This paper describes the generation of high current sheet beam directly from Scandia doped dispenser cathode and their possible application in THz sources.
ISBN:
(纸本)9781424414383
This paper describes the generation of high current sheet beam directly from Scandia doped dispenser cathode and their possible application in THz sources.
A new approach in combination of the effective medium theory with the equivalent unit in numerical simulation was developed to study the effective thermal conductivity of porous ceramics. The finite element method was...
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A new approach in combination of the effective medium theory with the equivalent unit in numerical simulation was developed to study the effective thermal conductivity of porous ceramics. The finite element method was used to simulate the heat transfer process which enables to acquire accurate results through highly complicated modeling and intensive computation. An alternative approach to mesh the material into small cells was also presented. The effective medium theory accounts for the effective thermal conductivity of cells while the equivalent unit is subsequently applied in numerical simulation to analyze the effective thermal conductivity of the porous ceramics. A new expression for the effective thermal conductivity, allowing for some structure factors such as volume fraction of pores and thermal conductivity, was put forward, and the results of its application was proved to be close to those of the mathematical simulation.
Mesocarbon microbeads （MCMB） and super fine mesophase powder （SFMP） were prepared firstly from a coal tar pitch and then hot-condensed into high-density isotropic carbon （HDIC） bulks under 160 MPa and finally si...
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Mesocarbon microbeads （MCMB） and super fine mesophase powder （SFMP） were prepared firstly from a coal tar pitch and then hot-condensed into high-density isotropic carbon （HDIC） bulks under 160 MPa and finally sintered at 1 000 ℃. By analyzing the thermogravimetric behavior of the MCMB and SFMP powders, their volume shrinkage and weight loss during sintering and the bulk density and flexural strengths of their sintered bulks, it was found that the smaller sizes and the richer β-resin contents of SFMP ha）re facilitated formation of sintered bulks with more compact isotropic structure and higher flexural strengths than MCMB. Because of the filling and bonding effects of SFMP on MCMB bulks, addition of SFMP, albeit a little, can greatly increase the flexural strengths of sintered bulks of MCMB. However, adding MCMB, even a slight amount, into SFMP can severely impair the flexural strength of sintered bulks. This might be attributed to both the crack initiation along the boundaries between MCMB and SFMP and the formation of layered texture of MCMB sphere.
Micro-arc oxidation （MAO） is an enhanced chemical technology in an electrolyte medium to obtain coating structures on valve-metal surfaces. Titanium oxide films obtained by MAO in the sodium phosphate electrolyte we...
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Micro-arc oxidation （MAO） is an enhanced chemical technology in an electrolyte medium to obtain coating structures on valve-metal surfaces. Titanium oxide films obtained by MAO in the sodium phosphate electrolyte were investigated. The films were composed mainly of TiO2 phases in the form of anatase and mille and enriched with Na and P elements at the surface. Their apafite-inducing ability was evaluated in a simulated body fluid （SBF）. When immersing in SBF for over 30 d, a preferential carbonated-hydroxyapatite was formed on the surfaces of the films, which suggests that the MAO-treated titanium has a promising positive biological response.
作者：
李国元任力School of Materials Science and Engineering
Nanyang Technological UniversitySingapore 639798 School of Materials Science and Engineering
Nanyang Technological UniversitySingapore 639798Key Laboratory of Specially Functional Materials and Advanced Manufacturing TechnologyInstitute of Materials Science and EngineeringSouth China University of TechnologyGuangzhou 510640China
A nonlinear optical (NLO) active alkoxysilane chromophore (SGDR1) was synthesized. A fluorinated polyimide/SGDR1 composite was prepared to improve the poor temporal stability of second-order NLO effects of the reporte...
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A nonlinear optical (NLO) active alkoxysilane chromophore (SGDR1) was synthesized. A fluorinated polyimide/SGDR1 composite was prepared to improve the poor temporal stability of second-order NLO effects of the reported poled sol-gel film. The poled composite film was characterized by FTIR, DSC, TGA and UV-Vis. The composite displays good hydrophobic properties, high glass transition temperature (266 ℃), and high decomposition temperature (433 ℃). The second harmonic coefficient d33 of the composite was measured to be 16.77 pm/V by using maker fringe technique. The new NLO composite exhibits 85 % of the original d33 over 720 h at 100 ℃ and possesses much better stability than the reported sol-gel film.
Super-fine mesophase powder (SFMP) was prepared from a coal tar pitch accompanying mesocarbon microbeads (MCMB) and then was manufactured into high density and isotropic carbon (HDIC) bulks. The influence of ß-re...
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ISBN:
(纸本)9781605600390
Super-fine mesophase powder (SFMP) was prepared from a coal tar pitch accompanying mesocarbon microbeads (MCMB) and then was manufactured into high density and isotropic carbon (HDIC) bulks. The influence of ß-resin content in SFMP precursors and sintering conditions has been studied on the performance of derived HDIC. It has found that, to obtain HDIC with excellent mechanical performance, suitable ß-resin content in SFMP and sintering rate are required. In the sintering range of 470°C-1000°C, higher temperature facilitate the formation of compact HDIC with high flexural strength. Volume shrinkage during sintering can be adopted to val-ate approximately the mechanical performance.
The effect of the ground granulated blast-furnace slag （ GGBFS ） addition, the modulus n （ mole rutio of SiO2 to Na2O ） and the concentrution of sodium silicate solution on the compressive strength of the materi...
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The effect of the ground granulated blast-furnace slag （ GGBFS ） addition, the modulus n （ mole rutio of SiO2 to Na2O ） and the concentrution of sodium silicate solution on the compressive strength of the material, i e alkuli-activated carbonatite cemeutitious material （ AACCM for short ） was investiguted. In addition, it is found that barium chloride has a sutisfiwtory retarding effect on the setting of AACCM in which more than 20% （ by mass ） ground carbonatite was replaced by GGBFS. As a result, a cementitious material, in which ground carbonatite rock served as dominative starting material, with 3-day and 28-day compressive strength greuter them 30 MPa and 60 MPa and with continuous strength gain beyond 90 days was obtained.
Residual stresses in ion-implanted NiTi alloy are measured by a combined method ofMoir6 interferometry and hole-drilling. Oxygen ions are implanted into the NiTi alloy under a voltage of 30 kV by a dose of 1.0×10...
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Residual stresses in ion-implanted NiTi alloy are measured by a combined method ofMoir6 interferometry and hole-drilling. Oxygen ions are implanted into the NiTi alloy under a voltage of 30 kV by a dose of 1.0×10^17ions/cm^2 for one hour. Subsequently, in order to avoid dimensional error, a hole is drilled exactly in the center of the sample. The distribution of residual stresses around the hole is measured. It is indicated that the method which combines the Moire interferometry with hole-drilling is able to be used to measure residual stresses produced by ion implantation.
The method of numerical simulation is used to fit the relationship between the photoconductivity in films and the illumination time. The generation and process rule of kinds of different charged defect states during i...
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The method of numerical simulation is used to fit the relationship between the photoconductivity in films and the illumination time. The generation and process rule of kinds of different charged defect states during illumination are revealed. It is found surprisingly that the initial photoconductivity determines directly the total account of photoconductivity degradation of sample.
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