Mn成分对CoFe/Pt_(50)(Cr_(100-x)Mn_x)_(50)体系交换偏置的影响

采用直流磁控溅射的方法制备了CoFe/Pt-CrMn交换偏置体系,反铁磁的Pt-CrMn是利用[Pt/CrMn]n多层膜并经过300℃、2h的退火获得。通过调整Mn的成分,系统地研究了体系交换偏置场的变化。获得了钉扎性能良好的L10相反铁磁钉扎材料Pt-CrMn,即CoFe/Pt50(Cr88Mn12)50钉扎体系,其界面交换耦合能为0.22×10-7J/cm2,截止温度(blocking temperature)为480℃。     

磁控溅射法制备IrMn顶钉扎自旋阀研究

通过高真空直流磁控溅射的方法,在玻璃和硅上淀积了结构为Ta/NiFe/CoFe/Cu/CoFe/IrMn/Ta的IrMn顶钉扎自旋阀薄膜。通过结构的改善和工艺条件的优化,自旋阀的磁电阻率达到9.12％,矫顽力为1.04×(10~3/4π)A/m。研究了Ta缓冲层厚度(小于6nm)对晶格结构和自旋阀性能的影响。结果表明,Ta为3nm时自旋阀磁电阻率最大,而矫顽力随着Ta厚度增大而减小。利用CoFe/Cu/CoFe SAF结构替换掉与IrMn相邻的CoFe被钉扎层,使交换偏置场从原来没有SAF的180×(10~3/4π)A/m上升到600×(10~3/4π)A/m左右,且交换偏置场随着SAF结构中两层CoFe的厚度差减小而增大。研究了RIE对自旋阀性能的影响,发现2min的RIE能使矫顽力减小33％,而磁电阻率几乎不受影响。     

具有SAF结构的IrMn基自旋阀材料的磁场退火研究

用磁控溅射法制备了被钉扎层为反铁磁(SAF)结构(CoFe/Ru/CoFe)的IrMn基顶钉扎自旋阀材料, 分别采用HRTEM、AFM、XPS对材料的结构和成分进行表征。首先, 制备的自旋阀材料分别在200℃、245℃、255℃、265℃的真空条件(＜10^-5 Pa)下退火4 h, 发现经265℃退火, 自旋阀材料会发生明显的层间扩散, 从而引起磁电阻率的降低。在选择合适退火温度(245℃)的基础上, 研究了退火磁场对自旋阀材料磁电阻率的影响。在245℃的真空环境下, 沿着材料的钉扎方向分别施加大小为80、160、240、400、560 kA/m的磁场退火4 h。实验发现经过80和160 kA/m的磁场退火后, 材料的磁电阻率由退火前的8.80%分别下降到5.87%和6.31%; 经240 kA/m的磁场退火后材料的磁电阻率变为7.91%; 经400 kA/m的磁场退火后磁电阻率增大到9.89%; 经560 kA/m的磁场退火后磁电阻率进一步增大到10.79%, 比退火前增加了22.6%。     

磁控溅射法制备IrMn底钉扎自旋阀研究

采用高真空直流磁控溅射的方法,在玻璃衬底上制备了结构为Ta／buffer layer／IrMn／CoFe／Cu／CoFe／NiFe／Ta的IrMn底钉扎自旋阀。研究了NiFe和Cu作为缓冲层对自旋阀磁性能的影响,并对缓冲层厚度进行了参数优化,当缓冲层厚度为2nm时自旋阀各项性能达到最佳。研究了退火制度对底钉扎自旋阀性能的影响,得到了30000e强磁场下200℃保温1h为最佳处理条件。通过结构的改善和工艺的优化,得到的底钉扎自旋阀的磁电阻率8．51％,矫顽场为0．50e,交换偏置场超过8000e。最后对自旋阀的底钉扎和顶钉扎结构进行了比较。     

CrPtMn顶钉扎自旋阀材料的交换耦合作用研究

反铁磁钉扎层和铁磁被钉扎层之间的交换耦合作用是高性能自旋阀材料研究中的一个关键因素。本工作研究了CrPtMn顶钉扎自旋阀材料中的交换耦合场(H_ex)与薄膜沉积条件以及退火处理之间的关系。研究表明: 沉积后的自旋阀材料中的H_ex大小与CrPtMn钉扎层的溅射工作气压关系不大, H_ex 约为7.96×10³ A/m。然而, 经过240℃退火2 h处理后, H_ex呈现出与CrPtMn沉积时的溅射工作气压相关的特性, 随着溅射工作气压的增加而增大。材料退火后的交换耦合场H_ex的温度特性良好, 室温下约为2.39×10⁴ A/m。Hex随着测试温度的升高而逐渐减小, 交换耦合场消失时的失效温度(blocking temperature)为315℃。     

Pt插层对NiFe/FeMn薄膜交换耦合的影响

采用磁控溅射方法制备了以Pt为缓冲层和保护层的NiFe/FeMn薄膜.在NiFe/FeMn界面插入Pt,发现交换偏置场(Hex)随着插层Pt厚度(tPt)的增加而减小.一个重要的现象是当Pt插层厚度为0.4nm时,在Het-tPt衰减曲线并非单纯指数下降,而是出现一个"凸起".通过对样品磁矩随Pt插层厚度的变化规律进行分析,发现随Pt插层厚度的增加,样品的磁矩先逐渐增大,然后又有所下降,并且稳定在某一值;表明在样品制备过程中,NiFe与FeMn之间的相互作用(如界面反应),使得在NiFe/FeMn界面存在磁死层,Pt的插入抑制了NiFe/FeMn界面磁死层的产生,有利于交换耦合;另一方面,Pt的插入隔离了NiFe和FeMn的直接接触,使得FeMn对NiFe的钉扎作用减弱,不利于交换耦合.两个方面的共同作用,使得当Pt插层为某一合适厚度时,Hex-tPt曲线出现"凸起".     

CoFe/Cu多层膜巨磁阻效应的研究

采用直流磁控溅射制备了多层膜Ta/缓冲层/[Co95Fe5/Cu]×12/Co95Fe5/Ta。实验发现,多层膜的磁阻性能受到缓冲层材料、各子层厚度以及退火处理的影响。采用优化的多层膜结构:Ni65Fe15Co20缓冲层厚8 nm、CoFe层厚1.55 nm、Cu层厚2.4nm,沉积态薄膜GMR值达到7.6%;而在外加磁场79.6×103A/m下,250℃保温2 h退火处理后,多层膜的GMR值进一步提高到11.9%,磁滞从18.7×102A/m降低到796 A/m。     

纳米Fe3O4对透钙磷石骨水泥的理化性能影响研究

将纳米Fe3O4按与透钙磷石骨水泥基质质量比为1∶20、1∶10及1∶5的比例加入,研究对其性能的影响。结果表明,随Fe3O4掺入增多,由于理化结构改变,骨水泥固化时间被延长至约9～27min;固化放热明显降低;可注射性和抗压强度先上升后下降,掺入比为1∶10时,可注射性(可注射系数约89%)及抗压强度(约45MPa)最优,显著高于掺杂前;在1.59×106 A/m磁场下,材料饱和磁化强度从0.49A.m2/kg增加到5.51A.m2/kg,矫顽力从233.23A/m增加到707.64A/m;降解速度减缓明显,当掺入比达1∶5时,材料28d浸泡失重率由未掺杂时的约14.9%下降到约7.5%。     

多孔氧化铝模板上TbFeCo薄膜的制备及磁性能

利用两步阳极氧化方法在玻璃基板上成功制造孔洞排列有序的多孔氧化铝基底,实验结果表明,孔洞大小范围在10～50nm,孔洞大小可通过氧化电压和氧化温度进行调节,随氧化电压和温度降低而减小.多孔氧化铝底层对其上溅射生长的TbFeCo磁性能有重要影响,多孔氧化铝基底对TbFeCo的畴壁运动有较强的钉扎作用,增大其矫顽力,矫顽力随孔洞的直径增大而减小,从15nm时的4.5×105A/m下降到40nm时的2.8×105A/m,并逐步趋近无AAO膜板时TbFeCo的矫顽力.同时多孔氧化铝基底的引入,使TbFeCo薄膜的矫顽力机制从以磁晶各向异性为主改变为以形状各向异性为主.     

Pt/(Pt/Co)n/FeMn/Pt多层膜中Pt插层对交换偏置场的影响

在具有垂直磁各向异性Pt／（Pt／Co）n／FeMn／Pt多层膜中的Co／FeMn界面插入极薄的Pt层时，其交换偏置场有明显提高。研究结果表明：由于在Co／FeMn界面存在界面反应，破坏了（Pt／Co）n多层膜中靠近FeMn层的Co层的垂直磁各向异性，导致垂直交换偏置场Hex减弱。当在（Pt/Co）n与FeMn界面之间插入Pt层时可以有效地阻止这一反应发生，从而提高了多层膜的垂直交换偏置场Hex。     

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.     

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 ...