Fe74Al4Ga2P12B4Si4块体非晶合金的纳米晶化及软磁性能研究

采用铜模铸造法制备了厚2mm的Fe74Al4Ga2P12B4Si4块体非晶合金.利用X射线衍射(XRD)、差热分析(DSC)和振动样品磁强计(VSM)研究了其晶化行为和软磁性能.结果表明,非晶合金的玻璃转变温度Tg为457.35℃,晶化开始温度Tx为497.65℃.合金的过冷液相区宽度△Tx达到40.30℃,表明合金具有较大的玻璃形成能力.F74Al4Ga2P12B4Si4合金的晶化是二级晶化过程.经520℃等温退火后析出α-Fe相,其晶粒尺寸为15.9nm;而经550℃等温退火后析出α-Fe相及微量的A10.3Si0.7Fe3和Fe3B相,其中α-Fe相的晶粒尺寸为17.4nm.非晶合金的饱和磁化强度为108.816emu/g、矫顽力Hc为574.97Oe;经520℃等温退火后,纳米晶合金的饱和磁化强度为106.875emu/g、矫顽力Hc为94.16Oe.退火实验结果表明,纳米晶化对材料的饱和磁化强度没有显著影响,但会显著降低材料的矫顽力.     

Fe86Zr5.5 Nb5.5 B3非晶合金的超高压烧结成型

为了获得致密的块状Fe86Zr55Nb55B3纳米晶合金,研究了高压快速烧结工艺参数对样品致密度和α-Fe相晶粒尺寸的影响.结果表明:快淬球磨破碎非晶粉末在5.5 GPa/3min烧结条件下,当Pw=1150 W后,可获得相对密度为98.3%、单相α-Fe纳米晶(16.3 nm)块体合金,且随着Pw和t的增加,样品相对密度和α-Fe相晶粒尺寸均略有增加,样品典型的比饱和磁化强度σs和矫顽力Hc分别为119.6 emu/g,63.8 Oe.     

一步法原位合成Fe_2O_3/Ag磁性核壳粒子

采用原位法一步合成了α-Fe2O3和Fe2O3/Ag磁性核壳粒子,通过XRD,TEM和UV光谱研究了Fe2O3/Ag核壳纳米复合材料的结构。结果表明:一步合成了α-Fe2O3,纳米α-Fe2O3粒子表面被Ag层包覆,纳米α-Fe2O3核的平均粒径大约为20～30nm,Ag壳层厚度为10～15nm,形成了核壳结构的电磁复合纳米粒子。α-Fe2O3/Ag核壳纳米复合材料导电率为0.317S/cm。α-Fe2O3粒子具有超顺磁性,饱和磁化强度为1.28A.m2.kg-1,矫顽力为8.2784kA.m-1。α-Fe2O3/Ag核壳粒子饱和磁化强度为0.92A.m2.kg-1,其矫顽力与α-Fe2O3粒子基本一致。     

NiFe2O4纳米粒子的水热合成及表征

以Ni(NO3)2·6H2O和Fe(NO3)3·9H2O为主要原料,在聚乙二醇(PEG)存在下,采用水热法制备了磁性NiFe2O4纳米粒子,用X射线衍射仪(XRD)、透射电子显微镜(TEM)和振动样品磁场计(VSM)等分析方法对样品进行了表征.结果表明:水热法合成的NiFe2O4纳米粒子为尖晶石结构,粒度分布均匀,为方形形貌,粒子直径范围在50～60nm;比饱和磁化强度为25.83emu/g,剩磁为6.167emu/g,矫顽力达85.87Oe.     

铁纳米粉体的磁性能研究

为了研究铁纳米粉体材料与常规材料在磁性能方面的不同,采用阳极弧放电等离子体方法制备了铁纳米粉体。利用X射线衍射(XRD)、透射电子显微镜(TEM)和振动样品磁强计(VSM)等测试手段对样品的形貌、晶体结构、粒度、磁性能进行表征,并对振动样品磁强计测量静态磁特性的原理进行了分析。测试结果表明,样品呈规则的球形链状分布,表面光洁,平均粒径为39nm,粒径范围分布区间窄,晶体结构为bcc结构的晶态;纳米结构材料与常规材料在磁结构上有差别,铁纳米粉体的饱和磁化强度Ms为53emu/g,剩余磁化强度Mr为1.5emu/g,矫顽力Hc为32.2Oe。     

油酸对微波水热法制备的纳米Fe_3O_4的影响

采用微波水热法制备纳米Fe3O4,并用油酸对其进行表面改性,获得油酸包覆的Fe3O4纳米粒子。利用XRD、FT-IR、TEM和振动样品磁强计对Fe3O4纳米粒子的结构、形貌、磁性能进行表征。结果表明:表面改性使得油酸分子中—COOH和Fe离子形成化学键;改性后的纳米Fe3O4粒子为粒度均匀的球形,具有良好的分散性,平均粒径约8nm;该产物具有超顺磁性,饱和磁化强度为61.8emu/g。     

不同酸对γ-Fe_2O_3/SiO_2纳米复合粉体特性的影响

以正硅酸乙酯及铁盐为原料,通过溶胶-凝胶法制备γ-Fe2O3/SiO2纳米复合粉体。采用红外吸收光谱、X射线衍射仪、透射电镜及振动样品磁强计等对复合粉体进行表征。结果表明:以不同铁盐为前驱体得到不同晶型的Fe2O3;不同酸对磁性复合粉体的性能有重要影响:加硝酸时,γ-Fe2O3大小为15nm,其饱和磁化强度大;加入醋酸时得到的γ-Fe2O3颗粒为5nm,且粒度分布变窄,但其饱和磁化强度明显下降;并对γ-Fe2O3在SiO2中的合成机理进行了探讨。     

反相微乳液法制备超顺磁性核壳Fe3O4@SiO2纳米颗粒

分别用一步法和两步法在Tritonx-100/正己醇/环己烷/水反相微乳液体系中,以纳米Fe3O4粒子为核,利用正硅酸乙酯在碱性条件下水解制备纳米Fe3O4@SiOz纳米颗粒.通过XRD、Fr-IR、SEM、TEM和VSM对复合颗粒的晶体结构、结合状态、表面形貌、微观特征和磁学特性进行了表征.结果表明,2种方法制备的Fe3O4核均为尖晶石结构,SiO2壳均为无定形结构;复合颗粒呈球形,且团聚在一起;相比较而言,一步法分散性较两步法要好;两者都具有超顺磁性,在室温、外场为1T时磁化强度分别为23emu/g、11emu/g.     

气-液反应法合成包覆型纳米铁粒子

采用气-液反应法合成了纳米级铁粒子,利用TEM、XRD、VSM等仪器对合成产物的晶态、物相、形貌、粒度和磁性进行了表征。结果表明,合成的产物为纳米级α-Fe,且粒子被均匀地包覆了表面活性剂,抗氧化性能明显提高。粒子的平均粒径为17.2nm,饱和磁化强度为113.57A·m2/kg,磁性能相对稳定。     

磁性羧甲基化壳聚糖纳米粒子的制备与表征

以化学共沉淀法制备了Fe3O4纳米粒子,壳聚糖经羧甲基化改性后接枝在Fe3O4颗粒表面,得到了磁性羧甲基化壳聚糖(Fe3O4/CMC)纳米粒子.利用透射电镜(TEM)、X射线衍射(XRD)、傅立叶红外光谱(FT-IR)及磁性测试对产物进行了表征.TEM表明Fe3O4纳米粒子被CMC包覆,粒径约10 nm;XRD分析表明复合纳米粒子中磁性物质为Fe3O4;FT-IR表明壳聚糖发生羧甲基反应以及在Fe3O4表面的接枝反应.Fe3O4/CMC纳米粒子具有超顺磁性,比饱和磁化强度25.73 emu/g,有良好的磁稳定性.     

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.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

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.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

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.     

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