非晶Mg65-xNi21Pr14Agx合金电极的制备及其放电性能

用 铜 模 喷 铸 法 制 备 了 非 晶Mg65-xNi21Pr14Agx合金,采用球磨方法细化了合金颗粒。系统研究了不同Ag含量对非晶合金电极充放电行为、放电容量、循环稳定性、高倍率放电等性能的影响规律。结果表明,Ag元素的添加改善了合金电极充/放电性能,随着Ag含量的增加,非晶合金电极的最大放电容量和循环稳定性均呈现先增大后减小的规律,其高倍率放电性能也有所提高,适量Ag的添加可明显改善非晶Mg-Ni-Pr系合金的放电性能。     

CNTs添加对MmMn0.4Co0.7Al0.3Ni3.4贮氢合金负极性能的影响

对商用MmMn0.4Co0.7Al0.3Ni3.4贮氢合金中添加多壁碳纳米管(CNTs)、Ni的电化学性能进行了研究.结果表明,CNTs的加入可以提高电极的放电容量和初始活化性能,合金中添加CNTs、CNTs+Ni的电极完全活化只需11个循环,其最大放电容量分别为255、271mAh/g.而添加Ni的电极则需24个循环才达到最大容量(245mAh/g);合金中添加CNTs、CNTs+Ni的电极具有更高的放电平台和更好的高倍率放电性能(HRD),在1000 mAh/g放电电流下,添加CNTs、CNTs+Ni、Ni以及未添加电极的HRD值依次为80.5%、83.9%、66.9%和62.4%,线性极化和电化学阻抗测试表明,CNTs的加入可有效减少欧姆电阻、提高电极表面的电荷迁移速率,更有利于在大电流下进行放电.     

添加Al对稀土系贮氢电极合金高温性能的影响

系统研究了添加Al的贮氢电极合金在高温下的电化学性能，结果表明：以Al部分替代稀土系贮氢合金中的Ni，使氢化物电极的平衡分解压降低，低高温下的放电容量升高，自放电降低，改善高倍率放电性能和循环稳定性。     

电镀镍-钴合金对La-Mg-Ni基贮氢合金电化学性能的影响

为了改善La-Mg-Ni基贮氢合金的循环稳定性和综合电化学性能,研究了电镀镍-钴合金对La0.88Mg0.12Ni2.95Mn0.10Co0.55Al0.10贮氢合金粉末表面形貌和电极电化学性能的影响.FESEM表明,电镀处理后合金粉末表面沉积了球状的镍-钴合金颗粒.电化学性能测试表明,贮氢合金电极的放电容量、高倍率放电性能和循环稳定性均得到了显著改善.200周循环时合金电极的容量保持率从未处理合金电极的60%提高到镀覆镍-钴合金的80%,在放电电流密度1080mA/g下的高倍率放电性能提高了23%.线性极化曲线和电化学阻抗分析结果显示,包覆镍-钴合金后贮氢合金电极表面的电荷转移速率加快,电催化活性提高.     

La0.7Mg0.3Ni2.65Co0.75-xMn0.1Six储氢电极合金的结构和电化学性能

系统研究了Si部分替代Co对La0.7Mg0.3Ni2.65Co0.75Mn0.1储氢电极合金结构和电化学性能的影响。XRD结果显示,随着Si替代量的增加,合金中(La,Mg)Ni3相的丰度逐渐降低,而LaNi5相的丰度逐渐增加,且含Si合金中出现了La2Ni7相。电化学测试表明,Si部分替代Co降低了合金的放电容量,但显著提高了其循环稳定性,改善了其高倍率放电性能。其中Si替代量x=0.15时合金的综合性能较好,合金最大放电容量323mAh/g,75次循环后的容量保持率约为71.9%,1250mA/g电流放电时的HRD可达55%。     

V_(1.95)Ti_(0.5)Cr_(0.5)NiO_(0.05)Al_xFe_y(x,y=0～0.05)贮氢合金的组织结构和电化学性能

为了获得有较高电化学放电容量和良好循环稳定性的V基固溶体贮氢电极合金,采用感应熔炼方法制备了一系列含Al和Fe的V基贮氢电极合金V1.95Ti0.5Cr0.5NiO0.05AlxFey(x,y=0~0.05),通过X射线衍射、金相显微镜和电化学测试等手段研究了添加不同含量的Al和Fe对合金显微组织和电化学性能的影响。结果表明,所有合金均由BCC结构的V基固溶体主相和TiNi基第二相组成。电化学测试表明,增加Al含量后,合金的最大放电容量由345.2mAh/g(x=0)增加到430.7mAh/g(x=0.05),同时合金的高倍率放电性能、交换电流密度和氢的扩散系数得到改善。而随着Fe含量的增加,合金的循环稳定性能得到了一定的提高,但是最大放电容量有所降低。     

热处理对贮氢合金V3TiNi0.56Al0.2电化学性能的影响

用自蔓延高温合成法制备了钒基固溶体贮氢合金V₃TiNi_0.56Al_0.2并进行热处理,通过X射线衍射对合金进行结构表征,并采用模拟电池和循环伏安法对其电化学性能进行研究.结果表明：1173、1573K热处理后,合金中第二相TiNi的衍射强度下降,合金的组织分布显得更为均匀,晶粒变大;热处理后合金充放电循环稳定性及高倍率放电性能得到改善,铸态合金的最大放电容量为350mAh·g^-1,热处理合金充放电时最大放电容量大于铸态合金,且循环稳定性有明显的改善,氢在合金中的扩散系数增大,高倍率放电性能较好.     

热处理对LPC(NiCoAlMn)_(5.0)贮氢合金电化学性能的影响

研究了不同温度 (673K、1 1 73K、1 3 73K)热处理对贮氢合金活化性能、放电容量以及高倍率放电等电化学性能的影响。结果表明 ,1 1 73K、1 3 73K热处理后 ,合金充放电循环稳定性及高倍率放电性能得到改善。其中 1 1 73K热处理合金在 0 .4C充放电时最大放电容量与铸态合金相比没有下降 ,而循环稳定性及高倍率放电性能有明显的改善 ,具有优良的综合电化学性能     

Ti0.4Zr0.1V1.1Mn0.5Ni0.4Crx（x=0,0.1,0.2,0.3）储氢合金的微观结构和电化学性能

采用XRD、SEM-EDS等方法对Ti0.4Zr0.1V1.1Mn0.5Ni0.4Crx(x=0,0.1,0.2,0.3)储氢合金的微观结构及电化学性能进行了表征。XRD分析结果表明Ti0.4Zr0.1V1.1Mn0.5Ni0.4Crx(x=0,0.1,0.2,0.3)储氢合金由BCC结构的V基固溶体主相和少量的C14Laves第二相组成。SEM-EDS分析结果表明,V基固溶体主相为树枝晶结构,C14Laves相呈网格状沿着主相晶界析出。电化学测试结果表明,Ti0.4Zr0.1V1.1Mn0.5Ni0.4Crx(x=0,0.1,0.2,0.3)氢化物电极在303K下,随Cr含量的增加,最大放电容量分别为574.6mAh/g、418.8mAh/g、368.8mAh/g和322.9mAh/g。当x=0.3时,合金电极在333K下的最大放电容量达到了824.1mAh/g。Cr的添加显著提高了合金电极的高倍率放电性能和循环寿命,40次充放电循环后Ti0.4Zr0.1V1.1Mn0.5Ni0.4Cr0.3合金电极的容量保持率为62.3%。     

CoZnB添加量对稀土基储氢合金电化学性能的影响

首先采用化学还原法制备了CoZnB非晶合金,随后用机械球磨法将其引入到稀土基合金La_(0.7) Mg_(0.3)Ni_(3.5)中制备成复合物,考察了CoZnB的添加量对La_(0.7) Mg_(0.3)Ni_(3.5)合金电化学性能的影响。实验结果表明,加入CoZnB非晶合金后,复合物合金电极首次放电即可达到最大放电容量,高倍率放电性能得到了显著改善,电荷转移阻抗和极限电流密度均高于La_(0.7) Mg_(0.3)Ni_(3.5)合金电极。复合物合金电极La_(0.7) Mg_(0.3)Ni_(3.5)-CoZnB(质量比1∶1)的最大放电容量高达487.5mAh/g,800mA/g放电电流密度下的复合物合金电极La_(0.7) Mg_(0.3)Ni_(3.5)-CoZnB(质量比2∶1)的高倍率放电性能(HRD)可达94.8%。     

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.     

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...     

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 ...