M.H.Khedr
材料科学技术（英文）
CO2 is a major component of the greenhouse gases, which causes the global warming. To reduce CO2 gas, high activity nanosized Ni+2 substituted Fe2TiO5 samples were synthesized by conventional ceramic method. The effect of the composition of the synthesized ferrite on the H2-reduction and CO2-catalytic decomposition was investigated. Fe2TiO5 (iron titanate) phase that has a nanocrystallite size of ~80 nm is formed as a result of heating Fe2O3 and TiO2 while the addition of NiO leads to the formation of new phases (~80 nm) NiTiO3 and NiFe2O4, but the mixed solid of NiO and Fe2O3 results in the formation of NiFe2O4 only. Samples with Ni+2=0 shows the lowest reduction extent (20%); as the extent of Ni+2 increases, the extent of reduction increases. The increase in the reduction percent is attributed to the presence of NiTiO3 and NiFe2O4 phases, which are more reducible phases than Fe2TiO5. The CO2 decomposition reactions were monitored by thermogravimetric analysis (TGA) experiments. The oxidation of the H2-reduced Ni+2 substituted Fe2TiO5 at 500℃ was investigated. As Ni+2 increases, the rate of reoxidation increases. Samples with the highest reduction extents gave the highest reoxidation extent, which is attributed to the highly porous nature and deficiency in oxygen due to the presence of metallic Fe, Ni and/or FeNi alloy. X-ray diffraction (XRD) and transmission electron microscopy (TEM) of oxidized samples show also the presence of carbon in the sample containing Ni+2>0, which appears in the form of nanotubes (25 nm).
关键词:
Nanocrystallite
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M.H.Khedr
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A.A.Farghali
材料科学技术（英文）
Copper ferrite, CuFe2O4, one of the important ferrites due to its interesting electrical, magnetic and structural properties, is obtained by a novel self flash combustion of a homogeneous mixture of one mole copper acetate monohydrate, Cu(CH3COO)2•H2O, and two moles of iron (III) acetate basic, Fe(CHCOO)2•OH. Nanocrystalite (89 nm) copper ferrite (less than 100%) is obtained at lower temperatures, whereas 100% copper ferrite is obtained after calcination at 1000℃. Thermal analysis (TG and DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), photo microscopy, magnetic and porosity measurements have been carried out for the specimens obtained after calcinations at 700, 800, 900 and 1000℃ to characterize the conversion efficiency of the powder precursors to copper ferrite. It was found that increasing temperature leads to great improvement in the magnetic properties. By increasing calcination temperature from 700～1000℃ saturation magnetic flux density (Bs) increased from 17.8 to 40.8 emu/g, while remnant magnetic flux density (Br) increased from 10.1 to 17.11 emu/g.
关键词:
Copper ferrite
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null
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null
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Xinbin HU
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Mei ZHANG
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Xiaochun WU
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Lin LI
材料科学技术（英文）
Based on the local equilibrium assumption, coarsening behavior of M23C6 carbide at 700℃ in H13 steel was simulated by DICTRA software. The results from the calculations were compared with transmission electron microscopy (TEM) observations. The results show the interfacial energy for M23C6 in H13 steel at 700℃ is thus probably 0.7 J•m-2, which fits the experiments well. The influence of composition and temperature on the coarsening rate was also investigated by simulations. Simulations show a decrease in the coarsening rate when V/Mo ratio is increased, while the coarsening rate increases with increasing temperature.
关键词:
DICTRA Simulation
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碳化物粗化
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界面能
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H13钢
Yong LIU
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Baiyun HUANG
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Kechao ZHOU
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Hongwu OUYANG
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Yuehui HE
材料科学技术（英文）
In order to overcome the shortcomings of conventional hot pressing, a novel near net-shape technique, called radial hot pressing, for P/M parts with large height-to-diameter (H/D) ratio was introduced. Effects of processing parameters on the microstructures and density of P/M TiAl base alloy valves were studied. Results show that the radial hot pressing is an effective technique for manufacturing valves with a H/D ratio of about 10:1, and the perfect joint interface between the Mo sheet and the parts is helpful for subsequent HIPing.
关键词:
Near net-shape technique
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刘红斌
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龚承元
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苏建勇
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朱孟府
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马军
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张西正
膜科学与技术
doi:10.3969/j.issn.1007-8924.2002.03.014
介绍了工业规模的EDI膜堆和1 m3/h RO-EDI高纯水设备的研制情况,进行了设备的稳定性试验和EDI产水的水质分析,并与离子交换树脂进行了技术经济性能比较.
关键词:
电去离子
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反渗透
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制药用水
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高纯水
刘金荣
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黄焦宏
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金培育
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李满才
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成永顺
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徐来自
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邱巨峰
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杨保荣
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杨文志
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王贵
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王正德
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张泽玉
稀土
doi:10.3969/j.issn.1004-0277.2001.06.011
为了选择合适的磁制冷材料,得到材料的磁热效应,即ΔS-T曲线,必须测出材料在不同温度下的M-H曲线.我们采用脉冲磁场的方式提供测试所需的高磁场,自行研制了符合测试精度要求的M-H曲线测试装置,测试了金属Gd的-50℃～50℃之间的每隔10℃的不同温度下的M-H曲线.
关键词:
磁热效应
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脉冲磁场
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磁熵变
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M-H曲线
陈灵
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曾德长
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邱万奇
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董小虹
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黎炳雄
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黄拿灿
材料热处理学报
对M2和H13钢进行离子渗氮-多弧离子镀TiAlCrN膜复合表面改性,并采用电子探针、X射线衍射、扫描电镜、纳米压痕和微米划痕仪等手段分析了薄膜的成分、组织结构与力学性能.结果表明,不同衬底对膜的成分及微观结构影响不大.TiAlCrN/M2和TiAlCrN/H13复合膜的膜基结合力都比较高,而TiAlCrN/M2复合膜的综合力学性能优于TiAICrN/H13.
关键词:
离子镀
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渗氮
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TiAlCrN涂层
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微观结构
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硬度
Chemical Physics Letters
A theoretical method for studying the inter-relation between the local structure and EPR spectra is established by diagonalizing the complete energy matrices. For [M(H(2)O)(6)]XCl(6): Mn(2+) (M = Zn, Mg, Cd, Ca; X = Pt, Sn) systems, the calculated results demonstrate that the local structures around the octahedral Mn(2+) centers in the doped systems are very similar despite of the host crystals being different. Furthermore, it is shown that the EPR zero-field parameter D depends simultaneously on the local structure parameters R and h while (a - F) depends mainly on R, whether the doped systems are at liquid-nitrogen temperature or room temperature. (C) 2008 Elsevier B.V. All rights reserved.
关键词:
electron-paramagnetic-resonance;single-crystals;spectra;field;ions;spectroscopy;copper(ii);complexes;behavior;mn(ii)
