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Constitutive modeling of compression behavior of TC4 tube based on modified Arrhenius and artificial neural network models

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Rare Metals 2016年第2期35卷 162-171页

作者： Zhi-Jun Tao He Yang Heng Li Jun Ma Peng-Fei Gao State Key laboratory of Solidification Processing School of Materials Science and Engineering Northwestern Polytechnical University

Warm rotary draw bending provides a feasible method to form the large-diameter thin-walled（LDTW）TC4 bent tubes, which are widely used in the pneumatic system of aircrafts. An accurate prediction of flow behavior of TC4 tubes considering the couple effects of temperature,strain rate and strain is critical for understanding the deformation behavior of metals and optimizing the processing parameters in warm rotary draw bending of TC4 tubes. In this study, isothermal compression tests of TC4 tube alloy were performed from 573 to 873 K with an interval of 100 K and strain rates of 0.001, 0.010 and0.100 s^（-1）. The prediction of flow behavior was done using two constitutive models, namely modified Arrhenius model and artificial neural network（ANN） model. The predictions of these constitutive models were compared using statistical measures like correlation coefficient（R）, average absolute relative error（AARE） and its variation with the deformation parameters（temperature, strain rate and strain）. Analysis of statistical measures reveals that the two models show high predicted accuracy in terms of R and AARE. Comparatively speaking, the ANN model presents higher predicted accuracy than the modified Arrhenius model. In addition, the predicted accuracy of ANN model presents high stability at the whole deformation parameter ranges, whereas the predictability of the modified Arrhenius model has some fluctuation at different deformation conditions. It presents higher predicted accuracy at temperatures of 573-773 K, strain rates of 0.010-0.100 s^（-1）and strain of 0.04-0.32, while low accuracy at temperature of 873 K, strain rates of 0.001 s^（-1）and strain of ***, the application of modified Arrhenius model is limited by its relatively low predicted accuracy at some deformation conditions, while the ANN model presents very high predicted accuracy at all deformation conditions,which can be used to study the compression behavior of TC4 tube at the temperature range of 573-

关键词： TC4 tube Compression behavior Constitutive model Modified Arrhenius model Neural network model

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Electric-stress reliability and current collapse of different thickness SiN_x passivated AlGaN/GaN high electron mobility transistors

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Chinese Physics B 2010年第4期19卷 369-374页

作者：杨凌胡贵州郝跃马晓华全思杨丽媛姜守高 Key laboratory for Wide Band-Gap Semiconductor materials and Devices School of MicroelectronicsXidian University

This paper investigates the impact of electrical degradation and current collapse on different thickness SiNx passivated AlGaN/GaN high electron mobility transistors. It finds that higher thickness SiNx passivation can significantly improve the high-electric-field reliability of a device. The degradation mechanism of the SiNx passivation layer under ON-state stress has also been discussed in detail. Under the ON-state stress, the strong electric-field led to degradation of SiNx passivation located in the gate-drain region. As the thickness of SiNx passivation increases, the density of the surface state will be increased to some extent. Meanwhile, it is found that the high NH3 flow in the plasma enhanced chemical vapour deposition process could reduce the surface state and suppress the current collapse.

关键词： SiNx passivated AlGaN/GaN high electron mobility transistors degradation current collapse surface states

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THE ROLE OF HYDROGEN-BONDING INTERACTION IN POLY(VINYL ALCOHOL)/POLY(ACRYLIC ACID) BLENDING SOLUTIONS AND THEIR FILMS

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Chinese Journal of Polymer Science 2010年第6期28卷 903-911页

作者： Nan-xi Chen Jun-hua Zhang State Key laboratory of Polymer materials Engineering of China Sichuan UniversityChengdu 610065China

The aim of this work is to investigate the hydrogen-bonding interaction in poly(vinyl alcohol)(PVA)/poly(acrylic acid)(PAA) blending system and its influence on rheological properties in solution and the physical properties in solid state. Introducing PAA into PVA solutions resulted in a thickening behavior of blend *** viscosity of the solutions increased with PAA content increasing,and a maximum viscosity could be obtained when the ratio of PVA/PAA was 70/30. The intermolecular hydrogen-bonding and miscibility between PVA and PAA in solid state were investigated by differential scanning calorimetry(DSC),Fourier transform infrared spectroscopy(FTIR) and mechanical *** results displayed the great influence of introducing PAA on the properties of blending *** tensile strength increased from 89.31 MPa to 119.8 MPa and Young’s modulus improved by over 300%with increasing PAA concentration compared with those of pure PVA *** systematically studying the rheological behaviors of solutions and the physical properties of films,the influence of hydrogen-bonding in solutions and solid states were discussed.

关键词： Polymer blending Rheology Hydrogen-bonding Molecular network Miscibility

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Warm-white persistent luminescence of Lu3Al2Ga3O12：Pr^3＋ phosphor

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Journal of Rare Earths 2017年第1期35卷 47-52页

作者： FENG Lin WANG Zhenbin CAO Cheng ZHANG Teng ZHANG Jiachi CI Zhipeng ZHAO Zhengyan WANG Yuhua Key laboratory for Magnetism Magnetic materials of the Ministry of Education Lanzhou University Lanzhou 730000 China

A warm-white emitting persistent luminescence phosphor Lu3Al2Ga3O12：Pr^3＋ was synthesized by solid state method at 1600 °C in air. The refined crystal structure of Lu3Al2Ga3O12 host was solved by X-ray diffraction（XRD）. The photoluminescence spectra, decay curve and thermoluminescence were investigated. It was revealed that the persistent luminescence originated from the f-f transitions of Pr^3＋ emitters at Lu^3＋ sites in LuO8 polyhedrons, and it showed white color due to the ^3P0→^3H4, ^3P1→^3H5, ^3P0→^3H5, ^3P0→^3H6, ^3P0→^3F2, ^3P0→^3F3 and ^3P0→^3F4 transitions of Pr^3＋ emitters in a wide range. The persistent luminescence of Pr^3＋ in this host could be promoted by f-d transition（278 nm） but f-f transitions, due to the different thermal activation energy. The persistent luminescence of the optimal sample could be actually recorded for 3 h by the definition of 0.32 mcd/m^2 and was visible for more than 7 h by dark-adapted vision in darkness. The initial depth of the dominant shallow traps was calculated to be about 0.56 eV, which is suitable for persistent luminescence. The different roles of the shallow and deep traps on the persistent decay process were investigated. Accordingly, the persistent luminescence processes and mechanism of the as-synthesized Lu3Al2Ga3O12：Pr^3＋ phosphors were proposed.

关键词： persistent luminescence Lu3Al2Ga3O12 Pr3+ phosphor rare earths

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Graphene Fibers: Advancing Applications in Sensor, Energy Storage and Conversion

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Chinese Journal of Polymer Science 2019年第6期37卷 535-547页

作者： Guan-Hang Yu Qing Han Liang-Ti Qu Beijing Key laboratory of Photoelectronic/Electrophotonic Conversion materials Key Laboratory of Cluster Science Ministry of Education School of Chemistry Beijing Institute of Technology

Graphene fibers are a kind of novel carbon fibers assembled by orderly aligned graphene sheets with high flexibility, good conductivity, high thermal conductivity, and low density, which make them possible to be widely used in high-performance and multifunctional compound materials as well as flexible electronic devices. In this review, we summarize the research progress in the synthesis of graphene fibers, and their applications in sensor, energy storage, and energy conversion. Furthermore, the current issues and some prospects for the future trend of graphene fibers are discussed.

关键词： Graphene fibers Assembly Functionalization Sensor Energy storage and conversion

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Tempering Stability of Fe-Base Hardfacing Layer Containing RE and Multiple Alloying

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Journal of Rare Earths 2005年第S1期23卷 399-402页

作者：刘建华陈华杨庆祥曾宪文胡文涛赵洪力 Key laboratory of Metastable materials Science and Technology Yanshan University Qinhuangdao 066004 China

After tempering treatment at different conditions, the tempering stability of Fe-base hardfacing layer containing RE and multiple alloying was investigated. The results show that after heat preservation at 560 ℃ and tempering for 4 h the hardness value of Fe-base hardfacing layer containing RE and multiple alloying can reach HRC57; By repeatedly heating circle 700 ℃17 ℃ for 150 times, the hardness value of Fe-base hardfacing layer can reach HRC43, tempering stability is higher and causes the secondary hardening phenomenon. Reasons for higher tempering stability of Fe-base hardfacing layer were analyzed by means of metallographic, XRD, TEM and EDS.

关键词： Fe-base hardfacing layer tempering stability multiple alloying rare earths

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BaCe_(0.8)Fe_(0.1)Ni_(0.1)O_(3−δ)-impregnated Ni-GDC by phase-inversion as an anode of solid oxide fuel cells with on-cell dry methane reforming

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Journal of Advanced Ceramics 2024年第6期13卷 834-841页

作者： Yanya Liu Jun Luo Cheng Li Bo Liu Dong Yan Jian Li Lichao Jia School of materials Science and Engineering State Key Laboratory of Materials Processing and Die&Mould TechnologyHuazhong University of Science and TechnologyWuhan 430074China

BaCe_(0.8)Fe_(0.1)Ni_(0.1)O_(3−δ)(BCFN)in a perovskite structure is impregnated consecutively by BCFN solution and BCFN suspension into a phase-inversion prepared NiO–Gd_(0.1)Ce_(0.9)O_(2−δ)(GDC)scaffold as an anode for solid oxide fuel cells(SOFCs)with on-cell dry reforming of methane(DRM).The whole pore surface of the scaffold is covered by small BCFN particles formed by BCFN solution impregnation;the large pores near the scaffold surface are filled by BCFN aerogels with a high specific surface area produced by BCFN suspension impregnation,which act as a catalytic layer for on-cell *** reduction,the anode consists of a Ni–GDC scaffold and BCFN particles with exsolved FeNi3 *** BCFN-impregnated Ni–GDC anode has higher electrical conductivity,electrochemical activity,and resistance to carbon deposition,with which the cell shows maximum power densities between 1.44 and 0.92 W·cm^(−2) when using H_(2) and between 1.09 and 0.50 W·cm^(−2) when using CO_(2)–CH_(4) at temperatures ranging from 750 to 600℃.A stable performance at 400 mA·cm^(−2) and 700℃is achieved using 45%CO_(2)–45%CH_(4)–10%N_(2) for more than 400 h without carbon deposition,benefiting from the impregnated BCFN aerogel with a high specific surface area and water adsorbability.

关键词： aerogel solid oxide fuel cells(SOFCs) phase-inversion dry reforming of methane(DRM) carbon resistance

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Recent progress on lithium-ion batteries with high electrochemical performance

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Science China Chemistry 2019年第5期62卷 533-548页

作者： Yong Lu Qiu Zhang Jun Chen Key laboratory of Advanced Energy materials Chemistry (Ministry of Education) College of ChemistryNankai University

Lithium-ion batteries(LIBs) have been widely used in many fields such as portable electronics and electric vehicles since their successful commercialization in the 1990 s. However, the electrochemical performance of current commercial LIBs still needs to be further improved to meet the continuously increasing demands for energy storage applications. Recently, tremendous research efforts have been made in developing next-generation LIBs with enhanced electrochemical performance. In this review, we mainly focus on the recent progress of LIBs with high electrochemical performance from four aspects, including cathode materials, anode materials, electrolyte, and separators. We discuss not only the commercial electrode materials(LiCoO_2,LiFePO_4, LiMn_2O_4, LiNi_xMn_yCo_zO_2, LiNi_xCo_yAl_zO_2, and graphite) but also other promising next-generation materials such as Li-, Mn-rich layered oxides, organic cathode materials, Si, and Li metal. For each type of materials, we highlight their problems and corresponding strategies to enhance their electrochemical performance. Nowadays, one of the key challenges to construct high-performance LIBs is how to develop cathode materials with high capacity and working voltage. This review provides an overview and future perspectives to develop next-generation LIBs with high electrochemical performance.

关键词： lithium-ion batteries electrochemical performance cathode anode electrolyte separator

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Effect of Co substitution on the glass forming ability and magnetocaloric effect of Fe88Zr8B4 amorphous alloys

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Science China(Physics,Mechanics & Astronomy) 2017年第7期60卷 81-84页

作者： LiangHua Gan LiYan Ma BenZhen Tang Ding Ding Lei Xia laboratory for Microstructure Institute of Materials Shanghai University Shanghai 200072 China

As greater attention is paid to energy consumption and global warming, magnetic refrigeration （MR） technologies based on the magneto-caloric effect （MCE） have been developed. Systems based on MR are expected to be more compact, energy efficient, and environmentally safe compared with traditional vapor-cycle refrigeration technologies .

关键词： Effect of Co substitution on the glass forming ability and magnetocaloric effect of Fe Co Figure Zr8B4 amorphous alloys

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A series of conducting gel electrolytes for quasi-solid-state quantum dot-sensitized solar cells with boosted electron transfer processes

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Journal of Energy Chemistry 2018年第2期27卷 335-341页

作者： Qiming Yang Wen Yang Jialong Duan Peizhi Yang Key laboratory of Advanced Technique & Preparation for Renewable Energy materials Ministry of EducationYunnan Normal University School of materials Science and Engineering Ocean University of China

To pursue electron-generation stability with no sacrifice of photovoltaic performance has been a persistent objective for all kinds of solar cells. Here, we demonstrate the experimental realization of this objective by quasi-solid-state quantum dot-sensitized solar cells from a series of conducting gel electrolytes composed of polyacrylamide（PAAm） matrix and conductive polymers [polyaniline（PANi）, polypyrrole（PPy） or polythiophene（PT）]. The reduction of Sx2- occurred in both interface and three dimensional framework of conducting gel electrolyte as a result of the electrical conduction of PANi, PPy and PT toward refluxed electrons from external circuit to Pt electrode. The resulting solar cells can yield the solarto-electrical conversion efficiency of 2.33%, 2.25% and 1.80% for PANi, PPy and PT based gel electrolytes,respectively. Those solar cells possessed much higher efficiency than that of 1.74% based on pure PAAm gel electrolyte owing to the enhanced kinetics for Sx2- ？ S2- conversion. More importantly, the stability of quasi-solid-state solar cell is significantly advanced, arising from the localization of liquid electrolyte into the three dimensional framework and therefore reduced leakage and volatilization.

关键词： Quantum dot-sensitized solar cells Conducting gel electrolyte Charge transfer Stability Micropomus structure

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