TG.Nieh(Lawrence Livermore National Laboratory
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P.O.Box 808
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L-350
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Livermore
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CA 94551
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USA )
材料科学技术（英文）
Intermetallic beryllides are potential light-weight, high-temperature structural materials. In this paper. the processing techniques, microstructure. deformation, and oxidation properties of intermetallic beryllides are described. In addition to nickel beryllides (NiBe). which is treated as a model system.other high beryllium-containing refractory beryllides, such as Nb2 Be17. VBe12. are also studied.The room temperature deformation and high-temperature creep properties of these beryllides are repor4ed. At room temperature. NiBe exhibits certain tensile ductility (~ 1 .3%). but all other beryllides are essentially brittle. Nonetheless, these beryllides become ductile at temperatures above approximately 1000℃. Their creep properties are presented. The creep properties are compared with those of intermetallic aluminides. Also. a comparison is made between the ductile-to-brittle transition behaviour of intermetallic beryllides and that of aluminides. Although beryllides are generally oxidation resistant at high temperatures, some beryllides, e.g., ZrBe13, suffer the pest reaction during oxidation at intermediate tem peratures. The pest mechanisms are proposed
关键词:
WADSWORTH Jeffrey and FLUSS Michael(Chemistry and Materials Science Directorate
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Lawrence Livermore National Laboratory
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Livermore
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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
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null
Corrosion Science
The early stages of the evolution of atmospheric corrosion of carbon steels exposed in both a laboratory simulated and a natural atmosphere environment in Shenyang have been observed by in situ scanning electron microscopy. In the case of laboratory cyclic wet-dry tests, even though the chloride content level is very low, filiform corrosion is initiated in the early stage. The filiform corrosion grows in random directions, forming a network of ridges. White nodules nucleate and grow on the ridges during continued corrosion and eventually connect with each other to form the initial corrosion scale. Pits were also found on the surface beneath corrosion products. In the case of a natural atmospheric environment, both filiform corrosion and other localized corrosion, such as pitting and inter-granular attack take place in the initial stage. It is obvious that there is variety of localized corrosion in the initial stage of atmospheric corrosion. (C) 2007 Elsevier Ltd. All rights reserved.
关键词:
steel;atmospheric corrosion;initial stage;localized corrosion;in-situ;iron;electrolyte;thickness
Author S.T. TU
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J.M. Gong and X. Ling Nanjing University of Chemical Technology
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Nanjing 210009
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ChinaManuscript received 18 October 1998
金属学报(英文版)
In order to interpret the test results of crossweld specimens for application in practical welded components, the present paper studies the high temperature behavior of laboratory cross weld specimens in terms of the uniaxial material tests and numerical simulations. It is found that the crossweld specimen may be used for the high temperature strength assessment, but can hardly be used for life assessment of the practical welded components, which depends on the loading conditions of the components.
关键词:
high temperature
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null
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null
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null
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null
张黎明
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李霞
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曹井国
应用化学
doi:10.3969/j.issn.1000-0518.2006.09.027
以1,8-二羟基蒽醌为对照,利用热重-差热分析仪对从大黄中分离纯化的游离羟基蒽醌(大黄酸、大黄素、芦荟大黄素、大黄素甲醚和大黄酚)进行了测定,得到这些样品的热分析图谱. 通过对其进行特征分析,结果表明各样品的TG曲线形状基本一致,但由于各单体中的1,8-二羟基蒽醌上所带基团不同,有不同的失重情况;所有苷元的DTA曲线都有2个明显的特征峰,但其峰形、峰位置和大小有明显的区别,因此可以用热重-差热分析法来鉴定从大黄药材分离纯化的游离羟基蒽醌.
关键词:
大黄
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游离羟基蒽醌
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热重法(TG)
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差热分析(DTA)
Materials Chemistry and Physics
The corrosion behaviour of CortenA weathering steel has been investigated using a laboratory accelerated test that involved cyclic wet/dry conditions in Qinghai salt lake water diluted 30 times The characteristics of the rust layers on tested samples were observed by SEM and EPMA analyzed by IRS and XRD and studied by polarization and EIS measurements The weight loss was almost linear indicating that the rust layer had no retarding effect on the corrosion process The crystalline components of the rust layers consisted primarily of beta-FeOOH magnetite (Fe(3)O(4)) and gamma-FeOOH As the corrosion proceeded the amount of beta-FeOOH decreased while that of magnetite and gamma-FeOOH increased XRD EDAX and EPMA indicated that the complex corrosion products magnesioferrite (MgFe(2)O(4)) and iowaite (Mg(4)Fe(OH)(8)OCl 4H(2)O) probably existed in the rust layer in which case they will have had an important Influence on the protectiveness of the rust layer The results of electrochemical measurements showed that the rust layer exhibited high reduction reactivity which facilitated the corrosion of weathering steel in the wetting process The large rust capacitance and small rust resistance indicated that the rust layer had a loose and porous structure which provided poor protection (c) 2010 Elsevier B V All rights reserved
关键词:
Elements;Corrosion test;Electrochemical techniques;Electron probe;low-alloy steels;atmospheric corrosion;carbon-steel;electrochemical;impedance;room-temperature;rust layers;iron;mechanism;products;environment
Surface & Coatings Technology
Using a halide-activated pack-cementation method but at a temperature (600 degrees C) noticeably lower than normal, an eta-Fe(2)Al(5) coating and two delta-Ni(2)Al(3) coatings with and without dispersions of CeO(2) nanoparticles were developed respectively on a low-carbon steel and the steel pretreated with an electrodeposited film of Ni or Ni-CeO(2). The erosion-corrosion (E-C) performance of the three aluminide coatings during 100 h exposure at similar to 600 degrees C in a coal-firing laboratory-scale fluidized-bed combustor (FBC) was investigated, by mounting the aluminized samples onto a rig which maintained rotation for accelerating the relative impacting speed of flying solid particles (mainly SiO(2) bed materials). The eta-Fe(2)Al(5) and the CeO(2)-free delta-Ni(2)Al(3) coatings experienced an unacceptable recession rate. Compared to the two CeO(2)-free aluminide coatings, the CeO(2)-dispersed delta-Ni(2)Al(3) coating offered profoundly improved E-C resistance, because the latter coating was not only strengthened by the CeO(2) dispersion and grain refinement, it also could grow a more adherent alumina scale. (C) 2011 Elsevier B.V. All rights reserved.
关键词:
Erosion-corrosion;CeO(2)-dispersion-strengthening;Aluminizing coating;Grain refinement;Hardening;Reactive element effect;oxidation resistance;reactive elements;alloy-steels;water-vapor;power-plant;nickel;combustion;mechanisms;additions;behavior
