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Effect of high magnetic fields on the solidification microstructure of an Al-Mn alloy

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Rare Metals 2009年第3期28卷 302-308页

作者： luo dawei GUO Jin YAN Zhiming LI Tingju School of Materials Science and Engineering Dalian University of Technology Dalian 116023 China State Key Laboratory of Materials Modification by Laser Ion and Electron Beams Dalian 116023 China

The effect of high magnetic fields on the morphology of Al-Mn phases was investigated. It is found that the tropism and the alignment of Al6Mn precipitated phases become regular under high magnetic fields. The stronger the high magnetic fields, the more regular the alignment of Al6Mn precipitated phases. Al6Mn precipitated phases can generate oriented alignment and aggregation under high magnetic fields through the observation of the quenched microstructure of the Al-Mn alloy at different temperatures. Meanwhile, the number of Al6Mn phases increases continuously along with the increasing function time of high magnetic fields. X-ray diffraction also indicates that Al6Mn phases generate obvious tropism under high magnetic fields. The process of aggregation and growth of Al6Mn precipitated phases under the function of high magnetic fields after orientation were analyzed and discussed.

关键词： high magnetic fields Al-Mn alloy Al-Mn phase orientation

Facile Preparation of Fe-N-C Oxygen Reduction Electrocatalysts from Metal Organic Frameworks for Zn-Air Battery

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Journal of Renewable Materials 2022年第5期10卷 1337-1348页

作者： Chengcheng Wang dawei luo Bingxue Hou Mortaza Gholizadeh Zanxiong Tan Xiaojie Han Shenzhen Polytechnic ShenzhenChina Key Laboratory of Energy Conversion and Storage Technologies(Southern University of Science and Technology) Ministry of Education ShenzhenShenzhenChina Aviation Engineering Institute Civil Aviation Flight University of ChinaGuanghanChina Faculty of Chemical and Petroleum Engineering University of TabrizTabrizIran

It is critical to study efficient,stable oxygen reduction reaction(ORR)electrocatalysts due to insufficient stability and expensive price of Pt/C catalysts for Zn-air ***–N–C electrocatalysts was synthesized by a facile solvent-green method and the efficiency of Fe–N–C optimized was studied as potential ORR electrocatalysts under alkaline *** indicated that it had excellent ORR activity with E_(1/2)of 0.93 V,which was competitive to that of Pt/C-JM under the same ***,the assembled Zn-air battery exhibited discharge potential and charge potential of 1.2 V,2.32 V at 5 mA cm^(−2)with high stability,***,all results illustrated that Fe–N–C is an excellent ORR electrocatalyst in the field of metal air ***,this work opens a good way to synthesize highly efficient electrocatalysts from metal organic framework and to investigate ORR mechanism of efficient chemical energy to electricity conversion.

关键词： Manuscript Fe-N-C electrocatalyst oxygen reduction reaction Zn-air battery

Design and characterization of metallic glass/graphene multilayer with excellent nanowear properties

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Friction 2022年第11期10卷 1913-1926页

作者： Qing ZHOU dawei luo Dongpeng HUA Wenting YE Shuo LI Qiguang ZOU Ziqiang CHEN Haifeng WANG State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’an 710072China Songshan Lake Materials Laboratory Dongguan 523808China Institute of Physics Chinese Academy of SciencesBeijing 100190China

The excellent properties of metallic glass(MG)films make them perfect candidates for the use in miniature systems and ***,their high coefficients of friction(COFs)and poor wear resistance considerably limit their long-term performance in nanoscale *** report the fabrication of a MG/graphene multilayer by the repeated deposition of Cu_(50)Zr_(50) MG with alternating layers of *** microstructure of the multilayer was characterized by the transmission electron microscopy(TEM).Its mechanical and nanotribological properties were studied by nanoindentation and nanoscratch tests,respectively.A molecular dynamics(MD)simulation revealed that the addition of graphene endowed the MG with superelastic recovery,which reduced friction during *** comparison with the monolithic MG film,the multilayer exhibited improved wear resistance and a low COF in repeated nanowear tests owing to the enhanced mechanical properties and lubricating effect caused by the graphene *** work is expected to motivate the design of other novel MG films with excellent nanowear properties for engineering applications.

关键词： metallic glass(MG) multilayer nanowear properties molecular dynamics(MD)simulation

Molecular dynamics simulation of the tribological performance of amorphous/amorphous nano-laminates

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Journal of Materials Science & Technology 2022年第10期105卷 226-236页

作者： Dongpeng Hua Wan Wang dawei luo Qing Zhou Shuo Li Junqin Shi Maosen Fu Haifeng Wang State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’anShaanxi 710072PR China

Because the amorphous/amorphous nano-laminates could enhance signifcantly the mechanical properties of the amorphous materials,they have been widely studied as a new group of structural *** this study,the nano-scratch performance of the Cu_(80)Zr_(20)/Cu_(20)Zr_(80)(A/B-type)and the Cu_(20)Zr_(80)/Cu_(80)Zr_(20)(B/A-type)amorphous/amorphous nano-laminates was evaluated by molecular dynamics *** dependences on the type of indenter,layer thickness,stacking mode and scratch depth were systematically *** is a signifcant size effect for the tribological properties of amorphous/amorphous nanolaminates that the friction force of the A/B-type increases with the increase of layer thickness,but the friction force of the B/A-type decreases as the layer thickness *** interface has an obvious obstruction effect on the shear deformation and reduces the plastic affected region below the scratched ***,the contact environment of the indenter bottom has an important influence on the normal force,so it’s not that the deeper the depth,the greater the normal *** it should not be ignored when evaluating the tribological properties of the amorphous/amorphous *** work can deepen the understanding of hetero-interface on the deformation mechanism during nano-scratch,and help to design amorphous nano-laminates with tailored tribological performance for practical applications.

关键词： Amorphous/amorphous nano-laminates Nano-scratch Molecular dynamics simulation Tribology

Liquid state dependent solidification of a Co-B eutectic alloy under a high magnetic field

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Journal of Materials Science & Technology 2022年第21期116卷 58-71页

作者： Yixuan He Fan Bu Yuhao Wu Jianbao Zhang dawei luo Zhangchi Bian Qing Zhou Tie Liu Qiang Wang Jun Wang Haifeng Wang Jinshan Li Eric Beaugnon State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Center of Advanced Lubrication and Seal Materials Northwestern Polytechnical UniversityXi’an 710072China Collaborative Innovation Center of NPU Shanghai 201108China Key Laboratory of Electromagnetic Processing of Materials(Ministry of Education) Northeastern UniversityShenyang 110819China Univ.Grenoble Alpes INSA ToulouseUniv.Toulouse Paul SabatierEMFLCNRSLNCMI38000 GrenobleFrance

The structure transition inside the Co-81.5at.%B alloy liquid has been studied by an in-situ magnetization measurement.A crossover was observed on the 1/M-T curve during the overheating process,indicating that a liquid-liquid structure transition(LLST)took place in the *** on this information,the effects of LLST on the solidification behavior,microstructure and tribology property were investigated *** sample solidified with the LLST exhibits significantly different solidification behaviors,i.e.,the nucleation undercooling and the recalescence extent are conspicuously enlarged,and the solidification time is *** a result,the microstructure is effectively refined and homogenized,and the hardness and wear resistance are significantly *** present work might be helpful for not only theoretically understanding the influence of LLST on the solidification behavior but also providing an alternative approach to tailor the microstructure and properties.

关键词： Liquid-liquid structure transition Solidification Magnetization Tribology property

Unique Double Carbon Protection Structured Co<sub>3</sub>O<sub>4</sub>Anode for Lithium Ion Battery

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Journal of Materials Science and Chemical Engineering 2020年第12期8卷 56-70页

作者： dawei luo Yuban Lei Ning Zhao Hang He Khan Abrar Kun Li School of Applied Chemistry and Biological Technology Shenzhen Polytechnic Shenzhen China Department of Resource Engineering Guangxi Modern polytechnic college Hechi China

In this study, novel Carbon aerogel (CA)/Co3O4/Carbon (C) composites with a double protective structure are synthesized through a solvothermal method and in-situ polymerization. The morphology and structure are characterized by X-ray diffraction, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Fourier transform infrared spectroscopy (FTIR). The loading content of active anode material Co3O4 in the composite is investigated by thermogravimetry, and the electrochemical properties of the composite are characterized by electrochemical impedance spectroscopy (EIS). The SEM results show that the nano-sized spherical Co3O4 particle is adhered to the inner Carbon aerogel (CA). The HRTEM result indicates the thickness of the prepared Carbon (C) up to 40 nm. Nano-sheet is coated on the surface of the Co3O4 particle. Compared with the pure Co3O4 anode materials, the Carbon aerogel (CA)/Co3O4/Carbon (C) composites have better transport kinetics for both electron and lithium-ion in EIS testing results, which may contribute to its higher specific capacity and higher first coulomb efficiency. Due to the unique structure of th

关键词： Carbon Protection Co3O4 Anode Lithium Ion Battery

Microstructure evolution and non-equilibrium solidification of undercooled Ni-29.8at% Si eutectic alloy melts

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Science China(Technological Sciences) 2010年第4期53卷 1043-1048页

作者： LU YiPing1,LI TingJu1,TENG HaiTao1,FU YaBo1,luo dawei1 &YANG GenCang2 1 School of Materials Science and Engineering,Dalian University of Technology,Dalian 116024,China 2 State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi’an710072,China 1. School of Materials Science and Engineering Dalian University of Technology Dalian 116024 China2. State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi’an 710072 China

Microstructure formation and transition of undercooled bulk Ni70.2Si29.8 eutectic alloy melt were investigated by melt fluxing,cyclical overheating and cooling under high-frequency vacuum *** maximum undercooling of the alloy melt amounted to 428 *** electron microscope(SEM),energy-dispersive X-ray spectroscopy(EDS) and optical microscopy techniques(OM) were adopted to investigate the microstructure and identify the phase *** cooling curves of eutectic alloys upon solidification which were subjected to different undercoolings were described and *** complex microstructure evolution was observed in the as-solidified samples with the increase of ***,an extremely fine microstructure was achieved at the max undercooling of 428 K,and the lamellar distance of about 50-100 nm was *** on the solution entropy of eutectic phases,the microstructure transition with the undercooling was *** results showed that the microstructure transition process was ascribed to solution entropy of transition,i.e.,the complex microstructure evolution was attributed to a transition from faceted-faceted(FF)→faceted-nonfaceted(FN)→nonfaceted-nonfaceted(NN) eutectic systems concurring with increased undercooling.

关键词： interface structure solidification entropy metals and alloys

废弃PET化学回收及制备不饱和聚酯树脂的研究进展

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化工进展 2022年第6期41卷 3279-3292页

作者：李志斌唐辉罗大伟应俏昆明理工大学化学工程学院云南昆明650504 老挝南塔师范学院自然科学部南塔南塔03000

随着聚对苯二甲酸乙二醇酯(PET)材料用量的大幅增长,大量废弃PET制品堆积造成的环境污染问题日益突出,其回收利用技术也随之广受关注。在不同的PET回收方法中,将PET降解为单体或低聚物的化学回收是效率最高、产物利用价值最大的方法,但... 详细信息

随着聚对苯二甲酸乙二醇酯(PET)材料用量的大幅增长,大量废弃PET制品堆积造成的环境污染问题日益突出,其回收利用技术也随之广受关注。在不同的PET回收方法中,将PET降解为单体或低聚物的化学回收是效率最高、产物利用价值最大的方法,但也存在反应条件苛刻、产物收率低等问题。本文详细梳理了水解法、甲醇醇解法、二元醇醇解法、胺解法和氨解法等化学回收方法的主要特点以及微波加热、离子液体、纳米技术等新兴技术在PET化学回收过程中的应用概况。通过对各种化学回收工艺的比较,文中得出二元醇醇解法是最具商业应用价值方法的结论。在此基础上,文中重点介绍了PET的二元醇解以及进一步制备不饱和聚酯树脂的化学过程、发展现状、制约因素和改进措施。分析表明,由PET二元醇解产物制备不饱和聚酯树脂是提高废弃PET资源化效率、丰富原料供给、推动产品升级的重要途径,开发高效、廉价、环保的新型催化剂或酶催化技术是废弃PET回收领域今后主要的发展方向。

关键词：聚对苯二甲酸乙二醇酯回收降解二元醇解制备不饱和聚酯树脂化学过程

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一种可测定生物体体表热导系数的装置

工程热物理学报 2000年第5期21卷 600-604页

作者：程曙霞罗大为钟明中国科学技术大学热科学与能源工程系安徽合肥230026

建立一台可测定生物体体表热导系数的试验装置。首先试验测定标准试样一新鲜甘油（ＡＲ级）及熔融石英玻璃（９９．９％ＳｉＯ２），其结果与ＴＰＲＣ推荐值偏差≤ ０．７％；其次用试验方法证实本文所利用的Ｔａｋｅｇｏｓｈｉ理论... 详细信息

建立一台可测定生物体体表热导系数的试验装置。首先试验测定标准试样一新鲜甘油（ＡＲ级）及熔融石英玻璃（９９．９％ＳｉＯ２），其结果与ＴＰＲＣ推荐值偏差≤ ０．７％；其次用试验方法证实本文所利用的Ｔａｋｅｇｏｓｈｉ理论模型的适用性；最后，根据生物活体会产生代谢热并维持恒定体温的特点，指出应用本装置去测定生物活体体表热导系数时必须满足的若干前提条件。

关键词：生物体热导系数体表试验装置