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作者： Zhao, Xueying Shi, Xun Chen, Lidong Bai, Shengqiang Zhang, Wenbing Tang, Xinfeng State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of Ceramics CAS Shanghai 200050 China Graduate School Chinese Academy of Sciences Beijing China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

Sr-filled skutterudite compounds SryCo4Sb 12 (y=0-0.20) were synthesized by melting method. XRD and EPMA results revealed that the obtained samples are single skutterudite phase with homogeneous chemical composition. The lattice parameters increase linearly with increasing Sr content in the range of y=0-0.20. The thermal conductivity, electrical conductivity and Seebeck coefficient were measured in the temperature range of 300-850K. The measurement of Hall effect was performed by Van de Pauw method at room temperature. The obtained Sr-filled skutterudite exhibits n-type conduction. The absolute value of the Seebeck coefficient of Sr yCo4Sb12 decreases with the increase of Sr content. The electrical conductivity increases with the increase of Sr content. The lattice thermal conductivity of SryCo4Sb12 is significantly depressed as compared with unfilled CoSb3. The maximum dimensionless thermoelectric figure of merit is 0.7 for Sr 0.20Co4Sb12 at 850K. Further optimization of chemical composition would improve the thermoelectric performance.

关键词： Strontium compounds

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Research on the heat treatment of cubic boron nitride powder

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of technology 2007年第10期29卷 121-123+127页

作者： Duan, Xing-Long Shao, Gang-Qin Wang, Jing Shi, Xiao-Liang Yan, Li Jiao, Lin State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China Henan Union Abrasives Corp Zhengzhou 450003 China

Cubic Boron Nitride powder was heat treated in N2 or in vacuum at different temperatures and dwell time. Its phase composition and morphology were investigated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. Results showed that the cubic Boron Nitride was transformed into hexagonal phase after heat treatment in N2 at 1350°C for 10 h, or in vacuum (pressure = 1-5 Pa) at 1550°C for 5 h, while no changes occurred in particle size and morphology.

关键词： cBN hBN Heat treatment Nitrogen Vaccum

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The preparation and thermal transport property of nanostructured Yb-filled CoSb3 induced by melt spinning technique

The preparation and thermal transport property of nanostruct...

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International Conference on Thermoelectrics (ICT)

作者： H. Li X.F. Tang X.L. Su W.Q. Cao Q.J. Zhang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan China

The Yb-filled Yb x Co 4 Sb 12 (times=0.2-0.5) bulk materials with special nanostructure were prepared by combining melt spinning method with spark plasma sintering (SPS). The microstructure and thermal transport property of Yb x Co 4 Sb 12 were investigated. The microstructure observations were performed by using high-resolution transmission electron microscopy and field emitted scanning electron microscopy (HRTEM and FESEM). The results show that ribbon-shaped samples after melt spinning are composed of nanocrystals and amorphous-like phases, and possess preferable crystal granularity and evengranular distribution with roller linear speed of 30 m/s and nozzle pressure of 0.02 MPa; the bulk materials after SPS are composed of minicrystals with 200 nm average diameter which is formed by nanocrystals with 5-20 nm diameter. This special microstructure increases grain boundary scattering notably, and has great effect on phonon behavior. As a result, the thermal conductivity of the material is decreased remarkably. Compared with the sample prepared by melting-quench-diffusion annealing method with the same filling fraction (times=0.5), thermal conductivity of the sample prepared by melt spinning method decreased 50% from 4.0 Wm -1 K -1 to 2.0 Wm -1 K -1 at 600 K, and the sample still possesses relatively high power factor.

关键词： Thermal conductivity Spinning Microstructure Nanostructured materials Electron emission Scanning electron microscopy Transmission electron microscopy Nanocrystals Grain boundaries Conducting materials

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Thermal shock experiment and simulation of ceramic/metal gradient thermal barrier coating

Thermal shock experiment and simulation of ceramic/metal gra...

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作者： Xiao, Jinsheng Liu, Kun Zhao, Wenhua Fu, Weibiao School of Automotive Engineering Wuhan University of Technology Hubei 430070 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Hubei 430070 China Department of Engineering Mechanics Tsinghua University Beijing 100084 China

A thermal shock experiment is designed to explore the thermal shock properties of ceramic/metal gradient thermal barrier coating. The specimens are heated up by oxygen-acetylene flame and cooled by water spray. The experiment procedure includes two stages, heating the specimen from the initial temperature 30°C for 40s, and then cooling for 20s. The heat transfer and the associated thermal stresses produced during the thermal shock procedure are simulated by finite element method. Experimental results indicated that the specimen of gradient coating behaves better in thermal shock experiments, which agree with the results of simulation.

关键词： Thermal barrier coatings

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Nanostructure and thermoelectric properties of p-type Bi0.5Sb1.5Te3 compound prepared by melt spinning technique

Nanostructure and thermoelectric properties of p-type Bi0.5S...

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International Conference on Thermoelectrics (ICT)

作者： W.J. Xie X.F. Tang G. Chen Q. Jin Q.J. Zhang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan China

P-type Bi 0.5 Sb 1.5 Te 3 bulk material with fine nanostructure has been prepared by combining melt spinning technique with spark plasma sintering (SPS), and the effects of microstructure on the thermoelectric transport properties are investigated. Bi 0.5 Sb 1.5 Te 3 ribbons with fine nanostructure are obtained during the melt spinning process and the grain sizes of Bi 0.5 Sb 1.5 Te 3 are about 5-15 nm observed by High-resolution transmission electron microscopy. Such structure has great influence on thermoelectric transport properties of Bi 0.5 Sb 1.5 Te 3 compound. Compared with zone melting and directing SPS samples, the lattice thermal conductivity of the sample processed by melt spinning decreases significantly due to the intensive phonon scattering induced by the fine nanostructure. The greatest thermoelectric figure of merit (ZT) of 1.20 is obtained at 300K for the sample which is prepared by melt spinning with roller linear speed of 10 m/s.

关键词： Thermoelectricity Bismuth Tellurium Spinning Nanostructured materials Plasma properties Thermal conductivity Sparks Plasma materials processing Plasma transport processes

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synthesis and electrical transport properties of p-type Ba8Ga16CdxGe30−x type-I clathrates

Synthesis and electrical transport properties of p-type Ba8G...

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International Conference on Thermoelectrics (ICT)

作者： Shukang Deng Xinfeng Tang Han Li Yonggao Yan QingJie Zhang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan China

P-type Ba 8 Ga 16 Cd x Ge 30-x (x=0.95, 1.00, 1.05, 1.10) type-I clathrates with different Cd contents were synthesized by combining melt method with spark plasma sintering (SPS). The effects of Cd content on electrical transport properties have been investigated. The results show that all samples exhibit p-type conduction. The Seebeck coefficient alpha and room temperature carrier mobility mu H decrease with the increasing Cd content. The electrical conductivity sigma and the room temperature carrier concentration N p increase with the increase of Cd content. In the low temperature range (T<150 K), the carrier scattering mechanism is mainly ionized impurity mechanism, and gradually changes to an acoustical mechanism with the rising temperature. The maximum power factor value of 0.35times10 -3 Wm -1 K -2 is obtained at 550 K for Ba 8 Ga 16 Cd 1.00 Ge 29.00 .

关键词： Plasma temperature Thermal conductivity Temperature distribution Thermoelectricity X-ray scattering Plasma properties Sparks Reactive power Conducting materials Inorganic materials

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Low temperature depositing diamond films in microwave plasma CVD method and its characterization

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of technology 2007年第4期29卷 49-51+78页

作者： Wang, Lin Wang, Yong-Ming Liu, Gui-Zhen Zhou, Jian School of Information Engineering Wuhan University of Technology Wuhan 430070 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

Diamond films were deposited by using CH4/A1-/H2 gas system and silicon (111) wafers as substrate in microwave plasma CVD (MPCVD) at low temperature about 350°C . The effects of the gas system and proportion, different microwave power, and different pretreatment methods of substrate on the microstructure of diamond films were respectively discussed. The diamond film samples were investigated by X-ray-diffraction (XRD) and scanning electron microscopy (SEM). The results showed that diamond (111) peak of XRD patterns was very low because of non-diamond phase and defects. The SEM images showed that diamond films were stacked with regular ranged and about 200 nm ball-like diamond secondary nucleation particles. The diamond films are consisted of no well-faceted particles.

关键词： Argon Diamond films Low temperature MPCVD

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Influence of Particle Size and Thickness of Material on Anti-voltage Strength of Energy-storage Composite

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MRS Online Proceedings Library 2007年第1期949卷 1-7页

作者： Luo, Dabing Guo, Yan Hua, Hao Liu, Hanxing Ouyang, Shixi State Key Laboratory of Advanced Technology for Materials¡¯ Synthesis and Processing Wuhan University of Technology Hubei People’s Republic of China Material College Wuhan university of Technology Wuhan Hubei People’s Republic of China State Key Laboratory of Advanced Technology for Materials¡¯ Synthesis and Processing Wuhan University of Techology Hubei People’s Republic of China

After combining the PVDF and BST powders with different particle sizes, the anti-voltage strengths of composites was tested. Although the concentrates of ceramic were all the same, their anti-voltage strengths were distinguished. The results showed that the bigger particles or less thickness of material could benefit to the anti-voltage strength and ultimately enhanced the energy storage density of composites. Moreover, the distribution of particle dimension also influenced the strengths of materials. Composite with homogeneous particles performed higher strength than that of composites with inhomogeneous particles.

关键词： energy-storage composite strength

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Research on liquid water transport for self-humidifying membrane of PEMFC

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of technology 2007年第11期29卷 4-6+43页

作者： Zhan, Zhi-Gang Li, Da-Yong Xiao, Jin-Sheng Pan, Mu Yuan, Run-Zhang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China School of Energy and Power Engineering Wuhan University of Technology Wuhan 430063 China

The proton exchange membrane could be sufficiently hydrated when a proton exchange membrane fuel cell (PEMFC) operated normally. Based on Springer model, the equation of the distribution of water molecules number bonded with SO4 in the membrane was derived. Considering the effects of the membrane thickness, operating temperature and current density, the water transfer in the membrane was analyzed. Conclusions were drawn that the thinner the membrane can be more easily self-hydrated;the thinner the membrane was and the higher the current density was, the less the time was needed to hydrate the membrane;when the thickness was less than 15 μm and current density was higher than 0.6 A/cm2, the time was decreased drastically. The conclusions were helpful for PEMFC's design and operation.

关键词： Fuel cell Proton exchange membrane Self-humidifying Transfer Water

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Analysis of heat transfer and thermal stress in thermal and environmental barrier coatings

Analysis of heat transfer and thermal stress in thermal and ...

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作者： Xiao, Jinsheng Liu, Chunxiao Zhao, Wenhua Fu, Weibiao School of Automotive Engineering Wuhan University of Technology Hubei 430070 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Hubei 430070 China State Key Laboratory of CAD and CG Zhejlang University Hangzhou Zhejiang 310058 China Department of Engineering Mechanics Tsinghua University Beijing 100084 China

A kind of gradient thermal and environmental barrier coating applied in internal combustion engine is brought forward to improve its reliability, emission and efficiency. The multi-layer plate and cylinder models are established for the simulations of heat transfer and thermal stress in the coatings. Both the theoretical and the numerical analysis with multi-layer cylinder model with coating inside are carried out and compared. The results show good agreement.

关键词： Thermal barrier coatings

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