组份变化对PZST陶瓷反铁电-铁电相变的影响

对ＦＥ－ＡＦＥ相界附近ＰＺＳＴ陶瓷结构性能及场诱相变临界以 随机份和温度的变化进行了研究,在相变临界温度ＴＦＥ－ＡＦＥ以下,被电场诱导出的铁电态在撤去电场后以亚稳态形式存在,随着温度升高,亚隐铁电态在此温度转变为反铁电态,随着Ｔｉ含量的增加,样品由方反铁电相穿越相界转变为三方铁电相,介电常数峰值εｍａｘ增大;同时亚稳铁电态→反铁电态相变温度ＴＦＥＦＥ和△Ｅ分别与ＴＦＥ－ＡＦＥ和Ｔｃ相关,随着ＴＥ     

PZT基陶瓷铁电－反铁电相界处各向异性的研究

本文研究了两个以ＰＺＴ瓷为基的系统：ＰＺＴ（Ｎｂ）和ＰＳＺＴ陶瓷在铁电－反铁电相界区域的压电和机电耦合等性能．结果表明，ＰＺＴ基陶瓷在该相界处具有高Ｋｔ和低Ｋｐ的性质．压电和机电耦合各向异性也比准同型相界要高，｜ｄ３３／ｄ３１｜＞５．５，Ｋｔ／Ｋｐ＞３．０．借助于电场诱导ＡＦ—Ｆ相变和反铁电双子晶格间的强耦合作用，对此现象作了较好解释．     

掺铌Pb(Zr,Sn,Ti)O3反铁电-铁电转换电场的研究

研究了掺铌PZST反铁电陶瓷中组份和温度对诱导反铁电－铁电相变转换电场的影响,测定了Pb0.99Nb0.02((Zr0.80Sn0.20)1-yTiy)0.98O3系中正向转换电场EF与组份y(Ti)的关系和电极化前后的反铁电／铁电相界。实验测量结果显示,某组份y(Ti)的反映电－铁电转换强度大小取决于该组份与铁电／铁电相界组份的差距。在Pb0.99Nb0.02((Zr0.80Sn0.20)1-yTiy)0.98O3系中随着试样温度升高,反向转换电场EB保持不变,正向转换电场EF和电滞△E降低。这一现象表明温度有助于降低反铁电－铁电相变的应能使得电场诱导反铁电－铁电相变容易进行,因此可以采用加热电极化方法来降低极化电场强度。     

PZT基陶瓷铁电—反铁电相界处各向异性的研究

本文研究了两个以ＰＺＴ陶瓷为基的系统：ＰＺＴ（Ｎｂ）和ＰＳＺＴ陶瓷在铁电－反铁电相界区域的压电和机电耦合等性能。结果表明，ＰＺＴ基陶瓷在该相界处具有高Ｋｔ和低Ｋｐ的性质。压电和机电耦合各向异性也比准同型相界要高，│ｄ３３／ｄ３１│〉５．５，Ｋｔ／Ｋｐ〉３．０。借助于电场诱导ＡＦ→Ｆ相变和反铁电双子晶格间的强耦合作用，对此现象作了较好解释。     

脉冲电场诱导的相变研究

反铁电陶瓷材料在电场诱导下发生反铁电-铁电相变.为了研究快速电场诱导相变,诱导电场选择高压脉冲电源产生的脉冲电场.反铁电陶瓷选用Pb(Zr,Sn,Ti)O3相图中位于反铁电-铁电相界附近,正向相变电场小于40kV/cm的锆锡钛酸铅.脉冲电源输出波形为2.7 μs电压脉冲,测量陶瓷样品两端的电压波形与所通过的电流波形,作出正向半周期的"脉冲电滞回线".可以看到反铁电陶瓷在脉冲电场诱导下发生了相变.     

形状记忆反铁电陶瓷的相变及有关的形状变化

用高温Ｘ射线衍射法和示差热分析法研究了记忆反铁电陶瓷中的相变，根据晶体学原理解释了反铁电→铁电相变时Ｘ射线衍射谱的变化，观察了伴随着这一相变所产生的形状变化。     

La掺杂Pb(Zr,Sn,Ti)O3陶瓷电场诱导相变的研究

研究了制作工艺对于反铁电陶瓷材料性能的影响,以及调压用PLZST在电场诱导下发生反铁电-铁电相变现象,对反铁电陶瓷在不同强度电场下所表现出的极化强度随电压变化进行了测试,记录结果表明,用于在持续电压作用下调压用反铁电陶瓷,对于处于反铁电-铁电开关电场附近(EAFE-FE)的电压波动调压效果最好.此时小电压波动能够引起较大范围内的极化强度值的变化,在此时对于能量的吸收作用最强.从而对于调压用反铁电陶瓷应根据陶瓷的电滞回线选择合适的调节范围.     

PbZrO3晶体反铁电相至电场感应铁电相相变的研究

仔细研究了电场感应PbZrO3铁电相的晶体结构。在PbZrO3处于反铁电相时，各离子位移方向与极轴垂直。在外电场感应下，Pb离子沿极轴方向有相同方向0．17A的位移，从而使晶体呈现铁电相特征，发生反铁电-铁电相变。此铁电相称之为电场感应铁电相（EFI，Electric—Field—Induced）。通过结构对称性分析，确定EFI铁电相的对称性是C2mm（G2v），用极矢量Ps作为序参量来描述相变时对称性的变化是合适的。     

低相变场细电滞回线(Pb,La)(Zr,Sn,Ti)O_3反铁电陶瓷的研究

对远离反铁电-铁电准同型相界的(Pb,La)(Zr,Sn,Ti)O3反铁电组分进行Ba2+掺杂,制备出了细电滞回线、低相变电场的反铁电陶瓷,反铁电-铁电相变电场仅为1.5kV/mm,电场回滞减小到0.2kV/mm,并且极化强度和应变量随电场增大几乎呈线性变化,可通过调节电场大小得到不同的应变量,有利于开辟这类材料新的应用领域。     

基于RAINBOW结构的反铁电陶瓷研究

还原制备了基于RAINBOW结构的反铁电陶瓷．给出了试样还原层微观结构及其还原规律;测试了试样的驱动性能并讨论了影响因素。研究结果表明：反铁电陶瓷还原性能较好．理想的还原条件为870℃保温2～3h;RAINBOW试样在相对较低的电场强度下即可发生反铁电-铁电相变．并得到很大的轴向位移(约190／μm);承载方向对试样的驱动性能具有决定性的影响。     

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.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.……     

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.     

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.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.