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Frontiers of structural and Civil engineering 2024年第1期18卷 66-79页

作者： Yaxin TAO Xiaodi DAI Geert de SCHUTTER Kim Van TITTELBOOM department of structural engineering and building materials Ghent UniversityGhent 9052Belgium

Robotic-based technologies such as automated spraying or extrusion-based 3-dimensional(3D)concrete printing can be used to build tunnel linings,aiming at reducing labor and mitigating the associated safety issues,especially in the high-geothermal environment.Extrusion-based 3D concrete printing(3DCP)has additional advantages over automated sprayings,such as improved surface quality and no rebound.However,the effect of different temperatures on the adhesion performance of 3D-printed materials for tunnel linings has not been investigated.This study developed several alkali-activated slag mixtures with different activator modulus ratios to avoid the excessive use of Portland cement and enhance sustainability of 3D printable materials.The thermal responses of the mixtures at different temperatures of 20 and 40℃ were studied.The adhesion strength of the alkali-activated material was evaluated for both early and later ages.Furthermore,the structural evolution of the material exposed to different temperatures was measured.This was followed by microstructure characterization.Results indicate that elevated temperatures accelerate material reactions,resulting in improved early-age adhesion performance.Moreover,higher temperatures contribute to the development of a denser microstructure and enhanced mechanical strength in the hardened stage,particularly in mixtures with higher silicate content.

关键词： alkali-activated material 3DCP tunnel lining high-geothermal environment adhesion

Synthesis and characterization of high entropy(TiVNbTaM)_(2)AlC(M=Zr,Hf)ceramics

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Journal of Advanced Ceramics 2024年第2期13卷 237-246页

作者： Lei Cao Qiqiang Zhang Lijing Du Shuai Fu Detian Wan Yiwang Bao Qingguo Feng Chunfeng Hu Key Laboratory of Advanced Technologies of materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China State Key Laboratory of Green building materials China Building Materials AcademyBeijing 100024China

The high-entropy design of MAX phases is expected to confer superior properties,but its study was hindered by the complex synthesis method and limited purity of samples.In this work,two noteworthy types of high-entropy MAX phase structural ceramics,high-entropy(TiVNbTaM)_(2)AlC(M=Zr,Hf),were designed and prepared by the in-situ synthesis using spark plasma sintering(SPS).The microstructure and lattice parameters of sintered samples were determined.Compared with the single-component MAX phases,the highly pure high-entropy(TiVNbTaZr)_(2)AlC sample had good physical and mechanical properties,including electrical conductivity of 0.96×106Ω^(-1)·m^(-1),thermal expansion coefficient of 3.65×10^(-6) K^(-1),thermal conductivity of 8.98 W·m^(-1)·K^(-1),Vickers hardness of 9.80 GPa,flexural strength of 507 MPa,fracture toughness of 5.62 MPa·m^(1/2),and compressive strength of 1364 MPa,which exhibited the remarkable hardening-strengthening effect.

关键词： MAX phase high-entropy ceramic microstructure physical properties mechanical properties

The shear strength of the interface between artificial rock and printed concrete at super-early ages

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Frontiers of structural and Civil engineering 2024年第1期18卷 51-65页

作者： Yong Yuan Xiaoyun Wang Jiao-Long Zhang Yaxin Tao Kim Van Tittelboom Luc Taerwe Geert De Schutter College of Civil engineering Tongji UniversityShanghai 200092China State Key Laboratory of Disaster Reduction in Civil engineering Tongji UniversityShanghai 200092China Belgium-China Joint Laboratory for Industrialized Construction Tongji UniversityShanghai 200092China Magnel-Vandepitte Laboratory for structural engineering and building materials Ghent UniversityGhent 9052Belgium

3D concrete printing has the potential to replace shotcrete for construction of linings of tunnels in hard rock.The shear strength of the interface between rock and printed concrete is vital,especially at super-early ages.However,traditional methods for testing the shear strength of the interface,e.g.,the direct shear test,are time-consuming and result in a high variability for fast-hardening printed concrete.In this paper,a new fast bond shear test is proposed.Each test can be completed in 1 min,with another 2 min for preparing the next test.The influence of the matrix composition,the age of the printed matrices,and the interface roughness of the artificial rock substrate on the shear strength of the interface was experimentally studied.The tests were conducted at the age of the matrices at the 1st,the 4th,the 8th,the 16th,the 32nd,and the 64th min after its final setting.A dimensionless formula was established to calculate the shear strength,accounting for the age of the printed matrices,the interface roughness,and the shear failure modes.It was validated by comparing the calculated results and the experimental results of one group of samples.

关键词： rock tunnel printed concrete interface fast bond shear test shear strength

Strategy for suppressing abnormal grain growth of ZK60 Mg alloy during solution by pre-compression:A quasi-in-situ study

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Journal of materials Science & Technology 2024年第4期171卷 115-128页

作者： Zhenxu Wang Liang Chen Jianwei Tang Cunsheng Zhang Guoqun Zhao Key Laboratory for Liquid-Solid structural Evolution and Processing of materials(Ministry of Education) Shandong UniversityJinanShandong 250061China department of Mechanical engineering Kyushu UniversityFukuoka 819-0395Japan

Abnormal grain growth(AGG)easily takes place in Mg alloys during high-temperature solutions,result-ing in deterioration of mechanical properties.Hence,the compression prior to solution(pre-compression)was conducted to suppress AGG,and the microstructure evolution as well as suppressing mechanisms was investigated based on quasi-in-situ analysis.After compression along the transverse direction,//ED grains preferentially nucleated and rapidly grew up,and the initial//ED texture was weakened.Two grain growth modes of heat-induced and strain-induced grain boundary migrations were found.The former was attributed to the high interfacial energy of grain boundaries with large curvature.The latter consumed the adjacent grains with high storage energy,forming abnormal grains with irregular shapes.The compression with a reduction>6%could obviously suppress AGG.The suppressing effects were mainly attributed to weakening the size advantage of//ED grains,increasing nucleation,reducing grain boundary character distribution,and redistributing storage energy distribution.After 12%compression along the transverse direction,30°misorientation of//ED grains and high energy grain boundaries were reduced.The{10-12}tensile twins and{10-15}high index twins induced by com-pression increased the nucleation of static recrystallization.Beside,compression introduces high-density dislocations,which also contributed to suppressing AGG behavior during solution.

关键词： Quasi-in-situ analysis Mg alloy Abnormal grain growth Compression Microstructure

Weakly Polarized Organic Cation-Modified Hydrated Vanadium Oxides for High-Energy Efficiency Aqueous Zinc-Ion Batteries

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Nano-Micro Letters 2024年第7期16卷 169-186页

作者： Xiaoxiao Jia Chaofeng Liu Zhi Wang Di Huang Guozhong Cao department of materials Science and engineering University of WashingtonSeattleWA 98195USA School of materials Science and engineering Tongji UniversityShanghai 201804People’s Republic of China

Vanadium oxides,par-ticularly hydrated forms like V_(2)O_(5)·nH_(2)O(VOH),stand out as promising cathode candidates for aqueous zinc ion batteries due to their adjustable layered structure,unique electronic characteristics,and high theoretical capacities.However,challenges such as vanadium dissolution,sluggish Zn^(2+)diffusion kinetics,and low operating voltage still hinder their direct application.In this study,we present a novel vanadium oxide([C_(6)H_(6)N(CH_(3))_(3)]_(1.08)V_(8)O_(20)·0.06H_(2)O,TMPA-VOH),developed by pre-inserting trimethylphenylammonium(TMPA+)cations into VOH.The incorporation of weakly polarized organic cations capitalizes on both ionic pre-intercalation and molecular pre-intercalation effects,resulting in a phase and morphology transition,an expansion of the interlayer distance,extrusion of weakly bonded interlayer water,and a substantial increase in V^(4+)content.These modifications synergistically reduce the electrostatic interactions between Zn^(2+)and the V-O lattice,enhancing structural stability and reaction kinetics during cycling.As a result,TMPA-VOH achieves an elevated open circuit voltage and operation voltage,exhibits a large specific capacity(451 mAh g^(-1)at 0.1 A g^(-1))coupled with high energy efficiency(89%),the significantly-reduced battery polarization,and outstanding rate capability and cycling stability.The concept introduced in this study holds great promise for the development of high-performance oxide-based energy storage materials.

关键词： Zinc-ion battery Vanadium oxide V_(2)O_(5)·nH_(2)O Pre-intercalation Interlayer engineering

Electrochemical Reduction of Benzo[b]thiophene 1,1-Dioxides with HFIP as Hydrogen Donor

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Chinese Journal of Chemistry 2024年第6期42卷 585-591页

作者： Ming-Zhong Guo Mei-Jin Mou Zhuo Chen Shao-Fei Ni Ming Li Li-Rong Wen Lin-Bao Zhang State Key Laboratory Base of Eco-Chemical engineering College of Chemistry and Molecular EngineeringQingdao University of Science & TechnologyQingdaoShandong266042 China department of Chemistry and Key Laboratory for Preparation and Application of Ordered structural materials of Guangdong Province Shantou UniversityShantouGuangdong515063 China

A straightforward electrochemical reduction of benzo[b]thiophene 1,1-dioxides with HFIP as the hydrogen donor has been reported in an undivided cell under metal-free conditions.Moreover,the tolerance of various functi... 详细信息

关键词： Electrochemistry Reduction Benzo[b]thiophene 1,1-dioxides Deuterium Hydrogen source

Assessing the energy saving potential of using adaptive setpoint temperatures:The case study of a regional adaptive comfort model for Brazil in both the present and the future

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building Simulation 2024年第3期17卷 459-482页

作者： Daniel Sánchez-García David Bienvenido-Huertas Carlos Rubio-Bellido Ricardo Forgiarini Rupp department of Electrical engineering University Carlos III of MadridMadridSpain department of building Simulation ZEROCEM SLSevilleSpain department of building Constructions University of GranadaGranadaSpain department of building Constructions II University of SevilleSevilleSpain Section of Design for Sustainability Department of Civil and Mechanical EngineeringTechnical University of DenmarkKgs.LyngbyDenmark

It has been found in recent years that using setpoint temperatures based on adaptive thermal comfort models is a successful method of energy conservation.Recent studies using adaptive setpoint temperatures incorporate international models from ASHRAE Standard 55 and EN16798-1.This study,however,has instead considered a regional Brazilian adaptive comfort model.This study investigates the energy demand arising from the use of a local Brazilian comfort model in order to assess the energy implications from the use of the worldwide ASHRAE Standard 55 adaptive model and various fixed setpoint temperatures.All of Brazil’s climate zones,full air-conditioning,mixed-mode building operating modes,present-day climate change scenarios,and future scenarios—specifically Representative Concentration Pathways(RCP)2.6,4.5,and 8.5 for the years 2050 and 2100—have all been taken into account in building energy simulations.The use of adaptive setpoint temperatures based on the Brazilian local model considering mixed-mode has been found to significantly reduce energy consumption when compared to static setpoint temperatures(average energy-saving values ranging from 52%to 58%)and the ASHRAE 55 adaptive model(average values ranging from 15%to 21%).Considering climate change and the mixed-mode Brazilian model,the overall energy demand for the three groups of climatic zones(annual average outdoor temperatures≤21℃,>21 and≤25℃and>25℃)ranged between 2%decrease and 5%increase,4%and 27%increase,and 13%and 45%increase,respectively.It is concluded as a consequence that setting setpoint temperatures based on the Brazilian local adaptive comfort model is a very efficient energy-saving method.

关键词： adaptive thermal comfort building energy simulation energy efficiency climate change adaptive setpoint temperatures local comfort mode

Recent Advances in Asymmetric structural Composites for Excellent Electromagnetic Interference Shielding: A Review

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Chinese Journal of Polymer Science 2024年第6期42卷 693-710页

作者： Ying Zhou Bai Xue Lan Xie Chang-Mei Wu Qiang Zheng department of Polymer materials and engineering College of Materials and Metallurgy Guizhou University National engineering Research Center for Compounding and Modification of Polymer materials National and Local Joint Engineering Research Center for Functional Polymer Membrane Materials and Membrane Processes State Key Laboratory of Public Big Data Guizhou University department of Polymer Science and engineering Zhejiang University

Since electromagnetic pollution is detrimental to human health and the environment, numerous efforts have been successively made to achieve excellent electromagnetic interference shielding effectiveness(EMI SE) via designing the hierarchical structures for electromagnetic interference(EMI) shielding polymer composites. Among the plentiful structures, the asymmetric structures are currently a hot spot, principally categorizing into multi-layered, porous, fibrous, and segregated asymmetric structures, which endows the high EMI shielding performance for polymer composites incorporated with magnetic, conductive, and/or dielectric micro/nano-fillers, due to the “absorption-reflection-reabsorption” shielding mechanism. Therefore, this review provides the retrospection and summary of the efforts with respect to abundant asymmetric structures and multifunctional micro/nano-fillers for enhancing EMI shielding properties, which is conducive to the booming development of polymeric EMI shielding materials for the promising prospect in modern electronics and 5-generation(5G) technology.

关键词： Asymmetric structure Microano functional filler Polymer composite Electromagnetic interference shielding

Enhancement of mechanical properties of GTAW joints for ZC63 magnesium alloy by post-weld heat treatment

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Journal of materials Science & Technology 2024年第2期169卷 251-263页

作者： Weiyang Zhou Qichi Le Ye Shi Qiyu Liao Tong Wang Qi Zou Clodualdo Aranas Jr Key Lab of Electromagnetic Processing of materials Ministry of EducationNortheastern UniversityShenyang 110819China Key Laboratory of Lightweight structural materials Liaoning ProvinceNortheastern UniversityShenyang 110819China School of materials Science and engineering Northeastern UniversityShenyang 110819China department of Mechanical engineering University of New BrunswickFrederictonE3B 5A3New BrunswickCanada

To further improve the microstructure and mechanical properties of gas tungsten arc welded(GTAW)welded joints for ZC63 magnesium alloy,post-weld heat treatment is carried out.It is found that the majority of the MgZnCu phase in the fusion zone(FZ)is dissolved in theα-Mg matrix under suitable heat treatment conditions.The remainder is diffusely distributed as rods or granules at the grain bound-aries.The excessive heat treatment temperature(460℃)leads to abnormal grain growth(AGG)in the FZ.The substructure gradient between the abnormally grown grains and the surrounding small grains pro-vides the driving force for AGG.Meanwhile,the dissolution of the MgZnCu phase weakens the hindering effect of the second phase on grain boundary migration,setting the stage for AGG.In addition,the detri-mental impact of the continuous MgZnCu phase on the mechanical properties of the welded joint is also lessened by its dissolution.The ultimate tensile strength(UTS),yield strength(YS)and elongation(EL)of the welded joints are 255 MPa,119 MPa and 27.0%,respectively,under the post-weld heat treatment process of 440℃×12 h.The welding coefficient of the welded joint reaches 97.0%,satisfying the service criteria set forth by the mechanical properties of the welded joints.

关键词： GTAW FZ Heat treatment AGG Mechanical properties

The action mechanism of the work done by the electric field force on moving charges to stimulate the emergence of carrier generation/recombination in a PN junction

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Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 1001-1014页

作者： Lingyun GUO Yizhan YANG Wanli YANG Yuantai HU department of Mechanics School of Aerospace EngineeringHubei Key Laboratory of Engineering Structural Analysis and Safety AssessmentHuazhong University of Science and TechnologyWuhan 430074China

It is discovered that the product of the current and the electric field in a PN junction should be regarded as the rate of work(power)done by the electric field force on moving charges(hole current and electron current),which was previously misinterpreted as solely a Joule heating effect.We clarify that it is exactly the work done by the electric field force on the moving charges to stimulate the emergence of non-equilibrium carriers,which triggers the novel physical phenomena.As regards to Joule heat,we point out that it should be calculated from Ohm’s law,rather than simply from the product of the current and the electric field.Based on this understanding,we conduct thorough discussion on the role of the electric field force in the process of carrier recombination and carrier generation.The thermal effects of carrier recombination and carrier generation followed are incorporated into the thermal equation of energy.The present study shows that the exothermic effect of carrier recombination leads to a temperature rise at the PN interface,while the endothermic effect of carrier generation causes a temperature reduction at the interface.These two opposite effects cause opposite heat flow directions in the PN junction under forward and backward bias voltages,highlighting the significance of managing device heating phenomena in design considerations.Therefore,this study possesses referential significance for the design and tuning on the performance of piezotronic devices.

关键词： piezoelectric semiconductor(PS) work done by electric field force thermal effect piezotronic device resistivity conductivity