球磨La2Mg17与Ni复合合金的电化学贮氢性能研究

利用机械合金化法制备了La2Mg17+200%(质量分数)Ni复合储氢合金,并对不同球磨时间时合金的微观结构和电化学性能进行研究。结果发现,在球磨过程中Ni粉诱导了La-Mg-Ni非晶/纳米晶结构的形成。XRD和HRTEM结果共同表征了球磨80h时,合金中有Ni金属的存在,且XRD衍射峰强度较低,宽化严重,SAD为宽化的多环,表明形成非晶结构。电化学及其反应动力学测试结果发现,不同球磨时间的电化学反应的动力学控制机理是不同的。球磨60和80h后合金中不仅存在La-Mg-Ni非晶相,同时也有催化剂金属Ni,使合金的表面电荷转移反应电阻较小,氢在合金体相内的扩散系数D 和极限电流密度IL均最大,最终导致80h的放电容量为最大值948.3mAh/g。然而,当合金的球磨时间为100和120h时,合金粉化到纳米级,100h的电荷转移反应电阻Rct最大,合金表面电化学反应缓慢,且合金体相内的极限电流密度和氢扩散系数均最小,属于合金电解液表面间的电荷转移和氢向体相内扩散联合控制的过程,必然导致其放电比容量较小。     

纳米晶-非晶Mg2Ni型合金的贮氢动力学

在合金中添加Cu及Nd,用真空快淬技术制备纳米晶-非晶Mg2Ni型(Mg24Ni10Cu2)100-xNdx(x=0,5,10,15,20)合金,研究了淬速及Nd含量对合金结构及贮氢动力学性能的影响。XRD及TEM分析结果表明,铸态合金具有多相结构,包括主相Mg2Ni和第二相Nd5Mg41、Mg6Ni和Nd Ni。快淬无Nd合金具有完全的纳米晶结构,而含Nd合金则具有纳米晶-非晶结构,表明添加Nd提高了合金的非晶形成能力。贮氢动力学测试结果表明,快淬和添加Nd显著提高了合金的气态及电化学贮氢动力学。合金的高倍率放电能力(HRD)随着淬速和Nd含量的增加先增加而后减小,这主要归因于快淬及添加Nd显著提高了合金的氢扩散系数(D)和极限电流密度(IL),同时增大了电荷转移阻抗(Rct)。     

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.     

球磨CeMg12+100%Ni合金热力学及电化学贮氢性能

用球磨工艺制备CeMg12+100%Ni电极合金,研究了球磨工艺对合金结构及电化学性能的影响。结果表明球磨CeMg12+100%Ni合金具有非晶纳米晶结构,由Mg2Ni相以及Ni相组成,其含量随球磨时间的延长而增加,这在一定程度上改善了合金的电化学放电性能。球磨非晶纳米晶具有较好的结构稳定性,在吸氢后形成的氢化物相仍保持非晶纳米晶尺度,这有利于降低氢化物的热稳定性,改善电化学放电性能。     

高能球磨Mg-Zr-Ni合金组织演变

为了改善Mg-Ni合金的电化学性能,采用高能球磨技术合成了Mg-Zr-Ni储氢合金,通过改变球磨条件和添加合金元素Zr,利用XRD物相分析和电化学测量技术,研究了Mg-Ni合金的组织演变过程及其对电化学容量的影响.结果表明,高能球磨Mg-Ni和Mg-Zr-Ni合金都经历了非晶态向纳米晶态的转变过程,用少量Zr替代部分Mg后,促进了高能球磨Mg-Zr-Ni合金的非晶化和纳米晶化的过程.与非晶态Mg(Zr)Ni相比,纳米晶的Mg(Zr)Ni中氢更易放出,放电曲线主要呈现高电位放电特征,添加Zr后合金的放电容量有所下降.     

纳米Mg2 Ni-Ni非晶合金的球磨制备和电极性能

球磨Mg2Ni合金粉和Ni粉制得纳米Mg2Ni-Ni非晶合金。用XRD和SEM分析表征了球磨过程中的相和结构的变化。模拟电池测试结果表明,Mg2Ni/Ni复合粉的首次放电容量随球磨时间的延长有明显提高。当球磨150h形成了纳米Mg2Ni-Ni非晶合金,其放电容量和电极循环性能得到明显改善。     

新型Ti—Cu—Ni基储氢合金的非晶化制备与电化学性能

采用先熔炼Ti2Cu再添加Ni粉进行复合球磨的工艺方法探索制备了Ti—Cu—Ni基非晶合金,并研究了Ni粉添加量和球磨时间对合金相结构与电化学储氢性能的影响。结果表明,Ni粉添加量和球磨时间对合金的相结构与电化学性能有显著影响。其中,晶态Ti2Cu熔铸合金的放电容量仅为3．7mAh／g;将其球磨120h后的放电容量仍然只有14．4mAh／g;当添加Ni粉复合球磨120h形成非晶结构后,其放电容量得到明显提高,其中TizCu＋50％Ni复合物的最大放电容量为82mAh／g,Ti2Cu＋100％Ni复合物的最大放电容量达到168mAh／g。同时,随着球磨时间的增加,合金的非晶化程度也增强,放电容量随之提高。研究发现,添加Ni粉进行复合球磨有助于Ti2Cu的非晶化转变,同时Ni还起到良好的电催化作用,改善了合金的电化学性能。     

非晶Ti-Al储氢电极合金的制备及其电化学性能

采用真空感应悬浮熔炼法制备了Ti3Al合金,将合金粉碎后与Ni粉进行机械球磨,从而制得非晶态Ti-Al储氢电极合金。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、电化学测试等方法研究了Ti-Al合金的微结构和电化学性能。XRD分析表明,未添加Ni粉球磨后,Ti3Al合金不发生非晶态转变,而添加Ni粉球磨后,Ti3Al合金由晶态转变为非晶态。电化学测试表明未添加Ni粉的Ti3Al合金最大放电容量仅为100.7mA·h·g-1;当添加Ni粉与合金进行球磨之后,随着Ni粉添加量的增加,合金最大放电容量先增加后减小;当Ni粉添加量为200wt%时,合金最大放电容量达到最大值476.7mA·h·g-1。对Ti3Al+200wt%Ni合金的进一步研究表明,随着球磨时间的增加,其最大放电容量先增加后减小。总之,Ni促进了Ti-Al合金的非晶转变,改善了合金的电化学性能,Ni粉的添加量和球磨时间对合金的电化学性能有显著影响。     

纳米Ce1-x(Eu0.5La0.5)xO2固溶体对Mg2Ni合金储氢性能催化作用研究

采用水热法合成纳米Ce1-x(Eu0.5La0.5)xO2(x=0、0.04)固溶体,系统研究固溶体在球磨条件下对Mg2Ni合金储氢性能的催化作用。XRD结果表明,随着Ce1-x(Eu0.5La0.5)xO2添加量的增大及球磨时间的延长,样品的非晶纳米晶含量增加;SEM结果显示,催化剂均匀分布在合金表面,随着球磨时间延长,团聚现象减少;催化剂对球磨样品的活性、最大放电容量和高倍率放电性能均有良好的催化作用,掺杂固溶体比纯CeO2具有更好的催化活性。     

低温烧结时间对AB_5型贮氢合金电极电化学动力学性能的影响

在流动Ar气氛保护下,将AB5型贮氢合金电极置于管式电阻炉中进行573K不同时间(30、60min,1、5h)烧结处理。通过恒流充放电,极化曲线和交流阻抗等测试方法研究了烧结电极的电化学性能。结果表明,0.2C(60mA/g)放电时,各合金电极最大放电容量不同程度降低,烧结时间增大到1h后,最大放电容量基本保持稳定。烧结处理电极高倍率放电性能(HRD)明显优于未处理电极,烧结时间越长,HRD值越高。1500mA/g电流放电时,烧结1h电极HRD值提高12.5%,烧结5h电极提高15%。同时各烧结电极极化电阻Rp,电荷转移电阻Rct随烧结时间增加而呈逐渐减小趋势,交换电流密度I0,极限电流密度IL以及氢扩散系数D均逐渐增大,烧结处理明显改善AB5型贮氢合金电极的动力学性能。     

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.