La0.6Sr0.4Co1-yFeyO3系阴极材料制备及表征

La1-xSrxCo1-yFeyO3系(LSCF)钙钛矿结构氧化物是一类性能优异的离子-电子混合导体,同时具有良好的化学稳定性和催化活性,有望作为中低温条件下工作的固体氧化物燃料电池阴极材料的候选材料.本文采用固相反应法制备了多孔La0.6Sr0.4Co1-yFeyO3(y=0.2～0.8)氧化物陶瓷,通过XRD,TG/DTA等测试技术研究了LSCF的结构与制备过程,采用直流四探针法测试了样品的电导率,同时考察了这类组成样品的热膨胀系数.结果表明,这类组成的电导率都有着相同的变化趋势,即先随温度升高而增大,至极大值后又开始降低.分析表明,除了存在小极化子导电机制外,同时还可能存在以下几种机理:1)热激发引起Co3 离子的电荷歧化;2)高温下氧空位生成导致的离子补偿;3)Fe4 较Co4 优先进行电子补偿.     

聚合物协助燃烧法合成La0.8Sr0.2Co0.5Fe0.5O3-δ纳米粉体

为开发新型高性能中温固体氧化物燃料电池阴极材料,以La、Sr、Co和Fe的硝酸盐、葡萄糖和丙烯酰胺为原料,在pH=8-10的碱性条件,通过聚合物协助燃烧法制备了La0.8 Sr0.2 Co0.5 Fe0.5 O3-δ(LSCF)钙钛矿相纳米粉体.用XRD、SEM和TEM表征了LSCF粉体的相结构和微观形貌,结果显示,在...     

La1-xSrxCo0.2Fe0.8O3-δ阴极材料的导电机理研究

La1-xSrxCo1-yFeyO3-δ系(LSCF)钙钛矿结构复合氧化物是一类性能优异的离子-电子混合导体,同时具有良好的化学稳定性和催化活性,是很好的中低温固体氧化物燃料电池(SOFC)阴极材料的候选材料.本文测试了制备出的La1-xSrxCo0.2Fe0.8O3-δ(x=0.1～0.5)系材料电导率并探讨了它们的离子导电、电子导电的微观机制,指出除了小极化子导电机制外,还可能有以下几种机理共同作用:1)热激发引起Co3 离子的电荷歧化;2)高温下氧空位生成导致的离子补偿;3)Fe4 较Co4 优先进行电子补偿.     

La0.6Sr0.4Co1-yFeyO3系阴极材料的电性能

La1-xSrxCo1-yFeyO3系(LSCF)钙钛矿结构氧化物是一类性能优异的离子-电子混合导体,同时具有良好的化学稳定性和催化活性,有望作为中低温下工作的固体氧化物燃料电池阴极材料的候选材料.本文考察了La0.6Sr0.4Co1-yFeyO3(y=0.2～0.8)系材料的导电机制.XPS光电子能谱分析表明,除了存在小极化子导电机制外,同时还可能存在以下几种机理:1)热激发引起Co3 离子的电荷歧化;2)高温下氧空位生成导致的离子补偿;3)Fe4 较Co4 优先进行电荷补偿.     

La0.6Sr0.4Co0.8Fe0.22O3粉末的合成与性能表征

La0.6Sr0.4Co0.8Fe0.22O3钙钛矿型氧化物具有良好的电子和离子混合导电性能．可作为中温固体氧化物燃料电池（ITSOFC）的阴极材料。本文中采用EDTA-柠檬酸法合成La0.6Sr0.4Co0.8Fe0.22O3（LSCF）粉末，借助差热-热重（DTA／TG）、X射线衍射（XRD）、扫描电镜（SEM）等分析手段．对阴极材料的合成、掺杂机理、与电解质（YSZ）间的高温化学相容性进行了研究和讨论。结果表明：干凝胶的最佳煅烧温度为800℃。所合成的粉末具有单一的钙钛矿结构，平均粒径约为40nm；掺杂后的LSCF仍保持菱方结构；当SOFC的运行温度低于800℃时，LSCF与YSZ具有良好的化学相容性。     

LSCF系钙钛矿型致密透氧膜的制备及其透氧性能

通过柠檬酸-EDTA络合法合成了不同的A位Sr取代的LSCF系钙钛矿型粉体材料La0.1Sr0.9Co0.8Fe0.2O3-δLa0.3Sr0.7Co0.8Fe0.2O3-δLa0.5Sr0.5Co0.8Fe0.2O3-δ和La0.8Sr0.2Co0.8Fe0.2O3-δ采用XRD测试手段对粉体及膜片的晶体结构进行了表征.用静压片法制备透氧膜,并测定了LSCF系钙钛矿膜的透氧量,分析了温度和A位Sr不同掺杂量等因素对膜透氧性能的影响.结果表明,该系列膜的透氧量均随着温度升高而增大,随着Sr掺杂量的增加而增大.并在850℃下对透氧膜100h透氧稳定性进行实验研究,结果表明,膜片的透氧量随时间没有明显变化,表现出良好的稳定性.     

固体氧化物燃料电池多层复合阴极的制备及性能研究

为了改善固体氧化物燃料电池的阴极热循环性能,采用喷涂方法在Ce0.8Sm0.2O1.9（SDC）电解质片的表面制备了La0.6Sr0.4Co0.2Fe0.8O3（LSCF）-（SDC）3层复合阴极,各层LSCF所占比例依次为40%、70%和100%（质量分数）.X射线衍射结果表明,LSCF与SDC无明显的反应.每层材料的热膨胀系数随LSCF含量的增加而增大,电阻率随LSCF含量的增加而下降.SEM观测证明阴极呈现多孔的微结构,且与电解质表面接触良好.在中温（500～800℃）测得的阴极极化曲线和阻抗谱结果表明,多层阴极材料具有比单层LSCF阴极更好的电化学性能和热循环稳定性,5次热循环后性能衰退从58%下降到12%.     

中温固体氧化物燃料电池阴极材料Ba1-xSrxCo0.7Fe0.2Nb0.1O3-δ的制备与性能研究

采用固相法合成Ba1-x Srx Co0.7Fe0.2Nb0.1O3-δ(x=0、0.1、0.2、0.3、0.4)阴极材料。利用X射线衍射(XRD)和扫描电子显微镜(SEM)对其结构和微观形貌进行了表征。XRD测试结果表明Ba1-x Srx Co0.7Fe0.2Nb0.1O3-δ样品经1000℃,烧结10 h后形成了立方钙钛矿结构。从样品的电镜照片看出样品具有均匀的孔隙率,电解质(Ce0.85Sm0.15O1.925)-阴极(Ba1-x Srx Co0.7Fe0.2Nb0.1O3-δ)之间的界面结合良好。电化学交流阻抗测试结果表明Ba1-x Srx Co0.7Fe0.2Nb0.1O3-δ中掺入Sr可以明显地降低阴极的极化电阻,随着Sr含量的增多,阴极的界面极化电阻(RP)先减少后增大,当Sr的含量x为0.2时Rp值最小。以Ce0.85Sm0.15O1.925(SDC)电解质为支撑体,Ni0.9Cu0.1-SDC为阳极,Ba0.8Sr0.2Co0.7Fe0.2Nb0.1O3-δ为阴极的单电池的最大功率密度在600℃时达到155 mW/cm2。实验结果表明Ba0.8Sr0.2Co0.7Fe0.2Nb0.1O3-δ材料是一种电化学性能较为优良的中温固体氧化物燃料电池阴极材料。     

中温固体氧化物燃料电池阴极材料Ln_(0.6)Sr_(0.4)Fe_(1-χ)Co_χO_(3-δ)的合成和性能表征

采用固相反应法合成了中温固体氧化物燃料电池阴极材料Ln0.6Sr0.4Fe1-χCoχO3-σ（Ln=La,Pr;Nd,Sm和Gd）粉体.对其进行结晶学表征,分析氧含量和失重与温度的关系,并研究了其电导率随温度的变化规律及其与Ce0.8Gd0.2O1.9（CGO）电解质的化学相容性.实验表明,600～800℃;所有样品的电导率均高于100S/cm,其中Nd0.6Sr0.4Co0.8Fe0.2O3-σ的电导率高达600S/cm,并且与CGO电解质都具有良好的化学相容性.     

固体氧化物燃料电池阴极材料La_(0.8)Sr_(0.2)Cu_(1-x)Co_xO_(2.5-δ)的制备和性能研究

为探索适于中温条件下使用的固体氧化物燃料电池的阴极材料,采用柠檬酸-硝酸盐燃烧合成法制备了La0.8Sr0.2Cu1-xCoxO2.5-δ(x=0～0.4)粉体。利用X-射线衍射(XRD)技术对粉体的性能进行了表征,XRD结果表明,经800℃焙烧的粉体的对称性较高,已形成钙钛矿结构。采用直流四电极法测试La0.8Sr0.2Cu1-xCoxO2.5-δ试样的电导率,测试温度范围为100～800℃,试样的电导率ln(σT)与1/T之间呈很好的线性关系,说明La0.8Sr0.2Cu1-xCoxO2.5-δ在测试温度范围内服从小极化子导电机制。Co掺杂量对试样的电导率和电导活化能有着明显的影响,当Co掺杂量为0时,La0.8Sr0.2CuO2.5-δ的电导率最高,电导活化能最小。     

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.