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Discontinuous crack-bridging model for fracture toughness analysis of nacre

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Discontinuous crack-bridging model for fracture toughness an...

Effects of pH value and substrate concentration on hydrogen production from the anaerobic fermentation of glucose

The 16th Annual Conference of Hong Kong Society of Theoretical and Applied Mechanics 2012、The 1st Mainland-Hong Kong Youth Forum on Mechanics 2012、The 8th Shanghai-Hong Kong Forum on Mechanics and Its Application 2012

作者： Y.Shao H.P.Zhao x.q.feng H.J.Gao Institute of Biomechanics and Medical Engineering Department of Engineering MechanicsTsinghua University Division of Engineering Brown UniversityProvidenceRI 02912USA

Studying the structure-property relation of biological materials can not only provide insight into the physical mechanisms underlying their superior properties and functions but also benefit the design and fabrication of advanced biomimetic *** this paper,we present a microstructure-based fracture mechanics model to investigate the toughening effect due to the crack-bridging mechanism of *** theoretical analysis demonstrates the crucial contribution of this mechanism to the high toughness of *** is found that the fracture toughness of nacre exhibits distinct dependence on the sizes of platelets,and the optimized ranges for the thickness and length of platelets required to achieve higher fracture toughness are *** addition,the effects of such factors as the mechanical properties of the

关键词： Discontinuous crack-bridging model for fracture toughness analysis of nacre

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Effects of pH value and substrate concentration on hydrogen ...

Correlation between test temperature, applied load and wear transition of Mg97Zn1Y2 alloy

第九届全国氢能学术会议

作者： Z.Li,H.Wang,x.q.feng,Y.Wang Northwest University,China

＜正＞The effects of pH value and substrate concentration on fermentative hydrogen production were investigated by using glucose as the feedstock and natural sludge obtained from the bed of a local river as *** natural sludge was boiled for half an hour to eliminate methane-forming bacteria and other pathogenic microbes,and then filled some nutrient stocks

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Journal of Magnesium and Alloys 2021年第2期9卷 592-603页

作者： J.An Y.x.Tian C.q.feng Key Laboratory of Automobile Materials Ministry of EducationDepartment of Materials Science and EngineeringJilin UniversityChangchun 130025PR China

Dry sliding wear tests were performed on Mg97 Zn1 Y2 alloy at various temperatures of 20,50,100,150 and 200°C using a pin-on-disc wear testing machine in order to reveal mild-severe(M-S)wear transition mechanism during elevated-temperature wear *** was shown that at each test temperature,the wear rate increased with increasing load,and all wear rate-load curves demonstrated two distinct stages *** and severe wear *** predominant wear mechanisms operating in mild and severe wear stages were analyzed,and they were indicated in the mild and severe wear regimes of a wear mechanism transition map,respectively.M-S wear transition mechanism was analyzed by comparison of microstructure transformation and hardness change in subsurfaces of samples tested in mild and severe wear stages,from which M-S wear transition mechanism was confirmed as softening of surface material arising from dynamic recrystallization(DRx)microstructure *** M-S wear transition load was found to have a linear relationship with test temperature,and decreased with rising test temperature.M-S wear transition obeyed a critical surface DRx temperature(SDT)criterion under given conditions,and the transition loads were estimated at various test temperatures by using the criterion.

关键词： Mg-alloys Elevated temperatures Wear rate Wear mechanism Wear transition

PARTICLE SIZE AND MICROSTRUCTURE OF Ni NANOPOWDERS PREPARED BY ANODIC ARC PLASMA

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 209-216页

作者： Z.q.Wei H.x.qiao J.F.Dai W.J.feng q.Wang P.x.Yan SchoolofSciences LanzhouUniversityofTechnologyLanzhou730050China CollegeofCivilEngineering LanzhouUniversityofTechnologyLanzhou730050China SchoolofPhysicalScienceandTechnology LanzhouUniversityLanzhou730000China

Pure Ni nanopowders were successfully prepared by the method of anodic arc disch arged plasma with homemade experimental apparatus. The particle size, mircostruc ture and morphology of the particles by this process were characterized via x-ra y powder diffraction (xRD), transmission electron microscopy (TEM) and the corre sponding selected area electron diffraction (SAED); The specific surface area an d pore parameters were investigated by multi-point full analysis of nitrogen ads orption-desorption isotherms at 77K by Brunauer- Emmett-Teller (BET) surface are a analyzer; The chemical composition were determined by x-ray energy dispersive spectrometry (xEDS) equipped in SEM and element analyze instrument. The experime nt results indicate that the samples by this method with high purity,the crystal structure of the particles is as same as the bulk material, is fcc structure, w ith average particle sizes about 47nm, ranging from 20 to 70nm, and distributed uniformly in spherical chain shapes, the specific surface areavis 14.23m2/g, po re volume of pore is 0.09cm3/g and average pore diameter is 23nm.

关键词： anodic arc plasma Ni nanopowder particle size structure composition.

Micro-scaled plastic yielding and shear-banding dynamics in metallic glasses

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Journal of Materials Science & Technology 2023年第21期152卷 237-246页

作者： D.x.Han G.Wang q.Wang R.feng x.D.Ma K.C.Chan C.T.Liu Institute of Materials Shanghai UniversityShanghai 200444China Department of Industrial and Systems Engineering The Hong Kong Polytechnic UniversityHong KongChina Neutron Scattering Division Oak Ridge National LaboratoryOak RidgeTN 37831United States Department of Material Science and Engineering College of Science and EngineeringCity University of Hong KongHong KongChina Center for Advanced Structural Materials College of Science and EngineeringCity University of Hong KongHong KongChina

Shear-banding behavior in metallic glasses plays a key role in the operation of plastic deformation,which is associated with yield *** a micro-scale,the shear-banding behavior must be affected by many factors from the test machine and the ***,in this study,comprehensively considering a machine compliance,a geometry imperfection of micro-pillar,and a substrate sink-in the machine-sample-substrate system,we developed a plastic-strength model at a micrometer scale in this study,which is evidenced by the microscale compressive properties of 18 kinds of metallic *** the-oretical model provides a guidance for the elastic limits and shear-banding dynamics of metallic glasses at the micro-scale,which can be applicable to characterize the microscale deformation behavior of other amorphous materials.

关键词： Metallic glasses Shear-banding dynamics Micro-compression Plastic deformation

An analysis of the chaotic motion of particles of different sizes in a gas fluidized bed

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Particuology 2008年第6期6卷 549-556页

作者： Y.q. feng A.B. Yu Lab for Simulation and Modelling of Particulate Systems School of Materials Science and Engineering University of New South Wales Sydney NSW 2052 Australia

The dynamic behavior of individual particles during the mixing/segregation process of particle mixtures in a gas fluidized bed is analyzed. The analysis is based on the results generated from discrete particle simulation, with the focus on the trajectory of and forces acting on individual particles. Typical particles are selected representing three kinds of particle motion： a flotsam particle which is initially at the bottom part of the bed and finally fluidized at the top part of the bed; a jetsam particle which is initially at the top part of the bed and finally stays in the bottom de-fluidized layer of the bed; and a jetsam particle which is intermittently joining the top fluidized and bottom de-fluidized layers. The results show that the motion of a particle is chaotic at macroscopic or global scale, but can be well explained at a microscopic scale in terms of its interaction forces and contact conditions with other particles, particle-fluid interaction force, and local flow structure. They also highlight the need for establishing a suitable method to link the information generated and modeled at different time and length scales.

关键词： Fluidization Segregation Discrete particle simulation Granular dynamics

Effect of Silver Content on Microstructure and Properties of Brass/steel Induction Brazing Joint Using Ag-Cu-Zn-Sn Filler Metal

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Journal of Materials Science & Technology 2011年第4期27卷 377-381页

作者： J. Cao L.x. Zhang H.q. Wang L.Z. Wu J.C. feng State KeyLab of AdvanCed Welding Production Technology Harbin Instituteof Technology Harbin 150001 China Center for Composite Materials and Structures Harbin Institute of Technology Harbin 150001 China

The induction brazing of brass to steel using Ag-Cu-Zn-Sn filler metal was investigated in this study. The influence of A8 content on the microstructure and properties were analyzed by means of optical microscopy, scanning electron microscopy and electron probe microanalysis. Defect free joint was achieved using Ag- Cu-Zn-Sn filler metal. The microstructure of the joint was mainly composed of Ag-based solid solution and Cu-based solid solution. The increase of A8 content and the cooling rate both led to the increase of the needle like eutectic structure. The tensile strength decreased with the increase of Ag content. The tensile strength at room temperature using Ag25CuZnSn filler metal reached 445 MPa. All fractures using Ag-Cu-Zn-Sn filler metal presented ductile characteristic.

关键词： Induction brazing Brass Steel Microstructure Tensile strength

Alkaline leaching mechanism of MSWI bottom ash: the pivotal role of Si(Al) chemical bonding environments

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Science China Technological Sciences 2025年

作者： Ningning SHAO Zekun JIAO Weipeng feng Yu JIN Fanlong KONG Zhijun DONG Zuotai ZHANG Institute of Technology for Marine Civil Engineering Shenzhen Institute of Information Technology (SZIIT) Guizhou NASH Ecological Technology Co. LTD School of Environmental Science and Engineering Key Laboratory of Municipal Solid Waste Recycling Technology and Management of Shenzhen City Southern University of Science and Technology (SUSTech)

Municipal solid waste incineration bottom ash(MSWIBA) is a complex assemblage of aluminosilicate materials encompassing diverse solid wastes. Thus, its complexity poses great challenges to their resource utilization. For the sake of the alkali activation use of MSWIBA, this work focused on the characterizations and alkaline leaching experiments of various classified MSWIBA after sorting. Among the different categories of MSWIBA, waste glass(BA-G) and other unidentified slags(BA-O) were identified as potential precursors for alkali activation use. The alkaline leaching experiments proved that alkaline concentration, reaction temperature, reaction time, and raw material classification influenced the leaching process and results. Among these, the Si/Al chemical bonding environments from the material type played a pivotal role. When the materials had qn(n>2) as the primary bonding structure, steric hindrance by the chain frameworks affected the alkali dissolution process, resulting in gradual disintegration from the outer layers inward. For the materials dominated by q1frameworks, OH-could penetrate the frameworks, leading to their rapid depolymerization and outward dissolution. Overall, the Si/Al bonding environment played a crucial role in alkaline dissolution, providing theoretical guidance for classifying the alkali-activation utilization of MSWIBA and other aluminosilicate solid wastes.

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Effects of welding parameters and post-heat treatment on mechanical properties of friction stir welded AA2195-T8 Al-Li alloy

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Journal of Materials Science & Technology 2018年第1期34卷 219-227页

作者： J. Zhang x.S. feng J.S. Gao H. Huang Z.q. Ma L.J. Guo Technical Center Shanghai Aerospace Equipments Manufacturer Shanghai 200245. China

In this study, the effects of main welding parameters （rotation speed （ω） and welding speed （υ）） on the microstructure, micro-hardness distribution and tensile properties of friction stir welded （FSW） 2195-T8 Al-Li alloy were investigated. The effects of T6 post-treatments at different solution and aging conditions on the mechanical properties and microstructure characteristics of the FSW joints were also investigated. The results show that with increasing to and v, both strength and elongation of the joints increase first, and then decrease with further increase of ω and υ. All the joints under varied welding parameters show significant strength loss, and the strength reaches only 65% of the base metal, The effect of T6 post-heat treatment on the mechanical properties of the joints depends on the solution and aging conditions. Two heat treatment processes （480 ℃×0.5 h quenching＋ 180 ℃× 12 h, 520 ℃× 0.5 h quenching＋ 180 ℃×12h aging） are found to increase the joint strength. Furthermore, low temperature quenching （480℃） is more beneficial to the joint strength. The joint strength can reach 85% of the base metal. Whereas both low temperature aging （140 ℃× 56h） and stepped aging （ 100 ℃× 12 h ＋ 180 ℃× 3 h） processes decrease the joint strength. After heat treatment all the joints show decreased ductility due to the obvious grain coarsening in the nugget zone （NZ） and thermo-mechanically affected zone （TMAZ）.

关键词： 2195-T8 Al-Li alloy Friction stir welding Welding parameters Post-heat treatment