanadium slag was proposed,wherein zeolite A and a V2O5/TiO2 system were synthesized.The structural properties of the as-synthesized zeolite A and the V2O5/TiO2system were characterized using various experimental techniques,including X-ray diffraction,X-ray fluorescence,scanning electron microscopy,and infrared spectroscopy.The results reveal that zeolite A and the V2O5/TiO2 system are successfully obtained with high purity.The results of gas adsorption measurements indicate that the prepared zeolite A exhibits high selectivity for CO2 over N2 and is a candidate material for CO2 capture from flue-gas streams.
基金financially supported by the National Natural Science Foundation of China(No.51474126)the Science and Technology Commission of Liaoning,China(No.L2013125)
文摘In this study, the key technologies of a 6-m long bearing steel ingot produced by electroslag remelting withdrawing(ESRW) process, including bifilar mode supply, slag system development, and design of mold, were studied based on the laboratory research achievements. The 6-m long ingot of bearing steel GGr15 with a cross-section of 300 mm × 340 mm was produced using the ESRW process with a bifilar mode and a multi-taper T-mold in a plant. The testing results show that the melting rate using the ESRW bifilar mode technology is three times faster than traditional electroslag remelting(ESR), and the power consumption is only 1,320 k Wh per ton steel. Through testing for the chemical composition, macrostructure and inclusions of remelted ingot, it can be concluded that the ESRW bifilar mode technology not only retains the characteristics of traditional ESR, but also improves the production efficiency and reduces the cost compared to traditional ESR.
基金This work was financially supported by the National Natural Science Foundation of China (No.50274006).
文摘In order to take data information from the slag property diagram in a ternarysystem automatically and actually, a picture recognition and drawing software has been developed byVisual Basic 6.0 based on the image coding principle of computer system and the graphicsprogramming method of VB. This software can transform the ternary system isopleth diagram frombitmap format to data file and establish a corresponding database which can be applied to rapidlyretrieve a mass of data and make correlative thermodynamics or kinetics calculation. Besides, itstill has the function of drawing the ternary system diagram which can draw different kinds ofproperty parameters in the same diagram.
文摘The magnesia based curable specimens with different Si3N4 contents were casted using sintered magnesite (w(MgO)=95%) as starting material, SiO2 micro-powder as binder, 0.3%, 4% and 5% β-Si3N4 powder replacing the equal addition of magnesia powder respectively. The slag resistance test was carried out at 1550℃ for 3h using Baosteel tundish slag and static crucible method. The result indicates that: introducing Si3N4 could obviously improve the slag resistance of MgO based castable, which increased with increasing Si3N4. Dense SiO2 sintered layer formed on the surface of magnesia based castable because of the oxidation of Si3N4 addition, which can prevent the further slag penetration. In the deep inner of castable, the partial-pressure of oxygen was very low, so Si3N4 can exist stably. Meanwhile in reducing atmosphere, Si3N4 was hard to be sintered, which resulted in the loose interior structure of MgO based castable.