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
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
Minh-Quy LE
,
Seock-Sam KIM
材料科学技术（英文）
Finite element analysis was carried out to investigate the conical indentation response of elastic-plastic solids within the framework of the hydrostatic pressure dependence and the power law strain hardening. A large number of 40 different combinations of elasto-plastic properties with n ranging from 0 to 0.5 and σy/E ranging from 0.0014 to 0.03 were used in the computations. The loading curvature C and the average contact pressure pave were considered within the concept of representative strains and the dimensional analysis. Dimensionless functions associated with these two parameters were formulated for each studied value of the pressure sensitivity. The results for pressure sensitive materials lie between those for Von Mises materials and the elastic model.
关键词:
Finite element analysis
,
null
,
null
,
null
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
Chinese Physics Letters
The electron paramagnetic resonance spectra of trigonal Mn(2+) centers in ZnNbOF(5)center dot 6(H(2)O) and CoNbOF(5)center dot 6(H(2)O) crystals are studied on the basis of the complete energy matrices for a d(5) configuration ion in a trigonal ligand field. It is demonstrated that the local lattice structure around a trigonal Mn(2+) center has an elongation distortion along the crystalline c(3) axis, and when Mn(2+) is doped in the ZnNbOF(5)center dot 6(H(2)O) and CoNbOF(5)center dot 6(H(2)O) crystals, there is a similar local distortion. From the EPR calculation, the local lattice structure parameters for trigonal Mn(2+) centers in ZnNbOF(5)center dot 6(H(2)O) and CoNbOF(5)center dot 6(H(2)O) are determined.
关键词:
phase-transition;ions;complexes;crystals;spectra;fe-3+;epr
Hongsheng DING
,
Jun JIA
,
Jingiie GUO
,
Yanqing SU
,
HengZhi FU
,
Jinshan LI
材料科学技术（英文）
A thermodynamic model has been built up for the interactions between molten Ti alloys and oxide molding materials in the way of decomposition and solution of molding materials, then the influences on the reaction free energy changes have been calculated and discussed.
关键词:
Physica B-Condensed Matter
On the basis of the defect model of trigonal Dy3+-O2- center in CaF2, the EPR parameters (g factors and hyperfine structure constants) for this trigonal center are calculated from the perturbation formulas. In the formulas, the contributions to EPR parameters due to the J-mixing among H-6(J) (J = 15/2, 13/2 and 11/2) states, the mixtures among the states with the same J-value and those between the lowest Kramers doublet Gamma(gamma) and other Kramers doublets Gamma(X) are included. In the calculation, the crystal field parameters are estimated from the superposition model. From the calculation, the EPR g factors g(\\), g(perpendicular to) are reasonably explained and the superposition model intrinsic parameters (A) over bar (2)(F-) and (A) over bar (2) (O2-) with R = 2.366 Angstrom are obtained. (C) 2003 Elsevier B.V. All rights reserved.
关键词:
EPR parameters;crystal-field theory;superposition model;Dy3+;CaF2;electron-paramagnetic-resonance;field parameters;single-crystals;ions
