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Preparation and properties of W–Cu–Zn alloy with low W–W contiguity

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Rare Metals 2016年第3期35卷 242-248页

作者： Ling-Ling Zheng Jin-xu liu Shu-Kui Li Shuang liu Qing-He Zou Xing-Wang Cheng School of Materials Science and Engineering Beijing Institute of Technology Mudanjiang North Alloy Tool Co. Ltd

The W–Cu–Zn alloy with a-brass matrix and low W–W contiguity was prepared by method of electroless copper plating combined with spark plasma sintering（SPS） *** effects of process and parameters on the microstructure and mechanical properties of the alloy were *** W–Cu–Zn alloy with a relative density of 96 % and a W–W contiguity of about 10 % was prepared by original fine tungsten particles combined with wet mixing method and SPS solid-state sintering method at 800℃ for 10 *** microstructure analysis shows that Cu–Zn matrix consists of nano-sized a-brass grains,and the main composition is Cu3Zn *** nano-sized Cu was coated on the surface of tungsten particles by electroless copper plating method,and the fairly low consolidation temperature and short solid-state sintering time result in the nano-sized matrix *** dynamic compressive strength of the W–Cu–Zn alloy achieves to1000 MPa,but the alloy shows poor ductility due to the formation of the hard and brittle Cu3Zn *** fine-grain strengthening and the solution strengthening of the Cu–Zn matrix phase are responsible for the high Vickers microhardness of about 300 MPa for W–Cu–Zn alloy.

关键词： W–Cu–Zn alloy Spark plasma sintering Microstructure Mechanical properties Microhardness

The template preparation and characterization of three new shapes of titania nanometer-array systems

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Chinese Science Bulletin 2006年第12期51卷 1515-1520页

作者： TIAN Yuming xu Mingxia liu Xiangzhi GE Lei School of Materials Science and Engineering Key Laboratory for Ad- vanced Ceramics and Machining Technology of Ministry of Education Tianjin University Tianjin 300072 China

A two-step anodization process was used to prepare highly ordered porous anodic alu- mina template (PAA). The template method was combined with the sol-electrophoresis deposition and sol-gel method to synthesize three types of nano- meter-array systems. The titania nano-arrays have a high specific surface area. The sol-gel template method was also applied to prepare the rod-shaped titania nanowire-arrays. The diameter of titania nanometer-array is about 50 nm; the length is about 20 μm; and the distance of neighboring two nanowires is about 100 nm. Through controlling the pore depth of the template, the membrane with peri- odical modulating titania nanodots was prepared. The diameter of the nanodots on the membrane surface was about 75 nm and the dot distance was about 100 nm. Also a compact structure has been found on the back face of the membrane. The sol-electrophoresis template method was used to prepare the nanowire-array system with the shape of string of candied haws. The diameter of nanowires was about 75 nm and the length was about 20 μm. The periodic concave-convex structures were found in each nanowire and the shape looked like string of candied haws. The three types of nano-array systems have a high specific surface area. It can be predicted that this type of surface modulating array system will have new properties and effects that are different from those of common membranes, nanodots and nanowires.

关键词：二氧化钛模板制备纳米排列溶胶-电泳溶胶-凝胶

Low Temperature Reduction Degradation Characteristics of Sinter,Pellet and Lump Ore

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Journal of Iron and Steel Research International 2011年第8期18卷 20-24页

作者： WU Sheng-li liu Xiao-qin ZHOU Qi xu Jian liu Cheng-song School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China

The reduction degradation characteristics of typical sinter, pellet and lump ore were tested with the reducing gas conditions simulating two kinds of irowmaking processes. The results show that, in the same condition of gas composition and temperature, the reduction degradation degree （RDI〈3.15mm） of sinter is high, RDI〈3.15mm of lump ore is low and RDI〈3.15 mm of pellet is in the middle level. With two kinds of gas composition simulating different iron-making processes, the reduction degradation indices （RDI） of three kinds of iron ores all present the tenden- cy of ＂inverted V-shape＂ in the temperature range from 450 to 650℃, and the RDI reach the maximum value at 550℃. The reduction degradation degrees of iron ores are extended when mixing the gas with hydrogen to increase the re duction potential, and the influence extent is discrepant for different iron ores. Colligating the increase amplitude of grains in small size fraction, the influence of reducing gas on lump ore is the greatest, the influence on sinter is the second, and the sensitivity of pellet on the reducing gas properties change is relatively small. As for the degradation form, lump ore and sinter both present the degradation ,of cracking, and the distribution of small grains generated from the cracking is in the range from 03 5 to 6. 3 mm uniformly. The lump ore presents surface cracking, while sin- ter presents integral cracking. The pellet presents the degradation of surface stripping, and the proportion of grains smaller than 0.5 mm is the highest, which is up to 90% in the grains smaller than 3.15 mm.

关键词： sinter pellet lump ore low temperature reduction degradation characteristic gas property

Porous epoxy thermosets obtained by a reaction-induced process and their characterizations

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Chinese Chemical Letters 2008年第11期19卷 1312-1314页

作者： Hao Ai Kai xu Huan liu Ming Cai Chen Key Laboratory of Palymer Materials for Electronics Guangzhou Institute of Chemistry Chinese Academy of Sciences P.O. Box 1122 Guangzhou 510650 China

A novel reaction-induced method with the aid of solvent for porous thermosetting epoxy was first carried out. Investigations of pore structure using scanning electron microscope （SEM） showed that porous epoxy networks with average pore size ranging from 3 to 20 μm were obtained. The pore structure generated by this method can be tailored by changing the solvent content.

关键词： Porous Rcaction-induced Epoxy Polymerization

Lepton-Flavor Violating Processes li → ljγ in Topcolor-Assisted Technicolor Models

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Communications in Theoretical Physics 2002年第10期38卷 461-464页

作者： YUE Chong-Xing xu Qing-Jun liu Guo-Li CCAST World Laboratory P.O. Box 8730 Beijing 100080 China College of Physics and Information Engineering Henan Normal University Xinxiang 453002 China College of Physics and Information Engineering Henan Normal University Xinxiang 453002 China College of Physics and Information Engineering Henan Normal University Xinxiang 453002 China

We consider the lepton-flavor violating (LFV) processes li → ljγ in the framework of topcolor-assistedtechnicolor (TC2) models. We find that the new gauge boson Z' predicted by TC2 models can give significantlycontributions to these processes via the flavor-changing couplings Z'lilj. The present experimental bound on the LFVprocess μ→ eγ gives severe constraints on the TC2 models. Using other experimental constraints on the Z' mass Mz,we obtain constraints on the lepton mixing factors KTμ and KTe. The future LFV experiments will probe into TC2models.

关键词： lepton flavor, topcolor-assisted technicolor (TC2)

Computer Simulation of Microstructure Evolution of 82B Rod at Different Cooling Rates

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Journal of Iron and Steel Research International 2008年第2期15卷 56-59,64页

作者： xu Jin-qiao liu Ya-zheng ZHOU Shu-mei Materials Science and Engineering School University of Science and Technology Beijing Beijing 100083 China

According to thermodynamics and kinetics of phase transformation,a mathematical model of phase transformation was proposed,and the microstructure evolution of an 82B rod at different cooling rates was simulated by using the FEM software Marc/Mentat,based on the measurement of time-temperature transformation（TTT）curves of the 82B *** simulated results were in good agreement with the actual *** the results of computer simulation it was found that the cooling rate of the 82B rod,after laying,should be controlled within 5-8 ℃/*** the microstructure of rod there were over 95% of pearlite volume fraction and a small quantity of dispersive martensite（less than 5%）.

关键词： computer simulation microstructure evolution controlled cooling 82B rod

First-principles investigation of the effects of B impurities on the mechanical properties of NiAl intermetallics

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Science China(Physics,Mechanics & Astronomy) 2011年第5期54卷 809-814页

作者： HU xueLan liu xu xu Zhou LIANG JiaChang WANG TianMin Sino-European Institute of Aviation Engineering Civil Aviation University of China Tianjin 300300 China Pyrology Subsidiary Company Tianjin Cement Industry Design & Research Institute Tianjin 300400 China College of Science Civil Aviation University of China Tianjin 300300 China Department of Physics Beijing University of Aeronautics and Astronautics Beijing 100191 China

We have investigated the effects of B impurities on the structure and mechanical properties of NiA1 intermetallics by using a first-principles pseudopotential total-energy method, based on the density functional theory with a generalized gradient approximation. We found that the impurity B atoms can either replace Ni atoms or Al atoms or both, depending on the surround- ing environment. We demonstrated that the presence of B will cause an increase in brittleness and a decrease in the ductility of NiAI for the Al-substitutional case, while causing an increase in the ductility of NiAl for the Ni-subtitutional case, based on the calculated elastic constants and the empirical criterions. This indicates that the effects of B impurities on the mechanical prop- erties of NiAl intermetallics are quite composition-dependent.

关键词： NiAl intermetallics B impurity mechanical first-principles

A Coupled Cavitation Model in an Oscillatory Oil Squeeze Film

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Computer Modeling in Engineering & Sciences 2020年第4期123卷 129-152页

作者： xu liu Xiaoyang Chen Rongyu Kang xuejin Shen Ben Ni Shanghai University Shanghai200072China Ford Motor Company DearbornMI 48126USA

In this paper,the oscillatory oil squeeze film is taken as a research object,and a coupled cavitation model based on the theory of bubble dynamics and hydrodynamic lubrication is used and a specific method of numerical calculation is *** the parallel-plate squeeze film test apparatus is used to validate the coupled cavitation *** pictures of the cavitation were captured by a high-speed camera and then processed to obtain the variation of the cavitation area in *** with the experimental results,the model can successfully predict the process of generation and development of *** the same time,the pressure variation calculated by the model is in good agreement with the experimental data and the value of negative pressure is close to the *** this basis,three new parameters that are related to bubble dynamics are studied by comparing the pressure and cavitation area variation in an oscillating squeeze oil *** results show that surface dilatational viscosity,initial radii of cavitation nuclei and number of bubbles per unit area have a significant influence on the generation time of the cavitation,the maximum tensile stress that the oil film can withstand,and the speed of the cavitation collapse respectively.

关键词： Bubble dynamics oscillatory oil squeeze film cavitation

A Characterization of Multidimensional Multi-knot Piecewise Linear Spectral Sequence and Its Applications

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Acta Mathematica Sinica,English Series 2013年第9期29卷 1679-1690页

作者： Xiao Na CUI xu liu Rui WANG Dun Yan YAN School of Mathematical Sciences University of Chinese Academy of Sciences School of Applied Mathematics Jilin University of Finance and Economics School of Mathematics Jilin University

We characterize a class of piecewise linear spectral sequences. Associated with the spectral sequence, we construct an orthonormal exponential bases for L2（[0,1）d）, which are called generalized Fourier bases. Moreo... 详细信息

关键词： Spectral sequences orthonormal exponential bases convergence analysis Bochner-Riesz means