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Synthesis of self-assembled nanorod vanadium oxide bundles by sonochemical treatment

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Journal of natural Gas Chemistry 2009年第3期18卷 312-318页

作者： y.H.Taufiq-yap y.C.Wong z.z.inal M.z.Hussein Centre of Excellence for Catalysis Science and Technology Faculty of ScienceUniversiti Putra Malaysia Department of Chemistry Faculty of ScienceUniversiti Putra Malaysia

Self-assembled nanorod of vanadium oxide bundles were synthesized by treating bulk V2O5 with high intensity sonochemical technique. The synthesized materials were characterized by X-ray diffraction （XRD）, scanning electron microscope （SEM）, transmission electron microscope （TEM） and temperature-programmed reduction （TPR） in H2. Catalytic behaviour of the materials over anaerobic n-butane oxidation was studied through temperature-programmed reaction （TPRn）. Catalytic evaluation of the sonochemical treated V2O5 products was also studied on microreactor. XRD patterns of all the vanadium samples were perfectly indexed to V2O5. The morphologies of the nanorod vanadium oxides as shown in SEM and TEM depended on the duration of the ultrasound irradiation. Prolonging the ultrasound irradiation duration resulted in materials with uniform, well defined shapes and surface structures and smaller size of nanorod vanadium oxide bundles. H2-TPR profiles showed that larger amount of oxygen species were removed from the nanorod V2O5 compared to the bulk. furthermore, the nanorod vanadium oxide bundles, which were produced after 90, 120 and 180 min of sonochemical treatment, showed an additional reduction peak at lower temperature （-850 K）, suggesting the presence of some highly active oxygen species. TPRn in n-butane/He over these materials showed that the nanorod V2O5 with highly active oxygen species showed markedly higher activity than the bulk material, which was further proven by catalytic oxidation of n-butane.

关键词： nanorod vanadium oxide sonochemical treatment butane oxidation

Structural & Magnetic Characterizations of niLizn nanoferrites Synthesized by Co-precipitation Method

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Journal of Materials Science & Technology 2011年第11期27卷 991-995页

作者： D.n. Rohadiana z.A.z. Jamal S.B. Jamaludin M.f. Bari J. Adnan Sustainable Engineering Research Cluster Universiti Malaysia Perlis School of Microelectronic Engineering Universiti Malaysia Perlis

Synthesis of ***（0.5-x）fe204 nanoparticles with x=0, 0.1, 0.2, 0.3, 0.4 and 0.5 were realized via coprecipitation method. X-ray diffraction （XRD） and vibrating sample magnetometer （VSM） measurements were performed on the samples to determine the characteristics of the crystal structures and the magnetic properties of the samples, respectively. The spinel phase structures of the samples were confirmed by XRD analysis. Patterns of decreased lattice parameter and increased crystallite size values were observed by increasing the Li concentration at longer synthesis reaction periods. Similarly, for the magnetic properties, both the saturation magnetization （Ms） and coercivity （Hc） were found to vary with increasing patterns at higher Li doping levels and longer synthesis reaction periods. The results and mechanisms concerned were discussed.

关键词： Lithium nickel zinc ferrite Co-precipitation Crystal structure Magnetic properties

EVOLUTiOn Of THE ELECTROCHEMiCAL CHARACTERiSTiCS DURing PiTTing CORROSiOn Of PURE ALUMinUM in SODiUM CHLORiDE SOLUTiOn

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Acta Metallurgica Sinica(English Letters) 2005年第4期18卷 525-532页

作者： z. zhang C. Cai f.H. Cao z.n. Gao J.Q. zhang C.n. Cao Department of Chemistry Zhejiang University Hangzhou 310027 China Department of Chemistry Ningxia University Yinchuan 750021 China State Key Laboratory for Corrosion and Protection of Metals Institute of Metal Research The Chinese

The corrosion behavior of pure aluminum in neutral 3.0% （mass fraction） sodium chloride （na-Cl） solution has been studied using electrochemical impedance spectroscopy （EiS） measurement in conjunction with the scanning electron microscopy （SEM） technique. EiS information on the evolution of pitting corrosion over a period of 15 days has been obtained and analyzed with equivalent circuit technique. The results shown that, during the ensemble constant immersion time, two time constants involved, the high frequency one originated from the protective layer on the corroding surface while the low frequenO, one from the diffusion process or the corrosion reaction and so on. And there existed a period for oxide film to growth and thickening prior to the of the attacking of chloride ions to the substrate. Meanwhile, good relationship between EiS and the material corrosion type/severity has been obtained, which has been interpreted according to the characteristics of corrosion process such as auto acceleration of pitting corrosion and the protection of local anodic reaction to the area around them.

关键词： pure aluminum pitting corrosion electrochemical impedance spectroscopy pit-rnorphology

Microscopic stresses in carbon nanotube reinforced aluminum matrix composites determined by in-situ neutron diffraction

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Journal of Materials Science & Technology 2020年第19期54卷 58-68页

作者： X.X.zhang J.f.zhang z.y.Liu W.M.Gan M.Hofmann H.Andrä B.L.Xiao z.y.Ma Sheny.ng national Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China German Engineering Materials Science Centre at MLz Helmholtz-Zentrum GeesthachtD-85747 GarchingGermany Heinz Maier-Leibnitz zentrum(MLz) Technische Universität MünchenD-85747 GarchingGermany fraunhofer institute for industrial Mathematics Fraunhofer-Platz 1Kaiserslautern 67663Germany

One of the most desired strengthening mechanisms in the carbon nanotube reinforced aluminum matrix composites(CnT/Al)composites is the load transfer strengthening mechanism(LTSM).However,a fundamental issue concerning the LTSM is that quantitative measurements of load partitioning in these composites during loading are very *** this study,in-situ neutron diffraction study on the tensile deformation of the 3 vol.%CnT/2009 Al composite and the unreinforced 2009 Al alloy was ***{311}and{220}diffraction elastic constants(DECs)of the 2009 Al alloy were *** those DECs the average stress in the 2009 Al matrix of the composite was *** the average stress in the CnTs was separated by using the stress equilibrium *** homogenization models were also applied to explain the stress evolution in each *** results agree with experimental *** the present case,the average stress in the CnTs reaches 1630 MPa at the yield strength of the composite based on linear regression of the measured data,which leads to an increment of yield strength by about 37 *** the result of this work,an approach to quantify load partitioning in the CnTs is developed for the CnT/Al composites,which can be applied to optimize the mechanical properties of the composites.

关键词： Carbon nanotubes Aluminum matrix composites in-situ neutron diffraction Load partitioning

R & D Of CAST SUPERALLOyS AnD PROCESSing fOR GAS TURBinE BLADES in BiAM

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Acta Metallurgica Sinica(English Letters) 1996年第6期9卷 457-463页

作者： y.f. Han and R.z. Chen(institute of Aeronautical Materials, Beijing 100095,China ) Beijing inst of Aeronautical Materials Beijing China

Research and development of cast superalloys and processing for turbine blades in BiAM during the last 35 years have been reviewed briefly in this paper.

关键词： cast nickel base superalloy turbine blade ceramic core shell Mold

fAiLURES AnD THE LifE Of fURnACE TUBES

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 419-425页

作者： f.z.Shen y.Ding D.M.Hou z.P.ning y.Lü T.B.Dong A.R.Tuohuti nanjing University of Technology Nanjing 210009 ChinaNanjing University of Technology Nanjing 210009 ChinaLutianhua Group Incorporated Luzhou 646300 ChinaLutianhua Group Incorporated Luzhou 646300 ChinaLutianhua Group Incorporated Luzhou 646300 ChinaSouthwestern Tarim Exploration & Development Company Zepu 844804 ChinaSouthwestern Tarim Exploration & Development Company Zepu 844804 China

it is showed after the furnace tubes serviced for 8-10 years that the density of damage in the HAz (heat affected zone) of the weld has higher than in parent metals, though the depth of damage is not equal to. By the test of creep crack growth, it is also acquired that under same mechanic parameter C* (t), the rate of creep crack growth in the HAz.is more than twice as fast as in parent metals. Two mechanisms (overheating and thermal shock) of failure occurred in an accident are presented. The stress of thermal shock is analyzed, in which the change of the elasticity modulus with the radius ET = /(r) is considered. Based on it, the safety region of the thermal shock is obtained. finally, two sets of curves for the safe life are suggested which can facilitate to estimate the remaining life of HK-40 or HP-nb tubes by their creep rupture data.

关键词： failure thermal stock creep crack growth remaining life furnace tube

Stabilization of Traffic flow Based on the Multiple information of Preceding Cars

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Communications in Computational Physics 2008年第4期3卷 899-912页

作者： D.f.Xie z.y.Gao X.M.zhao State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong UniversityBeijing 100044China. institute of System Science School of Traffic and TransportationBeijing Jiaotong UniversityBeijing 100044China.

To enhance the stability of traffic flow,a new car-following model is proposed by taking into account the support of intelligent transportation system(iTS)information,which includes both the headway and the velocity difference of multiple preceding *** new model is based on the Optimal Velocity(OV)model and its extended *** stability condition of the model is obtained by using the linear stability *** nonlinear analysis,the modified Korteweg-de Vries equation is constructed and solved,and the traffic flow is classified into three types,***,metastable,and *** jam phase can thus be described by the kink-antikink soliton solution for the mKdV *** numerical simulation results show that compared with previous models considering only one of the iTS information,the proposed model can suppress traffic jams more efficiently when both headway and velocity difference of arbitrary preceding cars are taken into *** results of numerical simulation coincide with the theoretical ones.

关键词： Traffic flow car-following model stability analysis iTS information

improving high-temperature mechanical properties of cast CrfeConi high-entropy alloy by highly thermostable in-situ precipitated carbides

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Journal of Materials Science & Technology 2021年第13期72卷 29-38页

作者： X.W.Liu n.Gao J.zheng y.Wu y.y.zhao Q.Chen W.zhou S.z.Pu W.M.Jiang z.T.fan State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan430074China institute of nuclear Physics and Chemistry China Academy of Engineering PhysicsMianyang 621999China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China School of Materials Engineering Purdue UniversityWest LafayetteIN 47907USA Southwest Technology and Engineering Research institute Chongqing 400039China Center for Electron Microscopy Wuhan UniversityWuhan 430072China

The Cr fe Co ni high-entropy alloy(HEA)exhibits excellent mechanical properties at lower temperatures due to its low stacking-fault energy,however,its medium-and high-temperature strengths are still *** consideration of the potential diversified applications,more strengthening approaches except for the previously proposed L12 phase hardening deserve further exploration due to its rapid coarsening tendency at high ***,we achieved significant high-temperature strengthening of the cast Cr fe Co ni HEA by in-situ precipitation of highly thermostable *** with 0.5 at.%and 1 at.%niobium and carbon were prepared by simple casting processes,*** cast,solute solution and aging.A highly thermostable microstructure was formed,which comprises very coarse grains accompanied with extensive thermostable carbide precipitates embedded,including submicrometer coherent nb C particles in grain interiors and intergranular coherent M_(23)C_(6)*** high thermostability of microstructure,which is beneficial for the high-temperature loading,is ascribed to the synergy of lacking growth driving force and zenner pinning effect by the *** properties tested at 673,873 and1073 K show that the yield strength and ultimate tensile strength are significantly increased by.nb/C doping,along with the elongation escalation at higher *** strengthening is mainly due to the precipitation hardening of carbide particles.

关键词： High-entropy alloy Carbides Precipitation High-temperature property Strengthening

A precision sampling system for fast corrector power supply of photon source

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Radiation Detection Technology and Methods 2023年第1期7卷 139-148页

作者： Peng Liu f.L.Long y.z.Du institute of High Energy Physics Chinese Academy of SciencesBeijing100049China University of Chinese Academy of Sciences Beijing100049China

Purpose At present,the high-energy photon source(HEPS)is under construction in *** has beam emittance lower than 40 pm *** order to ensure low beam emittance,a high-performance fast orbit feedback system(fOfB)is designed for fast and accurate correction of beam *** fOfB needs to have the smallest adjustment ***,as the execution unit of the fOfB system,the output current resolution of the fast corrector power supply.needs to be as small as *** fOfB systems,precise correction of beam orbit is required for fast corrector power supply with output current resolution better than 60μA.A precision digital sampling system needs to be designed to meet the high requirements of output current *** The precision operational amplifier is used to complete the scaling and sampling of *** precision operational amplifier is used as the front-end processing in the circuit design to complete the amplitude processing and ***,the precision operational amplifier is used as the driver of the precision analog to digital converter(ADC)chip.A precision ADC chips based on oversampling technology is *** this scheme,the selected ADC chip can have the advantages of both high speed and high precision.A simulation prototype is built for test,and the performance parameters of key chips in the design are *** A precision voltage reference is used to test the designed digital sampling *** test results showed that the acquisition system has an effective resolution of 21.6 *** HEPS fast corrector power supply is used for testing the developed precision sampling *** test result showed that the output current resolution of fast corrector power supply is lower than 16μA.

关键词： Photon source fOfB fast corrector High precision Over sampling ADC High resolution