双微乳液法制备CoFe2O4纳米颗粒及其磁性能研究

以TritonX-100/正己醇/正己烷/水为反应介质,采用双微乳液法合成了尖晶石型CoFe2O4磁性纳米颗粒.利用TG-DSC、FTIR、TEM、XRD、VSM等测试技术对CoFe2O4煅烧前后的结构和磁性能进行表征.结果表明,采用微乳液法制备的CoFe2O4前驱物经煅烧后可获得纳米级磁性微粒.煅烧温度对微粒粒径和磁性能有较大影响,经300℃煅烧后的微粒粒径为15nm,700℃煅烧后微粒粒径增大为52nm.样品的饱和磁化强度和剩余磁化强度也随热处理温度的升高而增加.     

棒状γ-Fe2O3纳米粒子的制备及表征

在聚乙二醇(PEG-400)存在的条件下,在溶液中FeCl3与NaOH反应所得的沉淀物经抽滤后,在空气中60℃干燥6h后再在不同温度下热处理.所得的各样品用XRD、Mossbauer谱、TEM及FTIR等手段进行了表征.结果表明,沉淀经60℃干燥6h后得到结晶较差的γ-Fe2O3粉体(含少量结晶较好的α-FeOOH).经300℃热处理1h后得长径比约为5的棒形γ-Fe2O3纳米粒子.     

制备条件对纳米NiO微粉的影响

用化学沉淀法制备了纳米立方NiO的微粉 ,研究了介质 pH、不同沉淀剂和热处理温度对纳米NiO粒子大小和聚结状态的影响。用NaOH作沉淀剂 ,控制介质 pH为 9～10 ,经 2 70～ 30 0℃热处理 4h ,制备得到粒子尺寸约 5nm ,在水中易重新分散的纳米NiO微粉     

纳米晶复合SrM永磁铁氧体的制备和交换耦合作用

采用sol-gel方法制备M型六角锶铁氧体。利用X光衍射、透射电子显微镜和VSM对纳米晶样品进行了研究。当热处理温度小于 80 0℃ ,样品存在复相。在同样条件下 ,压成薄片的样品存在硬磁与软磁SrFe12 O19/γ Fe2 O3 的纳米复合相的磁性交换耦合作用。温度为 80 0℃的薄片样品 ,比饱和磁化强度σS 为 75 .6emu/g ,内禀矫顽力Hcj 为6 0 15Oe ,最大磁能积 (BH) Max 为 1.87MGOe ,而粉末样品相应的分别为 75 .9emu/ g ,6 40 0Oe和 1.5 2MGOe。当热处理温度大于 85 0℃时 ,只有单一M相     

新方法制备Cu超细粉末以及Cu2O-Cu核-壳型复合粒子

以Cu(NO3)2·3H2O与Na2CO3·10H2O为原料沉淀法制得纳米CuO前驱体--碱式碳酸铜,在不同温度(200℃、300℃、400℃、500℃、600℃)下分别焙烧2h得到CuO粉末后,直接倒入室温下的正丁醇溶液中,发生氧化-还原反应,得到组成不同的各种产物.经XRD、TEM、SEM研究表明,产物的组成随上述热处理温度的改变而变化,500℃时可得到纯的纳米铜粉,600℃时可得到Cu2O-Cu核-壳型纳米粒子.     

纳米ZnFe_2O_4的制备及其光催化降解苯酚的协同效应

在干法室温条件下,利用滚压振动磨将金属锌制备成粒度大约40nm的锌粉,用化学共沉淀法制备粒度为10nm左右的Fe3O4。利用Zn-Fe3O4水解系统制备纳米ZnFe2O4,当温度达到300℃后,XRD图上明显出现ZnFe2O4的各个衍射峰,由透射电子显微镜可知,300℃和320℃时得到的纳米粒子都在20nm左右。分别用电子衍射、高分辨电镜对两个样品进行了表征。在距离6cm的30W紫外灯照射下,光催化降解苯酚的实验表明光催化降解的效率顺序为:ZnFe2O4-ZnO-Fe2O3>ZnO-Fe2O3>ZnFe2O4>ZnO>Fe2O3。     

新方法制备Cu超细粉末以及Cu2O-Cu核-壳型复合粒子

以Cu(NO3)2·3H2O与Na2CO3·10H2O为原料沉淀法制得纳米CuO前驱体--碱式碳酸铜,在不同温度(200℃、300℃、400℃、500℃、600℃)下分别焙烧2h得到CuO粉末后,直接倒入室温下的正丁醇溶液中,发生氧化-还原反应,得到组成不同的各种产物.经XRD、TEM、SEM研究表明,产物的组成随上述热处理温度的改变而变化,500℃时可得到纯的纳米铜粉,600℃时可得到Cu2O-Cu核-壳型纳米粒子.     

ZnFe2O4纳米结构制备及其M(o)ssbauer谱分析

通过水解Zn/Fe3O4纳米粒子制备ZnFe2O4纳米结构,采用XRD和TEM检测产品的成分和形貌变化,验证反应过程方程的正确性.结果表明:当反应温度为260℃时,产品中含有ZnO纳米棒,随着反应温度升至300℃,ZnO纳米棒逐渐消失,得到纯度较高的ZnFe2O4纳米颗粒,粒度分布在20～30nm范围内.产品的M(o)...     

纳米FePO4的合成及其正极材料LiFePO4/C的电化学性能研究

以Fe3+为铁源,采用控制结晶技术合成了纳米FePO4.xH2O,将FePO4.xH2O于500℃热处理4 h后得到纳米FePO4前驱体,然后通过碳热还原在不同温度下煅烧合成橄榄石结构的纳米LiFePO4/C样品.采用差热/热重、X射线衍射、扫描电镜、比表面测试、电化学性能测试等分析测试方法对纳米FePO4.xH2O、FePO4前驱体及不同煅烧温度下制得的纳米LiFePO4/C样品进行表征.研究结果表明,700℃烧结10 h合成LiFePO4/C样品的粒径在40~100 nm左右,比表面积为79.8 m2/g;700℃煅烧合成样品在电压2.5~4.2 V,倍率为0.1C、1C、5C、10C、15C时的放电比容量分别达到156.5、134.9、105.8、90.3和80.9 mAh/g,具有较好的倍率性能;样品还表现出较好的容量保持率.     

空气氧化法制备FePO_4超细颗粒

采用空气氧化法,以硫酸亚铁和磷酸为铁源和磷源,制备FePO4.2H2O,并在空气气氛下热处理后得到不含结晶水的FePO4粉体,采用X射线衍射、扫描电镜、元素含量分析等对合成产物进行表征。结果表明,当反应原料中铁、磷元素物质的量比为1∶2,反应温度为80℃时,产物为纯FePO4.2H2O,520℃热处理后为FePO4,其他条件下所得产物均含有杂质;聚乙二醇的加入有效抑制了颗粒晶体的长大,改善了颗粒的团聚程度,得到分散均匀的类球形颗粒。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Effect of Oxide Assisted Metal Nanoparticles on Microstructure and Morphology of Gallium oxide Nanowires

Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from