检索结果-南通市图书馆

矿物岩石地球化学通报 2018年第6期37卷 1180-1180页

作者： D.E.Canfield S.C.Zhang A.B.Frank X.M.wang H.J.Wang j.Su Y.T.Ye R.Frei 袁超

大气氧对生命大爆发具有重要意义。然而。前人通过Cr同位素研究表明,中元古代时期具有非常低的大气氧浓度(当今氧水平的0.1%),并不足以使得中元古代真核生物大爆发。Cr同位素是揭示大气氧化历史的一个非常有用的办法。由于Cr^3+物相发... 详细信息

大气氧对生命大爆发具有重要意义。然而。前人通过Cr同位素研究表明,中元古代时期具有非常低的大气氧浓度(当今氧水平的0.1%),并不足以使得中元古代真核生物大爆发。Cr同位素是揭示大气氧化历史的一个非常有用的办法。由于Cr^3+物相发生大陆氧化性风化作用,Cr同位素会发生分馏,重的53Cr同位素会倾向于进入氧化的镉酸盐中(Cr^4+),从而使得残留相(Cr^3+)中亏损重Cr同位素。

关键词： Cr^3+ 中元古代同位素氧浓度大气特征和分异生命大爆发

在动物内比较三维分子靶向超声成像和三维动态对比增强超声对结肠癌早期抗血管生成治疗疗效评估

在线全文

学校读者我要写书评

暂无评论

国际医学放射学杂志 2017年第2期 219-219页

作者： H.J.Wang A.M.Lutz D.hristov L.Tian j.K.Willmann 杨科 Department of Radiology Molecular Imaging Program at StanfordSchool of MedicineStanford University

摘要目的在动物内比较用靶向临床分级的血管内皮生长因子受体2(VEGFR2)的微气泡进行三维分子靶向超声成像和用非靶向微气泡进行三维动态对比增强超声对人结

关键词：超声成像对比增强超声三维动态分子靶向抗血管生成动物

Releasing the residual stress of C_(f)/SiC-Gh3536 joint by designing an Ag-Cu-Ti+Sc_(2)(WO_(4))_(3) composite filler metal

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

journal of Materials Science & Technology 2022年第13期108卷 102-109页

作者： P.wang X.Liu h.wang j.Cao j.Qi j.Feng State Key Laboratory of Advanced Welding and joining Harbin Institute of TechnologyHarbin 150001China

Due to native character of thermal expansion coefficient(CTE)mismatch between C_(f)/SiC and Gh3536,achieving high strength joint was a huge challenge for C_(f)/SiC-Gh3536 joints.herein,a composite filler metal of Ag-Cu-Ti+Sc_(2)(WO_(4))_(3) was developed to join C_(f)/SiC and Gh3536.This work introduced Sc_(2)(WO_(4))_(3) to Ag-Cu-Ti system as a negative thermal expansion(NTE)reinforcing phase to release joint residual stress.Sc_(2)(WO_(4))_(3) was evenly distributed in the brazing seam and reacted with Ti to form Ti_(3)O_(5) reaction layer.The results of finite element analysis showed that the residual stress of the joints was effectively released by introducing Sc_(2)(WO_(4))_(3) reinforcing phase,and the mises stress was decreased from447 to 401 MPa.The maximum shear strength of the C_(f)/SiC-Gh3536 joint brazed with Ag-Cu-Ti+6 vol%Sc_(2)(WO_(4))_(3) filler alloys was 64 MPa,which was about 2.6 times higher than that of Ag-Cu-Ti alloys.The results of this study provide a promising strategy for the introduction of new Sc_(2)(WO_(4))_(3) reinforcing phase in Ag-Cu-Ti system,and improve the reliability and feasibility of composite brazing alloy in brazing filed.

关键词： Negative thermal expansion Brazing Residual stress Composite brazing alloy CTE

A novel Mg-Gd-Y-Zn-Cu-Ni alloy with excellent combination of strength and dissolution via peak-aging treatment

在线全文

学校读者我要写书评

暂无评论

journal of Magnesium and Alloys 2023年第2期11卷 720-734页

作者： Y.h.Liu Z.R.Zhang j.wang Y.Li h.X.Li L.Y.jia j.h.wang j.S.Zhang State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China Dekai Intelligent Casting Co. Ltd.Hebei 072750China

Inferior absolute strength and dissolution properties are the main bottlenecks for the widespread application of dissolvable magnesium alloys in complex working environments for unconventional oil and gas resources.here,a novel functional peak-aged Mg-9.5Gd-2.7Y-0.9Zn-0.8Cu-0.4Ni(wt.%) alloy for fracturing tools is reported,and it possesses an ultimate tensile strength of 457.6 MPa,ultimate compressive strength of 620.7 MPa and dissolution rate of ~43.7 mg·cm^(-2)·h^(-1) in 3 wt.% KCl solutions at 93℃.The excellent strength of the agedalloy is primarily attributed to the combination of grain refinement,long-period stacking ordered(LPSO) strengthening,and precipitation strengthening induced by stacking fault and β’ phase,among which the precipitation strengthening is dominant.Further investigations confirm that the corrosion is triggered from the micro-galvanic coupling between the Mg matrix and the cathodic lamellar and block LPSO phases.Strip-shaped corrosion pits along with LPSO phases are subsequently formed,significantly accelerating corrosion.The β’ precipitates can effectively improve the strength without compromising the dissolution rate because of their nanoscale size.This study provides an excellent material selection for dissolvable fracturing tools and presents a strategy by which a synergistic combination of strength and dissolution rate is achieved via peak-aging treatment.

关键词： Dissolvable magnesium alloy Peak-aging treatment Mechanical properties Micro-galvanic corrosion

Review on hydrogen Embrittlement of Press-hardened Steels for Automotive Applications

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2023年第7期36卷 1123-1143页

作者： Z.wang Q.Lu Z.h.Cao h.Chen M.X.huang j.F.wang General Motors China Science Lab Shanghai201206China Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong Kong999077China Key Laboratory for Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua UniversityBeijing100084China

Press-hardened steel(PhS)with an ultimate tensile strength(UTS)of 1500 MPa has been widely used in automotive body-in-white in the last two decades,due to its ultra-high strength and excellent formability that is achieved by hot stamping process.however,the application of PhS with UTS exceeding 1500 MPa in automotive industry could be deferred due to the increased risk of hydrogen embrittlement.To reduce this kind of risk,recent research efforts have been focused on various ways to optimize the microstructure of PhS.The present review intends to summarize these efforts,to highlight present solutions to address hydrogen embrittlement,and to shed light on directions for future improvement.The influence of microstructure on the hydrogen embrittlement of PhS has been discussed in terms of both the steel substrate and the surface condition.The substrate part covers the influence of martensite,carbides,inclusions,and retained austenite,while the surface part covers decarburization and oxidation,pre-coating,and trimming.

关键词： hot stamping Press-hardened steels Coating-free hydrogen embrittlement Fracture Al-Si coating

A new thermodynamically stable Nb_(2)Ni intermetallic compound phase revealed by peritectoid transition within binary Nb-Ni alloy system

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

journal of Materials Science & Technology 2022年第5期100卷 246-253页

作者： j.F.Zhao h.P.wang B.Wei School of Physical Science and Technology Northwestern Polytechnical UniversityXi’an 710072China

A new intermetallic compound of thermodynamically stable Nb_(2)Ni phase is discovered within Nb-Ni binary system,refreshing the current situation that there are only three stable intermediate phases of Nb_(7)Ni_(6),NbNi_(3) and NbNi_(8).The new stable phase is generated from the peritectoid transition:(Nb)+Nb_(7)Ni_(6)→Nb_(2)Ni,and the transformation temperature is 1533 K.This refreshes the current equilibrium Nb-Ni binary phase diagram.It is confirmed by transmission electron microscopy and the annealing experiments,which is determined to be the FCC structure(Pearson:cF96,space grope:Fd-3m O2,a=11.888A).Furthermore,the equilibrium properties of Nb_(2)Ni phase are produced by density functional theory,including the formation energy,cohesive energy,bulk modulus and lattice constant.

关键词： Intermetallic compound Peritectoid transition Transmission electron microscopy Density functional theory Nb alloy

Analyzing the Effects of Key Design Factors of a Negative-Differential-Resistance(NDR)Microfluidic Oscillator–an Equivalent-Circuit-Model Approach

在线全文

学校读者我要写书评

暂无评论

Advances in Applied Mathematics and Mechanics 2022年第6期14卷 1381-1399页

作者： j.W.Wu h.M.Xia Z.P.wang W.wang h.j.Du School of Mechanical Engineering Nanjing University of Science and TechnologyNanjingJiangsu 210094China Singapore Institute of Manufacturing Technology 73 Nanyang DriveSingapore 637662Singapore School of Mechanical and Aerospace Engineering Nanyang Technological University50 Nanyang AvenueSingapore 639798Singapore

Numerical study on dynamic hydroelastic problems is usually rather complex due to the coupling of fluid and solid mechanics.here,we demonstrate that the performance of a hydroelastic microfluidic oscillator can be analyzed using a simple equivalent circuit model.Previous studies reveal that its transition from the steady state to the oscillation state follows the negative-differential-resistance(NDR)mechanism.The performance is mainly determined by a bias fluidic resistor,and a pressurevariant resistor which further relates to the bending stiffness of the elastic diaphragm and the depth of the oscillation chamber.In this work,a numerical study is conducted to examine the effects of key design factors on the device robustness,the applicable fluid viscosity,the flow rate,and the transition pressure.The underlying physics is interpreted,providing a new perspective on hydroelastic oscillation problems.Relevant findings also provide design guidelines of the NDR fluidic oscillator.

关键词： Microfluidic oscillator hydroelastics equivalent circuit model negative differential resistance