有机铁电薄膜的研究进展

有机铁电薄膜材料因具有光电效应、压电效应、铁电等性能,可广泛应用于电子器件而备受关注.综述了聚偏氟乙烯[Poly(vinylidene fluoride)]及其共聚物铁电材料的结构和性能,从有机铁电薄膜的3种疲劳机理和降低疲劳的措施出发,综述了近年来国内外在铁电薄膜电疲劳研究方面所取得的进展,总结了有机铁电薄膜的应用,提出了今后可能开展的工作.     

PZT铁电薄膜结构及疲劳特性研究

铁电薄膜的电疲劳是铁电存储器等应用的主要障碍，我们用Ｓｏｌ－ｇｅｌ（溶胶－凝胶）方法制备ＰＺＴ铁电薄膜，对其结构和疲劳特性的研究表明，组分及工艺因素合影响薄膜的结构，具有玫瑰花形的ＰＺＴ薄膜内部存在较多的带电缺陷，在外电场作用下１０＾６周期后出现疲劳，改进组分配方或改进热处理工艺，使薄膜为纯钙钛矿结构，薄膜的寿命可超过１０＾１１周期。     

铁电薄膜与底电极之间界面的异质结效应

铁电薄膜与底电极之间由于高温扩散而形成了界面层，且观察到其对薄膜电性能的影响类似于硅衬底上铁电薄膜的异质结效应。基于能带理论的考虑，建立物理模型来解释其影响。该界面异质结模型不仅可以解释铁电薄膜的界面分层、电滞回线不对称等现象，而且还成功地解释了电滞回线中心在极化轴上的偏移和疲劳循环过程中的偏移增加，并探讨了这种偏移对铁电薄膜疲劳特性的影响。     

铁电薄膜与底电极之间界面的异质结效应

铁电薄膜与底电极之间由于高温扩散而形成了界面层，且观察到其对薄膜电性能的影响类似于硅衬底上铁电薄膜的异质结效应。基于能带理论的考虑，建立物理模型来解释其影响。该界面异质结膜型不仅可以解释铁电薄膜的界面分层、电滞回线不对称等现象，而且还成功地解释了电滞回线中心在极化轴上的偏移和疲劳循环过程中的偏移增加，并探讨了这种偏移对铁电薄膜疲劳特性的影响。     

铁电薄膜及铁电存储器的研究进展

铁电薄膜是具有铁电性且厚度尺寸为数纳米到数微米的薄膜材料,因其在非挥发性铁电随机存储器方面的潜在应用而受到广泛关注.综述了新型无铅、无疲劳Bi4Ti3O12(BIT)基铁电薄膜材料的制备和改性及性能表征方法,阐述了铁电薄膜的3种失效机制及铁电薄膜存储器的研究现状,最后提出了铁电薄膜及存储器今后可能的研究方向.     

PYZT铁电薄膜的制备及特性研究

用sol－gel方法制备了掺Y的PZT铁电薄膜，研究了PYZT溶胶的成胶机理。探讨了Y掺入量对PYZT铁电薄膜的结构、介电、铁电、漏电流和疲劳特性的影响。     

铁电薄膜过渡层材料的研究进展

具有介电、铁电、压电等特性的铁电薄膜在动态随机存储器、移相器等功能器件上拥有广泛的应用前景,但其疲劳现象已成为应用的严重障碍,在衬底与铁电薄膜之间添加氧化物过渡层可以改善这种现象.综述了普通氧化物、钙钛矿型氧化物、超导氧化物等作为过渡层材料对铁电薄膜结构与性能的影响.     

有机铁电P(VDF-TrFE)薄膜极化疲劳特性

本文研究了有机铁电薄膜的极化疲劳过程.研究发现,随着疲劳过程的深入,薄膜铁电峰的峰位逐渐向高电压方向偏移,而薄膜的极化-电压滞洄线也逐渐变得圆滑,且剩余极化值随之下降.进一步的研究表明,只有双极性电压才能导致铁电疲劳的出现,而双极性电压的频率直接影响铁电疲劳速率:频率越高,疲劳越慢.文中对有机铁电疲劳机理做了初步探讨.     

钛酸锶钡(BST)薄膜的介电性能机理研究进展

钛酸锶钡 (BST)薄膜是一种重要的铁电薄膜 ,应用广泛 ,是高新技术研究的前沿和热点之一。简要介绍BST薄膜的制备方法和应用 ,重点讨论BST薄膜的极化、电压非线性、漏电流的机理、表征及影响因素 ,并综述了铁电薄膜的疲劳机制和消除疲劳措施等方面的研究进展 ,提出了研究中需要解决的一些问题     

钛酸锶钡（BST）薄膜的介电性能机理研究进展

钛酸锶钡(BST)薄膜是一种重要的铁电薄膜，应用广泛，是高新技术研究的前沿和热点之一。简要介绍BST薄膜的制备方法和应用，重点讨论BST薄膜的极化、电压非线性、漏电流的机理、表征及影响因素，并综述了铁电薄膜的疲劳机制和消除疲劳措施等方面的研究进展，提出了研究中需要解决的一些问题。     

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.……     

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...     

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 ...