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Interfacial reaction between AZ91D magnesium alloy melt and mild steel under high temperature

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China Foundry 2024年第2期21卷 159-167页

作者： Jia-hong Dai Jian-yue Zhang bin Jiang Xiang-jun xu Zhong-tao Jiang hong-mei Xie Qing-shan Yang Guo-qing Zhang College of Materials Science and Engineering Yangtze Normal UniversityChongqing 408100China National Engineering Research Center for Magnesium Alloys College of Materials Science and EngineeringChongqing UniversityChongqing 400044China Chongqing Jiulongyuan High-tech Industry Group Co. Ltd.Chongqing 400080China Loncin Industry Co. Ltd.Chongqing 400080China Department of Materials Science and Engineering The Ohio State UniversityColumbusOH 43210USA Chongqing Key Laboratory of Materials Surface&Interface Science Chongqing University of Arts and SciencesChongqing 402160China School of Metallurgy and Material Engineering Chongqing University of Science and TechnologyChongqing 401331China

The metallurgical quality control of magnesium(Mg)and Mg alloys in melting process is required to ensure a satisfied mechanical and corrosion performance,while the typical used steel crucible introduces impurities and interfacial interaction during melting ***,a systematic study about impurities diffusion and interfacial interaction between molten Mg and steel is *** the present study,the interfacial reaction between molten AZ91D Mg alloy and mild steel during melting process was investigated with the melting temperatures of 700℃,750℃ and 800℃.The results show that Al(Fe,Mn)intermetallic layer is the intermetallic primarily formed at the interfaces of AZ91D melt and mild ***,Al_(8)(Mn,Fe)5is indexed between Al(Fe,Mn)and ***_(3)C appears between the mild steel and Al(Fe,Mn)at 700℃ and 750℃,but absent at 800℃ due to the increased solubility of carbon in Mg *** is found that the growth of the intermetallic layer is controlled by diffusion mechanism,and Al and Mn are the dominant diffusing species in the whole interfacial reaction *** measuring the thickness of different layers,the growth constant was *** increases from 1.89(±0.03)×10^(-12)m^(2)·s^(-1)at 700℃ to 3.05(±0.05)×10^(-12)m^(2)·s^(-1)at 750℃,and 5.18(±0.05)×10^(-12)m^(2)·s^(-1)at 800℃.Meanwhile,the content of Fe is linearly increased in AZ91D with the increase of holding time at 700℃ and 750℃,while it shows a significantly increment after holding for 8 h at 800℃,indicating holding temperature is more crucial to determine the Fe content of AZ91D than holding time.

关键词： AZ91D mild steel interface reaction intermetallic growth kinetics

Segregation of Mg-6Gd alloy under natural convection:From macro solute distribution to micro dendrite growth

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China Foundry 2024年第5期21卷 613-624页

作者： hong-xu Chen Ang Zhang Hao Li Yu Gao Yu-hong Cui Guang-sheng Huang bin Jiang Fu-sheng Pan National Engineering Research Center for Magnesium Alloys National Key Laboratory of Advanced Casting TechnologiesCollege of Materials Science and EngineeringChongqing UniversityChongqing 400044China

Segregation is a serious defect in alloy ingots which severely deteriorates materials *** segregation defect in Mg-6Gd alloy is studied by coupling macro thermal-solutal-convection transport and micro dendrite *** macroscopic fluid dynamics and mass transfer equations are resolved to forecast the segregation behavior under conditions of continuous temperature variation during the solidification *** numerical model is validated by testing double-diffusive natural convection in a closed square cavity.A phase field model is then applied to simulate the micro dendrite growth,using macro undercooling and liquid flow velocity as boundary *** show that the multiscale segregation behavior,including macro solute distribution and micro dendritic morphology,is strongly dependent on the temperature condition and the liquid convection,which provides guidance for reducing and eliminating the segregation defect.

关键词： magnesium alloy segregation numerical simulation phase-field simulation multiscale

Grain refinement of 5A06 aluminum alloy welds caused by tungsten inert gas welding arc characteristics under Ar-He alternating gas supply conditions:a coupled method of water-cooled copper plate test/numerical simulation

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Journal of Iron and Steel Research International 2024年第3期31卷 767-777页

作者： hong-bin Dai Jian Miao Jia-xin Lin School of Materials Science and Engineering Harbin University of Science and TechnologyHarbin 150040HeilongjiangChina

The welding arc,as a carrier for the conversion of electrical energy to thermal energy,has a direct impact on the quality of welding by its properties and *** the tungsten inert gas(TIG)welding process under the condition of Ar-He alternating gas supply,the arc is alternately converted between Ar arc and He arc with an alternating gas supply cycle,which has obvious arc change *** FLUENT software was used to numerically simulate the characteristics of the TIG arc under the condition of alternating gas supply,and the arc temperature field,arc pressure,electric potential and current density distribution under the condition of alternating gas supply were *** with the real-time data of arc pressure measured by the water-cooled copper plate with holes,it is proved that the TIG arc has obvious dynamic characteristics under the condition of Ar-He alternating gas *** unique dynamic TIG arc acts on the 5A06 aluminum alloy weld,causing the molten pool to stir,resulting in uniform microstructure and grain refinement at the weld,and thereby improving the mechanical properties of the welded joint.

关键词： Alternating gas supply Grain refinement Numerical simulation Tungsten argon arc morphology Microstructure Mechanical property

过渡金属Tc及其氮化物TcN,TcN_2,TcN_3与TcN_4低压缩性的第一性原理计算研究

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物理学报 2009年第8期58卷 5645-5652页

作者：许红斌王渊旭河南大学物理与电子学院计算材料科学研究所开封475004

采用基于密度泛函理论的第一性原理计算方法研究了Tc及其氮化物的弹性性质、电子结构、原子布局数等,并分析和计算了它的氮化物的理论硬度.结果表明随着Tc中氮的掺入量的渐增,出现层状结构,它们的弹性模量并非单调增加,其中TcN的体弹模... 详细信息

采用基于密度泛函理论的第一性原理计算方法研究了Tc及其氮化物的弹性性质、电子结构、原子布局数等,并分析和计算了它的氮化物的理论硬度.结果表明随着Tc中氮的掺入量的渐增,出现层状结构,它们的弹性模量并非单调增加,其中TcN的体弹模量最大而剪切模量最小;层状结构的TcN3的剪切模量最大而体弹模量最小,TcN4的理论计算硬度最大.说明在Tc的氮化物中,其体弹模量与材料的晶体结构、平均每个原子上的电荷密度和材料的质量密度有关;化学键的共价性结构和氮元素的含量对理论计算硬度有正作用;而剪切模量的极大值则与其层状结构及体系中一定量的方向基本一致的N—N键相关.

关键词：第一性原理弹性性质电子结构

Auxiliary ball milling to prepare WS_(2)/graphene nanosheets composite for lithium-ion battery anode materials

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Tungsten 2024年第1期6卷 124-133页

作者： Yong-Lin Wu Jia-bin hong Wei-xu Zhong Chun-Xiang Wang Zhi-Feng Li Sydorov Dmytro Jiangxi Provincial Key Laboratory of Power Batteries and Materials Jiangxi University of Science and TechnologyGanzhou 341000China Faculty of Materials Metallurgy and Chemistry Jiangxi University of Science and TechnologyGanzhou 341000China Institute of Bioorganic Chemistry and Petrochemistry National Academy of Sciences of UkraineKiev 02160Ukraine

A novel nano-WS_(2)/graphene nanosheets(GNSs)composite is obtained by ball milling with xylitol as auxiliary agent and hightemperature *** improves the shear force during ball milling and well overcomes the van der Waals interactions between the interlayer of graphite and WS_(2).Through high-temperature calcination,GNSs and WS_(2) nanosheets can form tight interface *** produced WS_(2)/GNSs composites can be used as anode materials for lithium-ion batteries,while maintaining a high reversible specific capacity of 705 mAh·g^(-1)with the capacity retention of 95%at a current density of 250 mA·g^(-1)after 200 cycles,mainly because WS_(2)/GNSs composites have a higher Li^(+)diffusion coefficient of 2.2×10^(-9)cm^(2)·s^(-1)and a higher specific surface area of 70.10 m^(2)·g^(-1).As a result,the xylitol-assisted ball milling method designed in this work is suitable for extended preparation of peeling of two-dimensional layer materials into nanosheets.

关键词： Lithium-ion battery Anode material WS_(2) Graphene nanosheets Auxiliary ball milling

Phonon-blockade-based multiple-photon bundle emission in a quadratically coupled optomechanical system

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Frontiers of physics 2024年第3期19卷 207-215页

作者： Ye-Jun xu hong Xie Interdisciplinary Research Center of Quantum and Photoelectric Information Chizhou UniversityChizhou 247000China Department of Mathematics and Physics Fujian Jiangxia UniversityFuzhou 350108China

We propose a scheme to realize antibunched multiple-photon bundles based on phonon blockade in a quadratically coupled optomechanical *** adjusting the detunings to match the conditions of phonon blockade in the photon sidebands,we establish super-Rabi oscillation between zero-photon state and multiple-photon states with adjustable super-Rabi frequencies under appropriate single-phonon resonant *** the system dissipation into account,we numerically calculate the standard and generalized second-order functions of the cavity mode as well as the quantum trajectories of the state populations with Monte Carlo simulation to confirm that the emitted photons form antibunched multiple-photon ***,the desirable n-photon states are reconstructed after a direct phonon emission based on phonon blockade,and thus the single-phonon emission heralds the cascade emission of n-photon *** proposal shows that the optomechanical system can simultaneously behave as antibunched multiple-photon emitter and single-phonon *** a nonclassical source could have potential applications in quantum information science.

关键词： multiple-photon bundle emission phonon blockade optomechanical system

2D Ca/Nb-based perovskite oxide with Ta doping as highly efficient H_(2)O_(2)synthesis catalyst

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Nano Research 2024年第6期17卷 4934-4942页

作者： Xingchen Yang Yang Gao Xiaohui xu Wenqiang xu Denghui Wang bin Luo Dong Liu Tao Liang bin Wang CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and TechnologyBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Nanomaterials Centre School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnologythe University of QueenslandSt LuciaQLD 4072Australia State Key Laboratory of Organic–Inorganic Composites College of Chemical EngineeringCollege of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029China Hangzhou Institute for Advanced Study University of Chinese Academy of SciencesHangzhou 310024China State Key Lab of Silicon Materials Zhejiang UniversityHangzhou 310027China

Perovskite oxides(POs)are emerging as a class of highly efficient catalysts for reducing oxygen to H_(2)*** a rich variety of POs-based catalysts have been developed by tuning the complex composition,a highly efficient PO catalyst that is able to alter the reaction pathway from a 4e−process to a 2e−process for H_(2)O_(2)production has rarely been *** modified the structure and composition of a Ca-and Nb-based PO material by realizing a uniform two-dimensional(2D)morphology and varied Ta doping,resulting in the 2D Ca_(2)Nb_(3−x)Ta_(x)O_(10)−(x=0,0.5,1,and 1.5)monolayer *** obtained catalysts exhibit a dominant 2e−pathway and show exceptional H_(2)O_(2)production *** typical Ca_(2)Nb_(2.5)Ta_(0.5)O_(10)−nanoflakes showed an onset potential of 0.735 V *** hydrogen electrode(RHE),a remarkably high selectivity over 95%across a wide range of 0.3-0.7 V,an impressively high Faradaic efficiency of 94%,and a notable H_(2)O_(2)productivity of 1571 mmol·gcat^(−1)·h^(−1).These findings highlight the great potential of 2D perovskite oxide nanoflakes as advanced electrocatalysts for 2e−oxygen reduction reaction.

关键词： perovskite oxide H_(2)O_(2) two-electron oxygen reduction reaction catalyst Ca_(2)Nb_(3-x)Ta_(x)O_(10)-nanoflakes

Fiber optic displacement sensor used in railway turnout contact monitoring system

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Optoelectronics Letters 2019年第3期15卷 165-169页

作者： xu hong-bin LI Feng ZHAO Wei-gang TIAN Xiu-shu DU Yan-liang GAO Yang School of Civil Engineering Beijing Jiaotong UniversityBeijing100044China Structure Health Monitoring and Control Institute Shijiazhuang Tiedao UniversityShijiazhuang050043China School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing100044China

Railway turnout contact monitoring is very important in high-speed rail operation systems. In order to measure the distance between the sharp rail and the basic rail in a switch system, a wide-range, high-precision fiber Bragg grating(FBG) displacement sensor was designed. Because the distance between the sharp and basic rails is always greater than 14 cm, the measurement range width and accuracy of the proposed sensor system are ensured through the use of a long spring and a beam of constant strength. A differential compensation method is used to eliminate temperature effects. Test results show that the resolution of the proposed sensor is 0.040 mm and the measuring range is 0—170 mm. A field test was also carried out to evaluate the performance of the sensors.

关键词： FBG Fiber optic displacement sensor used in railway turnout contact monitoring system

Prospects for green steelmaking technology with low carbon emissions in China

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Carbon Energy 2024年第2期6卷 1-24页

作者： Zhang Fucheng hong Lukuo xu Ying College of Metallurgy and Energy North China University of Science and TechnologyTangshanHebeiChina Hebei Iron and Steel Laboratory TangshanHebeiChina

The steel industry is a major source of CO_(2) emissions,and thus,the mitigation of carbon emissions is the most pressing challenge in this *** this paper,international environmental governance in the steel industry is reviewed,and the current state of development of low-carbon technologies is ***,low-carbon pathways for the steel industry at the current time are proposed,emphasizing prevention and treatment ***,the prospects of low-carbon technologies are explored from the perspective of transitioning the energy structure to a“carbon-electricity-hydrogen”***,steel enterprises should adopt hydrogen-rich metallurgical technologies that are compatible with current needs and process flows in the short term,based on the carbon substitution with hydrogen(prevention)and the CCU(CO_(2) capture and utilization)concepts(treatment).Additionally,the capture and utilization of CO_(2) for steelmaking,which can assist in achieving short-term emission reduction targets but is not a long-term solution,is *** conclusion,in the long term,the carbon metallurgical process should be gradually supplanted by a hydrogen-electric synergistic approach,thus transforming the energy structure of existing steelmaking processes and attaining near-zero carbon emission steelmaking technology.

关键词： carbon capture and utilization carbon emission hydrogen metallurgy low-carbon technology steel industry