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A Creep Equation Based on Thermal Activation

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International Journal of Minerals,Metallurgy and materials 1998年第1期12卷 44-46页

作者： Jiyue Sun Guoliang Chen (State key laboratory for advanced Metals and materials, university of science and Technology beijing, beijing 100083, china) State key laboratory for advanced Metals and materials University of Science and Technology Beijing Beijing 100083 China

The creep equation proposed in so called θ projection concept is developed in the concept of thermal activation of creep. The measured creep curves of A286 alloy are fitted by the equation. The activation energy in theequation is evaluated, and creep rupture lives are predicted. The results are confirmed by creep tests of up to 13years.

关键词： creep creep curve equation creep rupture life A286 superalloy

Theoretical calculation and experimental study of influence of oxygen vacancy on the electronic structure and hemocompatibility of rutile TiO_2

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science china(Technological sciences) 2009年第9期52卷 2742-2748页

作者： LEI YiFeng,LENG YongXiang,YANG Ping,WAN GuoJiang & HUANG Nan key laboratory of advanced materials Technology of ministry of education,department of materials science and engineering,Southwest Jiaotong university,Chengdu 610031,china key laboratory of advanced materials Technology of ministry of education Department of Materials Science and Engineering Southwest Jiaotong University Chengdu 610031 China

In this work,the relationship between electronic structure and hemocompatibility of oxygen deficient rutile TiO2-x was studied by both theoretical calculation and experimental study. Based on the local density functional theory,first-principals method was performed to calculate the electronic structure of rutile TiO2 with different oxygen vacancy concentration. In the range of less than 10% of (or equal) physically realistic O vacancy concentration,the band gap of rutile TiO2 increases with increasing O vacancy concentration,leading the TiO2 changes from a p-type to an n-type semiconductor. The valance band of TiO2 is predominated by O 2p orbital,while the conduction band is occupied by Ti 3d orbital for different O vacancy concentration. The O vacancy results in the occupation of electrons at the bottom of conduction band of TiO2,and the donor density increases with increasing O vacancy concentration. When materials come in contact with blood,the n-type semiconductor feature of oxygen deficient TiO2-x with the bottom of conduction band occupied by electrons would prevent charge transfer from fibrinogen into the surface of materials,thus inhibiting the aggregation and activation of platelets,therefore improving the hemocompatibility of rutile TiO2-x.

关键词： rutile TiO2 oxygen vacancy electronic structure hemocompatibility

Dense coding scheme using superpositions of Bell-states and its NMR implementation

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science china(Physics,Mechanics & Astronomy) 2005年第1期48卷 57-67页

作者： ZHANG Jingfu, XIE Jingyi, DENG Zhiwei & LU Zhiheng key laboratory for Quantum Information and Measurements, department of Physics, tsinghua university, beijing 100084, china Center for Quantum Information, tsinghua university, beijing 100084, china department of materials science and engineering, beijing Normal university, beijing 100875, china Testing and Analytical Center, beijing Normal university, beijing 100875, china department of Physics, beijing Normal university, beijing 100875, china 1. key laboratory for Quantum Information and Measurements Department of Physics Tsinghua University 100084 Beijing China 2. Center for Quantum Information Tsinghua University 100084 Beijing China 3. department of materials science and engineering Beijing Normal University 100875 Beijing China 4. Testing and Analytical Center Beijing Normal University 100875 Beijing China 5. department of Physics Beijing Normal University 100875 Beijing China

Dense coding using superpositions of Bell-states is proposed. The generalized Grover's algorithm is used to prepare the initial entangled states, and the reverse process of the quantum algorithm is used to determine the entangled state in the decoding measurement. Compared with the previous schemes, the superpositions of two Bell-states are exploited. Our scheme is demonstrated using a nuclear magnetic resonance (NMR)quantum computer. The corresponding manipulations are obtained. Experimental results show a good agreement between theory and experiment. We also generalize the scheme to transmit eight messages by introducing an additional two-state system.

关键词： dense coding, superpositions of Bell-states, generalized Grover's algorithm, nuclear magnetic res-onance, quantum computer.

Nd-doped barium titanate ceramics with various Ti/Ba ratios prepared by sol-gel method

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science china Chemistry 2005年第z1期48卷 60-64页

作者： SHI Qizhen,CUI Bin,WANG Hui,TIAN Jing,CHANG Zhuguo & HOU Yudong department of Chemistry,Northwest university,Shaanxi key laboratory of Physico-lnorganic Chemistry,Xi’an 710069,china key laboratory of advanced Functional materials of china education ministry,beijing university of Technology,beijing 100022,china 1. department of Chemistry Northwest University Shaanxi Key Laboratory of Physico-lnorganic Chemistry 710069 Xi’an China 2. key laboratory of advanced Functional materials of china education ministry Beijing University of Technology 100022 Beijing China

The Nd-doped BaTiO3 nanocrystalline powders and ceramics with different Ti/Ba ratios were prepared by sol-gel method. Phases and microstructures of the Nd-doped BaTiO3based powders and ceramics were characterized by XRD, SEM and TEM methods. The results revealed that the powders synthesized by sol-gel method were nanometer scale (30-60 nm)and were mainly composed of cubic BaTiO3 with a small amount of BaCO3. After sintering at high temperature, both cubic BaTiO3 and BaCO3 were transformed into tetrahedron BaTiO3 *** dielectric properties of the ceramics were also determined and the influence of Ti/Ba ratio on the dielectric properties was discussed. The Tc did not change with the variation of Ti/Ba ratio,while the εmax increased firstly and then decreased. The excess TiO2 is benefit for the modification of ceramics' microstructure and dielectric properties.

关键词： sol-gel method, dielectric properties, nanometer materials, Nd-doped barium titanate, Ti/Ba mole ratio.

Study on the hardening mechanism of cement asphalt binder

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science china(Technological sciences) 2010年第5期53卷 1406-1412页

作者： YANG JinBo,YAN PeiYu,KONG XiangMing & LI Xiang key laboratory of Structural engineering and Vibration of education ministry of china,department of Civil engineering,tsinghua university,beijing 100084,china 1. key laboratory of Structural engineering and Vibration of education ministry of china Department of Civil Engineering Tsinghua University Beijing 100084 China

The hydration and hardening mechanism of cement asphalt binder(CAB) was *** early hydration process,hydration products and paste microstructure of CAB made by Portland cement and anionic asphalt emulsion were investigated by calorimetry,X-ray diffraction,and environmental scanning electron *** early hydration process of CAB can be characterized as 5 stages similar to those of Portland *** is no chemical reaction detected between cement and asphalt,hence no new hydration products other than those of Portland cement are *** hardening of CAB begins with the hydration of *** the hydration of cement comes into the acceleration period and its exothermic rate comes to the maximum,the coalescence of asphalt particles in asphalt emulsion is *** the hardened system of CAB,it was found that the hydration products of cement form the skeleton and are covered by the continuous asphalt *** formed an interpenetrating network *** emulsifiers in the asphalt emulsion may retard the hydration process of cement.

关键词： cement asphalt binder asphalt emulsion Portland cement hydration coalescence

MEAM Potential with Angular Dependence for TiAl

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Rare Metals 2001年第1期20卷 13-17页

作者： Xiaodong Ni, Xitao Wang, Guoliang Chen (Physics department, university of science and Technology beijing, beijing 100083, china State key laboratory for advanced Metals and materials, university of science and Technology beijing, beijing 100083, china) Univ Sci & Technol beijing Dept Phys Beijing 100083 Peoples R China Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China

The modified embedded atom method (MEAM) is an empirical extension of the embedded atom method (EAM) that includes angular forces. By fitted to the lattice constants, the cohesive energy, the APE (anti-phase boundary) energy, and the vacancy formation energy of TiAl, an accurate MEAM potential is obtained for the TiAl system with L10 structure. The calculation results of the properties of TiAl are in good agreement with experiments and the results of first principle (F.P.) calculations.

关键词： embedded atom method TiAl alloy angular dependence potential intermetallics

Effect of Curing Regime on Bonding Strength of EVA Modified Mortar to Tile

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Journal of Wuhan university of Technology(materials science) 2010年第2期25卷 346-348页

作者：何代华 School of materials science & engineering University of Shanghai for Science Technology key laboratory of advanced Civil engineering materials Ministry of Education Tongji University

Ethylene-Vinyl Acetate （EVA） redispersible powder and latex were used to modify mortar. Three kinds of curing regimes： standard curing, high temperature curing and freeze-thaw circle curing were adopted to cure the bonded samples. Bonding strength of EVA modified mortar was tested at 28 days. The development of bonding strengths under all three curing regimes were discussed and compared. The experimental results show that bonding strength increases with the increase of EVA content in mortar. The curing regime used within 28 days is critical according to the bonding strengths values under three curing regimes for different ages. The reasons of that the EVA can improve the bonding strength were analyzed.

关键词： EVA redispersible powder latex bonding strength curing regime

Distribution of Nb atom in the TiAl+Nb system

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Rare Metals 2001年第1期20卷 5-12页

作者： Xiaodong Ni, Xidong Hui, Guoliang Chen (Applied science School, university of science and Technology beijing, beijing 100083, china State key laboratory for advanced Metals and materials, university of science and Technology beijing, china) Appl. Sci. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

Based on MEAM (the modified embedded atom method) potential and an average atom model similar to B-W (Bragg-Williams) method, the distribution of Nb atoms in TiAl+Nb compounds with various composition was calculated. The calculation results showed that Nb atoms prefer to occupy the Ti sublattice of L10 structure for all compounds in question. With increasing atomic fraction of Nb and Al, Nb atoms exhibited a trend of ordered distribution on the Ti sublattice and result in a new L10 derivative superlattice structure.

关键词： Computer simulation Intermetallics Superlattices Ternary systems

Structure Evolution of Bulk Metallic Glass Zr_(52.5)Ni_(14.6)Al_10Cu_(17.9)Ti_5 during Annealing

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Journal of materials science & Technology 2000年第4期16卷 357-361页

作者： Guo HE, Zan BIAN and Guoliang CHEN (State key laboratory of advanced Metals and materials, university of science and Technology beijing,beijing 100083, china) State key laboratory of advanced Metals and materials University of Science and Technology Beijing Beijing 100083 China

Bulk metallic glass Zr_52.5Ni_14.6Al_10Cu_17.9Ti_5 was prepared by melt injection casting method. Its glass transition and crystallization temperatures were determined by differential scanning calorimetry (DSC) to be 631 K and 710 K respectively. By analysis of X-ray diffractometry (XRD) and transmission electron microscopy (TEM ), the predominant crystallized phase of Zr_2Ni0.67O0.33 distributed on glass state matrix was detected after annealing at 673 K for 600 s. The transformation to Zr_2Ni_0.67O_0.33 and a small amount of ZrAl and Zr_2Cu took place after annealing for 600 s at temperature from 703 K to 723 K. With increasing annealing temperature from 753 K to 823 K, the amounts of ZrAl and Zr_2Cu increased, but the size of the crystals did not significantly change. The transformation to Zr_2Ni_0.67O_0.33 is interface-controlled, but is diffusion-controlled to Zr_2Cu and ZrAl. With increasing annealing temperature up to 200 K above T_x, the nanometer grains became very fine because of the increase of nucleation rate for Zr_2Cu and ZrAl.

关键词： Structure Evolution of Bulk Metallic Glass Zr Ti5 during Annealing Al10Cu Ni Cu