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Crystallization behavior of Zr_(52) Cu_(18) Ni_(15) Al_(10) Ti_5 bulk glass with quenched-in crystals

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中国有色金属学会会刊：英文版 2000年第3期10卷 345-348页

作者： BIAN Zhan(边赞), HE Guo(何国), CHEN Guo liang(陈国良) State key laboratory of advanced Metals and materials, university of science and Technology beijing, beijing 100083, P.R.china Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China

Zr 52 Cu 18 Ni 15 Al 10 Ti 5 bulk glass samples with a diameter of 8 mm prepared by copper mold with water cooling have a mixing structure of amorphous phase and quenched in crystals. By isothermal annealing at different temperatures, the crystallization process of the glass alloy is shown to be a multi staged crystallization reaction as follows: Am+quenched in crystals→Am′+cellular phase+(Zr, Ti) Al→Am′+cellular phase+(Zr, Ti) Al+(Zr, Ti) 2(Cu, Ni). Morphology of the quenched in crystals changes from dot or dendritic phase in the as cast bulk glass to cellular phase at different annealing states. The residual region surrounded by the cellular phase has a mixing structure of nano scale phase and amorphous phase.

关键词： bulk glass quenched in crystals crystallization nano scale phases

Experimental study on drying of typical MSW under incinerator-like conditions

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science china(Technological sciences) 2007年第5期50卷 636-643页

作者： ZHANG YanGuo1, CHEN MeiQian2, MENG AiHong1, LI QingHai1 & CHEN YunXuan2 1 key laboratory for Thermal science and Power engineering of ministry of education, tsinghua university, beijing 100084, china 2 School of Mechanical, Electronical and Control engineering, beijing Jiaotong university, beijing 100044, china 1. key laboratory for Thermal science and Power engineering of ministry of education Tsinghua University Beijing 100084 China 2. School of Mechanical Electronical and Control Engineering Beijing Jiaotong University Beijing 100044 China

In this paper, a series of experiments were conducted to investigate the drying of typical municipal solid wastes (MSW) in a muffle incinerator. From the experimental drying characteristic curves, the effects of temperature on drying process were observed to be more obvious in the low temperature region than in the high tem- perature region in muffle incinerator. At a specified drying temperature, drying time was highly dependent upon the packed waste thickness, having an exponent rela- tion with the thickness. When the drying temperature increased or the thickness of potato bulks was diminished, the maximum drying rate reduced. Based on the first-order reaction, activation energy (Ea), and factor A of potato and cabbage were determined.

关键词： drying, MSW, potato blocks, cabbage stems, temperature, dying rate

Role of C and Fe in Grain Refinement of an AZ63B Magnesium Alloy by Al-C Master Alloy

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Journal of materials science & Technology 2005年第6期21卷 822-826页

作者： Yichuan PAN+, Xiangfa LIU and Hua YANG key laboratory of Liquid Structure and Heredity of materials, ministry of education, Shandong university,Jinan 250061, china key laboratory of Liquid Structure and Heredity of materials Shandong University Jinan 250061 China

In this study, grain refining effect of Al-1.5℃ master alloy was examined on an AZ63B magnesium alloy, and the refining mechanism was studied through investigating the role of C and Fe in this process. The results show that addition of Al-1.5℃ master alloy leads to significant decrease of the mean grain size from about 270μm to 50μm at the center of the AZ63 alloy ingot. Grain refinement by carbon addition is mainly due to the heterogeneity nucleation on the Al-, C-, O-, Fe- and Mn-rich particles, but not constitutional undercooling caused by the carbon solute element. Fe plays an important role in the formation of the nucleating particles, but not acts as an inhibiting element.

关键词： Grain refinement AZ63B Magnesium Al-C master alloy Nucleating particle

Mechanism of High Temperature Deformation in Cast Ti46Al8.5Nb0.2W Alloy

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Journal of university of science and Technology beijing 2001年第4期8卷 290-294页

作者： Zicheng Liu, Junpin Lin, Yanli Wang, Zhi Lin, Guoliang Chen State key laboratory for advanced Metals and materials, university of science and Technology beijing, beijing 100083, china Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China

Compression tests A ere conducted in the two phase Ti46Al8.5Nb0.2W alloy with a cast microstructure under the strain rates ranging from 2x10(-5) s(-1) to 10(-2) s(-1) at temperatures ranging front 900degreesC to 1100degreesC. It was found that there exist approximately linear relationships between the flow stress and the logarithm of strain rate at different temperatures. The strain rate dependence was analzed by the thermal activation theory and dislocation climbing is regarded as the controlling mechanism during high temperature compression tests.

关键词： Ti46%Al8.5%Nb0.2%W high temperature compression strain rate dislocation climbing

Lightning electromagnetic field generated by grounding electrode considering soil ionization

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Progress in Natural science:materials International 2006年第9期16卷 1002-1006页

作者： ZENG Rong , HE Jinliang, ZHANG Bo and GAO Yanqing (State key laboratory of Power Systems, department of Electrical engineering, tsinghua university, beijing 100084, china) State key laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing 100084 China

A circuit model with lumped time-variable parameter is proposed to calculate the transient characteristic of grounding electrode under lightning current, which takes into consideration the dynamic and nonlinear effect of soil ionization around the grounding electrode. The ionization phenomena in the soil are simulated by means of time-variable parameters under appropriate conditions. The generated electromagnetic field in the air is analyzed by using electrical dipole theory and image theory when the lightning current flows into the grounding electrode. The influence of soil ionization on the electromagnetic field is investigated.

关键词： electromagnetic field grounding electrode soil ionization transient characteristic.

Effects of Surface-Active Elements Sulfur on Flow Patterns of Welding Pool

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Journal of materials science & Technology 2005年第3期21卷 408-414页

作者： Yuzhen ZHAO, Yongping LEI and Yaowu SHI School of materials science and engineering, beijing university of Technology, beijing 100022, china School of materials science and engineering Beijing University of Technology Beijing 100022 China

A 3D mathematical model is developed to calculate the temperature and velocity distributions in a moving gas tungsten arc (GTA) welding pool with different sulfur concentrations. It has been shown that, the weld penetration increases sharply with increasing sulfur content. When sulfur content increases beyond 80 × 10-6, the increase in sulfur content does not have an appreciable difference on the welding pool size and shape, and the depth/width remains constant. Sulfur changes the temperature dependence of surface tension coefficient from a negative value to a positive value and causes significant changes on flow patterns. The increase in soluble sulfur content and the decrease at free surface temperature can extend the region of positive surface tension coefficient. As sulfur content exceeds 125×10-6, the sign of surface tension coefficient is positive. Depending upon the sulfur concentrations, three, one or two vortexes that have different positions, strength and directions may be found in the welding pool. The contrary vortexes can efficiently transfer the thermal energy from the arc, creating a deep welding pool. An optimum range of sulfur content is 20-150×10-6.

关键词： Surface-active elements Sulfur Plow patterns Depth/width

Suppression of Phase and Amplitude Damping Decoherence in a Three-Level Atom in A-Configuration Using Bang-Bang Controls

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Communications in Theoretical Physics 2007年第7期48卷 71-74页

作者： WANG Yan-Hui LIU Xiao-Shu LONG Gui-Lu1 key laboratory for Atomic and Molecular Nanosciences and department of Physics,tsinghua university,beijing 100084,china2 tsinghua National laboratory for Information science and Technology,tsinghua university,beijing 100084,china key laboratory for Atomic and Molecular Nanosciences and department of Physics Tsinghua University Beijing 100084 China tsinghua National laboratory for Information science and Technology Tsinghua University Beijing 100084 China

In this paper,we present decoupling bang-bang operations for the suppression of general decoherence,bothamplitude and phase damping,in a three-level system in *** give a program to design a sequence ofperiodic twinbor... 详细信息

关键词： bang-bang operation general decoherence three-level system

Ln_2MO_4 cathode materials for solid oxide fuel cells

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science china Chemistry 2011年第6期54卷 898-910页

作者： ZHAO Hui, LI Qiang & SUN LiPing key laboratory of Functional Inorganic Material Chemistry, ministry of education School of Chemistry and materials science, Heilongjiang university, Harbin 150080, china 1. key laboratory of Functional Inorganic Material Chemistry Ministry of Education School of Chemistry and materials science Heilongjiang University Harbin 150080 China

One of the major challenges to develop "intermediate temperature" solid oxide fuel cells is finding a novel cathode material, which can meet the following requirements: (1) high electronic conductivity; (2) chemical compatibility with the electrolyte; (3) a matched thermal expansion coefficient (TEC); (4) stability in a wide range of oxygen partial pressure; and (5) high catalytic activity for the oxygen reduction reaction (ORR). In this short review, a survey of these requirements for K2NiF4-type material with the formula Ln2MO4, Ln = La, Pr, Nd, Sm; M = Ni, Cu, Fe, Co, Mn, is presented. The composition-dependent TEC, electrical conductivity and oxygen transport property are considered. The Ln2MO4 materials exhibit improved chemical stability and compatibility with most of the traditional electrolytes. The complete fuel cells integrated with Ln2MO4 materials as cathodes show promising results. Furthermore, these materials are considered as cathodes of protonic ceramic fuel cell (PCFC), and/or anodes of high temperature steam electrolysis (HTSE). First results show excellent performances. The versatility of these Ln2MO4 materials is explained on the basis of structural features and the ability to accommodate oxygen non-stoichiometry.

关键词： intermediate temperature solid oxide fuel cells (ITSOFCs) cathode K2NiF4-type structure oxygen non-stoichiometry

Removal of Volatile Organic Compounds by Adsorption and Photocatalytic Oxydation

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Journal of Wuhan university of Technology(materials science) 2007年第3期22卷 450-452页

作者：许德平黄正宏 Lab of advanced materials Department of Materials Science and EngineeringTsinghua University School of Chemical and Environmental engineering China University of Mining and Technology

Based on the study of equilibrium adsorption on viscose rayon-based activated carbon fiber （ACF） by gravimetric method, mounting of TiO2 on PAN-based activated carbon cloth （ACC） and their photocatalytic activity as well as adsorption performance for benzene were investigated. The crystallinity of TiO2 and pore structure were characterized by XRD and N2 adsorption. The results show that crystallinity of TiO2 and pore structure could be postulated by heat treatment condition. Both crystallinity of TiO2 and pore structure of hybrid have effects on photocatalytic performance of TiO2-mounted ACC. It would be more attractive and prospective for the combination of TiO2 photocatalytic activity and adsorption ability of porous materials.

关键词： volatile organic compounds activated carbon cloth TiO2