S形扁钢在轧制过程中变形量大且不均匀,存在明显的加工硬化现象。将30Mn Si S形扁钢在680℃,走线速率分别为3,6,9 m/min进行连续退火处理,对不同退火走线速率下30Mn Si S形扁钢的力学性能及金相组织进行了比较。结果表明:30Mn Si S形扁...S形扁钢在轧制过程中变形量大且不均匀,存在明显的加工硬化现象。将30Mn Si S形扁钢在680℃,走线速率分别为3,6,9 m/min进行连续退火处理,对不同退火走线速率下30Mn Si S形扁钢的力学性能及金相组织进行了比较。结果表明:30Mn Si S形扁钢随退火走线速率的降低抗拉强度及硬度降低;当走线速率达到6 m/min时,30Mn Si S形扁钢基本完成再结晶,抗拉强度及硬度变化趋势趋于平缓。30Mn Si S形扁钢在不同退火走线速率下组织均为粒状珠光体组织,引起其力学性能变化的原因在于再结晶晶粒的大小。展开更多
Mg−Nd−Zn−Zr magnesium alloy(JDBM)has been studied widely as biodegradable medical material.To process high quality JDBM wires,effects of annealing on the mechanical properties and degradation behavior after drawing we...Mg−Nd−Zn−Zr magnesium alloy(JDBM)has been studied widely as biodegradable medical material.To process high quality JDBM wires,effects of annealing on the mechanical properties and degradation behavior after drawing were studied by microscopic observations,tensile and immersion tests.The as-extruded wires with a diameter of 3 mm could be drawn up to 9 passes without annealing until 125%cumulative drawing deformation.Complete recrystallization occurred after annealing at 325℃ for 30 min,350℃ for 5 min or 450℃for 3 min,respectively.Room temperature tensile tests and simulated body fluid immersion tests showed that annealing at slightly elevated temperature for short time could obtain better properties due to the finer grain size and more dispersive distribution of precipitates.For this study,annealing at 350℃ for 5 min is the best parameters which can be utilized to further fabricate fine wires.展开更多
Palladium(Pd)‐based catalysts are essential to drive high‐performance Suzuki coupling reactions,which are powerful tools for the synthesis of functional organic compounds.Herein,we developed a solution‐rapid‐annea...Palladium(Pd)‐based catalysts are essential to drive high‐performance Suzuki coupling reactions,which are powerful tools for the synthesis of functional organic compounds.Herein,we developed a solution‐rapid‐annealing process to stabilize nitrogen‐mesoporous carbon supported Pd single‐atom/cluster(Pd/NMC)material,which provided a catalyst with superior performance for Suzuki coupling reactions.In comparison with commercial palladium/carbon(Pd/C)catalysts,the Pd/NMC catalyst exhibited significantly boosted activity(100%selectivity and 95%yield)and excellent stability(almost no decay in activity after 10 reuse cycles)for the Suzuki coupling reactions of chlorobenzenes,together with superior yield and excellent selectivity in the fields of the board scope of the reactants.Moreover,our newly developed rapid annealing process of precursor solutions is applied as a generalized method to stabilize metal clusters(e.g.Pd,Pt,Ru),opening new possibilities in the construction of efficient highly dispersed metal atom and sub‐nanometer cluster catalysts with high performance.展开更多
In large loop transient electromagnetic method(TEM),the late time apparent resistivity formula cannot truly reflect the geoelectric model,thus it needs to define the all-time apparent resistivity with the position inf...In large loop transient electromagnetic method(TEM),the late time apparent resistivity formula cannot truly reflect the geoelectric model,thus it needs to define the all-time apparent resistivity with the position information of measuring point.Utilizing very fast simulated annealing(VFSA) to fit the theoretical electromagnetic force(EMF) and measured EMF could obtain the all-time apparent resistivity of the measuring points in rectangular transmitting loop.The selective cope of initial model of VFSA could be confirmed by taking the late time apparent resistivity of transient electromagnetic method as the prior information.For verifying the correctness,the all-time apparent resistivities of the geoelectric models were calculated by VFSA and dichotomy,respectively.The results indicate that the relative differences of apparent resistivities calculated by these two methods are within 3%.The change of measuring point position has little influence on the tracing pattern of all-time apparent resistivity.The first branch of the curve of all-time apparent resistivity is close to the resistivity of the first layer medium and the last branch is close to the resistivity of the last layer medium,which proves the correctness of the arithmetics proposed.展开更多
文摘S形扁钢在轧制过程中变形量大且不均匀,存在明显的加工硬化现象。将30Mn Si S形扁钢在680℃,走线速率分别为3,6,9 m/min进行连续退火处理,对不同退火走线速率下30Mn Si S形扁钢的力学性能及金相组织进行了比较。结果表明:30Mn Si S形扁钢随退火走线速率的降低抗拉强度及硬度降低;当走线速率达到6 m/min时,30Mn Si S形扁钢基本完成再结晶,抗拉强度及硬度变化趋势趋于平缓。30Mn Si S形扁钢在不同退火走线速率下组织均为粒状珠光体组织,引起其力学性能变化的原因在于再结晶晶粒的大小。
基金This work was financially supported by the National Natural Science Foundation of China(No.U1804251)the Shanghai Municipal Commission of Economy and Information,China(No.GYQJ-2019-1-27)+2 种基金the Science and Technology Commission of Shanghai Municipality,China(Nos.18441908000,19441906300,19441913400)the Shenzhen’s Three Renowned Project,China(No.SZSM201612092)the Shanghai Jiao Tong University Medical-engineering Cross Fund,China(No.YG2019ZDA02).
文摘Mg−Nd−Zn−Zr magnesium alloy(JDBM)has been studied widely as biodegradable medical material.To process high quality JDBM wires,effects of annealing on the mechanical properties and degradation behavior after drawing were studied by microscopic observations,tensile and immersion tests.The as-extruded wires with a diameter of 3 mm could be drawn up to 9 passes without annealing until 125%cumulative drawing deformation.Complete recrystallization occurred after annealing at 325℃ for 30 min,350℃ for 5 min or 450℃for 3 min,respectively.Room temperature tensile tests and simulated body fluid immersion tests showed that annealing at slightly elevated temperature for short time could obtain better properties due to the finer grain size and more dispersive distribution of precipitates.For this study,annealing at 350℃ for 5 min is the best parameters which can be utilized to further fabricate fine wires.
文摘Palladium(Pd)‐based catalysts are essential to drive high‐performance Suzuki coupling reactions,which are powerful tools for the synthesis of functional organic compounds.Herein,we developed a solution‐rapid‐annealing process to stabilize nitrogen‐mesoporous carbon supported Pd single‐atom/cluster(Pd/NMC)material,which provided a catalyst with superior performance for Suzuki coupling reactions.In comparison with commercial palladium/carbon(Pd/C)catalysts,the Pd/NMC catalyst exhibited significantly boosted activity(100%selectivity and 95%yield)and excellent stability(almost no decay in activity after 10 reuse cycles)for the Suzuki coupling reactions of chlorobenzenes,together with superior yield and excellent selectivity in the fields of the board scope of the reactants.Moreover,our newly developed rapid annealing process of precursor solutions is applied as a generalized method to stabilize metal clusters(e.g.Pd,Pt,Ru),opening new possibilities in the construction of efficient highly dispersed metal atom and sub‐nanometer cluster catalysts with high performance.
基金Projects(40804027,41074085) supported by the National Natural Science Foundation of ChinaProject(09JJ3048) supported by the Natural Science Foundation of Hunan Province,ChinaProject(200805331082) supported by the Research Fund for the Doctoral Program of Higher Education,China
文摘In large loop transient electromagnetic method(TEM),the late time apparent resistivity formula cannot truly reflect the geoelectric model,thus it needs to define the all-time apparent resistivity with the position information of measuring point.Utilizing very fast simulated annealing(VFSA) to fit the theoretical electromagnetic force(EMF) and measured EMF could obtain the all-time apparent resistivity of the measuring points in rectangular transmitting loop.The selective cope of initial model of VFSA could be confirmed by taking the late time apparent resistivity of transient electromagnetic method as the prior information.For verifying the correctness,the all-time apparent resistivities of the geoelectric models were calculated by VFSA and dichotomy,respectively.The results indicate that the relative differences of apparent resistivities calculated by these two methods are within 3%.The change of measuring point position has little influence on the tracing pattern of all-time apparent resistivity.The first branch of the curve of all-time apparent resistivity is close to the resistivity of the first layer medium and the last branch is close to the resistivity of the last layer medium,which proves the correctness of the arithmetics proposed.
