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research on Ultrasonic Vibration Grinding of the Hard and Brittle materials

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Chinese Journal of Aeronautics 2006年第B12期19卷 9-13页

作者： YANG Xin-hong HAN Jie-cai ZHANG Yu-min ZUO Hong-bo ZHANG Xue-jun research station on material science and engineering for postdoctoral fellows Harbin Institute of Technology Harbin 150001 China Centre for Composite materials Harbin Institute of Technology Harbin 150001 China

It is well known that grinding techniques are main methods to machine hard and brittle materials such as engineering ceramics. But the conventional grinding has many shortcomings such as poorer surface finish, quicker wear and tear of grinding tools, lower efficiency and so on. Ultrasonic vibration grinding （UVG） which combines ultrasonic machining and grinding emerged as a developing and promising technique in recent years. In this paper, experimental studies on UVG were conducted on several kinds of hard and brittle material by altering processing parameters such as vibration frequency and its amplitude, diamond abrasive grit size, cutting depth, feeding speed and rotary speed of tools. The experimental results show that alteration in any of above mentioned parameters will bring effects on the processed surface finish of these materials. Of them, the diamond abrasive grit size has the greatest. Moreover, conventional grinding experiments were also carried out on these materials. By comparison, it was found that the UVG is superior to the conventional method in terms of the ground surface quality, the working efficiency and the wear rate of tools.

关键词： ultrasonic vibration grinding (UVG) hard and brittle materials surface roughness wear extent

Preparation and Characterization of La_(0.8)Sr_(0.2)MnO_(3-δ) Cathode for SOFCs Fabricated Using Azeotropic Distillation Method

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Journal of Rare Earths 2006年第z2期24卷 93-97页

作者：朴金花孙克宁张乃庆徐莘周德瑞 Department of Applied Chemistry Harbin Institute of Technology research station on material science and engineering for Postoral fellows Harbin Institute of TechnologyHarbin 150001China

Strontium doped lanthanum manganite (LSM) powders were synthesized by three different routes: azeotropie distillation, sol-gel and solid state reaction respectively. The LSM samples, made by azeotropic distillation and sol-gel methods were prepared by firing at 1000℃for 6 h, and the LSM sample, made by solid state reaction method was produced by sintering at 1400℃for 18 h. The samples were characterized by XRD, TEC, SEM, EIS and polarization performance analysis. The results show that all the samples made by different methods have pure orthorhombic LSM phase, however exhibit different micro structure and electrochemical characterization, which relates to the different synthesis methods. The solid state reaction method produces the samples with larger particle size compared with azeotropic distillation and sol-gel methods. The powders made by azeotropic distillation method have less agglomerated particles compared with that made by sol-gel method because the precursor in the former is dispersed in n-butanol before sintering. The polarization current density of powder made by azeotropic distillation method was twice of that made by sol-gel method and four times of that made by solid state reaction method. The values of polarization resistance (Rp) are 0.35Ω·cm for the cathode synthesized by azeotropic distillation route, which is much lower than sol-gel (1.5Ω·cm2) and solid state reaction (2.3Ω·cm2) at 800℃.

关键词： cathode azeotropic distillation solid oxide fuel cell rare earths

Mechanical Properties of Two Kinds of New Cold-Formed Flange-Closed Welding Section Members

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沈阳建筑大学学报（自然科学版） 2011年第6期27卷 1021-1032页

作者：武胜 College of Civil engineering Northeast Forestry University Workstation for postdoctoral fellows of Heilongjiang Construction engineering Group research station on Civil engineering for postdoctoral fellows of Harbin Institute of Technology

The hollow flange beam(HFB) is a unique cold-formed steel section developed in Australia for use as a flexural ***′s a particular cross section with two torsion rigid closed triangular flanges and a comparatively flexible web,and it is a type of high efficient cross *** paper presents two kinds of new cold-formed flange-closed welding sections named HF1 and HF2 according to different section component and parameters of *** finite element method has been adopted to investigate the mechanical properties such as buckling mode,deformation process,rigidity,ductility and correlation curve of two kinds of new section members which being subjected to axial compression,flexure,combined compression and *** comparisons of the consumed steel quantities of per unit load carrying capacity between new section members and the same section dimensions of cold-formed C-section members have been carried *** conclusions can be drawn from above work that the new sections have some superior properties including higher load carrying capacity and section modulus,sufficient section stiffness,and difficult occurrence for the sub element local *** new sections are suitable for bearing flexure,compression,combined compression and *** new sections′ consumed steel quantities of per unit load carrying capacity are almost half as those of the same dimension C-section members′.The experimental investigation is carried out further on the new cold-formed flange-closed welding section members and can be used in the practical engineering.

关键词： hollow flange beam cold-formed steel members finite element analysis mechanical properties

Study on the influences of ionization region material arrangement on Hall thruster channel discharge characteristics

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Plasma science and Technology 2018年第2期20卷 47-55页

作者：胡翔段萍宋继磊李文庆陈龙边兴宇 College of science Dalian Maritime University Transportation engineering postdoctoral research station Dalian Maritime University

There exists strong interaction between the plasma and channel wall in the Hall thruster,which greatly affects the discharge performance of the *** this paper,a two-dimensional physical model is established based on the actual size of an Aton P70 Hall thruster discharge *** particle-in-cell simulation method is applied to study the influences of segmented low emissive graphite electrode biased with anode voltage on the discharge characteristics of the Hall thruster *** influences of segmented electrode placed at the ionization region on electric potential,ion number density,electron temperature,ionization rate,discharge current and specific impulse are *** results show that,when segmented electrode is placed at the ionization region,the axial length of the acceleration region is shortened,the equipotential lines tend to be vertical with wall at the acceleration region,thus radial velocity of ions is reduced along with the wall *** axial position of the maximal electron temperature moves towards the exit with the expansion of ionization ***,the electron-wall collision frequency and ionization rate also increase,the discharge current decreases and the specific impulse of the Hall thruster is slightly enhanced.

关键词： Hall thruster segmented electrode particle-in-cell wall material

Structure and Electrochemical Properties of LiMgxMn2-xO)4 Cathode materials for Li-Ion Batteries

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Journal of Rare Earths 2006年第S2期 147-150页

作者：戴长松霍慧彬王殿龙王福平 The research station on material science and engineering for postdoctoral fellows Harbin Institute of Technology Department of Applied Chemistry Harbin Institute of Technology

The magnesium-substituted spinel LiMgxMn2-xO4 (x=0, 0.05, 0.1, 0.2) materials were prepared by adipic acid-assisted sol-gel method at 800 ℃ for 12 h in air. The synthesized spinel materials were examined by X-ray diffraction (XRD), scanning electron microscope (SEM), galvanostatic charge-discharge test and cyclic voltammetry (CV). XRD and SEM show that all samples exhibit the same pure spinel phase and good crystal structure. Charge-discharge test indicates that the initial capacity of LiMn2O4, LiMg0.05Mn1.95O4, LiMg0.1Mn1.9O4 and LiMg02Mn1.8O4 is 123.3, 120.4, 116.8 and 114.4 mAh·g-1, respectively. After 50 cycles, its capacity retention is 86.5%, 90.6%, 92.2% and 93.5%, respectively. CV reveals that the reversibility of LiMgxMn2-xO4 increases with increasing of magnesium content.

关键词： lithium ion battery cathode material LiMgxMn2-xO4 structure electrochemical properties

Activated nitrogen-enriched carbon/carbon aerogel nanocomposites for supercapacitor applications

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中国有色金属学会会刊：英文版 2009年第S3期19卷 738-742页

作者：秦川丽卢幸尹鸽平白续铎金政 research station on material science and engineering for Postoral fellows School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China Key Laboratory of Functional Polymer materials School of Chemistry and Material SciencesHeilongjiang UniversityHarbin150080China

Activated nitrogen-enriched carbon/carbon aerogel nanocomposites (ANC/ACA) were prepared by synthesis of melamine resin/carbon aerogel composites, carbonization and KOH activation. Novel asymmetric supercapacitors consisting of Ni(OH)2/Co(OH)2 as anode and ANC/ACA with different composite ratios as cathode were assembled. The influence of composite ratio on electrochemical performances of materials was detected by cycle voltammetry (CV) and galvanostatic charge/discharge methods. The results of XPS and SEM show that N atoms exist in the ANC/ACA and ANC/ACA shows nanometer and honeycomb structure with more pores. When the composite ratio of ANC/ACA is 12-1, the ANC/ACA shows the highest Cp1 (312.8 F/g) vs 103.4 F/g of ACA and 230.1 F/g of ANC. And the optimal asymmetric supercapacitor with the ANC/ACA as cathode also shows the best electrochemical performances. The optimal supercapacitor is stable over 100 cycles. When the current density is 50 mA/cm2, the Cp2, Ep and P of the optimal supercapacitor are still 57.3 F/g, 9.0 W·h/g and 1 302.1W/kg, respectively.

关键词： supercapacitor melamine carbon aerogels nanocomposites nitrogen

Electrochemical properties of La_(0.8)Sr_(0.2)FeO_(3-δ) based composite cathode for intermediate temperature SOFC

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Rare Metals 2006年第z1期25卷 390-392页

作者： ZHANG Naiqing SUN Kening JIA Dechang ZHOU Derui The research station on material science and engineering for Postoral fellows Harbin Institute of Technology Harbin 150001 China Department of Applied Chemistry Harbin Institute of Technology Harbin 150001 China Department of Applied Chemistry Harbin Institute of Technology Harbin 150001 China The Research Station on Material Science and Engineering for Postoral Fellows Harbin Institute of Technology Harbin 150001 China Department of Applied Chemistry Harbin Institute of Technology Harbin 150001 China

La0.8Sr0.2FeO3-δ is a new kind of cathode material for intermediate SOFC, but its electrochemical activity is relative poor for the lanthanum gallate based solid oxide fuel cell. In this paper, a novel composite cathode of La0.8Sr0.2FeO3-δ/La0.9Sr0.1Ga0.8Mg0.2O3-δ was prepared on the LSGM electrolyte substrate by screen-printing method. The results of cathodic polarization measurements show that the overpotential decreases significantly when the composite cathode is used instead of the La0.8Sr0.2FeO3-δ single layer cathode. The cathodic overpotential of the composite La0.8Sr0.2FeO3-δ/La0.9Sr0.1Ga0.8Mg0.2O3-δ cathode is 150 mV at the current density of 0.2 A·cm-2 at 800 ℃, while the cathodic overpotential of the La0.8Sr0.2FeO3-δ single layer cathode is higher than 260 mV at the same condition. The electrochemical impedance spectroscopy was employed to investigate the polarization resistance of the cathode. The polarization resistance of the composite cathode is 1.20 Ω·cm2 in open circuit condition, while the value of the single La0.8Sr0.2FeO3-δ cathode is 1.235 Ω·cm2.

关键词： solid oxide fuel cell lanthanum gallate La0.8Sr0.2FeO3-δ composite cathode

Electrochemical performance of nano-scale β-Ni(OH)_2 prepared at different transformations of pH value

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Journal of Harbin Institute of Technology(New Series) 2008年第2期15卷 160-163页

作者：赵力张利军韩喜江张翠芬 postdoctoral station of material science and engineering Harbin Institute of Technology postdoctoral Work station Jiangsu Shuangdeng Group Co.LtdJiangyan 225526China Dept of Applied Chemistry Harbin Institute of Technology

The influence of transforming pH values on the electrochemical performance of nano-scale Ni （OH）2 was analyzed. The measurement results of XRD indicate that the nano-scale Ni （OH） 2 prepared at different transformations of pH value is β （ Ⅱ ）-phase with different crystal lattice parameters. Cyclic voltammograms （CV） and electrochemical impedance spectroscopy（EIS） measurement results show that transformations of pH value affect the proton diffusion coefficient （D） and charge-transfer resistance （Re,） of the material. The simulation *** experiment shows that the sample prepared at a pH of 10. 1 exhibits the maximum specific capacity （327.8 mAh/g） and higher discharge platform, the discharge performance of electrodes depends on both D and Rct, so the kinetics characteristics that electrodes reaction is controlled by both mass-transfer step and charge- transfer step are put forward.

关键词： nano-material Ni(OH)2 electrochemical transformations of pH value

Manufacturing Microporous Foam Zinc materials with High Porosity By Electrodeposition

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Journal of Wuhan University of Technology(materials science) 2011年第5期26卷 843-846页

作者：田庆华 School of Metallurgical science & engineering Central South University postdoctoral Ambulatory station of Metallurgical engineering Central South University

In order to get foam zinc materials of porous metal electrode,a novel method for preparing foam zinc was proposed,in which the polyurethane foam with diameter of 0.3 mm as substrate was processed by degreasing,roughening,activating,electroless plating and *** main factors affecting the process,such as ZnSO4 content,temperature,pH value,current density,and electrodes distance,were investigated *** optimal process conditions are 250 g/L ZnSO4,20 g/L Al2（SO4）3,40 g/L KAl（SO4）2,30 g/L Na2SO4,pH=3.5,4.0 cm of electrodes distance and 0.04 A/cm2 current density at 30 ℃.The result shows that adding ultrasonic on the process can elevate the deepening plating ability and current *** zinc material with a high porosity of 92.2% and a three-dimensional network structure can be fabricated by electrodeposition.

关键词： electrodeposition foam zinc microporous high porosity