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Improvement on hydrogen generation properties of Zr(BH4)4·8NH3

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Progress in Natural science:Materials International 2021年第1期31卷 41-46页

作者： D.F.Wu L.Z.Ouyang J.M.Huang J.W.Liu H.Wang X.S.yang H.shao M.Zhu school of Materials science and Engineering Guangdong Provincial Key Laboratory of Advanced Energy Storage Materials South China University of Technology Guangdong Research Institute of Rare Metals Guangdong Key Laboratory of Rare Earth Development and Application China-Australia Joint Laboratory for Energy & Environmental Materials Key Laboratory of Fuel Cell Technology of Guangdong Province Advanced Manufacturing Technology Research Centre Department of Industrial and Systems Engineering The Hong Kong Polytechnic University Joint Key Laboratory of the Ministry of Education Institute of Applied Physics and Materials Engineering (IAPME) University of Macau

Hydrolysis of Zr(BH4)4·8NH3in deionized water can generate high purity hydrogen at room temperature.However, the sluggish hydrolysis kinetics of Zr(BH4)4·8NH3hinders its practical use. To improve its hydrogen generation properties, the effects of magnetic stirring, changing hydrolysis solution and tuning the ammonia coordination number on the hydrolysis properties of Zr(BH4)4·8NH3were investigated. Results show that both changing hydrolysis solution and tuning the ammonia coordination number can enhance the hydrolysis kinetics.The hydrolysis kinetics properties of Zr(BH4)4·8NH3were significantly improved in MgCl2and CoCl2solutions.The Zr(BH4)4·8NH3(x ≤ 8) samples were synthesized by a ball-milling method with different ammonization time(10, 60 and 180 min). Both the hydrolysis kinetics and hydrogen yield of Zr(BH4)4·8NH3(x ≤ 8) were enhanced as the ammonia coordination number(x) decreased. Thus, tuning ammonia coordination number is an effective way to control the hydrolysis properties of Zr(BH4)4·8NH3(x ≤ 8).

关键词： Hydrogen production Zr(BH 4 ) 4 ·8NH 3 Hydrolysis properties Ammonia coordination number

The hydrogen storage properties of Mg3LaNi0.1and Mg3LaNi0.1Co0.1

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The hydrogen storage properties of Mg3LaNi0.1and Mg3LaNi0.1C...

A hybrid tracking control strategy for an unmanned underwater vehicle aided with bioinspired neural dynamics

第九届全国氢能学术会议

作者： L.Z.Ouyang,X.S.yang,H.W.Dong,M.Zhu south China University of Technology,China

Hydrogen storage properties,composition and microstructures of the MgLa and MgLaNi alloys have been investigated previously,the results show that MgLa and

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IET Cyber-systems and Robotics 2022年第3期4卷 153-162页

作者： Zhe xu Tao Yan simon x.yang s.Andrew Gadsden school of Engineering University of GuelphGuelphOntarioCanada Department of Mechanical Engineering McMaster UniversityHamiltonOntarioCanada

Tracking control has been a vital research topic in robotics.This paper presents a novel hybrid control strategy for an unmanned underwater vehicle(UUV)based on a bio-inspired neural dynamics model.An enhanced backstepping kinematic control strategy is first developed to avoid sharp velocity jumps and provides smooth velocity commands relative to conventional methods.Then,a novel sliding mode control is proposed,which is capable of providing smooth and continuous torque commands free from chattering.In comparative studies,the proposed combined hybrid control strategy has ensured control signal smoothness,which is critical in real‐world applications,especially for a UUV that needs to operate in complex underwater environments.

关键词： backstepping bioinspired neural dynamics sliding mode control unmanned underwater vehicle

The intrinsic nonlinear multiscale interactions among the mean flow, low frequency variability and mesoscale eddies in the Kuroshio region

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science China Earth sciences 2019年第3期62卷 595-608页

作者： yang yang x.san LIANG school of Marine sciences Nanjing University of Information Science and Technology school of Atmospheric sciences Nanjing University of Information Science and Technology

Using a new functional analysis tool, multiscale window transform(MWT), and the MWT-based localized multiscale energetics analysis and canonical transfer theory, this study reconstructs the Kuroshio system on three scale windows, namely,the mean flow window, the interannual-scale(low-frequency) window, and the transient eddy window, and investigates the climatological characteristics of the intricate nonlinear interactions among these windows. significant upscale energy transfer is observed east of Taiwan, where the mean Kuroshio current extracts kinetic energy from both the interannual and eddy windows.It is found that the canonical transfer from the interannual variability is an intrinsic source that drives the eddy activities in this region. The multiscale variabilities of the Kuroshio in the East China sea(ECs) are mainly controlled by the interaction between the mean flow and the eddies.The mean flow undergoes mixed instabilities(i.e., both barotropic and baroclinic instabilities) in the southern ECs, while it is barotropically stable but baroclinically unstable to the north. The multiscale interactions are found to be most intense south of Japan, where strong mixed instabilities occur; both the canonical transfers from the mean flow and the interannual scale are important mechanisms to fuel the eddies. It is also found that the interannual-scale energy mainly comes from the barotropically unstable jet, rather than the upscale energy transfer from the high frequency eddies.

关键词： Kuroshio Multiscale window transform Canonical transfer Multiscale energetics analysis Multiscale interaction Barotropic instability Baroclinic instability

Eutectic-reaction brazing of Al_(0.3)CoCrFeNi high-entropy alloys using Ni/Nb/Ni interlayers

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Journal of Materials science & Technology 2022年第26期121卷 245-255页

作者： Y.Lei J.sun x.G.song M.x.yang T.L.yang J.Yin state Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China Beijing Power Machinery Institute Beijing 100074China sichuan Aerospace Changzheng Equipment Manufacturing Co. Ltd.Chengdu 610100China

In this study,a novel eutectic-reaction brazing of Al_(0.3)CoCrFeNi high-entropy alloys(HEAs)^(1)was investigated with a design of laminated Ni/Nb/Ni interlayers.The typical Al_(0.3)CoCrFeNi brazing seam consisted of proeutecticγ,the lamellar eutectic structure composed of face-centered cubic(FCC)phase(eutecticγ)and C14 Laves,as well as a few amounts of Nb based solid solution.A high density of nanoscale ordered L1_(2)(γ)phase was precipitated withinγphase matrix.With the brazing temperature raised from 1200 to 1320℃,the dissolution volume of Al_(0.3)CoCrFeNi alloy into Ni-Nb liquid was increased.The microstructure of the brazing seam changed from hypereutectic(blocky Laves+γphase)to eutectic(Laves+eutecticγ)to hypoeutectic structures(proeutecticγ+Laves/γeutectic structure).The shear strength of joints was increased gradually due to the formation of eutectic lamellae and the cellular growth of proeutecticγphase.The maximum shear strength of the joint brazed at 1320℃for 10 min was up to 592 MPa,reaching 95%of the base metal.The joint mainly ruptured in the soft proeutecticγphase in a ductile fracture mode.

关键词： High-entropy alloys Brazing Eutectic structure shear strength

Bulk nanocrystalline W-Ti alloys with exceptional mechanical properties and thermal stability

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Journal of Materials science & Technology 2022年第19期114卷 16-28页

作者： H.x.xue x.C.Cai B.R.sun x.shen C.C.Du x.J.Wang T.T.yang s.W.xin T.D.shen Clean Nano Energy Center State Key Laboratory of Metastable Materials Science and TechnologyYanshan UniversityQinhuangdao 066004China CssC 723rd Research Institute China State Shipbuilding Corporation LimitedYangzhou 225000China

Nanocrystalline(NC)W metals and alloys often exhibit higher radiation tolerance and strength than their coarse-grained counterparts.However,their thermal stability is low,making it difficult to achieve bulk NC W metals and alloys by consolidation using conventional techniques such as pressure-less sintering,hot-explosive-compaction sintering,and spark plasma sintering.Here we report the synthesis and mechanical properties of bulk NC W_(100-x)Ti_(x)(x=10 at.%-30 at.%)alloys prepared by consolidating mechanically alloyed NC powders under a high-temperature/high-pressure condition.Adding 20 at.%-30 at.%Ti largely improves the sinterability of NC W-Ti alloy powders.The room-temperature microhardness and compressive yield strength of consolidated bulk NC W_(80)Ti_(20) alloy are∼16.9 and 6.0 GPa,respectively,which are mainly caused by grain boundary strengthening and significantly higher than those of previously reported W and W alloys.The ultimate compressive strength of bulk NC W_(80)Ti_(20) measured between 900 and 1100°C deceases with increasing temperature.This behavior can be explained by the activation of Rachinger grain boundary sliding.No grain growth is observed in bulk NC W_(80)Ti_(20) after compression at 1000°C.Theoretical calculation suggests that it is the segregation of Ti at grain boundaries that decreases the specific grain boundary free energy and makes the NC W_(80)Ti_(20) alloy thermodynamically stable.

关键词： Nanocrystalline W-Ti alloys segregation Grain boundary energy strength Hardness

Excellent strength-ductility combination in Co_(36)Cr_(15)Fe_(18)Ni_(18)Al_(8)Ti_(4)Mo_(1)multi-principal element alloys by dual-morphology B2 precipitates strengthening

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Journal of Materials science & Technology 2023年第3期134卷 60-66页

作者： x.s.Liu R.Li x.F.Fan Q.Q.Liu x.Tong A.x.Li s.xu H.yang s.B.Yu M.H.Jiang C.Huo P.F.Yu M.T.Dove G.Li state Key Laboratory of Metastable Materials science and Technology Yanshan UniversityQinhuangdao 066004China College of Computer science Sichuan UniversityChengdu 610065China school of Physical and Chemical sciences Queen Mary University of LondonMile End RoadLondon E14NSUnited Kingdom school of Mechanical Engineering Dongguan University of TechnologyDongguan 523808China

Precipitation strengthening provides one of the most widely-used mechanisms for strengthen-ing multi-principal-element alloys(MPEAs).Here,we report dual-morphology B2 precipitates in Co_(36)Cr_(15)Fe_(18)Ni_(18)Al_(8)Ti_(4)Mo_(1)MPEA obtained by thermo-mechanical processing.Electron microscopy charac-terization reveals that the dual-morphology B2 precipitates are either recrystallized B2 particles formed at the grain boundaries or triple junctions with recrystallization process,or rod-like within the non-recrystallized FCC matrix.The dual-morphology B2 precipitates enhance the yield strength and ultimate tensile strength up to 1120 MPa and 1480 MPa,respectively.This work suggests the mechanical proper-ties of the alloy can be optimized by B2 precipitation strengthening to meet the needs of engineering applications.

关键词： Multi-principal element alloys B2 precipitates Heterogeneous nucleation Precipitation strengthening

Curvature-induced noncommutativity of two different components of momentum for a particle on a hypersurface

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Communications in Theoretical Physics 2021年第2期73卷 73-77页

作者： Z Li x yang Q H Liu school for Theoretical Physics School of Physics and ElectronicsHunan UniversiyChangsha 410082China school of Materials science and Engineering Guilin University of Electronic TechnologyGuilin541004China synergetice Innovation Center for Quantum Efects and Applications(sICQEA) Hunan Normal UniversityChangsha 410081China

As a nonrelativistic particle constrained to remain on an(N−1)-dimensional((N≥2))hypersurface embedded in an N-dimensional Euclidean space,two different components pi and pj(i,j=1,2,3,...N)of the Cartesian momentum of the particle are not mutually commutative,and explicitly commutation relations[p^(^)_(i),p^(^)_(j)](≠0) depend on products of positions and momenta in uncontrollable ways.The generalized Dupin indicatrix of the hypersurface,a local analysis technique,is utilized to explore the dependence of the noncommutativity on the curvatures around a local point of the hypersurface.The first finding is that the noncommutativity can be grouped into two categories;one is the product of a sectional curvature and the angular momentum,and another is the product of a principal curvature and the momentum.The second finding is that,for a small circle lying a tangential plane covering the local point,the noncommutativity leads to a rotation operator and the amount of the rotation is an angle anholonomy;and along each of the normal sectional curves centering the given point the noncommutativity leads to a translation plus an additional rotation and the amount of the rotation is one half of the tangential angle change of the arc.

关键词： constrained motion quantization hypersurface Dirac brackets geometric momentum

Tuning the microstructure for superb corrosion resistance in eutectic high entropy alloy

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Journal of Materials science & Technology 2022年第14期109卷 197-208页

作者： s.shuang Q.Yua x.Gao Q.F.He J.Y.Zhang s.Q.shi Y.yang Department of Mechanical Engineering City University of Hong KongKowloon TongKowloonHong KongChina Department of Mechanical Engineering Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina Department of Materials science and Engineering City University of Hong KongKowloon TongKowloonHong KongChina

In this work,we demonstrate that the corrosion resistance of the FeCrNiCoNb_(0.5) eutectic high entropy alloy(EHEA)can be tuned by controlling the size of its eutectic structure.Through microstructure refinement,the EHEA exhibits a superb corrosion resistance in 1 M NaCl in terms of a very low corrosion current density and an ultra-high transpassviation potential,which outperforms a variety of other HEAs and conventional metals and alloys.At the fundamental level,the microstructure refinement results in a rapid formation of a thick and compact passive film with less Cl-adsorption on the EHEA,which results in significant enhancement in its corrosion resistance.The outcome of our research provides important insights into the design of corrosion resistant chemically complex alloys.

关键词： Eutectic high entropy alloy Passivation Transpassivation potential Microstructure size