The effects of heating rate （ranging from 50 to 300 ℃/s） during the final annealing process on microstructure evolution and magnetic properties of cold rolled non-oriented electrical steel were investigated. It was...The effects of heating rate （ranging from 50 to 300 ℃/s） during the final annealing process on microstructure evolution and magnetic properties of cold rolled non-oriented electrical steel were investigated. It was found that increasing heating rate increased the nucleation temperature and complete recrystallization temperature. At the same time, heating rate increasing could cause the substantially refined structures for the recrystallization grains and this grain refinement would decline when the heating rate was beyond 50 ℃/s. The recrystallization texture exhibited pronounced improvement with heating rate, such as the intensity decrease of 〈111〉//ND （normal direction） fiber and the intensity increase of { 110}%〈001〉 Goss texture component. The texture improvement and grain size refinement caused by heating rate increasing resulted in complicated variation of the magnetic properties. The magnetic induction （B50） keeps increasing while heating rate increases from 15 to 300 ℃/s which is due to the recrystallized texture optimization caused by rapid heating. The core losses （P1.5/50） decrease while heating rate increases from 15 to 100 ℃/s; however, the core losses would increase when heating rate is higher than 100 ℃/s, which is caused by the mean grain size refinement after rapid heating annealing. The results indicate that recrystallization texture and the magnetic properties of the non-oriented electrical steel can be improved definitely by rapid heating during the final annealing treatment.展开更多
A coupled mathematical model was developed to describe the flow field,temperature distribution of molten steel in the tundish with the channel type induction heating.The molten steel motion was dominated under the com...A coupled mathematical model was developed to describe the flow field,temperature distribution of molten steel in the tundish with the channel type induction heating.The molten steel motion was dominated under the combined effect of the thermal buoyancy and the electro-magnetic forces(EMFs)due to the channel type induction heating.The results indicate that the thermal loss of molten steel in the tundish can be compensated effectively by the channel type induction heating.In addition,the molten steel would flow upward under the thermal buoyancy which can reduce the erosion of refractory.Moreover,the upward flow would increase the residence time of the molten steel in the tundish which provide more opportunities for the inclusion to reach the top surface of the tundish.展开更多
As one of the most spectacular energy release events in the solar system,solar flares are generally powered by magnetic reconnection in the solar corona.As a result of the re-arrangement of magnetic field topology aft...As one of the most spectacular energy release events in the solar system,solar flares are generally powered by magnetic reconnection in the solar corona.As a result of the re-arrangement of magnetic field topology after the reconnection process,a series of new looplike magnetic structures are often formed and are known as flare loops.A hot diffuse region,consisting of around 5–10 MK plasma,is also observed above the loops and is called a supra-arcade fan.Often,dark,tadpole-like structures are seen to descend through the bright supra-arcade fans.It remains unclear what role these so-called supra-arcade downflows(SADs)play in heating the flaring coronal plasma.Here we show a unique flare observation,where many SADs collide with the flare loops and strongly heat the loops to a temperature of 10–20 MK.Several of these interactions generate clear signatures of quasi-periodic enhancement in the full-Sun-integrated soft X-ray emission,providing an alternative interpretation for quasi-periodic pulsations that are commonly observed during solar and stellar flares.展开更多
In the induction heating of airport pavement to remove snow and ice,soft magnetic geopolymer composite(SMGC)can be used to gather the dissipated electromagnetic energy,thus enhancing the energy utilization efficiency....In the induction heating of airport pavement to remove snow and ice,soft magnetic geopolymer composite(SMGC)can be used to gather the dissipated electromagnetic energy,thus enhancing the energy utilization efficiency.The aim of this work is to analyze the influence mechanism of iron powder content on the electromagnetic and mechanical performance of SMGC,so as to provide theoretical guidance for the design of soft magnetic layer within airport pavement structure.The results show that the increase of iron powder content reduces the resistance and magnetoresistance of SMGC by decreasing the content of non-magnetic phases between iron powder.However,the reduction of iron powder spacing also provides a shorter transmission path for the inter-particle eddy currents in the SMGC specimen,which enhances the exchange coupling between iron powder,thus increasing the electromagnetic loss.Therefore,the compatibility between magnetic permeability and electromagnetic loss should be considered comprehensively in the mix design of SMGC.In addition,although iron powder can enhance the mechanical properties of SMGC by improving the density of geopolymer matrix,the excessive amount of iron powder can lead to a weak interfacial transition zone between geopolymer matrix and iron powder.According to the induction heating results,optimized SMGC can improve the energy transfer efficiency of induction heating by 24.03%.展开更多
Ruthenium has been hailed as a competitive alternative for platinum toward hydrogen evolution reaction(HER),a critical process in electrochemical water splitting.In this study,we successfully prepare metallic Ru nanop...Ruthenium has been hailed as a competitive alternative for platinum toward hydrogen evolution reaction(HER),a critical process in electrochemical water splitting.In this study,we successfully prepare metallic Ru nanoparticles supported on carbon paper by utilizing a novel magnetic induction heating(MIH)method.The samples are obtained within seconds,featuring a Cl-enriched surface that is unattainable via conventional thermal annealing.The best sample within the series shows a remarkable HER activity in both acidic and alkaline media with an overpotential of only-23 and-12 mV to reach the current density of 10 mA/cm^(2),highly comparable to that of the Pt/C benchmark.Theoretical studies based on density functional theory show that the excellent electrocatalytic activity is accounted by the surface metal-Cl species that facilitate charge transfer and downshift the d-band center.Results from this study highlight the unique advantages of MIH in rapid sample preparation,where residual anion ligands play a critical role in manipulating the electronic properties of the metal surfaces and the eventual electrocatalytic activity.展开更多
This work particularly focuses on compensating Joule heat in under-heated areas occurred when thin steel bar is(<20 mm)heated by transverse flux induction heater(TFIH).The under-heated areas take place in range of ...This work particularly focuses on compensating Joule heat in under-heated areas occurred when thin steel bar is(<20 mm)heated by transverse flux induction heater(TFIH).The under-heated areas take place in range of 50~150 mm from the both edges,so Transverse Flux Induction Coil(TFIC)including a magnetic core is proposed and optimized to supplement this fault.The solutions on the electromagnetic field are obtained numerically by commercial code MAXWELL 3D software from ANSYS Corp.and then,verified experimentally by pilot-scale tests,in which the TFIH was manufactured with a nominal power of 100 kW at a fundamental frequency of 1 kHz.Ultimately,TFIC having geometrically the optimized magnetic core made the heating pattern U-shaped,so could supply a desirable temperature profile for the rolling process.展开更多
Microwave is an electromagnetic wave and consists of the electric and the magnetic fields.The microwave electric field interacts with dielectric materials and heat is generated due to the dielectric loss,which is a ma...Microwave is an electromagnetic wave and consists of the electric and the magnetic fields.The microwave electric field interacts with dielectric materials and heat is generated due to the dielectric loss,which is a major mechanism of microwave heating of water.Microwave magnetic field interaction with materials has to be discussed in terms of two different mechanisms.The first class is the induction current generation in(mainly)metallic materials, which gives rise the Joule heat,although the penetration distance into metals are limited within a microns or less.In this article,a characteristic application of microwave induction heating of metal thin film is presented.The second class is the microwave interaction with the ferro(or ferri)magnetic materials.Effect of ferromagnetic resonance(FMR)is taken into consideration as the fundamental heating mechanism of the ferro-magnetic materials.The FMR heating behavior of Fe_3O_4 is presented.Discussion is made for the phenomena observed in the experiments.展开更多
The axis symmetric analysis method can neither handle initial curved plates nor be used in the optimization of coil shapes because an axis symmetric coil is the only shape to analyze in this method. But the method usi...The axis symmetric analysis method can neither handle initial curved plates nor be used in the optimization of coil shapes because an axis symmetric coil is the only shape to analyze in this method. But the method using some discrete divisions and steps, can overcome these difficulties and show more accurate, reasonable results of temperatures and deflections in flat or curved plates with initial curvature, than those in the axis symmetric analysis method. Traditionally, the coil shape in induction heating is circular shape and it needs the moving process along heating lines. To overcome these, the “long type coil” with some linear parallel coils is proposed. It does not need the moving process along heating lines and reduces the heating process time. The results of experiments are compared with those of simulation.展开更多
基金Item Sponsored by National Natural Science Foundation of China (50874010 ,50802008) Program for New Century Excellent Talents in University of China (NCET-05-0101)
文摘The effects of heating rate （ranging from 50 to 300 ℃/s） during the final annealing process on microstructure evolution and magnetic properties of cold rolled non-oriented electrical steel were investigated. It was found that increasing heating rate increased the nucleation temperature and complete recrystallization temperature. At the same time, heating rate increasing could cause the substantially refined structures for the recrystallization grains and this grain refinement would decline when the heating rate was beyond 50 ℃/s. The recrystallization texture exhibited pronounced improvement with heating rate, such as the intensity decrease of 〈111〉//ND （normal direction） fiber and the intensity increase of { 110}%〈001〉 Goss texture component. The texture improvement and grain size refinement caused by heating rate increasing resulted in complicated variation of the magnetic properties. The magnetic induction （B50） keeps increasing while heating rate increases from 15 to 300 ℃/s which is due to the recrystallized texture optimization caused by rapid heating. The core losses （P1.5/50） decrease while heating rate increases from 15 to 100 ℃/s; however, the core losses would increase when heating rate is higher than 100 ℃/s, which is caused by the mean grain size refinement after rapid heating annealing. The results indicate that recrystallization texture and the magnetic properties of the non-oriented electrical steel can be improved definitely by rapid heating during the final annealing treatment.
基金Item Sponsored by National Natural Science Foundation of China[No.50934008]National Natural Science Foundation of China[NO.50904014]
文摘A coupled mathematical model was developed to describe the flow field,temperature distribution of molten steel in the tundish with the channel type induction heating.The molten steel motion was dominated under the combined effect of the thermal buoyancy and the electro-magnetic forces(EMFs)due to the channel type induction heating.The results indicate that the thermal loss of molten steel in the tundish can be compensated effectively by the channel type induction heating.In addition,the molten steel would flow upward under the thermal buoyancy which can reduce the erosion of refractory.Moreover,the upward flow would increase the residence time of the molten steel in the tundish which provide more opportunities for the inclusion to reach the top surface of the tundish.
基金The authors thank the SDO,GOES,and RHESSI teams for providing the data,and Shinsuke Takasao for helpful discussion.This work was supported by NSFC grants 11825301 and 11790304,Strategic Priority Research Program of CAS(grant XDA17040507)NASA LWS grant 80NSSC19K0069,NSF grants AST-1735405 and AGS-1723436 to New Jersey Institute of Technology(NJIT)NASA grant 80NSSC18K0732 and NASA's SDO/AIA contract(NNG04EA00C)to the Lockheed Martin Solar and Astrophysics Laboratory.AIA is an instrument onboard the SDO,a mission for NASA's Living With a Star program.
文摘As one of the most spectacular energy release events in the solar system,solar flares are generally powered by magnetic reconnection in the solar corona.As a result of the re-arrangement of magnetic field topology after the reconnection process,a series of new looplike magnetic structures are often formed and are known as flare loops.A hot diffuse region,consisting of around 5–10 MK plasma,is also observed above the loops and is called a supra-arcade fan.Often,dark,tadpole-like structures are seen to descend through the bright supra-arcade fans.It remains unclear what role these so-called supra-arcade downflows(SADs)play in heating the flaring coronal plasma.Here we show a unique flare observation,where many SADs collide with the flare loops and strongly heat the loops to a temperature of 10–20 MK.Several of these interactions generate clear signatures of quasi-periodic enhancement in the full-Sun-integrated soft X-ray emission,providing an alternative interpretation for quasi-periodic pulsations that are commonly observed during solar and stellar flares.
基金This work was supported by National Key Research and Development Project(2020YFB1600102,2020YFA0714302)National Natural Science Foundation of China(51878164,51922030,52208430)+2 种基金Fundamental Research Funds for the Central Universities of China(2242022R10059)Natural Science Foundation of Jiangsu Province(SBK2021042206)Southeast University“Zhongying Young Scholars”Project,and Shuangchuang Program of Jiangsu Province(JSSCBS20210058).
文摘In the induction heating of airport pavement to remove snow and ice,soft magnetic geopolymer composite(SMGC)can be used to gather the dissipated electromagnetic energy,thus enhancing the energy utilization efficiency.The aim of this work is to analyze the influence mechanism of iron powder content on the electromagnetic and mechanical performance of SMGC,so as to provide theoretical guidance for the design of soft magnetic layer within airport pavement structure.The results show that the increase of iron powder content reduces the resistance and magnetoresistance of SMGC by decreasing the content of non-magnetic phases between iron powder.However,the reduction of iron powder spacing also provides a shorter transmission path for the inter-particle eddy currents in the SMGC specimen,which enhances the exchange coupling between iron powder,thus increasing the electromagnetic loss.Therefore,the compatibility between magnetic permeability and electromagnetic loss should be considered comprehensively in the mix design of SMGC.In addition,although iron powder can enhance the mechanical properties of SMGC by improving the density of geopolymer matrix,the excessive amount of iron powder can lead to a weak interfacial transition zone between geopolymer matrix and iron powder.According to the induction heating results,optimized SMGC can improve the energy transfer efficiency of induction heating by 24.03%.
基金National Science Foundation,Grant/Award Numbers:CHE-1900235,CHE-2003685Office of Science,Office of Basic Energy Sciences,of the U.S.Department of Energy,Grant/Award Number:DE-AC02-05CH11231+3 种基金U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,Grant/Award Number:DE-AC02-76SF00515NSF MRI program,Grant/Award Number:AST-1828315Grant-in-Aid of Research,Grant/Award Number:G20211001-639National Academy of Sciences,administered by Sigma Xi,The Scientific Research Society。
文摘Ruthenium has been hailed as a competitive alternative for platinum toward hydrogen evolution reaction(HER),a critical process in electrochemical water splitting.In this study,we successfully prepare metallic Ru nanoparticles supported on carbon paper by utilizing a novel magnetic induction heating(MIH)method.The samples are obtained within seconds,featuring a Cl-enriched surface that is unattainable via conventional thermal annealing.The best sample within the series shows a remarkable HER activity in both acidic and alkaline media with an overpotential of only-23 and-12 mV to reach the current density of 10 mA/cm^(2),highly comparable to that of the Pt/C benchmark.Theoretical studies based on density functional theory show that the excellent electrocatalytic activity is accounted by the surface metal-Cl species that facilitate charge transfer and downshift the d-band center.Results from this study highlight the unique advantages of MIH in rapid sample preparation,where residual anion ligands play a critical role in manipulating the electronic properties of the metal surfaces and the eventual electrocatalytic activity.
文摘This work particularly focuses on compensating Joule heat in under-heated areas occurred when thin steel bar is(<20 mm)heated by transverse flux induction heater(TFIH).The under-heated areas take place in range of 50~150 mm from the both edges,so Transverse Flux Induction Coil(TFIC)including a magnetic core is proposed and optimized to supplement this fault.The solutions on the electromagnetic field are obtained numerically by commercial code MAXWELL 3D software from ANSYS Corp.and then,verified experimentally by pilot-scale tests,in which the TFIH was manufactured with a nominal power of 100 kW at a fundamental frequency of 1 kHz.Ultimately,TFIC having geometrically the optimized magnetic core made the heating pattern U-shaped,so could supply a desirable temperature profile for the rolling process.
文摘Microwave is an electromagnetic wave and consists of the electric and the magnetic fields.The microwave electric field interacts with dielectric materials and heat is generated due to the dielectric loss,which is a major mechanism of microwave heating of water.Microwave magnetic field interaction with materials has to be discussed in terms of two different mechanisms.The first class is the induction current generation in(mainly)metallic materials, which gives rise the Joule heat,although the penetration distance into metals are limited within a microns or less.In this article,a characteristic application of microwave induction heating of metal thin film is presented.The second class is the microwave interaction with the ferro(or ferri)magnetic materials.Effect of ferromagnetic resonance(FMR)is taken into consideration as the fundamental heating mechanism of the ferro-magnetic materials.The FMR heating behavior of Fe_3O_4 is presented.Discussion is made for the phenomena observed in the experiments.
文摘The axis symmetric analysis method can neither handle initial curved plates nor be used in the optimization of coil shapes because an axis symmetric coil is the only shape to analyze in this method. But the method using some discrete divisions and steps, can overcome these difficulties and show more accurate, reasonable results of temperatures and deflections in flat or curved plates with initial curvature, than those in the axis symmetric analysis method. Traditionally, the coil shape in induction heating is circular shape and it needs the moving process along heating lines. To overcome these, the “long type coil” with some linear parallel coils is proposed. It does not need the moving process along heating lines and reduces the heating process time. The results of experiments are compared with those of simulation.
