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Fabrication of High-purity Ternary Carbide Ti_3AlC_2 by Spark Plasma Sintering(SPS)Technique

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Journal of Wuhan University of Technology(Materials Science) 2008年第2期23卷 177-180页

作者： SONG Jinghong yang haitao The Centre for Materials Research and Analysis Wuhan University of Technology Wuhan 430074 China Shenzhen University Shenzhen Key Lab of Special Functional MaterialsShenzhen 518060 China

The effect of silicon on synthesis of Ti3AlC2 by spark plasma sintering （SPS） from TiC/Ti/Al powders was investigated. X-ray diffraction （XRD） and scanning electron microscope （SEM） were used for phase identification and microstructure evaluation. The results show that addition of silicon can considerably accelerate the synthesis reaction of Ti3AlC2 and fully dense, essentially single-phase （purity 〉98%） polycrystalline Ti3AlC2 could be successfully obtained by sintering 2TiC/lTi/lAl/0.2Si powders at 1 200- 1 250 ℃ under a pressure of 30 MPa. SEM photographs show that the obtained Ti3AlC2 samples from mixtures powders are in plane-shape with a size of about 2-5 μm and 10-25 μm in the thickness dimension and elongated dimension, respectively.

关键词： Ti3AlC2 ceramics carbides microstructure layered structures

Sucrose pyrolysis assembling carbon nanotubes on graphite felt using for vanadium redox flow battery positive electrode

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Journal of Energy Chemistry 2018年第2期27卷 451-454页

作者： haitao yang Chuanlin Fan Qingshan Zhu State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sdences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization Kunming 650093 Yunnan China

In the present paper, multi-walled carbon nanotubes（MWCNTs） are successfully assembled on graphite felt（GF） using sucrose pyrolysis method for the first time. The in situ formed pyrolytic carbon is chosen as the binder because it is essentially carbon materials as well as CNTs and GF which has a natural tendency to achieve high bonding strength and low contact resistance. The MWCNTs/GF electrode is demonstrated to increase surface area, reduce polarization, lower charge transfer resistance and improve energy conversion efficiency comparing with GF. This excellent electrochemical performance is mainly ascribed to the high electro-catalytic activity of MWCNTs and increasing surface area.

关键词： Vanadium redox flow batteries Multi-walled carbon nanotubes Sucrose pyrolysis Positive electrode materials Reversibility

High-purity, low-Cl V2O5 via the gaseous hydrolysis of VOCl3 in a fluidized bed

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Particuology 2020年第2期18卷 9-15页

作者： Chuanlin Fan Jie Xu haitao yang Qingshan Zhu State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of Multiphase Complex Systems.Institute of Process Engineering Chinese Academy of SciencesBeijing 100190China

Present-day all-vanadium redox flow batteries(VRFBs)generally require high purity vanadium oxide as a raw *** chlorination procedure presents distinct technical advantages with regard to preparing high purity vanadium pentoxide(V2O5)using vanadium oxytrichloride(VOCl3)as a highly pure *** efficiently prepare high purity V2Os from VOCl3,a single-step fluidized bed chemical vapor deposition(FBCVD)method was explored in the present *** on thermodynamic analyses,the direct and complete conversion of VOCl3 to V2O5 is difficult,and may result in a small amount of residual Cl in the ***,the effects of temperature and the H2O/VOCl3 molar ratio on the quantity of residual Cl were *** Cl concentration was found to decrease with increasing temperature or increasing H2O/VOCl3 molar ***,Cl was determined to be present only in the form of Cl-V bonds,while Cl-H and Cl-Cl bonds were not detected in a V2O5 product made at 200℃with a H2O/VOCl3 molar ratio of 18.A Cl concentration of less than 0.05 wt%was obtained under the optimal synthesis conditions,demonstrating that the FBCVD method is a viable means of preparing high purity V2O5 via the gaseous hydrolysis of VOCl3.

关键词： Chlorination procedure High purity VOCl3 FBCVD High purity V2O5 Gaseous hydrolysis Chlorine

An Improved Deadbeat Predictive Current Control of PMSM Drives Based on the Ultra-local Model

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Chinese Journal of Electrical Engineering 2023年第2期9卷 27-37页

作者： Yongchang Zhang Wenjia Shen haitao yang School of Electrical and Electronic Engineering North China Electric Power UniversityBeijing 102206China School of Electrical and Control Engineering North China University of TechnologyBeijing 100144China

Deadbeat predictive current control(DPCC)has been widely applied in permanent magnet synchronous motor(PMSM)drives due to its fast dynamic response and good steady-state ***,the control accuracy of DPCC is dependent on the machine parameters’*** practical applications,the machine parameters may vary with working conditions due to temperature,saturation,skin effect,and so *** a result,the performance of DPCC may degrade when there are parameter mismatches between the actual value and the one used in the *** solve the problem of parameter dependence for DPCC,this study proposes an improved model-free predictive current control method for PMSM *** accurate model of the PMSM is replaced by a first-order ultra-local *** model is dynamically updated by online estimation of the gain of the input voltage and the other parts describing the system *** obtaining this ultra-local model from the information on the measured stator currents and applied stator voltages in past control periods,the reference voltage value can be calculated based on the principle of DPCC,which is subsequently synthesized by space vector modulation(SVM).This method is compared with conventional DPCC and field-oriented control(FOC),and its superiority is verified by the presented experimental results.

关键词： Deadbeat control current control robustness PMSM drives

Clocking Effect in a Two-Stage Compressor with Different Inter-Blade-Row Gaps

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Journal of Thermal Science 2004年第1期13卷 8-15页

作者： Hongyan Huang haitao yang Guotai Feng Zhongqi Wang Harbin Inst Technol Harbin 150001 Peoples R China

A multi-stage axial compressor has inherently unsteady flow fields because of the following main reasons: (1) relative positions between rotor and stator airfoil; (2) the buildup of converted wakes lead to complex wake/wake and wake/airfoil interactions. The distributions of the potential flows and wakes in the flow passage are depended on the relative positions of blade rows in axial and circumference direction, so variations in the relative axial positions (axial gap) and circumferential positions (clocking effect) of stators or rotors can change these distributions, leading to different compressor efficiency. The current study presents the experimental/numerical result of a low-speed axial compressor, considering the combined effects of stator clocking and variation of axial gaps. Testing was conducted in Two-Stage Axial Compressor Facility in Harbin Institute of Technology. In the test, time averaged data were collected. The results of experimental and time accurate flow calculation for 2 axial gaps, 8 clocking positions for each gap are compared. It is shown that clocking determines the degree of interaction of a stator with the wake of another upstream stator for different gaps between the blade rows.

关键词： clocking compressor gap wake loss.

Failure Patterns and Energy Analysis of Shaft Lining Concrete in Simulated Deep Underground Environments

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Journal of Wuhan University of Technology(Materials Science) 2020年第2期35卷 418-430页

作者： ZHOU Yucheng LIU Juanhong yang haitao JI Hongguang College of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China Beijing Key Laboratory of Urban Underground Space Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of High-efficient Mining and Safety of Metal Mines Ministry of EducationUniversity of Science and Technology BeijingBeijing 100083China

The failure patterns and energy evolution of three types of shaft lining concrete subjected to static and dynamic loading were *** energy and damage characteristics of concrete were determined by means of a uniaxial hydraulic servo machine,acoustic emission (AE) equipment,a split Hopkinson pressure bar (SHPB) and an ultrasonic wave *** experimental results indicate that the confluence of multiple cracks forms a penetrating cross section in normal high-strength concrete (NHSC) under the condition of static loading,while the elastic energy that surges out at failure can cause tremendous damage when subjected to dynamic loading.A single crack was split into multiple propagation directions due to the presence of fibres in steel fibre-reinforced concrete (SFRC);adding fibre to concrete should be an effective way to dissipate *** non-steam-cured reactive powder concrete (NSC-RPC) designed in this paper can store and dissipate more energy than normal concrete,as NSC-RPC exhibits a strong ability to resist *** NSC-RPC to the long-service material of a shaft lining structure in deep underground engineering is quite effective.

关键词： shaft lining concrete failure pattern energy evolution non-steam-cured reactive powder concrete

Microwave dielectric high-entropy ceramic Li(Gd_(0.2)Ho_(0.2)Er_(0.2)Yb_(0.2)Lu_(0.2))GeO_(4) with stable temperature coefficient for low-temperature cofired ceramic technologies

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Journal of Materials Science & Technology 2021年第34期93卷 28-32页

作者： Huaicheng Xiang Lei Yao Junqi Chen Aihong yang haitao yang Liang Fang Shenzhen Key Laboratory of Special Functional Materials Shenzhen Engineering Laboratory for Advanced Technology of CeramicsGuangdong Research Center for Interfacial Engineering of Functional MaterialsCollege of Materials Science and EngineeringShenzhen UniversityShenzhen 518060China Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province.College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060China Guangxi Key Laboratory of Optical and Electronic Materials and Devices College of Materials Science and EngineeringGuilin University of TechnologyCuilin 541004China

High-entropy ceramics are new single-phase materials with at least four cation or anion *** large configurational entropy is believed to enhance the simultaneous solubility of many components,which can be used to optimize certain *** this work,a high-entropy oxide,Li(Gd_(0.2)Ho_(0.2)Er_(0.2)Yb_(0.2)Lu_(0.2))GeO_(4)(LRG)was explored as a microwave dielectric ceramic for lowtemperature cofired ceramic *** LRG high-entropy ceramic with an olivine structure formed in the sintering temperature range of 1020-1100℃.The minimal distortion(5×10^(-4))of the[RO_(6)]octahedron led to a stable temperature coefficient of resonant frequency(τf)of-5.3 to-2.9 ppm/℃.Optimal microwave dielectric properties were achieved in the high-entropy ceramics at 1080℃ for 4 h with a relative density of 94.9%,a relative permittivity(ε_(r))of 7.2,and a quality factor(Q×f)of 29000 GHz(at15.3 GHz).For low-temperature cofired ceramic technology applications,the sintering temperature of the LRG high-entropy ceramic was reduced to 900℃ by the addition of 3 wt%H_(3)BO_(3),which exhibited outstanding microwave dielectric properties(ε_(r)=7.6,Q×f=11700 GHz,and τ_(f)=-7.4 ppm/℃)and a good chemical compatibility with silver.

关键词： High-entropy ceramic Octahedral distortion Microwave dielectric properties Stableτ_(f)

Fabrication of NiO Buffer Layer for YBCO Coated Conductors by Combining Sputtering and SOE Method

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Journal of Rare Earths 2004年第z2期22卷 130-132页

作者： Liu Huizhong yang Jian yang haitao Wang Xiaohua Gu Hongwei Yuan Guansen Superconducting Materials Research Center General Research Institute for Nonferrous MetalBeijing 100088China National Center of Analysis and Testing for Nonferrous Metal and Electronic Materials Beijing 100088China

In research of YBCO coated conductors, the development of a oxide template for epitaxial growth of YBCO is very important. Matsumoto et al have demonstrated the potential of the surface oxidation epitaxial (SOE) route for formation a cube textured NiO layer on nickel tapes. The epitaxial NiO functions as a buffer layer of chemical reaction between YBCO and nickel, and as a template for the epitaxial growth of YBCO. However, the surface quality of NiO is difficult to control and defects such as crack, spall and deep grooves exist in SOE NiO layer. A new approach combining sputtering and SOE method to obtain crack-free and cube textured NiO layer were reported. Ni tapes prepared by the combination of rolling and recrystallization were used for this work. A coating of Ni was first deposited on the tapes via magnetron sputtering. Then on the coating tapes, continuous and textured NiO layer were achieved by SOE technology.

关键词： YBCO coated conductor buffer layers SOE sputtering

POSITIVE SOLUTIONS AND INFINITELY MANY SOLUTIONS FOR A WEAKLY COUPLED SYSTEM

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Acta Mathematica Scientia 2020年第5期40卷 1585-1601页

作者： Xueliang DUAN Gongming WEI haitao yang School of Mathematical Sciences Zhejiang UniversityHangzhou 310027China College of Science University of Shanghai for Science and TechnologyShanghai 200093China

We study a Schrodinger system with the sum of linear and nonlinear *** index theory,we obtain infinitely many solutions for the system with periodic potent ***,by using the concentration compactness met hod,we prove t... 详细信息

关键词： coupled Schrodinger system ground state solution infinitely many solutions concentration compactness principle