检索结果-南通市图书馆

Synthesis and Characterization of Er3+∶Y3Al5O12 nanocrystalline Powders Prepared by Sol-Gel Method

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2006年第Z1期24卷 125-127页

作者： Li Zhanfa Yuan Duorong Duan Xiulan Shi Xuzhong Song Jian'an Wang Lihua State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China

Nano-sized Er3+∶Y3Al5O12 powders was successfully prepared via a simple sol-gel route at as low a temperature at 800 ℃ whereas a temperature much higher is necessary to obtain this compound by solid state synthesis (about 1500 ℃). The phase purity, composition and microstructural features of the materials were analyzed by means of X-ray diffraction(XRD), infrared spectroscopy(IR) and transmission electron microscopy(TEM), and no other intermediate phase were observed to form in the range of 700～1000 ℃. The luminescence spectra of Er3+ substituted for Y3+ in YAG in 1% content was characterized on samples at different temperature.

关键词： preparation YAG nanocrystalline powders sol-gel method

Crystallization process and soft magnetic properties of nanocrystalline (Fe0.5 Co0.5 ) 86 Hf7 B6 Cu1 alloy used in elevated temperature applications

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2004年第Z1期14卷 478-481页

作者： LIANG Xiu-bing J.Ferenc T.Kulik XU Bin-shi Faculty of Materials Science and Engineering Warsaw University of Technologyul. Woeoska 141 Warsaw 02-507 Poland National Key Laboratory for Remanufacturing Academy of Armored Forces Engineering Beijing 100072 China Faculty of Materials Science and Engineering Warsaw University of Technologyul. Woeoska 141 Warsaw 02-507 Poland Faculty of Materials Science and Engineering Warsaw University of Technologyul. Woeoska 141 Warsaw 02-507 Poland National Key Laboratory for Remanufacturing Academy of Armored Forces Engineering Beijing 100072 China

nanocrystalline (Fe0.5 Co0.5 )86 Hf7 B6 Cu1 HITPERM alloy was investigated as the candidate of soft magnetic material for high temperature applications, compared with Fe86 Hf7B6 Cu1 NANOPERM alloy. Amorphous alloy ribbons were prepared by single-roller melt-spinning technology. Crystallization process of as-quenched ribbon was investigated using differential scanning calorimeter at different heating rates. The coercivity was determined from quasi-static hysteresis loop measured at room temperature using a computerized hysteresis loop tracer. X-ray diffraction with Cu Kα radiation was used to determine the structure. The vibrating sample magnetometer was usedto measure the magnetization as a function of temperature of the nanocrystllized alloys. That Co substitution for Fein alloy enhances the Curie temperature of amorphous alloy and the magnetization of nanocrystalline alloy at hightemperature. After annealing amorphous precursor, the optimum nanocrystalline alloy obtained shows the local minimum coercivity. The coercivity increases with the increasing annealing temperature corresponding to the formation of ferromagnetic phase in the secondary crystallization.

关键词： nanocrystalline soft magnetic material crystallization process activation energy coercivity magnetization

Molecular Dynamic Simulation of Lattice Distortion Region Produced by Rounded Grain Boundary in nanocrystalline Materials

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2002年第3期18卷 254-256页

作者： XiaoweiWANG J.Rifkin 等 ShenyangNationalLaboratoryforMaterialsScience InstituteofMetalResearchChineseAcademyofSciencesShenyang110016China InstituteofMaterialsScience UniversityofConnecticutUSA

The distortion structure in nanocrystalline NiAl is studied using molecular dynamics simulation. The rounded grain boundaries in these nanograins are a direct source for the observed lattice distortion. The change of ... 详细信息

关键词： Molecular dynamic simulation nanocrystalline Distortion region

Synthesis,Characterization and Electromagnetic Studies on nanocrystalline Co_(0.5)Zn_(0.5)Fe_2O_4 Synthesized by Polyacrylamide Gel

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2008年第3期24卷 628-632页

作者： Ruiting MA Yanwen TIAN Haitao ZHAO Gang ZHANG Hui ZHAO School of Materials Science and Engineering Shenyang Ligong University Shenyang 110168 China School of Materials and Metallurgy Northeastern University Shenyang 110004 China

nanocrystalline Co0.5Zn0.5Fe2O4 ferrite was synthesized by polyacrylamide gel method. The electromagnetic and microwave absorption properties of the ferrite were investigated. The results indicated that calcining temperature of the ferrite had a significant influence on the effective properties of the ferrite. When the calcining temperature was 500, 600 and 700℃, the average size of particles was 10, 30 and 80 nm, respectively. The dielectric loss （ε″） and magnetic loss （μ″） of the ferrite was around 0.65 and 0.29 at 8.2 GHz, respectively. Microwave absorption properties of the ferrites were simultaneously influenced due to the strong correlation between reflection loss and electromagnetic parameters of the ferrite.

关键词： Polyacrylamide gel nanocrystalline Co0.5Zn0.5Fe2O4 Electromagnetic properties

Thermal stability of nanocrystalline layer prepared by surface mechanical attrition in 0Cr18Ni9Ti stainless steel

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2004年第Z1期14卷 210-214页

作者： WANG Hong-bin WU Xiao-chun XU Ling-yun School of Materials Science and Engineering Shanghai University Shanghai 200072 China School of Materials Science and Engineering Shanghai University Shanghai 200072 China School of Materials Science and Engineering Shanghai University Shanghai 200072 China

By means of surface mechanical attrition (SMA), a nanostructured surface layer was formed on a 0Cr18Ni9Ti austenite stainless steel plate. A strain-induced martensite transformation was observed during SMA treatment, and a single magnetic martensite phase layer with thickness of about 30 μm was gotten. The grain growth and phase transformations in the nanocrystalline layer are investigated during heating. The grain growth exponent for nanocrystalline polycrystalline steel is estimated. The kinetics mechanism governing the grain growth in the nanocrystalline layer is discussed. The martensite in the surface layer is quite stable and the temperature at which the reverse transformation of martensite to austenite starts during heating is about 500 ℃.

关键词： grain growth phase transformation surface mechanical attrition surface nanocrystalline layer

Effect of Electroplating Parameters on Microstructure of nanocrystalline Nickel Coatings

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2010年第1期26卷 82-86页

作者： A.M. Rashidi A. Amadeh Faculty of Engineering Razi University School of Metallurgy & Materials Engineering University College of Engineering University of Tehran

In order to achieve the optimum conditions for electroplating nanocrystalline nickel coating from Watts-type bath, the effect of some process parameters namely, bath temperature, current density, and saccharin addition on grain size and texture coefficient （TC= I（200）/I（111）） of the deposits were investigated by X-ray diffraction （XRD）. The results showed that in a bath containing 5 g/L saccharin, by increasing the bath temperature from 45℃ to 55℃, the grain size decreased, whereas further increase of bath temperature resulted in a contrary effect. By increasing the current density from 10 to 75 mA/cm^2, both the grain size and TC decreased, while further increase in current density had no significant effect on the grain size. At a given current density, the grain size and TC decreased rapidly by increasing the saccharin content before leveling off at 3 g/L of saccharin. Finally, based on the grain refining the optimum conditions for producing nanocrystalline nickel coating from Watts-type bath have been proposed.

关键词： Electroplating Grain size nanocrystalline Coating

Study on nanocrystalline Rare Earth Mg-Based System Hydrogen Storage Alloys with AB_3-Type

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2006年第Z2期24卷 343-346页

作者：唐仁衡卢其云肖方明彭能王英 Research Institute of Rare Metal Guangzhou Research Institute of Non-Ferrous Metals

A sort of rare earth Mg-based system hydrogen storage alloys with AB3-type was prepared by double-roller rapid quenching method. The alloys were nanocrystalline multi-phase structures composed of LaNi3 phase and LaNi5 phase by X-ray diffraction and scanning electron microscopy analyses, and the suitable absorption/desorption plateau was revealed by the measurement of P-C-I curve. Electrochemical studies indicate that the alloys exhibit good electrochemical properties such as high capacity and stable cycle life, and the discharge capacity is 369 mAh·g-1 at 0.2 C (72 mA·g-1), after 460 cycles, the capacity decay was only 19.4% at 2 C (720 mA·g-1).

关键词： nanocrystalline double-roller rapid quenching rare earth Mg-based compounds hydrogen storage alloy

Synthesis and characterization of nanocrystalline Ni produced by cryomilling in liquid nitrogen

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2007年第2期26卷 147-151页

作者： YANG Bin FAN Jianzhong HAO Bin TIAN Xiaofeng CHENG Junsheng ZHANG Jishan State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China International Centre for Materials Physics Chinese Academy of Sciences Shenyang 110016 China National Engineering and Technology Research Center for Nonferrous Metals Composites General Research Institute for Nonferrous Metals Beijing 100088 China

NanocrystaUine Ni powders were successfully fabricated by mechanically milling at cryogenic temperature （cryomilling） with 1 wt.%Y2O3 particles. The experimental results have shown that the Ni grain size is reduced to 25 nm after 2 h of cryomilling in the presence of the Y2O3 particles. The cryomiUed Ni/Y2O3 powders can maintain their nanocrystalline structure up to 900℃, or 62% of the melting point of Ni. A bulk nanocrystalline Ni/Y2O3 material with a thermally stable grain size of approximately 100 nm was produced by cryomilling, cold isostatic pressing, followed by hot isostatic pressing. The microhardness of bulk nanocrystalline Ni/1wt.%Y2O3 is 315 DPH, which is two times as high as that of conventional Ni.

关键词： nanocrystalline mechanical milling nickel characterization

Highly oriented NdFeB nanocrystalline magnets from partially recombined compacts with ultrafine grain size by reactive deformation under low pressure

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2015年第12期33卷 1298-1302页

作者：余云萍李军刘颖王仁全郑青连利仙 College of Materials Science and Engineering Sichuan University

The partially recombined compacts with ultrafine grain size were taken advantage of preparing anisotropic nanocrystalline magnets with full density and homogenous microstructure and texture by reactive deformation under low pressure. Because of the ul- trafine grain size of the precursors, the partially recombined phases could quickly achieve recombination. The results suggested that the newly recombined Nd2Fe14B grains with fme grain size could undergo deformation immediately during the desorp- tion-recombination reaction, and then an obvious anisotropy and uniform alignment would be obtained. The magnetic properties, （BH）max=214 kJ/m3, Br= 1.26 T, Hcj=463 kA/m, were obtained after being treated for 5 min at 820 ℃ in high vacuum under low pres- sure less than 26 MPa. Microstructures of the magnets were analyzed using X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM） respectively. Magnetic measurements were carried out using a vibrating sample magnetometer （VSM） with the maximum field of 2.88 T. Accurate phase contents were measured by a Mossbauer spectrometer.

关键词： NdzFe14B nanocrystalline HDDR deformation anisotropy rare earths