铂修饰LSM电极对ZrO2氧敏特性的影响

以固相反应合成La0．7Sr0．3MnO3和YSZ，采用密封材料封装烧结LSM和YSZ，丝网印刷LSM作电极，制备极限电流型氧传感器。在500℃测试氧敏元件极限电流随氧气浓度变化的响应。测试结果表明，LSM电极经Pt修饰后，提高了氧敏元件信号的稳定性，与相同条件制备的Pt电极信号差别不大。     

快速凝固高温铝合金纳米相的粗化

用XRD、TEM和EDX分析确认：快凝Al－8．47Fe－1．26V－1．67Si合金在高温时效后，显微组织由．ffcα－Al和bccα－Al13（F3，V）3Si弥散纳米粒子组成．后者的粗化动力学规律符合体扩散控制的LSW机制．在427和482℃高温状态下的界面能分别为0．185和0．245J·m-2，即α粒子与基体间存在非共格关系     

纳米硅/单晶硅异质结二极管的电学特性

利用高真空PECVD系统在p型单晶硅上沉积掺磷n型纳米硅薄层（nc-Si:H),形成纳米硅／单晶硅Np异质结二极管,通过C－V和J－V测试研究了二极管的电学性质。C－V特性指出该异质结为突变型。J－V特性表明二极管具有很好的温度稳定性和整流特性。正偏压时二极管存在两种输运机制：小偏压时（＜0．8V）二极管电流由耗尽层纳米硅薄层一侧的载流子复合过程决定,纳米硅薄层由于能带弯曲而减小了禁带宽度,这是该二极管温度稳定性好的根本原因;大偏压（＞1．0V）时电输运符合电荷限制电流（SCLC）模型。负偏压时电流主要来自空间电荷区中的产生电流。     

用InGaN蓝光LED与YAG荧光粉制造自然白光LED

报导了用国内自行研制的InGaN/GaN蓝光发光二极管（LED）与钇铝石榴石（YAG）荧光粉结合而得的白光发光二极管（W－LED），在室温，正向电压3．5V，正向电流20mA时，W－LED轴向亮度为1cd,CIE色坐标为（0．31，0．38），接近纯白色（0．33，0．33）。     

多相流动淡水体系中碳钢冲刷腐蚀电化学行为的研究

在含砂淡水流动体系中对HG60碳钢进行了电化学测量,用旋转圆柱电极方法研究了冲刷腐蚀条件下影响20A碳钢阴极行为的两个因素。结果显示,水流速度的提高、固体颗粒物的存在都能使氧的传输加强,提高氧的极限扩散电流,使碳钢的冲蚀情况加剧,在1800－3000r/min（线速度小于2．17m/s)转速条件下,碳钢在0．1mol/L硫酸钠介质中的冲刷腐蚀由氧的扩散控制;当水流速度进一步提高（≥8m/s)时,碳钢的阴极反应可能转变为扩散和活化共同控制。     

PSA空气分离吸附过程中的压降特性研究

根据PSA分离空气制氧的基本理论，通过对我们自行研制的产氧量为Q＝（1－5）L／min的双吸附柱的小型PSA分离空气制氧系统进行的吸附过程的压力降的计算，分析了影响空气流经多孔吸附介质压降特性的操作参数，分子筛结构参数等重要因素。结果表明：（1）空气流经PSA吸附柱多孔吸附介质的压降随流速的增大而增大，在较低流速范围内（v=0.05m/s-0.1m/s)，流速对压降的影响较小，在流速较高时，流速对压降的影响较大；（2）压降随空隙率的增大而减小，对于较高流速，低空隙率范围内（ε＝0．32－0．4）空隙率对压降影响很大，是影响压降的最主要因素；（3）压降随多孔吸附介质颗粒直径的增大而减小，在吸附介质颗粒直径较小的范围内（d=1.6-2.0mm)这种变化较明显。     

共压共烧法制备La_(0.8)Sr_(0.2)(Ga_(0.8)Mg_(0.2))_(0.1)Fe_(0.9)O_(3-δ)致密扩散障碍层极限电流型氧传感器

采用固相合成法制备了La_(0.8)Sr_(0.2)(Ga_(0.8)Mg_(0.2))_(0.1)Fe_(0.9)O_(3-δ)(LSGMF)混合导体和La_(0.8)Sr_(0.2)Ga_(0.8)Mg_(0.2)O_(3-δ)(LSGM)固体电解质,利用XRD、TGA、范德堡直流四探针法和热膨胀仪等对试样进行了分析。以LSGMF为致密扩散障碍层,以LSGM为氧泵层,采用共压共烧结法制备了极限电流型氧传感器,利用SEM和EDS对LSGMF/LSGM陶瓷体横截面的微观形貌和成分进行了分析。结果表明:LSGMF具有菱方钙钛矿结构(R-3c空间群),它在650℃失重速率最快,其电导率随温度的升高而增大;300~1000℃范围,LSGM与LSGMF的热膨胀系数分别为12.51×10~(–6)/℃和12.80×10~(–6)/℃。650~850℃范围,氧传感器具有良好的极限电流平台,lg I_L(极限电流I_L)与1000/T呈线性关系,LSGMF中氧离子的扩散激活能为0.4008 e V。800℃、0.3mol%x(O_2)21.0mol%时,极限电流IL与氧含量x(O_2)间的关系为:I_L(m A)=10.285x(O_2)(mol%),R=0.9982。LSGMF和LSGM结合牢固,未产生裂纹,EDS分析基本符合各化合物的化学计量比。     

交流电压、电流和功率国家计量基准

中国计量科学研究院建立的交流电压、电流和功率基准,1986年经原国家计量局批准。该基准的工作原理是应用热电效应,使交流电流、电压和功率分别与直流电流、电压和功率产生相等的热电效应,从而使交流电流、电压和功率的量值准确地溯源于直流、电阻和电压国家计量基准。该基准达到的技术指标①电流测量范围：0．ciA－10A（对40HZ－1500HZ）0．ciA—10A（对150（）H－15000HZ）不确定度：ZX10’（k二3）3X10－’（k二3）稳定度：IX10－’②电压测量范围：0．SV－600V不确定度：交直流转换＜5X10－‘综合测量＜2X10－’（k二3）稳…     

具有LSM致密扩散障碍层的片式极限电流型氧传感器

采用了一种新的有效工艺,制备出了以8mol％Y₂O₃稳定的ZrO₂为固体电解质基体材料,以La_0.8Sr_0.2MnO₃混合导体材料为致密扩散障碍层的极限电流型氧传感器,避免了YSZ和LSM两种材料在烧结时收缩率不匹配的问题,且能够很好给出全范围空燃比的极限电流.该传感器与以往的极限电流型传感器相比具有结构简单,响应更快,工作稳定,成本低廉等优点,有很好的应用前景.     

编读往来

编辑同志：你好！读了第7期“法制计量”中“允差在计量监督中的地位”一文后，觉得下面几点值得探讨。在文章中提到的非自动衡器检定段的划分和允差的规定，有些含糊不清的地方，文章以500型杠杆秤为例，“从零到最大秤量划分了大、中、小3个检定段，对每个检定段规定了一个兄差，为（0－500）d±0．5d，（500－2000）d±1．0d，（2000）－Max）±1．5d”。为了叙述方便，我把每个检定段（量段）以1来表示。1；（0－500）d20．sd是正确的，但！。（50－200）dtl．de和（2000－Max）。1．sd就含糊了，如梭100kg匕An）时是用l；段的允差或l…     

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.