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Phase-field simulation for the evolution of solid/liquid interface front in directional solidification process

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Journal of Materials Science & Technology 2019年第6期35卷 1044-1052页

作者： Yuhong Zhao Bing Zhang Hua Hou weipeng chen Meng Wang College of Materials Science and Engineering North University of China Taiyuan 030051 China State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xian 710072 China

In this study, the phase field method was used to study the multi-controlling factors of dendrite growth in directional solidification. The effects of temperature gradient, propelling velocity, thermal disturbance and growth orientation angle on the growth morphology of the dendritic growth in the solid/liquid interface were discussed. It is found that the redistribution of solute leads to multilevel cavity and multilevel fusion to form multistage solute segregation, and the increase of temperature gradient and propelling velocity can accelerate the dendrite growth of directional solidification, and also make the second dendrites more developed, which reduces the primary distance and the solute segregation. When the temperature gradient is large, the solid-liquid interface will move forward in a flat interface mode,and the thermal disturbance does not affect the steady state behavior of the directionally solidified dendrite tip. It only promotes the generation and growth of the second dendrites and forms the asymmetric dendrite. Meanwhile, it is found that the inclined dendrite is at a disadvantage in the competitive growth compared to the normal dendrite, and generally it will disappear. When the inclination angle is large, the initial primary dendrite may be eliminated by its secondary or third dendrite.

关键词： Phase field method Directional solidification Interface morphology Multi-control factors

Effect of lanthanide contraction on a series of "sulfate-templated" transition-rare-earth metal clusters:Synthesis,structures and magnetic properties

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Journal of Rare Earths 2024年第11期42卷 2150-2155,I0006页

作者： Kaipeng Bai Pengfei Sun Mohamed Saber Lassoued Caihong Fan Chang Huang Yanzhen Zheng weipeng chen Frontier Institute of Science and Technology State Key Laboratory of Electrical Insulation and Power EquipmentXi'an Key Laboratory of Electronic Devices and Materials ChemistrySchool of ChemistryXi'an Jiaotong UniversityXi'an710054China Instrument Analysis Center of Xi'an Jiaotong University Xi'an710054China

Twelve novel transition-rare-earth metal clusters,formulated as [Ni_(18)Pr_(14)(μ_(3)OH)_(14)(dmpa)_(10)(mmt)_(10)(SO_(4))_(4)(CH_(3)COO)_(16)]·9CH_(3)OH·5H_(2)O(1,H_(3)dmpa=dimethylolpropionic acid,and Hmmt=2-me rcapto-5-methyl-1,3,4-thiadiazole) [Ni_(36)RE_(102)(OH)_(138)(mmt)_(18)(Hdmpa)_(30)(H_(2)dmpa)_(12)(CH_(3)COO)_(72)(NO_(3))_(36)(SO_(4))_(18)(H_(2)O)_(30)]·Br_(6)(RE=Nd(2),Sm(3),Eu(4) and Gd(5))[Ni_(12)RE_(10)(μ_(3)-OH)_(10)(dmpa)_(8)(mmt)_(8)(S(_(4))2(CH_(3)COO)_(8)(H_(2)O)_(4)]·8CH_(3)OH·7H_(2)O(RE = Tb(6),Dy(7),Ho(8),Er(9) and Y(10)) [Ni_(8)Pr_(8)(μ_(3)-OH)_(8)(mmt)_(8)(Hdpga)_(16)(CH3COO)_(8)]·8CH_(3)OH(11,H_(2)dpga=diphe nyl-glycolic acid),and [Ni_(16)Tb_(6)(μ_(3)-OH)_(24)(mmt)_(8)(Hdpga)_(4)(dpga)_(4)(CH_(3)COO)_(2)(NO_(3))_(4)(H_(2)O)_(2)]·12CH_(3)OH·5H_(2)O(12),were synthesized solvothermally by using different ligand combinations and rare earth nitrates.X-ray crystal structure analyses reveal that complexes 1 and 12 possess sandwich-like *** 2-5 are isostructural and feature a hexagonal structure,shaped like a "Star of David".Isostructural 6-10 present ring-like structure,as well as the cluster *** structural variations of these complexes can be attributed to the effect of lanthanide ***,the template effect of SO_(4)^(2-) anion derived from the slow decomposition of Hmmt ligand also plays a significant role in the formation of cluster *** insitu mechanism for the generation of sulfate anion is briefly ***,the magnetic properties of complexes 2-11 were studied which show typical antiferromagnetic interactions.

关键词： Rare earths Transition-rare-earth metal clusters Mixed-ligand strategy Sulfate-templated Lanthanide contraction Exchange coupling

Corrosion Behavior of Graphene Nanosheets Reinforced Magnesium Matrix Composites in Simulated Body Fluids

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 525-536页

作者： Liwen chen Jianhui Jing Lulu Zhang Jing Li weipeng chen Limin Li Yuan Zhao Hua Hou Yuhong Zhao School of Materials Science and Engineering Collaborative Innovation Center of Ministry of Education and Shanxi Province for High-Performance Al/Mg Alloy MaterialsNorth University of ChinaTaiyuan 030051China Shanxi Key Laboratory of Advanced Manufacturing Technology School of Mechanical EngineeringNorth University of ChinaTaiyuan 030051China School of Materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuan 030024China Beijing Advanced Innovation Center for Materials Genome Engineering University of Science and Technology BeijingBeijing 100083China Institute of Materials Intelligent Technology Liaoning Academy of MaterialsShenyang 110004China

Magnesium(Mg)alloy is considered as a promising biodegradable implant material but restricted to rapid ***,the new strategies based on thixomolding process had been explored to utilize the outstanding anti-permeability of graphene nanosheets(GNPs)while inhibit its galvanic corrosion with the matrix,so as to improve the corrosion resistance of *** agglomerate of GNPs with 0.9 wt%content is the main reason for the deterioration of corrosion performance due to the formation of micro-galvanic *** grain refinement of composites with 0.6 wt%content had positive effects on the better corrosion *** process adjusting,the unique distributions of GNPs along grain boundaries play a vital role in improving the corrosion *** can be ascribed to the following mechanisms:(I)The barriers can be established between the Mg matrix and corrosive medium,hence blocking the charge transfer at the interface;(II)The GNPs can effectively promote apatite deposition on the Mg matrix,leading to form dense apatite layers and prevent the further invasion of SBF;(III)The GNPs acting as reinforcements exists in the corrosion layer and apatite layer,impede the apatite layer falling off from the Mg *** findings broaden the horizon for biomedical applications in Mg matrix composites to realize desired performances.

关键词： Magnesium matrix composite Graphene nanosheets Corrosion resistance

Simultaneously improving thermal conductivity,mechanical properties and metal fluidity through Cu alloying in Mg-Zn-based alloys

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Journal of Magnesium and Alloys 2024年第9期12卷 3823-3839页

作者： Yuntao Zhang Wei Liu weipeng chen Zhiqiang Li Hua Hou Yuhong Zhao School of Materials Science and Engineering Collaborative Innovation Center of Ministry of Education and Shanxi Province for High-performance Al/Mg Alloy MaterialsNorth University of ChinaTaiyuanShanxi 030051PR China Beijing Advanced Innovation Center for Materials Genome Engineering University of Science and Technology BeijingBeijing 100083PR China School of Materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuanShanxi 030024PR China Institute of Materials Intelligent Technology Liaoning Academy of MaterialsShenyang 110004PR China

Mg-Zn-based alloys have been widely used in computer,communication,and consumer(3C)products due to excellent thermal ***,it is still a challenge to balance their mechanical performance and thermal ***,we investigate microstructure,mechanical performance,thermal conductivity and metal fluidity of Mg-5Zn(wt.%)alloy after Cu alloying by experimental and simulation ***,Mg-5Zn alloy consist ofα-Mg matrix and interdendritic MgZn *** the Cu content increases,however,MgZn phases disappear but intragranular Mg_(2)Cu and interdendritic MgZnCu phases appear in Mg-5Zn-Cu ***,the grain size ofα-Mg phase is refined and the volume fraction of MgZnCu phase increases as the Cu content ***,Cu addition is found to improve thermal conductivity of Mg-5Zn alloy ***,Mg-5Zn-4Cu alloy exhibits the best thermal conductivity of 124 W/(m·K),which is mainly due to the significant reduction in both solid solubility of Zn in theα-Mg matrix and lattice distortion ofα-Mg ***,a stable crystal structure of MgZnCu phase also contributes to an increased thermal conductivity based on first principles and molecular dynamics ***,Cu addition simultaneously enhances strength and ductility of Mg-5Zn *** yield strength and elongation of Mg-5Zn-6Cu alloy reach 117 MPa and 18.0%,respectively,which is a combined result of refinement,solution,second phase,and dislocation ***,combined with a phase field simulation,we found that Cu addition enhances metal fluidity of Mg-5Zn *** the one hand,Cu alloying not only delays dendrite growth but also prolongs solidification *** the other hand,MgZnCu phase stabilizes the dendrite growth of theα-Mg phases by reducing energy consumption during solidification of liquid *** work demonstrates that Cu alloying is an ideal strategy for synergistically improving the thermal conductivity,mechanical performance and metal fluidi

关键词： Mg-Zn-Cu alloy Phase field Molecular dynamics Thermal conductivity Metal fluidity

A New Family of SO_(4)^(2–)-Templated 3d-4f High-Nuclearity Clusters:Syntheses,Structures,and Magnetic Properties

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Chinese Journal of Chemistry 2024年第20期42卷 2438-2444页

作者： Caihong Fan Kaipeng Bai Qiancheng Luo Tian Han Chang Huang Yanzhen Zheng weipeng chen Frontier Institute of Science and Technology State Key Laboratory of Electrical Insulation and Power EquipmentXi'an Key Laboratory of ElectronicDevicesandMaterials ChemistrySchoolof ChemistryInstrumentAnalysis CenterXi'an JiaotongUniversityXi'an Shaanxi 710049China

The precise syntheses of transition-rare-earth metal clusters with desired structures remain a great ***,by utilizing SO_(4)^(2-)anion released by in-situ decomposition of sodium dodecyl sulfate(SDS)as a template,a series of novel high-nuclearity 3d-4f clusters,formulated as[Ni_(24)Pr_(22)(μ_(3)-OH)_(31)(pida)_(24)(SO_(4))_(4)(NO_(3))_(9)(CH_(3)COO)_(3)]·Br_(4)·(NO_(3))_(11)·_(16)H_(2)O·25CH_(3)OH(1,H_(2)pida=N-phenyliminodiacetic acid),[Ni_(24)Nd_(22)(μ3-OH)_(31)(pida)_(24)(SO_(4))_(4)(NO_(3))_(9)(CH_(3)COO)_(3)]·Br_(4)·(NO_(3))_(11)·14H_(2)O·24CH_(3)OH(2)and[Ni_(24)Gd_(22)(μ3-OH)_(36)(bida)_(24)(SO_(4))_(7)(NO_(3))_(3)(CH_(3)COO)_(3)]·(SO_(4))·Br_(4)·(NO_(3))_(4)·31H_(2)O·32CH_(3)OH(3,H_(2)bida=N-benzyliminodiacetic acid),have been successfully isolated.X-ray crystal structure analyses reveal that all the cationic{Ni_(24)RE_(22)}cores in 1-3 possess a ball-like structure with C_(3v)symmetry,and can be viewed as consisting of an inner{RE_(22)}core and an outer{Ni_(24)}*** 1 and 2 to 3,due to the lanthanide contraction effect,the coordination numbers for rare-earth metal centers in{RE_(22)}are different,resulting in different number of SO_(4)^(2-)and NO_(3)^(-)anions to support and stabilize the skeleton ***,the magnetic properties of complexes 1-3 were also *** result revealed that complexes 1-3 show antiferromagnetic/ferrimagnetic interactions,and 3 exhibits magneto-caloric effect at ultralow temperatures with a maximum-ΔSm(magnetic entropy change)value of 33.03 J·kg^(−1)·K^(−1)at 3.0 K and 7 T.

关键词： Transition-Rare-earth metal Cluster Anionic template Magnetic exchange Magnetic refrigeration

Hendecanuclear [Cu_(6)Gd_(5)] magnetic cooler with high molecular symmetry of D_(3h)

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Chinese Chemical Letters 2021年第2期32卷 838-841页

作者： weipeng chen Guojun Zhou Zhuolun Gou Sen Wang Yuanqi Zhai Tian Han Jurgen Schnack Yanzhen Zheng Shenzhen Research School and Frontier Institute of Science and Technology(FIST) State Key Laboratory for Mechanical Behavior of MaterialsMOE Key Laboratory for Nonequilibrium Synthesis of Condensed MatterXi'an Key Laboratory of Sustainable Energy and Materials Chemistry and School of ScienceXi'an Jiaotong University.Xi'an 710054China School of Chemistry and Chemical Engineering Shaanxi Normal UniversityXi'an 710119China Faculty of Physics Bielefeld UniversityD-33501 BielefeldPO Box 100131Germany

A new family of isostructural 3 d-4 f polymetallic complexes,formulated as [Cu_(6)Ln_(5)(μ_(3)OH)_(9)(C_(4)H_(8)O_(2)N)_(6)(C_(5)H_(4)ON)_(6)(H_(2)O)_(9)]·(ClO_(4))_(6)·(H_(2)O)_(22)(Ln=Pr,1;Nd,2;Sm,3;Eu,4;Gd,5),was successfully isolated through the simple hydrolysis reaction of 2-aminoisobutyric acid,2-hydroxypyridine,Cu(CH_(3)COO)_(2)·H_(2)O,and Ln(ClO_(4))_(3)·6 H_(2)***,the [Cu_(6)Ln_(5)] clusters with high molecular symmetry of D_(3h) are rare examples of2-aminoisobutyric acid-based 3 d-4 f *** successful theoretical modeling of 5 yielded that the Gd-Gd exchange is of order 0.2 K,whereas the Gd-Cu exchange is an order of magnitude *** data collected for comp lex 5 yield a magnetic entropy change(-ΔSm) of 19.6 J kg^(-1) K^(-1)<1 at 3 K and 7 T,which may be attributed to the weak magnetic interactions between the component metal ions.

关键词： Polymetallic complexes Lanthanide elements Hydrothermal reaction Magnetic interactions Magnetic refrigeration

The mechanism of dentine hypersensitivity:Stimuli-induced directional cation transport through dentinal tubules

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Nano Research 2023年第1期16卷 991-998页

作者： Nuo chen Jingjing Deng Shengjie Jiang Xiang-Yu Kong Teng Zhou Kai Zhao Zuohui Xiao Huimin Zheng weipeng chen Congcong Zhu Xinyu Liu Liping Wen Yan Wei Xuliang Deng Lei Jiang Beijing Laboratory of Biomedical Materials Department of Geriatric DentistryPeking University School and Hospital of StomatologyBeijing 100081China Central Laboratory Peking University School and Hospital of StomatologyBeijing 100081China CAS Key Laboratory of Bio-inspired Materials and Interfacial Science Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China Mechanical and Electrical Engineering College Hainan UniversityHainan 570228China School of Future Technology University of Chinese Academy of Sciences Beijing 100049China

Dentine hypersensitivity is an annoying worldwide disease,yet its mechanism remains *** long-used hydrodynamic theory,a stimuli-induced fluid-flow process,describes the pain ***,no experimental evidence supports the ***,we demonstrate that stimuli-induced directional cation transport,rather than fluid-flow,through dentinal tubules actually leads to dentine *** in vitro/in vivo electro-chemical and electro-neurophysiological approaches reveal the cation current through the nanoconfined negatively charged dentinal tubules coming from external stimuli(pressure,pH,and temperature)on dentin surface and further triggering the nerve impulses causing the dentine ***,the cationic-hydrogels blocked dentinal tubules could significantly reduce the stimuli-triggered nerve action potentials and the anionhydrogels counterpart enhances those,supporting the cation-flow transducing dentine ***,the inspired ion-blocking desensitizing therapies have achieved remarkable pain relief in clinical *** proposed mechanism would enrich the basic knowledge of dentistry and further foster breakthrough initiatives in hypersensitivity mitigation and cure.

关键词： dentine hypersensitivity cation transport dentinal tubules Ionic-current-rectification

Temperature difference-enhanced salinity gradient energy conversion enabled by thermostable hydrogel membrane with anti-swelling property

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Nano Research 2023年第8期16卷 11288-11295页

作者： Zhehua Zhang Teng Zhou Xiang-Yu Kong Yadong Wu Weiwen Xin Yanglansen Cui Linsen Yang Tingyang Li Xin Li Qingchen Wang weipeng chen Lei Jiang Liping Wen Key Laboratory of Bio-inspired Materials and Interfacial Science Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100049China School of Future Technology University of Chinese Academy of SciencesBeijing 100049PChina College of Mechanical and Electrical Engineering Hainan UniversityHaikou 570228China Binzhou Institute of Technology Binzhou 256600China

Coupling low-grade heat(LGH)with salinity gradient is an effective approach to increase the efficiency of the nanofluidic-membrane-based power ***,it is a challenge to fabricate membranes with high charge density that ensures ion permselectivity,while maintaining chemical and mechanical stability in this composite ***,we develop a bis[2-(methacryloyloxy)ethyl]phosphate(BMAP)hydrogel membrane with good thermal stability and anti-swelling property through self-crosslinking of the selected *** taking advantage of negative space charge and three-dimensional(3D)interconnected nanochannels,salinity gradient energy conversion efficiency is substantially enhanced by temperature *** and experimental results verify that LGH can largely weaken the concentration polarization,promoting transmembrane ion *** a result,such a hydrogel membrane delivers high-performance energy conversion with a power density of 11.53 W·m^(−2)under a negative temperature difference(NTD),showing a 193%increase compared with that without NTD.

关键词： ion transport temperature difference-enhanced salinity gradient energy self-crosslinking hydrogel membranes space charge

Osmotic-Enhanced-Photoelectrochemical Hydrogen Production Based on Nanofluidics

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CCS Chemistry 2023年第9期5卷 2012-2022页

作者： Pei Liu Xiao-Ya Gao Li-Jun Zhang weipeng chen Yuhao Hu Xiang-Yu Kong Xu-Bing Li Liping Wen chen-Ho Tung Li-Zhu Wu Lei Jiang Key Laboratory of Bio-inspired Materials and Interfacial Science Key Laboratory of Photochemical Conversion and Optoelectronic MaterialsTechnical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190 School of Future Technology University of Chinese Academy of SciencesBeijing 100049

Harvesting clean energy such as solar energy and salinity gradient energy directly from the surrounding environment has attracted great attention.A promising proof-of-concept combination of cation-selective membrane-based osmotic energy with photoelectrochemical-based solar energy has been developed,highlighting the great potential for the direct conversion of osmotic energy to hydrogen *** the help of a 50-fold concentration gradient,the MXene-CdSe quantum dots system exhibits the highest photocurrent enhancement ratio(Δ/_(L-H)/Δ/_(L-L)),and the hydrogen production is increased by about 33%at a bias of 0 V versus reversible hydrogen *** converting osmotic energy and solar energy into hydrogen energy suggests the possibility of coupling osmotic energy with other renewable energy sources.

关键词： nanofluidics ion transport H2 evolution energy conversion artificial photosynthesis