脉冲电压沉积制备金属Ni纳米线阵列及磁性能

以硫酸溶液为电解质,采用两步电化学阳极氧化法制备了氧化铝有序多孔膜,孔径为20nm,孔间距为50nm左右,孔洞密度为4.5×1010个/cm2.以此多孔膜为模板,以脉冲信号为沉积电压制备了金属Ni纳米线阵列,单根纳米线直径为15～20nm,择优取向为Ni(220)晶面.磁滞回线结果表明垂直于膜面的方向为易磁化方向,当磁场垂直于膜面时,矩形比高达90.5%,矫顽力为63.84kA/m.     

阳极氧化铝膜的制备和磁性纳米阵列

目的 为了获得一定的纳米孔排列结构。方法 采用了电化学阳极氧化法制备氧化铝纳米结构。可以得到具有不同参数的密集排列的六角形结构膜,其中的纳米孔具有高绘横比。结果 我们制备了阳极氧化铝膜,而后得到了Ｆｅ纳米阵列,从磁滞回线讨论了它的垂直磁化特性。结论 以阳极氧化铝膜为模板,在其中沉积磁性纳米颗粒,可以得到了磁性纳米阵列,它具备高的垂直磁化特性。     

多孔阳极氧化铝模板上电子束蒸发沉积TiO_2

以硫酸、草酸溶液为电解液,采用二次阳极氧化法制备了初始孔径在20~120 nm、孔间距在40~250 nm、孔深在200 nm~80μm范围内的具有高度有序纳米孔阵列的多孔阳极氧化铝(porous anodic alumina,PAA)模板。以PAA模板为基片,采用真空电子束蒸发的方法在PAA模板上制备了具有高度有序的TiO2纳米点阵列。利用场发射扫描电子显微镜和原子力显微镜对其形貌进行了表征。研究表明,所形成的TiO2纳米点阵列具有同其基底PAA模板相同的序列结构。对TiO2纳米点阵列的生长形成机理进行了讨论。     

高压下多孔阳极氧化铝薄膜的制备与光学性能研究

利用电化学方法在丙二酸的乙二醇溶液中制备多孔阳极氧化铝,并通过控制溶液浓度对氧化铝的厚度、孔径、孔间距进行了调控。实验发现,在氧化电压为500V时制备出的氧化铝模板孔间距大,且色彩饱和度高,其UV-Vis反射波峰随着溶液浓度的增大产生红移。在浓度为1.5mol/L丙二酸的乙二醇溶液中,制备出的阳极氧化铝薄膜孔间距能够达到400nm,并且在红光区(约622nm处)其UV-Vis反射光谱存在一个极大峰值。     

自旋极化电流辅助的超快反磁化特性研究

基于微磁学模拟方法研究了椭圆纳米薄膜的超快反磁化特性。提出一种利用弱直流自旋极化电流辅助的场驱动进动反磁化新机制。新机制可以有效扩宽脉冲持续时间窗口,在宽的脉冲持续时间范围内可实现进动磁反转而无需精确控制;也可有效抑制磁反转后长时间磁振荡,缩短有效反磁化时间。时间窗口的扩宽和进动磁反转后磁振荡的衰减依赖于自旋极化电流密度。磁反转后的磁振荡由多种不同的自旋波模式构成,自旋转移力矩可以调制磁体有效阻尼,加速磁能量的耗散。     

自旋极化电流辅助的超快反磁化特性研究

基于微磁学模拟方法研究了椭圆纳米薄膜的超快反磁化特性。提出一种利用弱直流自旋极化电流辅助的场驱动进动反磁化新机制。新机制可以有效扩宽脉冲持续时间窗口,在宽的脉冲持续时间范围内可实现进动磁反转而无需精确控制;也可有效抑制磁反转后长时间磁振荡,缩短有效反磁化时间。时间窗口的扩宽和进动磁反转后磁振荡的衰减依赖于自旋极化电流密度。磁反转后的磁振荡由多种不同的自旋波模式构成,自旋转移力矩可以调制磁体有效阻尼,加速磁能量的耗散。     

CoFe/Cu/CoFe/IrMn自旋阀结构多层膜磁化反转过程的研究

通过高真空直流磁控溅射的方法制备了结构为//Ta(5nm)/Co75 Fe25(5nm)/Cu(2.5nm)/Co75Fe25(5nm)/Ir20 Mn80(12nm)/Ta(8nm)的顶钉扎自旋阀结构多层膜,研究了磁场循环次数、反向饱和场等待时间和磁场变化率对自旋阀结构多层膜磁化反转过程的影响.结果表明,磁场循环次数和反向饱和场等待时间对自由层的磁化反转过程没有影响,而在被钉扎层中出现了练习效应和时间效应;磁场变化率对被钉扎层和自由层的前、后支反转场的影响变化趋势相似,但反铁磁层对被钉扎层的反转有一定的影响.     

阳极氧化铝模板孔间距影响因素的研究进展

研究阳极氧化铝模板的孔间距与电解液、温度和氧化电压等影响因素的关系现状。指出孔间距受电解液种类和氧化电压的影响最大,而电解液浓度和温度的影响甚微,模板的孔间距随电压的增加而增加。通过调整电解液和氧化电压可制备所需孔间距的模板。制备大孔间距模板可采用磷酸做电解液配以较大的氧化电压。制备孔间距小于10nm的模板可采用硫酸做电解液配以较小的氧化电压,但当电压很低时阳极氧化反应可能无法进行,可以用较高的脉冲电压代替;也可先采用H2SO4和Al2(SO4)3混合液做电解液辅以较小电压或脉冲电压进行氧化。     

阳极氧化法制备二氧化钛纳米管阵列的形貌

采用阳极氧化法,以NH4F-乙二醇-水溶液为电解质,在钛片上制备了TiO2纳米管阵列,并研究了电解电压和电极距离对TiO2多孔薄膜形貌的影响。结果表明,通过优化电解电压,可以调控二氧化钛纳米管阵列的内径在20～145nm之间;通过调节两电极间的间距,在金属钛片上制备了完整的二氧化钛纳米孔阵列。并采用有限元模拟二氧化钛层中的电流密度分布,探讨了二氧化钛纳米管阵列和纳米孔阵列的形成。     

草酸溶液中制备大孔间距的通孔PAA模板

为了制备规则有序、大孔间距的多孔阳极氧化铝(PAA)模板,通过在传统的草酸溶液中添加乙醇以及阶梯升压的方法,使草酸溶液的耐压从原来的40V左右提高至150V,制备了大孔径(约200nm)、大孔间距(约350nm)的有序PAA模板。详细研究了这种高电压氧化得到的具有较厚阻挡层PAA模板的通孔工艺,实验结果表明,在5%(质量分数)磷酸水溶液中30℃下浸泡180min,可以得到有序的PAA通孔模板,首次计算了阻挡层的减薄速率为约1.26nm/min。     

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 ...     

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     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.