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Thermo-activated Dislocation Emission at the Cu/Nb Interface Revealed by Molecular Dynamics Simulations

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Journal of Materials Science & Technology 2011年第8期27卷 714-718页

作者： Dejun Yu Yue Zhang kaiming wang Anshan Normal University Anshan 114005 Chiila University of Science and Technology LiaoNing Anshan 114051 China

Nanolayered Cu-Nb composites offer a series of enhanced properties for their use in extreme conditions, e.g. high field magnets and high irradiation resistance. However, the stability of the Cu/Nb heterogeneous interface needs confirmation under various conditions. In the present work, molecular dynamics simulations were carried out to investigate the interracial behavior under various temperatures with initial stress at the interface. It is found that the interface becomes unstable at simulation temperatures higher than O00 K, resulting in the emission of dislocations and loops within one or more slip systems. The emission process is Found to be thermally-activated, i.e., the higher temperature, the shorter annealing time needed. The present study is believed to assist the experimental synthesis of the Cu-Nb multilayer nanocomposites For multiple applications.

关键词： Interface Dislocation Molecular dynamics Thermo-activation

A numerical investigation on deep shale gas recovery

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Energy Geoscience 2021年第4期2卷 274-284页

作者： Changqing Liu Yan Liang kaiming wang Research Institute of Exploration and Exploitation SINOPEC East China Oil and Gas CompanyNanjingJiangsu210000China Jiangsu Maritime Institute Nanjing210000China

In recent years,exploration and development of deep shale gas(at a burial depth of 3,500-4,500 m)has become a hotspot in the ***,the state of gas storage and transporting mechanism for deep shale gas under high pressure and temperature have not been thoroughly explored,compared with its shallower counterpart.A numerical model for deep shale gas recovery considering multi-site nonisothermal excess adsorption has been established and applied using Finite Element *** from the simulation reveal the following.(1)Excess desorption significantly impacts early-stage performance of deep shale gas well;the conventional way for shallower shale gas development,in which the density of adsorbed gas is not distinguished from that of free gas,overestimates the gas in place(GIP).(2)Although thermal stimulation can speed up the desorption and transporting of deep shale gas,the incremental volume of produced gas,which is impacted not only by seepage velocity but also density of gas,is insignificant,far from *** an additional 2.03%of cumulative gas would be produced under treatment temperature of 190C and initial reservoir temperature of 90C in a period of 5 years.(3)Matrix porosity,which can be measured on cores in laboratory and/or estimated by using well logging and geophysical data,is the most favorable parameter for deep shale gas *** 60%increase in matrix porosity,an extra 67.25%shale gas on a daily base would be recovered even after 5-year depletion production;(4)Production rate for gas wells in shale reservoirs at 3,500 m and 4,500 m deep would be raised by 5.4%in a 5-year period if the depth of target interval would increase by 340 m without thermal treatment according to the numerical model proposed in the study.

关键词： Deep shale gas Excess adsorption Multi-site Langmuir isotherm Non-isothermal Discrete fracture network

Microstructure and wear behavior of IC10 directionally solidified superalloy repaired by directed energy deposition

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Journal of Materials Science & Technology 2021年第34期93卷 71-78页

作者： Guan Liu Dong Du kaiming wang Ze Pu Dongqi Zhang Baohua Chang State Key Laboratory of Tribology Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China

Directed energy deposition has been used to repair superalloy components in aero engines and gas ***,the microstructure and properties are generally inhomogeneous in components because of the different processing ***,the microstructures and wear behavior of different zones(substrate,HAZ,and deposit)are investigated for the IC10 directionally solidified superalloy repaired by the directed energy deposition *** is found that the microstructure of the deposited layers is strongly textured with a-fiber texture in the building direction,and the texture intensity is continuously increased along the building *** kinds ofγ’phase(primary and secondaryγ’phase)can be found in the heat-affected zone(HAZ),and the average size of primaryγ’phase is smaller than that in the substrate due to *** the deposit layers,the size ofγ’phase is much smaller than those in the substrate and the primaryγ’phase of HAZ;both size and the fraction of theγ’phase decreases with the increase of building *** wear rate of the substrate is the smallest,indicating the best wear resistance;while the wear rate of HAZ is the largest,indicating the worst wear resistance in the repaired *** wear rates in the deposit layers increase from the bottom to the top zones,showing a decreasing wear *** wear is found to be the dominant wear mechanism of the repaired alloy,and the resistance to which is closely related to the fraction ofγ’phase in the *** understanding of the influence of microstructure on wear resistance allows for a more informed application of inhomogeneous superalloy components repaired by directed energy deposition in industry.

关键词： Directed energy deposition Directionally solidified superalloy Microstructure Wear behavior Repairing

Effect of uneven noise source and/or station distribution on estimating the azimuth anisotropy of surface waves

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Earthquake Science 2018年第4期31卷 175-186页

作者： Laiyu Lu kaiming wang Zhifeng Ding Institute of Geophysics China Earthquake Administration

With the development of the dense array,the surface wave velocity and azimuthal anisotropy under the array can be directly obtained by beamforming the noise cross-correlation functions(NCFs). However, the retrieval of the Green’s function by cross-correlating the seismic noise requires that the noise source has a uniform distribution. For the case with uneven noise source, the azimuthal dependence on the sources in the expression for the spatial coherence function, which corresponds to the NCF in the time domain,has the same form as the azimuthal dependence of the surface wave velocity in weakly anisotropic media. Therefore, the uneven noise source will affect the surface wave anisotropy extraction. In this study, three passive seismic methods, i.e.,beamforming, SPAC(spatial autocorrelation), and NCF, are compared to demonstrate that an uneven source distribution and uneven station distribution have equivalent effects on the outcome from each method. A beamforming method is proposed to directly extract the velocity and azimuthal anisotropy of surface waves. The effect of uneven noise source and/or station distribution on estimating the azimuth anisotropy of surface waves was investigated using data from the ChinArray Phase Ⅱ. A method for correcting the apparent anisotropy in beamforming results caused by an uneven station distribution is suggested.

关键词： beamforming uneven seismic noise source uneven station distribution azimuthal anisotropy

CCSD(T) study on the structures and chemical bonds of AnO molecules (An = Bk–Lr)

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Chinese Physics B 2021年第3期30卷 220-224页

作者： Xiyuan Sun Pengfei Yin kaiming wang Gang Jiang College of Science Sichuan Agricultural UniversityYa’an 625014China Institute of Atomic and Molecular Physics Sichuan UniversityChengdu 610065China

The molecular geometries and dissociation energies of AnO (An = Bk–Lr) molecules were first obtained at thecoupled-cluster single-, double-, and perturbative triple-excitations [CCSD(T)] level of theory. Four hybrid functionals,B3LYP, M06-2X, TPSSh, and PBE0, were also employed in the calculations for the sake of comparison. In comparison ofthe CCSD(T) results, B3LYP, TPSSh, and PBE0 functionals can obtain more appropriate results than M06-2X and *** analyses on molecular orbitals show that the 7s, 6d, and 5f atomic orbitals of actinide (An) atoms participate in thebonding of An–O bonds. The partial covalent nature between An and O atoms is revealed by QTAIM analyses.

关键词： ab initio calculation AnO(Bk-Lr)molecules density functional theory(DFT) chemical bond

One step hot-pressing method for hybrid Li metal anode of solid-state lithium metal batteries

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Journal of Materials Science & Technology 2023年第22期153卷 32-40页

作者： kaiming wang Yifei Chen Liang Zhang Qihang Zhang Zhi Cheng Yining Su Fei Shen Xiaogang Han State Key Laboratory of Electrical Insulation and Power Equipment School of Electrical EngineeringXi’an Jiaotong UniversityXi’an 710049China School of Future Technology Xi’an Jiaotong UniversityXi’an 710049China Key Laboratory of Smart Grid of Shaanxi Province Xi’anXi’an 710049China National Innovation Platform(Center)for Industry-Education Integration of Energy Storage Technology Xi’an 710049China

Safety issues induced by infinite anode volume change and uncontrolled lithium(Li)dendrite growth have become the biggest obstacle to the practical application of Li metal *** addition,the tra-ditional rolling method makes it difficult to manufacture thin Li foil with high mechanical strength and low Li ***,a three-dimensional(3D)lithophilic carbon paper/copper(Cu)current collector hybrid anode with ultra-low Li metal content is prepared by a hot-pressing *** highly re-versible and stable lithiophilic layer LiC_(x) formed in situ by heating/pressing treatment provides abun-dant nucleation sites and reduces the Li nucleation overpotential,thereby effectively suppressing Li den-drite ***,the volume change and pulverization problems of Li metal anode during depo-sition/stripping also can be accommodated by the 3D *** optimization effect has been directly confirmed by in-situ optical and ex-situ scanning electron microscope ***,highly sta-ble performance(158.4 mA h g^(-1) at 2 C after 200 cycles with a capacity retention of 95.24%)in Li@LCP-Cu||NCM811 coin cell can be ***,the solid-state battery assembled with the hybrid anode,poly(vinylidene fluoride)(PVDF)-based polymer electrolyte and polyethylene oxide(PEO)interface functional layer also exhibits the best electrochemical and safety performance,which also proves that the Li@LCP-Cu anode has great potential for application in solid-state batteries.

关键词： Hot-pressing Hybrid anode Lithiophilic layer licx Li dendrite Solid-state batteries

Long Period Fiber Gratings Written in Photonic Crystal Fibers by Use of CO2 Laser

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Photonic Sensors 2013年第3期3卷 193-201页

作者： Yiping wang Changrui LIAO Xiaoyong ZHONG Jiangtao ZHOU Yingjie LIU Zhengyong LI Guanjun wang kaiming YANG Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education/Guangdong Province ShenzhenUniversity Shenzhen 518060 China

Photonic crystal fibers are usually divided into two different types of fibers： solid-core photonic crystal fibers （PCFs） and air-core photonic bandgaps fibers （PBFs）. We presented the fabrication methods and applications of long period fiber gratings （LPFGs） written in these two types of photonic crystal fibers by use of a CO2 laser. A stain sensor with a high sensitivity was demonstrated by use of an LPFG written in solid-core PCFs. An in-fiber polarizer based on an LPFG was fabricated by use of a focused CO2 laser beam to notch periodically on a PCF. A novel LPFG was written in an air-core PBF by use of a CO2 laser to collapse periodically air holes in the fiber cladding.

关键词： Long period fiber gratings fiber Bragg gratings photonic crystal fibers photonic bandgap fibers CO2 lasers

Introduction of nanotwins into nanoprecipitations strengthened CoCrNiMo_(0.2) alloy to achieve strength and ductility trade-off:A comparative research

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Journal of Materials Science & Technology 2023年第25期156卷 172-182页

作者： Hao Zhang Ziyi Ren Yonggang Tong Yongle Hu Xixi Ji Lingwei Yang kaiming wang Jingzhong Fang Hui Chen Xiubing Liang College of Automotive and Mechanical Engineering Changsha University of Science and TechnologyChangsha 410114China Hypervelocity Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000China School of Civil Engineering Changsha University of Science and TechnologyChangsha 410111China National Institute of Defense Technology Innovation Academy of Military Science PLA ChinaBeijing 100072China

Normal strengthening methods through precipitations and deformation obviously enhance the strength of metallic materials while resulting in the sacrifice of ductility,and synergistic improvement of strength and ductility is currently an urgent *** we developed a cryogenic deformation combined with an annealing method to fabricate CoCrNiMo_(0.2) medium entropy alloy,which achieved an ultrahigh strength of 1.8 GPa with synergistic improvement in strength and ***,mechanical performance,and strengthening mechanisms of the developed alloys were investigated compared with that prepared by the regular room temperature deformation *** was found that high-density nanotwins were produced in CoCrNiMo_(0.2) MEA via cryogenic *** grains,hard precipitations,and high volume fraction of nanotwins greatly strengthened the alloy,obtaining a yield and ultimate tensile strength of 1400 MPa and 1800 *** improvement of the developed alloy was mainly attributed to the production of deformation nanotwins due to the lower stacking fault energy,which greatly increases the dislocation storage ability,and thus,the ductility of the alloy was enhanced.

关键词： Nanotwins Mechanical properties Deformation behavior Strengthening mechanisms

Electrode structure enabling dendrite inhibition for high cycle stability quasi-solid-state lithium metal batteries

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Journal of Energy Chemistry 2023年第4期79卷 232-241页

作者： kaiming wang Ao Yu Zhiyi Zhou Fei Shen Manni Li Liang Zhang Weichang Guo Yifei Chen Le Shi Xiaogang Han State Key Laboratory of Electrical Insulation and Power Equipment School of Electrical EngineeringXi’an Jiaotong UniversityXi’an 710049ShaanxiChina School of Future Technology Xi’an Jiaotong UniversityXi’an 710049ShaanxiChina National Innovation Platform(Center)for Industry-Education Integration of Energy Storage Technology Xi’an 710049ShaanxiChina

Lithium(Li)metal batteries(LMBs)are widely regarded as the ultimate choice for the next generation of high-energy–density ***,the uncontrollable growth of Li dendrites formed by inhomogeneous deposition seriously hinders its *** many studies have achieved significant results in inhibiting the formation of Li dendrites,it is still impossible to eradicate them ***,regulating the deposition behavior,such as the growth direction of unevenly deposited Li,is preferable to unilaterally suppressing them in some *** we report a structured anode that can confine the deposited Li within holes and tune it to become vertical-up/horizontal-centripetal mixed growth mode by optimizing the electric field/Li^(+)concentration *** Li^(+) adsorbed by the poly(amic acid)(PAA)insulating layer coated on the anode surface can form the Li^(+)concentration gradient pointing to the center of the *** with the special electric field formed by the hole structure,it is favorable for the Li^(+)to move into the vertically arrayed holes and simultaneously deposit on the bottom and ***,both in-situ and ex-situ observations confirm that the growth mode is changed and the Li deposition morphology is denser,which can greatly delay capacity fading and prolong cycle life in both liquid and quasi-solid-state *** the results show that the novel anode provides a new perspective for deep research into solid-state LMBs.

关键词： Lithium metal batteries Structured anode Deposition behavior Quasi-solid-state