Hongtao SUN
,
Hongfang WANG
,
Liangying ZHANG and Xi YAO(Electronic Materials Research Laboratory
,
Xi'an Jiaotong University
,
Xi'an
,
710049
,
China)
材料科学技术（英文）
Under the mechanically free and clamped boundary conditions, electromechanical resonances of ceramic multilayer capacitors are calculated using vibration and piezoelectric equations. Multilayer capacitors made of ferroelectric BaTiO3 and Pb(Mg1/3Nb2/3)O3 ceramics have been used to examine the theoretical calculation. Frequency spectra of impedance and phase angle, capacitance and loss tangent of the capacitors under dc bias fields are carefully measured. A sudden change around the resonant frequency is observed in these spectra. A damped resonance indicates a defective capacitor while an undamped resonance is corresponding to defect free.Experimental results suggest that it is possible to use the spectra as a real time nondestructive evaluation method.
关键词:
Masahiko MORINAGA
,
Yoshinori MURATA
,
Hiroshi YUKAWA
材料科学技术（英文）
A molecular orbital approach to materials design has recently made great progress. This approach is based on the electronic structure calculations by the DV-Xα cluster method. In this paper recent progress in this approach is reviewed. In particular, it is stressed that New PHACOMP approach is useful for predicting the formation of topologically close-packed (TCP) phases (e.g., σ phase and μphase ) in nickel based superalloys. Compared to the current PHACOMP, New PHACOMP provides a better tool for designing those alloys which are free from such TCP precipitates at service temperatures. In addition, the d-electrons concept is shown for alloy design and development.
关键词:
High temperature materials
,
null
,
null
,
null
WADSWORTH Jeffrey and FLUSS Michael(Chemistry and Materials Science Directorate
,
Lawrence Livermore National Laboratory
,
Livermore
,
CA 94551)
金属学报(英文版)
The role of the National Laboratories is summarized from the era of post World War II to the present time. The U.S. federal government policy for the National Laboratories and its influence on their materials science infrastructure is reviewed with respect to .determining overall research strategies, various initiatives to interact with industry (especially in recent years),building facilities that serve the nation, and developing leading edge research in the materials sciences. Despite reductions in support for research in the U.S. in recent years, and uncertainties regarding the specific policies for Research &Development (R&D) in the U.S., there are strong roles for materials research at the National Laboratories. These roles will be centered on the abilities of the National Laboratories to field multidisciplinary teams, the use of unique cutting edge facilities, a focus on areas of strength within each of the labs,increased teaming and partnerships, and the selection of motivated research areas. It is hoped that such teaming opportunities will include new alliances with China, in a manner similar, perhaps, to those recently achieved between the U.S. and other countries.
关键词:
: U.S. Materials Science. U.S. National Laboratories and Facilities
,
null
W.GAOZ.W.LI
中国腐蚀与防护学报
Oxidation of metallic components often results in degradation and structural failure, prevention is therefore an important topic. On the other hand, oxidation process creates new products such as metal oxides, can be used as a production route. A well-known process in semiconductor industry is that oxidation in dry or wet atmosphere is a popular way for growth of multi-functional SiO2 films on Si wafers. Recently, oxidation processes under controlled conditions (atmosphere, temperature, and time) are used to prepare various oxides, carbides, or nitrides with micro-/nano-structures, well-defined composition, dimension, shape and properties. The use of oxidation now includes thin film and nano-/micro-sized devices, and porous oxides for sensing and catalysis purposes. This paper introduces the research activities in the authors' group on applications of oxidation as a tool for synthesis of functional materials.
关键词:
oxidation
,
null
,
null
,
null
G.Q. Zhang
金属学报(英文版)
The status of research, development of superalloys and materials processing & fabrication technologies for aero-engine applications in China Aviation Industry, with an emphasis on recent achievements at BIAM including directionally solidified and single crystal superalloys for blade and vane applications, wrought superalloys for aero-engine disks and rings, and powder metallurgy (PM) superalloys for high performance disk applications were described. It was also reviewed the development of new class of high temperature structural materials, such as structural intermetallics, and advanced material processing technologies including rapid solidification, spray forming and so on. The trends of research and development of the above mentioned superalloys and processing technologies are outlined. Cast, wrought and PM superalloys are the workhorse materials for the hot section of current aero-engines. New high temperature materials and advanced processing technologies have been and will be the subject of study. It is speculated that high performance, high purity and low cost superalloys and technologies will play key roles in aero-engines.
关键词:
superalloy
,
null
,
null
新型炭材料
The state-of-the-art research and development of various carbons for possible application as the electrode material in electrochemical capacitors (ECs) are summarized. The main factors affecting the properties of ECs are carefully reviewed, from the material characteristics such as specific surface area, pore size distribution and pore volume, surface functional groups and graphitic orientation of the carbon materials, to the electrode characteristics and electrochemical aspects such as electrode preparation process, electrode density and thickness, electrode conductivity and pseudo-capacitance, etc. In particular, an overview is given of the most recent progress in electrochemical capacitors using carbon nanotubes as the electrode material and the prospect of their use in this application is highlighted.
关键词:
electrochemical capacitors;carbon electrode;carbon nanotubes;double-layer capacitors;activated carbon;nanotube electrodes;supercapacitor electrodes;organic electrolyte;deposition;fiber
新型炭材料
Electrochemical capacitors (ECs) store energy in eletric double-layers formed along the interface of electrode material and electrolyte, this produces an extremely large capacitance compared with the traditional capacitors. The fundamental principles of electrochemical capacitors are briefly introduced, and the key materials used like electrode materials, electrolytes, separator and current collector materials are summarized. Electrochemical capacitors with pseudocapacitance, such as metal oxides, polymers and hybrid capacitors, are also discussed. The characteristics, possible application fields, the development state, the future R&D prospects for electrochemical capacitors are highlighted.
关键词:
electrochemical capacitors;supercapacitors;storage of electric energy;principles
J Y Wu
,
Z.M. Tang
,
W Shi andR.Z. Wang (Institute of Refrigeration and Cryogenics Engineering
,
Shanghai Jiao Tong University
,
Shanghai 200030
,
China)
金属学报(英文版)
A transient method with rectangular pulse heating has been developed to measure the thermal conductivity of highly porous materials such as activated carbon, zeolite and silica gel. By this method the thermal conductivity can be measured quickly and accu-rately. In this paper, a set of automatically controlled testing equiptnent is presented.The measuring method is analysed. The thermal conductivities of some samples, such as activated carbon and zeolite, are measured by the equipment. A group of useful data has been obtained.
关键词:
thermal conductivity
,
null
,
null
