Reaction behaviors of sulfur and iron compounds in sodium aluminate solutions were investigated. The results show that iron compounds can remarkably remove the S2 but cannot get rid of S2Oc2-, SO^2- and SO4^-2 in sodi...Reaction behaviors of sulfur and iron compounds in sodium aluminate solutions were investigated. The results show that iron compounds can remarkably remove the S2 but cannot get rid of S2Oc2-, SO^2- and SO4^-2 in sodium aluminate solutions. The removal efficiency of S^2- using ferrous compound and ferric compound can reach 86.10% and 92.70% respectively when the iron compounds were added with a molar ratio of 2：1 compared with the sulfur in liquors at 100℃. Moreover, several same compounds are formed in those two desulfurization processes with ferrous or ferric compounds, including erdite, hematite, amorphous ferrous sulfide, polymerized sulfur-iron compounds and ferric sulfate. The major difference between these two processes is that the erdite generated from ferrous compounds at the initial reaction stage will convert to a sodium-free product FeS2 at the subsequent stage.展开更多
Selective hydrogenation of substituted nitroarenes is an important reaction to obtain amines.Supported metal catalysts are wildly used in this reaction because the surface structure of supports can tune the properties...Selective hydrogenation of substituted nitroarenes is an important reaction to obtain amines.Supported metal catalysts are wildly used in this reaction because the surface structure of supports can tune the properties of the supported metal nanoparticles(NPs)and promote the selectivity to amines.Herein,Pt NPs were immobilized on Fe OOH,Fe_(3)O_(4)andα-Fe_2O_(3)nanorods to synthesize a series of iron compounds supported Pt catalysts by liquid phase reduction method.Chemoselective hydrogenation of 3-nitrostyrene to 3-aminostyrene was used as probe reaction to evaluate the performance of the catalysts.The results show that Pt/Fe OOH exhibits the highest selectivity and activity.Fe OOH support with pores and-OH groups can tune the electronic structure of Pt NPs.The positive charge of Pt NPs supported on Fe OOH is key factor for improving the catalytic performance.展开更多
The utilization of highly reactive and high-strength coke can enhance the efficiency of blast furnace by promoting indirect reduction of iron oxides.Iron compounds,as the main constituent in iron-bearing minerals,have...The utilization of highly reactive and high-strength coke can enhance the efficiency of blast furnace by promoting indirect reduction of iron oxides.Iron compounds,as the main constituent in iron-bearing minerals,have aroused wide interest in preparation of highly reactive iron coke.However,the effects of iron compounds on pyrolysis behavior of coal and metallurgical properties of resultant cokes are still unclear.Thus,three iron compounds,i.e.,Fe;O;,Fe;O;and FeC;O;·2H;O,were adopted to investigate their effects on coal pyrolysis behavior and metallurgical properties of the resultant cokes.The results show that iron compounds have slight effects on the thermal behavior of coal blend originated from thermogravimetric and differential thermogravimetric curves.The apparent activation energy varies with different iron compounds ranging from 94.85 to 110.11 kJ/mol in the primary pyrolysis process,while lower apparent activation energy is required for the secondary pyrolysis process.Iron compounds have an adverse influence on the mechanical properties and carbon structure of cokes.Strong correlations exist among coke reactivity,coke strength after reaction,and the content of metallic iron in cokes or the values of crystallite stacking height,which reflect the dependency of thermal property on metallic iron content and carbon structure of cokes.展开更多
The disconnection between teaching,learning,and evaluation is particularly pronounced in traditional high school chemistry teaching.To align with the demands of the new curriculum standards for talent development,it i...The disconnection between teaching,learning,and evaluation is particularly pronounced in traditional high school chemistry teaching.To align with the demands of the new curriculum standards for talent development,it is essential to implement reforms and innovations in teaching methods.This paper initially elucidates the integrated concept of teaching,learning,and evaluation,as well as its practical significance in the classroom.Subsequently,it explores the effective teaching design centered on the theme of iron and its compounds,actively investigating the implementation approach of the integration principle of teaching,learning,and evaluation in classroom.Furthermore,the paper emphasizes the pivotal role of the evaluation part in fostering the professional development of teachers and enhancing the core competencies of students,ultimately aiming to achieve high efficiency and quality in chemistry classroom teaching.展开更多
The distribution and form of iron and calcium compounds were studied using hydrogenation feedstock and hydrogenation products with different space velocities as the research object.The content of metallic elements,suc...The distribution and form of iron and calcium compounds were studied using hydrogenation feedstock and hydrogenation products with different space velocities as the research object.The content of metallic elements,such as calcium and iron in hydrogenation feedstock,and extract samples were determined via flame atomic absorption spectrometry.The water-soluble iron and calcium species in oil samples were determined by an IC2010 high-throughput ion chromatograph.Nearly 60%-80%of the iron or calcium compounds were mainly concentrated in resins and asphaltenes.Iron and calcium compounds mainly exist in the form of oil-soluble metal species in hydrogenation feedstock and hydrogenation products.Under certain conditions of reaction temperature,pressure,and volume ratio of hydrogen to oil,when the reaction space velocity was 0.6 h^(−1),about 30%of the iron or calcium compounds were converted from oil-soluble to water-soluble species after hydrogenation.When the reaction space velocity was decreased from 1.70 to 0.60 h^(−1),the proportion of iron compounds converted from oil-soluble to water-soluble increased from 8.4%to 28%.Moreover,the proportion of calcium compounds converted from oil-soluble to water-soluble increased from 10%to 37%.This denotes that with decreasing reaction space velocity,the ratio of oil-soluble to water-soluble species increases.Water-soluble iron and calcium compounds are present in the form of inorganic salts,such as chlorate and sulfate.This study helps in understanding the removal mechanism of iron and calcium compounds and optimizing the operating conditions of residue hydrogenation.展开更多
This study was conducted to determine the content,distribution and transformation of iron oxides in the soils of the Middle Euphrates regions in Iraq.The study included four sites:Tuwairij area in Karbala Governorate,...This study was conducted to determine the content,distribution and transformation of iron oxides in the soils of the Middle Euphrates regions in Iraq.The study included four sites:Tuwairij area in Karbala Governorate,College of Agriculture at the University of Kufa in Najaf Governorate,College of Agriculture at the University of Qadisiyah in Diwaniyah Governorate,and the Nile District in Babylon Governorate.The results showed that the soils of Najaf and Qadisiyah were superior in terms of their content of total free iron oxides(Fet)compared to the soils of Karbala and Babylon.The relative distribution of free iron oxides was generally close among the studied sites,with a homogeneous pattern in the distribution of these oxides within the soil horizons.As for silicate iron oxides(Fes),a homogeneous pattern was observed in the soil of Babylon with its content increasing with depth,while these patterns varied in the soils of Karbala,Najaf and Qadisiyah.Regarding the ratios of crystalline iron oxides(Fed/Fet),the study showed that the Babylon and Qadisiyah soils recorded the highest values,while these values were lower in the Najaf and Karbala soils.On the other hand,amorphous iron oxides(FeO)showed similar values in the Najaf and Qadisiyah soils.In general,these results clearly showed the effect of environmental and geochemical factors of the study areas on the distribution and transformations of iron oxides in the soil of the Middle Euphrates regions.展开更多
Iron overload is closely related to many diseases. Iron overload is a risk factor that triggers a series of health problems. The toxicity of iron is that iron can catalyze the formation of oxygen free radicals and can...Iron overload is closely related to many diseases. Iron overload is a risk factor that triggers a series of health problems. The toxicity of iron is that iron can catalyze the formation of oxygen free radicals and can be used as a nutrient necessary for the growth of microorganisms and tumor cells. The sensitivity of human cells to iron toxicity varies widely. Causes of iron overload include genetic factors, behavioral factors and environmental factors. With the rapid development of modem industry, iron and its compound dust distribution industry and the increasingly widespread, in the iron pigment production, mechanical casting, iron ore mining and iron smelting operations will produce a lot of iron and its compound dust, Its impact on the human body has been of concern. Long-term exposure to iron and its compounds can cause different degrees of damage to the respiratory system, resulting in iron in vivo disorder. The relationship between iron metabolism and lung injury has also begun to be concerned, and maintaining iron homeostasis is important for lung injury and its protection.展开更多
A series of both unsupported and coal‐supported iron–oxygen compounds with gradual changes in microstructure were synthesized by a precipitation‐oxidation process at 20 to 70°C.The relationship between the mic...A series of both unsupported and coal‐supported iron–oxygen compounds with gradual changes in microstructure were synthesized by a precipitation‐oxidation process at 20 to 70°C.The relationship between the microstructures and catalytic activities of these precursors during direct coal liquefaction was studied.The results show that the microstructure could be controlled through adjusting the synthesis temperature during the precipitation‐oxidation procedure,and that compounds synthesized at lower temperatures exhibit higher catalytic activity.As a result of their higher proportions ofγ‐FeOOH orα‐FeOOH crystalline phases,the unsupported iron–oxygen compounds synthesized at 20–30°C,which also had high specific surface areas and moisture levels,generate oil yields 4.5%–4.6%higher than those obtained with precursors synthesized at 70°C.It was also determined that higher oil yields were obtained when the catalytically‐active phase formed by the precursors during liquefaction(pyrrhotite,Fe1-xS)had smaller crystallites.Feed coal added as a carrier was found to efficiently disperse the active precursors,which in turn significantly improved the catalytic activity during coal liquefaction.展开更多
New composition perovskite-type compounds with formula Sr0.6Bi0.4FeO2.7,Sr1-xBixFeO3-y(x=0.1 to 0. 9 in interveral of 0.1),and Ba1.5Pt0.5Mn2O6 have been synthsized and structurally characterized.The crystal structure ...New composition perovskite-type compounds with formula Sr0.6Bi0.4FeO2.7,Sr1-xBixFeO3-y(x=0.1 to 0. 9 in interveral of 0.1),and Ba1.5Pt0.5Mn2O6 have been synthsized and structurally characterized.The crystal structure of Sr0.6Bi0.4FeO2.7has been determined by X-ray single crystal diffraction,and the data of neutron powder diffraction collected at both room temperature and elevated temperature(380℃).The compound Sr0.6Bi0.4FeO2.7 crystallizes in the cubic space group of Pm3m with Z=1,a=3.9330(6) at room temperature,a=3.9498(6)A at 380℃.The magnetic structure from the neutron powder diffraction data collected at room temperature is consistent with a simple G-type antiferromagnetism and has a magnetic moment of 4.98 μB per Fe atom.The structures of Sr1-xBixFeO3-y with x other than 0.4 were also refined from the X-ray powder diffraction data.The data were consistent with a tetragonal cell when x=0.1,a rhombohedral cell when x= 0.9,and a cubic cell for x=0.2～0.8.From single crystal X-ray diffraction data,Ba1.5Pt0.5Mn2O6 crystallizes in hexagonal space group of P63mc with a= 5.7722 (6),c=4.4504(9),V=128.42(2),Z=1.The Sr(1-x)BixFeO(3-y)are found to be a good electronic and ionic conductor.展开更多
Abstract： The demand for high performance cast aluminum alloy components is often disturbed by increasing impurity elements, such as iron accumulated from recycled scraps. It is strongly required that coarse plate-li...Abstract： The demand for high performance cast aluminum alloy components is often disturbed by increasing impurity elements, such as iron accumulated from recycled scraps. It is strongly required that coarse plate-like iron compound of β-Al5FeSi turns into harmless form without the need for applying refining additives or expensive virgin ingots. The microstructural modification of Al-7mass%Si alloy billets with different iron contents was examined by applying ultrasonic vibration during the solidification. Ultrasonically melt-treated billets were thixocast right after induction heating up to the semisolid temperature of 583 ℃, the microstructure and tensile properties were evaluated in the thixocast components. Globular primary reAl is required to fill up a thin cavity in thixocasting, so that the microstructural modification by ultrasonic melt-treatment was firstly confirmed in the billets. With ultrasonic melt-treatment in the temperature range of 630 ℃ to 605 ℃, the primary α-AI transforms itself from dendrite into fine globular in morphology. The coarse plate-like β-AIsFeSi compound becomes markedly finer compared with those in non-treated billets. Semisolid soaking up to 583 ℃, does not appreciably affect the size of β-AIsFeSi compounds; however, it affects the solid primary reAl morphology to be more globular, which is convenient for thixocasting. After thixocasting with preheated billets, eutectic silicon plates are extremely refined due to the rapid solidification arising from low casting temperature. The tensile strength of thixocast samples with different iron contents does not change much even at 2mass% of iron, when thixocast with ultrasonically melt-treated billets. However, thixocast AI-7mass%Si-2mass%Fe alloy with non-treated billets exhibits an inferior strength of 80 MPa, compared with 180 MPa with ultrasonically melt-treated billets. The elongation is also improved by about a factor of two in thixocastings with ultrasonically melt-treated billets for all iron contents of AI-7mass%Si alloys, for example, the elongation of 11% in thixocast of AI-7mass%Si-0.5mass%Fe alloy with ultrasonically melt-treated billets, 5% in that with non-treated billets.展开更多
Ammonia is a crucial raw ingredient used in the manufacturing of fer-tilizers and pharmaceuticals,which are major sectors of the national economy in the chemical and agricultural industries.The conventional Haber–Bos...Ammonia is a crucial raw ingredient used in the manufacturing of fer-tilizers and pharmaceuticals,which are major sectors of the national economy in the chemical and agricultural industries.The conventional Haber–Bosch method is still in use in the industry today to manufacture NH3,and the production process emits a significant quantity of CO_(2),which does not match the current standards for the achievement of carbon neutrality.The nitrogen reduction reaction(NRR)technology has garnered a lot of attention lately because of its benefits,which include being environmentally friendly,sustainable,and able to function in mild environments.However,NRR is still in its early stages of development and confronts numerous difficult issues,including slow reaction kinetics,low ammonia yield rates and Faradaic efficiency(FE),and a dearth of effective research on nitrogen fixation as a whole.This paper aims to promote the industrialization of NRR,summarizing the progress of iron‐based catalysts,including single atomic catalysts,organic frameworks,metal oxides the,and alloys.Eventually,this paper discusses the strate-gies for improving NH3 yield rates and FE,improving reaction kinetics,and building a sustainable overall nitrogen fixation system.The deve-lopment of iron‐based catalysts in other fields has also been prospected.展开更多
基金Project(51374239)supported by the National Natural Science Foundation of China
文摘Reaction behaviors of sulfur and iron compounds in sodium aluminate solutions were investigated. The results show that iron compounds can remarkably remove the S2 but cannot get rid of S2Oc2-, SO^2- and SO4^-2 in sodium aluminate solutions. The removal efficiency of S^2- using ferrous compound and ferric compound can reach 86.10% and 92.70% respectively when the iron compounds were added with a molar ratio of 2：1 compared with the sulfur in liquors at 100℃. Moreover, several same compounds are formed in those two desulfurization processes with ferrous or ferric compounds, including erdite, hematite, amorphous ferrous sulfide, polymerized sulfur-iron compounds and ferric sulfate. The major difference between these two processes is that the erdite generated from ferrous compounds at the initial reaction stage will convert to a sodium-free product FeS2 at the subsequent stage.
基金the financial support provided by the National Natural Science Foundation of China(Nos.22072164,21773269,51932005 and 21761132025)the Liao Ning Revitalization Talents Program(No.XLYC1807175)。
文摘Selective hydrogenation of substituted nitroarenes is an important reaction to obtain amines.Supported metal catalysts are wildly used in this reaction because the surface structure of supports can tune the properties of the supported metal nanoparticles(NPs)and promote the selectivity to amines.Herein,Pt NPs were immobilized on Fe OOH,Fe_(3)O_(4)andα-Fe_2O_(3)nanorods to synthesize a series of iron compounds supported Pt catalysts by liquid phase reduction method.Chemoselective hydrogenation of 3-nitrostyrene to 3-aminostyrene was used as probe reaction to evaluate the performance of the catalysts.The results show that Pt/Fe OOH exhibits the highest selectivity and activity.Fe OOH support with pores and-OH groups can tune the electronic structure of Pt NPs.The positive charge of Pt NPs supported on Fe OOH is key factor for improving the catalytic performance.
基金supported by the National Natural Science Foundation of China(Grant No.51474042)
文摘The utilization of highly reactive and high-strength coke can enhance the efficiency of blast furnace by promoting indirect reduction of iron oxides.Iron compounds,as the main constituent in iron-bearing minerals,have aroused wide interest in preparation of highly reactive iron coke.However,the effects of iron compounds on pyrolysis behavior of coal and metallurgical properties of resultant cokes are still unclear.Thus,three iron compounds,i.e.,Fe;O;,Fe;O;and FeC;O;·2H;O,were adopted to investigate their effects on coal pyrolysis behavior and metallurgical properties of the resultant cokes.The results show that iron compounds have slight effects on the thermal behavior of coal blend originated from thermogravimetric and differential thermogravimetric curves.The apparent activation energy varies with different iron compounds ranging from 94.85 to 110.11 kJ/mol in the primary pyrolysis process,while lower apparent activation energy is required for the secondary pyrolysis process.Iron compounds have an adverse influence on the mechanical properties and carbon structure of cokes.Strong correlations exist among coke reactivity,coke strength after reaction,and the content of metallic iron in cokes or the values of crystallite stacking height,which reflect the dependency of thermal property on metallic iron content and carbon structure of cokes.
文摘The disconnection between teaching,learning,and evaluation is particularly pronounced in traditional high school chemistry teaching.To align with the demands of the new curriculum standards for talent development,it is essential to implement reforms and innovations in teaching methods.This paper initially elucidates the integrated concept of teaching,learning,and evaluation,as well as its practical significance in the classroom.Subsequently,it explores the effective teaching design centered on the theme of iron and its compounds,actively investigating the implementation approach of the integration principle of teaching,learning,and evaluation in classroom.Furthermore,the paper emphasizes the pivotal role of the evaluation part in fostering the professional development of teachers and enhancing the core competencies of students,ultimately aiming to achieve high efficiency and quality in chemistry classroom teaching.
基金supported by the National Natural Science Foundation of China (No. 21576292)the independent innovation research project of China University of Petroleum (East China) (No. 22CX0300A)
文摘The distribution and form of iron and calcium compounds were studied using hydrogenation feedstock and hydrogenation products with different space velocities as the research object.The content of metallic elements,such as calcium and iron in hydrogenation feedstock,and extract samples were determined via flame atomic absorption spectrometry.The water-soluble iron and calcium species in oil samples were determined by an IC2010 high-throughput ion chromatograph.Nearly 60%-80%of the iron or calcium compounds were mainly concentrated in resins and asphaltenes.Iron and calcium compounds mainly exist in the form of oil-soluble metal species in hydrogenation feedstock and hydrogenation products.Under certain conditions of reaction temperature,pressure,and volume ratio of hydrogen to oil,when the reaction space velocity was 0.6 h^(−1),about 30%of the iron or calcium compounds were converted from oil-soluble to water-soluble species after hydrogenation.When the reaction space velocity was decreased from 1.70 to 0.60 h^(−1),the proportion of iron compounds converted from oil-soluble to water-soluble increased from 8.4%to 28%.Moreover,the proportion of calcium compounds converted from oil-soluble to water-soluble increased from 10%to 37%.This denotes that with decreasing reaction space velocity,the ratio of oil-soluble to water-soluble species increases.Water-soluble iron and calcium compounds are present in the form of inorganic salts,such as chlorate and sulfate.This study helps in understanding the removal mechanism of iron and calcium compounds and optimizing the operating conditions of residue hydrogenation.
文摘This study was conducted to determine the content,distribution and transformation of iron oxides in the soils of the Middle Euphrates regions in Iraq.The study included four sites:Tuwairij area in Karbala Governorate,College of Agriculture at the University of Kufa in Najaf Governorate,College of Agriculture at the University of Qadisiyah in Diwaniyah Governorate,and the Nile District in Babylon Governorate.The results showed that the soils of Najaf and Qadisiyah were superior in terms of their content of total free iron oxides(Fet)compared to the soils of Karbala and Babylon.The relative distribution of free iron oxides was generally close among the studied sites,with a homogeneous pattern in the distribution of these oxides within the soil horizons.As for silicate iron oxides(Fes),a homogeneous pattern was observed in the soil of Babylon with its content increasing with depth,while these patterns varied in the soils of Karbala,Najaf and Qadisiyah.Regarding the ratios of crystalline iron oxides(Fed/Fet),the study showed that the Babylon and Qadisiyah soils recorded the highest values,while these values were lower in the Najaf and Karbala soils.On the other hand,amorphous iron oxides(FeO)showed similar values in the Najaf and Qadisiyah soils.In general,these results clearly showed the effect of environmental and geochemical factors of the study areas on the distribution and transformations of iron oxides in the soil of the Middle Euphrates regions.
文摘Iron overload is closely related to many diseases. Iron overload is a risk factor that triggers a series of health problems. The toxicity of iron is that iron can catalyze the formation of oxygen free radicals and can be used as a nutrient necessary for the growth of microorganisms and tumor cells. The sensitivity of human cells to iron toxicity varies widely. Causes of iron overload include genetic factors, behavioral factors and environmental factors. With the rapid development of modem industry, iron and its compound dust distribution industry and the increasingly widespread, in the iron pigment production, mechanical casting, iron ore mining and iron smelting operations will produce a lot of iron and its compound dust, Its impact on the human body has been of concern. Long-term exposure to iron and its compounds can cause different degrees of damage to the respiratory system, resulting in iron in vivo disorder. The relationship between iron metabolism and lung injury has also begun to be concerned, and maintaining iron homeostasis is important for lung injury and its protection.
文摘A series of both unsupported and coal‐supported iron–oxygen compounds with gradual changes in microstructure were synthesized by a precipitation‐oxidation process at 20 to 70°C.The relationship between the microstructures and catalytic activities of these precursors during direct coal liquefaction was studied.The results show that the microstructure could be controlled through adjusting the synthesis temperature during the precipitation‐oxidation procedure,and that compounds synthesized at lower temperatures exhibit higher catalytic activity.As a result of their higher proportions ofγ‐FeOOH orα‐FeOOH crystalline phases,the unsupported iron–oxygen compounds synthesized at 20–30°C,which also had high specific surface areas and moisture levels,generate oil yields 4.5%–4.6%higher than those obtained with precursors synthesized at 70°C.It was also determined that higher oil yields were obtained when the catalytically‐active phase formed by the precursors during liquefaction(pyrrhotite,Fe1-xS)had smaller crystallites.Feed coal added as a carrier was found to efficiently disperse the active precursors,which in turn significantly improved the catalytic activity during coal liquefaction.
文摘New composition perovskite-type compounds with formula Sr0.6Bi0.4FeO2.7,Sr1-xBixFeO3-y(x=0.1 to 0. 9 in interveral of 0.1),and Ba1.5Pt0.5Mn2O6 have been synthsized and structurally characterized.The crystal structure of Sr0.6Bi0.4FeO2.7has been determined by X-ray single crystal diffraction,and the data of neutron powder diffraction collected at both room temperature and elevated temperature(380℃).The compound Sr0.6Bi0.4FeO2.7 crystallizes in the cubic space group of Pm3m with Z=1,a=3.9330(6) at room temperature,a=3.9498(6)A at 380℃.The magnetic structure from the neutron powder diffraction data collected at room temperature is consistent with a simple G-type antiferromagnetism and has a magnetic moment of 4.98 μB per Fe atom.The structures of Sr1-xBixFeO3-y with x other than 0.4 were also refined from the X-ray powder diffraction data.The data were consistent with a tetragonal cell when x=0.1,a rhombohedral cell when x= 0.9,and a cubic cell for x=0.2～0.8.From single crystal X-ray diffraction data,Ba1.5Pt0.5Mn2O6 crystallizes in hexagonal space group of P63mc with a= 5.7722 (6),c=4.4504(9),V=128.42(2),Z=1.The Sr(1-x)BixFeO(3-y)are found to be a good electronic and ionic conductor.
基金financially supported by the Grants-in Aid for Scientific Research from the Ministry of Education,Science,Sports and Culture (No.23560898)
文摘Abstract： The demand for high performance cast aluminum alloy components is often disturbed by increasing impurity elements, such as iron accumulated from recycled scraps. It is strongly required that coarse plate-like iron compound of β-Al5FeSi turns into harmless form without the need for applying refining additives or expensive virgin ingots. The microstructural modification of Al-7mass%Si alloy billets with different iron contents was examined by applying ultrasonic vibration during the solidification. Ultrasonically melt-treated billets were thixocast right after induction heating up to the semisolid temperature of 583 ℃, the microstructure and tensile properties were evaluated in the thixocast components. Globular primary reAl is required to fill up a thin cavity in thixocasting, so that the microstructural modification by ultrasonic melt-treatment was firstly confirmed in the billets. With ultrasonic melt-treatment in the temperature range of 630 ℃ to 605 ℃, the primary α-AI transforms itself from dendrite into fine globular in morphology. The coarse plate-like β-AIsFeSi compound becomes markedly finer compared with those in non-treated billets. Semisolid soaking up to 583 ℃, does not appreciably affect the size of β-AIsFeSi compounds; however, it affects the solid primary reAl morphology to be more globular, which is convenient for thixocasting. After thixocasting with preheated billets, eutectic silicon plates are extremely refined due to the rapid solidification arising from low casting temperature. The tensile strength of thixocast samples with different iron contents does not change much even at 2mass% of iron, when thixocast with ultrasonically melt-treated billets. However, thixocast AI-7mass%Si-2mass%Fe alloy with non-treated billets exhibits an inferior strength of 80 MPa, compared with 180 MPa with ultrasonically melt-treated billets. The elongation is also improved by about a factor of two in thixocastings with ultrasonically melt-treated billets for all iron contents of AI-7mass%Si alloys, for example, the elongation of 11% in thixocast of AI-7mass%Si-0.5mass%Fe alloy with ultrasonically melt-treated billets, 5% in that with non-treated billets.
基金Jiangsu Natural Science Foundation,Grant/Award Number:BK20190460National Natural Science Foundation,Grant/Award Numbers:92163124,51888103,52006105Fundamental Research Funds for the Central Universities,Grant/Award Numbers:30920041113,30921013103。
文摘Ammonia is a crucial raw ingredient used in the manufacturing of fer-tilizers and pharmaceuticals,which are major sectors of the national economy in the chemical and agricultural industries.The conventional Haber–Bosch method is still in use in the industry today to manufacture NH3,and the production process emits a significant quantity of CO_(2),which does not match the current standards for the achievement of carbon neutrality.The nitrogen reduction reaction(NRR)technology has garnered a lot of attention lately because of its benefits,which include being environmentally friendly,sustainable,and able to function in mild environments.However,NRR is still in its early stages of development and confronts numerous difficult issues,including slow reaction kinetics,low ammonia yield rates and Faradaic efficiency(FE),and a dearth of effective research on nitrogen fixation as a whole.This paper aims to promote the industrialization of NRR,summarizing the progress of iron‐based catalysts,including single atomic catalysts,organic frameworks,metal oxides the,and alloys.Eventually,this paper discusses the strate-gies for improving NH3 yield rates and FE,improving reaction kinetics,and building a sustainable overall nitrogen fixation system.The deve-lopment of iron‐based catalysts in other fields has also been prospected.
