材料期刊网

芳香/脂肪族共聚脲多孔膜的微观形态及其性能的初步研究

李雪莲 , 朱利民 , BRANFORD-WHITE Christopher , 陈大俊

膜科学与技术 doi:10.3969/j.issn.1007-8924.2010.01.009

在相同制膜条件下,采用扩散致相转化法制备了芳香/脂肪族共聚脲多孔膜.通过对孔隙率、力学性能的测试及扫描电镜的微观分析,讨论了凝胶浴体系中溶剂的体积百分数及同类制膜大分子的不同链段结构对膜微观结构和机械性能的影响.实验结果表明:随着凝固浴中溶剂体积百分含量的增加,多孔膜表面的微孔直径逐渐增大;而相应截面的指状孔有缩小的趋势,直到最终消失而形成完全海绵状孔的截面形态;制膜大分子本身的结构对膜形态结构及性能有重大影响:三种共聚脲多孔膜都具有非对称结构,不同结构的共聚脲制备出的多孔膜各自的表面、截面形态都不相同;多孔膜的机械性能也都各不相同,其中芳香族共聚脲多孔膜具有最好的机械性能.

关键词: 芳香/脂肪族 , 共聚脲 , 多孔膜 , 膜形态 , 膜性能

Rheocast structure in a hypoeutectic high chromium white iron

Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing

The rheocast structure in a hypoeutectic high chromium white iron was studied. By analyzing the microstructure of the special subgrain boundaries, it was found that the solute enriched special subgrain boundaries, usually thought to be the boundaries of agglomerated separated grains, were in fact evolved from bent thin roots of dendrite arms. Further examination of the relationship between cooling rate and grain size revealed that a dendrite arm with a thin root could be bent or sheared off. At the cooling rate that favors the formation of thin rooted long dendrite arms, a fine rheocast structure can be gained. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词: high chromium white iron;rheocast structure;subgrain boundary;semisolid state;alloy;solidification;behavior;flow

INFLUENCES OF MODIFIERS ON SURFACE PROPERTIES OF WHITE CARBON BLACK AND MECHANICAL PROPERTIES OF SILICONE RUBBER

D.M. Zheng , J. Yan and B.Q. Jiang Chemical Engineering Department of Nanchang University , Nanchang 330029 , China

金属学报(英文版)

Various of modifiers were used to modify the surface activity of white carbon black. The oil absorption, viscosity, hydrophobic rate and burning loss of white carbon black and the mechanical propertiess of silicone rubber were measured. The influences of the modifiers on the properties of white carbon black and the mechanical properties of silicone rubber were discussed.

关键词: white carbon black , null , null

STRUCTURAL CHANGE IN HEAT AFFECTED ZONE AND ITS INFLUENCE ON PROPERTIES OF WELDED WHITE CAST IRON

ZOU Zengda WANG Yong REN Dengyi Shandong Polytechnic University , Jinan , China

金属学报(英文版)

The structural change in heat affected zone(HAZ)and its influence on properties of welded white cast iron have been investigated by means of thermal cycle simulation technique.The structure of the white cast iron at peak temperature 800℃ was examined as cementite in pearlitic matrix,of which the hardness and impact toughness are the lowest,while the struc- ture after cyclic heating at high peak temperature is mainly cementite together with twin martensite,of which the hardness and impact toughness are rather higher.The phase bounda- ries in the structure of low hardness are smooth and regular as well as with fine precipitates. Both the cleavage and interphase fracture were revealed in the structure of low hardness,while the transgranular fracture was found in those areas of higher hardness.

关键词: white cast iron , null , null

Transparent Ce:Y3Al5O12 ceramic phosphors for white light-emitting diodes

Applied Physics Letters

We present our recent achievement of a transparent ceramic able to produce white light when directly combined with commercially available blue light emitting diodes. The photoluminescence properties of ceramic phosphor (Y1-xCex)(3)Al5O12 are studied as a function of doping fraction (x = 0.0005-0.0020). The emission color is tunable by variations of Ce3+ concentration and ceramic phosphor thickness. A maximum luminous efficacy exceeding 93 lm/W at a low correlated color temperature of similar to 4600 K is obtained, which is superior to samples made from commercial phosphor powders. Hence, the present transparent ceramic phosphor is expected to be an ideal candidate for generating white light. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4742896]

关键词: optical-properties;luminescence;emission;color

Application of Rietveld Refinement to Investigate the High Chromium White Cast Iron Austempered at Different Temperatures

HOU Qingyu , HUANG Zhenyi , WANG Jingtao

钢铁研究学报(英文版)

The effect of austempering temperature on the microstructure and properties of a high chromium white cast iron was investigated with the Rietveld refinement method. The result shows that the upper bainite exists in the sample austempered at 623 K and the martensite, lower bainite, M7C3, and retained austenite exist in the samples austempered at 563 K and 593 K. The relative content of the retained austenite increases with increasing the austempering temperature from 563 K to 623 K. The higher hardness, impact toughness and impact abrasive wear resistance can be obtained for the specimen austempered at 593 K.

关键词: high chromium white cast iron;austempering;retained austenite;Rietveld refinement;microstructure;properties

Effect of Boron and Heat Treatment on Mechanical Properties of White Cast Iron for Mining Application

Havva Kazdal Zeytin , Hakan Yildirim , Banu Berme , Selim Duduolu , Gürkan Kazdal , Adem Deniz

钢铁研究学报(英文版)

Heat treatment methods were applied to white cast iron for improving the impact and wear resistance. Additionally, chemical composition optimization was made. Furthermore, the effect of boron addition on such applications was investigated. Samples were investigated by using optical and electron microscope methods. Hardness, wear and impact tests were conducted. The results showed that the secondary carbides in the standard alloy were iron-enriched, needle-like carbides M3C when the boron-added alloy contained Fe23(C,B)6 type, globular secondary carbides. It was concluded that heat treatment B provided higher wear and hardness properties, compared to the standard heat treatment. Optimum mechanical properties were obtained by lower destabilisation temperatures and increasing temperature reduced the wear resistance and hardness.

关键词: white cast iron , mining application , impact resistance , wear , toughness

Flexible White Organic Light-Emitting Diodes Based on Single-Walled Carbon Nanotube:Poly(3,4-ethylenedioxythiophene)/Poly(styrene sulfonate) Transparent Conducting Film

Japanese Journal of Applied Physics Part 1-Regular Papers Brief Communications & Review Papers

Single-walled carbon nanotube:poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) hybrid film (SWCNT:PEDOT/PSS) hybrid conducting film was obtained by using spray-coating technique, based on which a white flexible organic light emitting diode (FOLED) was fabricated with the structure of SWCNT:PEDOT/PSS/N,N-diphenyl-N,N-bis(1-napthyl)-1,1-biphenyl-4,4-diamine/5,6,11,12-tetraphenylnaphthacene:4,4'-bis(2,2'-diphenylvinyl)-1,1'-biphenyl/4,7-diphenyl-1,1'-phenanthroline/LiF/Al. The hybrid film exhibited superior surface morphology, electrical conductivity to the pure SWCNT network. The as-fabricated FOLED showed a stable white emission that is close to the equi-energy white point upon bending, and the light-emitting efficiency of the device was significantly improved by using the hybrid film as anode. The hybrid film holds promise for application in flexible lighting and display. (C) 2012 The Japan Society of Applied Physics

关键词: solar-cells;electrodes;nanotubes;flexibility;pedot/pss

Growth Defects in Langasite Crystals Observed with White Beam Synchrotron Radiation Topography

稀土学报(英文版)

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Growth Defects in Langasite Crystals Observed with White Beam Synchrotron Radiation Topography

稀土学报(英文版)

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