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Ultrasonic Frequency Fast-Convert Pulse Plasma Spraying Power Supply Topology

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稀有金属材料与工程 2011年第S4期40卷 297-301页

作者： Zhang Wei1,Qi Bojin1,Xu Haiying21School of Mechanical Engineering and Automation,BeiHang University,beijing 100191,China2beijing Aeronautical Manufacturing technology Research institute,beijing 100024,China BeiHang Univ Sch Mech Engn & Automat Beijing 1000191 Peoples R China beijing Aeronaut Mfg technol Res inst Beijing 100024 Peoples R China

Considering the high DC current and high pulse frequency characteristic of ultrasonic frequency fast-convert pulse plasma spraying process,a special power supply topology was proposed,which was composed of the mutual independent base current circuit and peak current *** current circuit was consisted of four parallel direct current power supplies,which was not only to meet the requirements of high power output,but also improved the reliability of power *** on the Boost circuit topology,a peak current circuit was designed,which could reduce effectively the output inductance influence and output ultrasonic frequency pulse high current with fast-convert rising and falling *** on the above techniques,the Ultrasonic frequency fast-convert pulse plasma spraying power supply was *** can output 5-1000A base current,0-250A peak current,and the pulse current frequency band is 20-100kHz,10%～80% duty ratio and pulse current change rate over 50A/μs.

关键词： Ultrasonic frequency pulse Fast-convert Plasma spraying

Study on Hydrophobic and Mechanical Properties of Fluoro-Carbon Film

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稀有金属材料与工程 2011年第S4期40卷 199-202页

作者： Ma Guojia1,2,Lin Guoqiang2,Sun Gang1,Wu Hongchen1 1Department of Physics and Optoelectronic technology,Dalian University of technology,Dalian 116024,China2National Key Laboratory of Science and technology on Power Beam Processes,beijing Aeronautical Manufacturing technology Research institute,beijing 100024,China beijing Aeronaut Mfg technol Res inst Natl Key Lab Sci & Technol Power Beam Proc Beijing 100024 Peoples R China Dalian Univ technol Dept Phys & Optoelect Technol Dalian 116024 Peoples R China

The purpose of this paper is to investigate the hydrophobic and mechanical behavior of the fluoro-carbon film on the ***-carbon films were fabricated on C/C and C/SiC composite by microwave ECR chemical vapor deposition combined with plasma source ion implantation technology (PSII).The films were investigated in terms of the surface morphology,chemical composition,hydrophobic behavior and mechanical *** hydrophobic property was determined by means of contact angle measurements,chemical bond structure was analyzed by fourier-transform infrared spectrum,and critical loading were measured by *** results showed that the fluorine presented mainly in the forms of CF2 group and C=CFx (x=1,2) in the film,the addition of fluorine to the carbon film had a critical influence on the *** force microscopy (AFM) were used for investigating the effect of surface morphology and roughness on hydrophobicity,it showed that fluoro-carbon films with appropriate surface morphology and roughness could achieve excellent hydrophobicity.

关键词： fluoro-carbon film microwave ECR CVD PSII hydrophobicity.

PLASTIC DEFORMATION BEHAVIOR OF ELECTROFORMED COPPER LINER OF SHAPED CHARGE AT DIFFERENT STRAIN RATES

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Acta Metallurgica Sinica(English Letters) 2003年第1期16卷 72-77页

作者： H.Y.Gao W.H.Tian A.L.Fan Q.Sun Dept. of Mat. Phys. and Chem. Univ. of Sci. and Technol. Beijing Beijing 100083 China 210 inst. Beijing 100081 China

The paper deals with different plastic deformation behavior of electroformed copper liner of shaped charge, deformed at high strain rate (about 1×107s-1) and normal strain rate (4×10-4s-1). The crystallographic orientation distribution of grains in recovered slugs which had undergone high-strain-rate plastic deformation during explosive detonation was investigated by electron backscattering Kikuchi pattern technique. Cellular structures formed by tangled dislocations and sub-grain boundaries consisting of dislocation arrays were detected in the recovered slugs. Some twins and slip dislocations were observed in specimen deformed at normal strain rate. It was found that dynamic recovery and recrystallization take place during high-strain-rate deformation due to the temperature rising, whereas the conventional slip mechanism operates during deformation at normal strain rate.

关键词： electroformation electron backscattering Kikuchi pattern cellular dislocation structure ultra-high-strain-rate deformation dynamic recovery and recrystallization

Failure wave motion of 3D-C/SiC composites subjected to shock compression

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Chinese Science Bulletin 2000年第5期45卷 408-411页

作者： Qingming Zhang Fenglei Huang Liming Han beijing inst technol State Key Lab Prevent & Control Explos Disasters Beijing 100081 Peoples R China

The response and failure behavior of 3D-C/S軨 composites subjected to shock compression have been experimentally studied. With the help of a one-stage light gas gun, the 3D-C/SiC composite samples, which are subjected to the plane shock compression by LY-12 aluminum flyer sheets with different speeds become available. Based on the analysis of observation for the curve of pressure vs time, which has been measured from the tests as well as from the samples, it is found that when the shock speed is larger than a critical value, the material of 3D-C/SIC will be comminuted and the failure surface will move from the shock plane to its inward direction in the waveform.

关键词： failure wave comminution 3D-fabric reinforced composite ceramic matrix composite.

Effect of Annealing on Mechanical Properties of TaN Film

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稀有金属材料与工程 2011年第S4期40卷 218-220页

作者： Liu Xing1,2,Ma Guojia1,2,Sun Gang2,Duan Yuping1,Liu Shunhua11School of Material and Engineering,Dalian University of technology,Dalian 116024,China2 Science and technology on Power Beam Processes Laboratory,beijing Aeronautical Manufacturing technology Research institute,beijing 100024,China beijing Aeronaut Mfg technol Res inst Sci & Technol Power Beam Proc Lab Beijing 100024 Peoples R China Dalian Univ technol Sch Mat & Engn Dalian 116024 Peoples R China

Tantalum nitride (TaN) films were synthesized on bearing steels and Silicon wafers by Electron Cyclotron Resonance microwave plasma source enhanced DC sputtering and the effects of annealing at different temperature on mechanical properties of TaN films were *** morphology and structure of the films were investigated by scanning electron microscope (SEM),X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS).The mechanical properties were evaluated using *** results showed that the hardness and modulus of TaN film without annealing presented the maximal value,but which intensely dropped down with the increase of annealing temperature between 423K and 473K,meanwhile structure and combination in the films partially changed,but this phenomenon disappeared beyond the *** is found that annealing is a key factor for altering structure and mechanical properties of TaN film.

关键词： magnetron sputtering TaN film annealing

Leakage in Mold Slit during Inverse Solidification

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Journal of University of Science and technology beijing 2001年第2期8卷 101-104页

作者： Zhang, JM Wang, XH Wang, WJ Univ Sci & technol beijing Met Sch Beijing 100083 Peoples R China

The liquid steel will be leaked from the slit between the bottom of solidification mold and mother sheet during inversion casting process. By substitution of the actual liquid steel, the Ph-Sn alloy and the numerical simulation can be used to study the fluid flow in the inversion solidification mold, the mother sheet critical speed is determined for preventing the leakage from the slit of bottom. When the mother sheet speed is more than 0.06 m/s, Pb-Sn liquid alloy will not leak from the slit of the mold. Otherwise, the Ph-Sn liquid alloy can leak from the slit of the mold.

关键词： leakage slit inverse solidification mold

A metric normalization of tree edit distance

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Frontiers of Computer Science 2011年第1期5卷 119-125页

作者： Yujian Li (1) liyujian@*** Zhang Chenguang (12) beijing Univ technol Coll Comp Sci & Technol Beijing 100124 Peoples R China Hainan Univ Coll Informat Sci & Technol Haikou 570228 Peoples R China

Traditional normalized tree edit distances do not satisfy the triangle inequality. We present a metric normalization method for tree edit distance, which results in a new normalized tree edit distance fulfilling the triangle inequality, under the condition that the weight function is a metric over the set of elementary edit operations with all costs of insertions/deletions having the same weight. We prove that the new distance, in the range [0, 1], is a genuine metric as a simple function of the sizes of two ordered labeled trees and the tree edit distance between them, which can be directly computed through tree edit distance with the same complexity. Based on an efficient algorithm to represent digits as ordered labeled trees, we show that the normalized tree edit metric can provide slightly better results than other existing methods in handwritten digit recognition experiments using the approximating and eliminating search algorithm （AESA） algorithm.

关键词： metric normalization tree edit distance,triangle inequality approximating and eliminating searchalgorithm (AESA)

Study on Transformation of CaO-Al_2O_3-SiO_2-MgO System Inclusions in ZG06Cr13Ni4Mo Stainless Steel

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Journal of Iron and Steel Research International 2011年第S2期18卷 341-346页

作者： LIU Jian-hui1,3, DONG Han1,3, ZHU Rong2, LI Shi-qi2 (1. institute for Structural Materials,Central Iron and Steel Research institute, beijing 100081,China 2. School of Metallurgical and Ecological Engineering,University of Science and technology beijing, beijing 100083,China 3. National Engineering Research Center of Advanced Steel technology, beijing 100081,China) Cent Iron & Steel Res inst Inst Struct Mat Beijing 100081 Peoples R China Univ Sci & technol beijing Sch Met & Ecol Engn Beijing 100083 Peoples R China Natl Engn Res Ctr Adv Steel technol Beijing 100081 Peoples R China

This paper aims at generally studying on the inclusions of ZGG06Cr13Ni4Mo ultra-low carbon stainless steel used for large scale hydraulic turbine sets. On the basis of analysis the industrial test samples, thermodynamic software FactSage is used to study inclusions transformation process in CaO-SiO2-Al2O3-MgO system while stainless steel is been smelting. The results illustrate the inclusions melting points and plasticity variation law. The reasonable inclusions plasticity controlling area is found out in low melting point. The melting point is up to 1280℃ While MgO weight concentration is 10% in CaO-SiO2-Al2O3-MgO system, SiO2, Al2O3 and CaO in inclusions are in weight concentration range of 50-70%, 10-20% and 10-40%, respectively. For purpose of gaining low melting point inclusions, silicon alumina radio in deoxidant should be controlled between 2-5 for ultra-low carbon stainless steel refining in industry.

关键词： ZG06Cr13Ni4Mo stainless steel low melting point inclusion thermodynamic calculation

The Dissymmetry of Friction Stir Welding Joints and Va-riable Polarity Plasma Arc Welding Joints Study

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稀有金属材料与工程 2011年第S4期40卷 84-89页

作者： Chen Shujun,Wang Long,Yu Yang beijing University of technology Mechanical Engineering,beijing100022,China beijing Univ technol Mech Engn Beijing 100022 Peoples R China

2219 aluminum alloys welding joints were prepared by Friction stir welding (FSW) and Variable polarity plasma arc welding (VPPAW).The microstructure of joints was characterized by means of OM,SEM,and *** measurements was performed to differentiate the joint zones and to evaluate the symmetry level of the joints with the help of nano-indentation *** dissymmetry of microstructure and mechanical properties was found both in FSW joint and VPPAW *** dissymmetry in FSW joint can not be suppressed due to the nature of the mixing head,but the symmetry and satisfactory welding joint can be obtained by changing the working pattern of VPPAW.

关键词： FSW VPPAW nano-indentation experiment "Half-leaf" zone dissymmetry