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technology and properties of YAG porous ceramics sintered by pressureless sintering method

Cailiao Rechuli Xuebao/Transactions of materials and Heat Treatment 2014年第SUPPL.1期35卷 8-12页

作者： Song, Jie-Guang Wang, Fang Du, Da-Ming Xu, Ming-Han Li, Shi-Bin Ji, Gang-Chang Chen, Fei School of Mechanical and Materials Engineering Jiujiang 332005 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China Hubei Key Laboratory of Advanced Technology of Automotive Components School of Automotive Engineering Wuhan University of Technology Wuhan 430070 China

In order to obtain more function materials sorts using the excellent properties of YAG, the YAG porous ceramics were successfully prepared by pressureless sintering method. The results show that the porosity of YAG porous ceramics sintered at 1500°C is similar with that of YAG porous ceramics sintered at 1550°C, however, the compressive strength of YAG porous ceramics sintered at 1550°C with more sintered necks is higher than that of YAG porous ceramics sintered at 1500°C. The porosity and the compressive strength of YAG porous ceramics sintered with holding time of 2 h are higher than that of YAG porous ceramics sintered with holding time of 1 h. The porosity and the compressive strength of YAG porous ceramics sintered with heating rate of 5°C/min are higher than that of YAG porous ceramics sintered with heating rate of 10°C/min. The porosity and the compressive strength of YAG porous ceramics sintered with removing carbon temperature of 800°C are higher than that of YAG porous ceramics sintered with removing carbon temperature of 1000°C. The suitable technology is sintering at 1550°C, holding for 2 h, heating rate of 5°C/min and removing carbon at 800°C, the porosity and the compressive strength of YAG porous ceramics are 59.4% and 8.55 MPa, respectively.

关键词： Porosity

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Effect of the grain boundary on the dielectric breakdown strength of (Ba0.4Sr0.6)TiO3 paraelectric ceramics with various grain sizes

Effect of the grain boundary on the dielectric breakdown str...

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IEEE International Symposium on Applications of Ferroelectrics (ISAF)

作者： Zhe Song Hanxing Liu Hua Hao Minghe Cao Qing Xu Zhonghua Yao Zhijian Wang Wei Hu Yatong Shi Zhiyong Yu State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 Hubei PR China

(Ba 0.4 Sr 0.6 )TiO 3 (BST) paraelectric ceramics (T c ≈ -67 °C) with various grain sizes (0.6-1.8 μm) were synthesized by oxalate co-precipitation method and prepared by conventional solid-state sintering process. With decreasing grain sizes, the dielectric breakdown strength increases gradually. Based on the conductivity activation energy analysis, it was found that the larger grain boundary density plays a dominant role in controlling dielectric breakdown strength for samples with smaller grain sizes (1.0 to 0.6 μm). While with the growth of grain sizes above 1.0 μm, the sharply decreasing dielectric breakdown strength is induced by a combined effect of lower grain boundary density and more intensive interface polarization.

关键词： Grain size Grain boundaries Dielectric breakdown Ceramics Polarization Dielectrics Energy storage

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Na(+) intercalation pseudocapacitance in graphene-coupled titanium oxide enabling ultra-fast sodium storage and long-term cycling

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Nature communications 2015年第1期6卷 6929页

作者： Chaoji Chen Yanwei Wen Xianluo Hu Xiulei Ji Mengyu Yan Liqiang Mai Pei Hu Bin Shan Yunhui Huang State Key Laboratory of Materials Processing and Die &Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China. Department of Chemistry Oregon State University Corvallis Oregon 97331-4003 USA. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing WUT-Harvard Joint Nano Key Laboratory Wuhan University of Technology Wuhan 430070 China.

Sodium-ion batteries are emerging as a highly promising technology for large-scale energy storage applications. However, it remains a significant challenge to develop an anode with superior long-term cycling stability and high-rate capability. Here we demonstrate that the Na(+) intercalation pseudocapacitance in TiO2/graphene nanocomposites enables high-rate capability and long cycle life in a sodium-ion battery. This hybrid electrode exhibits a specific capacity of above 90 mA h g(-1) at 12,000 mA g(-1) (∼36 C). The capacity is highly reversible for more than 4,000 cycles, the longest demonstrated cyclability to date. First-principle calculations demonstrate that the intimate integration of graphene with TiO2 reduces the diffusion energy barrier, thus enhancing the Na(+) intercalation pseudocapacitive process. The Na-ion intercalation pseudocapacitance enabled by tailor-deigned nanostructures represents a promising strategy for developing electrode materials with high power density and long cycle life.

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Study of bipolar transport properties of organic semiconductor CBP

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Guangdianzi Jiguang/Journal of Optoelectronics Laser 2015年第12期26卷 2267-2271页

作者： Yuan, Ling-Dao Wu, You-Zhi Zhang, Yun-Hu Zhang, Cai-Rong Zhang, Ding-Jun State Key Laboratory of Advanced Processing & Recycling of Nonferrous Metals School of Materials Science & Engineering Lanzhou University of Technology Lanzhou China Department of Applied Physics School of Science Lanzhou University of Technology Lanzhou China

The bipolar material 4, 4'-N, N'-dicarbazolylbiphenyl (CBP) is often used as a typical host materials in electrophosphorescent devices. In order to compare the relative transport speeds of hole and electron in CBP with CBP used as an active layer, electroluminescent (EL) devices with multilayer structures of anode/hole transporting layer/CBP/electron transporting layer/cathode were fabricated. An ultrathin layer of fac-tris(2-phenylpyridine)iridium (Ir(ppy)3) was inserted into CBP layer at different positions to obtain EL devices with different colors. Bipolar transport properties of CBP are investigated by comparing electroluminescences of different devices instead of mobilities of holes and electrons. The results show that the recombination of electrons and holes takes place mainly near the anode side, indicating that electrons move much faster than holes in CBP, or in other words, the mobility of an electron in CBP is greater than that of a hole. © 2015, Board of Optronics Lasers. All right reserved.

关键词： Electrons

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Study on preparation and thermal conductivity of high stability magnetorheological fluids

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Journal of the Chinese advanced materials Society 2014年第2期2卷 130-137页

作者： Haibin Cheng[a] Wang Hong[a] Chaosheng Liu[a][b][*] [a]State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan China[b]Zhuzhou Lince Group Co. Ltd. Zhuzhou China

A surface modifier, which has lipophilic groups and chelating groups, was synthesized, and used to modify the surface characteristics of carbonyl iron particles and prepare composite magnetic particles (CMPs). Then a set of oil-based magnetorheological (MR) fluids based on the CMPs were prepared. Finally, the relationship between thermal conductivity and concentration of MR fluids were studied, and an analysis model on thermal conductivity and concentration of MR fluids was built. The result shows that there is a linear correlation between thermal conductivity and concentration of MR fluids, namelykeff= 0.0245 Φ − 0.08 andkeff/kf= 0.167 Φ − 0.53 (10 ≤ Φ ≤ 50). Applying this model, the concentration variation of the MR fluids can be acquired on the basis of the thermal conductivity variation, and the model can be used to evaluate the sedimentation stability of the MR fluids.

关键词： magnetorheological fluids composite particles sedimentation thermal conductivity

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Preparation and Effect of Oxygen Annealing on the Electrical and Magnetic Properties of Epitaxial (0001) Zn_(1-x)Co_xO Thin Films

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Journal of Wuhan University of technology(materials Science) 2013年第5期28卷 893-897页

作者：罗嗣俊张联盟 WANG Chuanbin ZHOU Xuan SHEN Qiang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology

Epitaxial （0001）-oriented Zn1-xCoxO （x= 0.01, 0.05 and 0.1） thin films were grown on c-sapphire substrates by pulsed laser deposition. The XRD analysis, optical transmittance and XPS measurements revealed that the Co2＋ substituted Zn2＋ ions were incorporated into the lattice of ZnO in Zn1-xCoxO thin films. The electrical properties measurements revealed that the Co concentration had a non- monotonic influence on the electrical properties of the Zn1-xCoxO thin films due to the defects resulted from imperfections induced by Co substitution. The resistivity remarkably increased and the carrier concentration remarkably decreased in Zn1-x CoxO thin films after oxygen annealing at 600 ℃ under 15 Pa O2 pressure for 60 mins. Room-temperature ferromagnetic was observed and the ferromagnetic Co amount was smaller than the nominal Co concentration for Zn1-xCoxO samples before oxygen annealing. After oxygen annealing, the Zn1-x CoxO thin films exhibited paramagnetic behavior. It is suggested that the room-temperature ferromagnetic ofZn1-x CoxO thin films may attribute to defects or carriers induced mechanism.

关键词： Zn1-xCoxO thin film pulsed laser deposition oxygen annealing electrical properties magnetic property

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HIGHLY EFFICIENT GRAPHENE BASED CATALYST FOR OXYGEN REDUCTION REACTION

HIGHLY EFFICIENT GRAPHENE BASED CATALYST FOR OXYGEN REDUCTIO...

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10th IUPAC International Conference on Novel materials and their synthesis NMS-X(IUPAC第十届新材料及其合成国际会议)

作者： Daping He Peng Wu Xu Chen Hui Wu Shichun Mu State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070P.R.China

Hitherto, the low electrochemical stability of the catalyst is one of the big issues hindering the commercial application of proton exchange membrane fuel cells (PEMFCs) . In this work, more stable support materials based on functionalized graphene nanosheets (GNS), porous GNS, heteroatom doped GNS, and alternative GNS composites including GNS/nano-carbon (or nano-ceramics) sandwiches, nanoceramic wedged GNS, and core-shell graphene and amorphous carbon composites are prepared and applied in catalysts towards oxygen reduction reaction (ORR). based on the idea of bifunction of GNS to Pt catalysts, highly active and stable Pt/reduced graphene oxide (RGO) catalysts are developed by tuning the O/C atom ratio of RGO supports where the optimized O/C atom ratio of 0.14 is determined. Meantime, both perfluorosulfonic acid (PFSA) functionalized GNS and sulfonic acid group-grafted RGO supported Pt catalysts show a higher catalytic activity and a lower loss rate of electrochemical active area (ECA) in comparison with that of the plain Pt/GNS and conventional Pt/C catalysts. In addition, the N-doped RGO supported Pt catalyst (Pt/NRGO) is synthesized using a lyophilisation-assisted N-doping method, revealing a higher catalytic activity and a lower ECA loss of the Pt/NRGO catalyst to compare with that of the Pt/GO and Pt/C catalysts. In addition, to tackle the stacking issues of GNS which leads to the low mass transport property, the porous GNS are synthesized. Besides, we also describe a new strategy to synthesize GNS hybrids including GNS/nano-carbon (nano-creamics) sandwiches and nano-ceramic wedged GNS architectures. These unique architectures with highly dispersed Pt NPs exhibit much high catalytic activities towards ORR and an excellent electrochemical stability. At last, a new graphene @ amorphous carbon core-shell material also shows an excellent electrochemical property. This work was supported financially by the National Natural Science Foundation of China (NSFC) (No. 5

关键词： catalysts graphene oxygen reduction fuel cells

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Further Understanding of Conjugated Polymers for High Efficiency Solar Cells: A Case Study of PBnDT-FTAZ

Further Understanding of Conjugated Polymers for High Effici...

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中国化学会第29届学术年会

作者： Wei You State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Department of Chemistry University of North Carolina at Chapel Hill

PBnDT-FTAZ, a "weak donor-strong acceptor" polymer that combines benzodithiophene（BnDT） and fluorinated benzotriazole（FTAZ）, has received significant amount of attention because it is a peculiar material with many outstanding features that need to be further explained. For example, with a medium band gap of 2.0 V, PBnDT-FTAZ can still generate over 7% power conversion efficiency with a noticeably high fill factor over 70% in its BHJ cells with a relatively thick film（200 – 300 nm）. In this talk, I will discuss our ongoing efforts to further understand this interesting polymer. First, we discovered that all these interesting properties shown by PBnDT-FTAZ can only be obtained with polymers of a quite narrow range of molecular weight. Second, molecular engineering of PBnDT-FTAZ by substituting alkylthiol and selenophene in PBnDT-FTAZ give mixed results: Voc seems fixed around 0.8 V;however, Jsc can be further increased.

关键词： Conjugated Polymer Solar Cell

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Numerical simulation of hot stamping of front bumper

Numerical simulation of hot stamping of front bumper

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2014 International Conference on Frontiers of advanced materials and Engineering technology, FAMET 2014

作者： Guo, Yi Hui Ma, Ming Tu Zhang, Yi Sheng Zhou, Dian Wu Song, Lei Feng Co. Ltd. Chongqing 401122 China State Key Laboratory of Materials Processing and Die and Mould Technology Huazhong University of Science and Technology Wuhan 430074 China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Changsha 410082 China

ISBN: (纸本)9783038350774

LS-DYNA software was adopted to conduct research of numerical simulation on hot stamping of front bumper to calculate the temperature field distribution, stress field distribution, FLD figure and etc. of parts in the course of hot stamping so as to predict and analyze the formability of parts. ProCAST software was employed to conduct research of numerical simulation on solid quenching course concerning hot stamping to calculate temperature field distribution of tools and component of multiple stamping cycles;Based on the simulation, the hot stamping mould was developed. and the front bumper components of hot forming were stamped, Compared the test results with the simulation, both the results coincide basically with same variation *** obtain from numerical simulation can provide significant reference value to hot stamping part design, formability predication and tools cooling channel system design. © (2014) Trans Tech Publications, Switzerland.

关键词： Temperature

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Preparation and properties of Zn4Sb3Inδ thermoelectric compounds

Preparation and properties of Zn4Sb3Inδ thermoelectric comp...

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2014国际纳米技术和新能源材料研讨会——暨世界著名科学家来鄂讲学计划武汉论坛

作者： Dingguo Tang Wenyu Zhao Jian Yu Ping Wei Hongyu Zhou Wanting Zhu Qingjie Zhang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Key Laboratory of Catalysis and Materials Science of the State Ethnic Affair Commission & Ministry of Education South-Central University for Nationalities

Thermoelectric materials are capable of interconverting heat and electricity directly. The high thermoelectric performance of β-Zn4 Sb3 has drawn much attention for its application in the intermediate temperature ran... 详细信息

关键词： thermoelectric compounds Preparation and properties of Zn4Sb3In

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