材料表面和界面化学状态的俄歇化学效应研究EI

本文运用俄歇化学效应研究了三种纳米薄膜材料的表面，膜层及界面元素的化学状态。研究结果表明用作可燃气体传感器的氧化锡气敏薄膜在离子注Ｓｂ层中以ＳｂＳｎｏ＿ｘ物种存在，在无Ｓｂ层中则以Ｓｎｏｘ（ｘ＜１）形式存在。高能离子注入的金属Ｓｂ也以ＳｂＳｎＯｘ物种存在。具有太阳能选择性吸收功能的氮化铝薄膜则以ＡｌＮ＿ｘＯ＿ｙ物相存在。而ＡＰＣＶＤ法制备的氮化硅薄膜热氧化不稳定的本质则是由于成膜过程中在膜层中包埋了活性较强的自由硅，该自由Ｓｉ容易和热处理气氛中的残余氧反应，从而促进了Ｓｉ＿３Ｎ＿４簿膜层的氧化。     

ZnO-Bi2O3混合氧化物厚膜的结构和气敏性能

采用金属蒸气氧化的方法制备了针状ZnO和椭球形Bi2O3纳米颗粒作为气敏厚膜的原材料，其中得到的Bi2O3为δ相和β相的混合物．通过XRD和SEM分析了ZnO、Bi2O3以及ZnO-Bi2O3混合物厚膜的物相和表面形貌，并测试了厚膜的电导和气敏性能．结果发现纯Bi2O3对乙醇和丙酮蒸气有一定的气敏性能，表现为P型导电；与纯ZnO相比，ZnO-Bi2O3混合物厚膜对苯、甲苯和二甲苯的敏感度降低，这与厚膜晶粒尺寸增大、其晶界势垒高度增大有关，然而Bi2O3可能作为一种弱的催化剂提高了厚膜对乙醇和丙酮的敏感性能．     

八异戊氧基金属萘酞菁配合物旋涂膜的气敏性研究

用旋涂技术成功制备了一类新型萘酞菁配合物（八异戊氧基-2，3-金属萘酞菁）气敏薄膜．对薄膜进行了AFM分析，结果表明，薄膜表面均匀、平整。首次系统研究了萘酞菁配合物旋涂膜对NO2的气敏性，100℃时薄膜对NO2具有较好的响应、可逆性以及较快的响应和恢复时间。分析了配合物的中心金属对气敏性能的影响。     

Sb掺杂ZnTe薄膜结构及其光电性能

采用真空蒸发工艺在玻璃衬底上制备了ZnTe和掺Sb-ZnTe多晶薄膜,并在氮气气氛中对薄膜进行热处理.分别利用XRD、SEM、紫外-可见分光光度计、霍尔效应测试仪对薄膜的晶体结构、表面形貌、元素组成以及光学、电学性能进行表征,研究Sb掺杂量和热处理对薄膜性能的影响.结果表明:未掺杂薄膜为沿(111)晶面择优生长的立方相闪锌矿结构,导电类型为P型.Sb掺杂并未改变ZnTe薄膜晶体结构和导电类型,但衍射峰强度降低;Sb含量直接影响着Sb在ZnTe中的存在形式,掺Sb后抑制了薄膜中Te和Zn的结合,使薄膜中Te的含量增加;室温下薄膜的光学透过率和光学带隙取决于掺Sb浓度和退火温度,并且掺Sb后ZnTe薄膜的载流子浓度显著增加,导电能力明显增强.     

Ni修饰层对SnO2薄膜气敏性能影响

采用磁控溅射技术在SnO2薄膜表面修饰金属Ni，研究Ni修饰量对SnO2薄膜气敏性能影响。对Ni-SnO2薄膜进行表面成分分析，发现Ni的表面含量和化学价态对Ni-SnO2薄膜气敏性能影响至关重要。Ni的表面修饰量在3．4％-8．8％之间将有效提高SnO2薄膜对低浓度氢气的敏感性能。180℃工作温度下，表面含Ni3．4％的SnO2薄膜对1000ppm的氢气灵敏度最高为59．6，同时响应时间和恢复时间降低至15s和125s。Ni修饰量增加到23．4％，薄膜的气敏性能恶化，这是因为修饰层过厚，阻碍气体与SnO2材料接触。同时，XPS证实NiO是增加SnO2薄膜气敏性能的主要物质，增敏机理解释为Ni氧化后形成的NiO在SnO2薄膜上形成p-n结，促进元件的电导变化，从而提高了薄膜的气敏性能。     

ZrO2掺杂对SnO2薄膜电性及气敏性的影响

本研究不用金属醇盐而以无机盐ＳｎＣｌ２．２Ｈ２Ｏ为主体原料，以Ｚｒ（ＯＣ３Ｈ７）４为掺杂剂，无水乙醇为溶剂，采用溶胶－疑胶Ｓｏｌ－Ｇｅｌ）工艺制备了不同ＺｒＯ２掺杂份量的ＳｎＯ２薄膜，发现ＺｒＯ２薄膜在常温下对Ｈ２Ｓ气体具有较好的气敏性能，同时本文研究了ＺｒＯ２掺杂份量对ＳｎＯ２薄膜导电率及气敏性能的影响。     

退火处理对SnOx薄膜气敏性能的影响

采用直流反应溅射方法制备SnOx气敏薄膜,并且在200℃～1000℃的氧化性气氛中进行退火处理.本文研究了退火工艺对二氧化锡薄膜的相结构和表面形貌的影响,并采用XPS表征了不同退火工艺下薄膜表面化学成分的变化.另外,比较了退火工艺对薄膜的电阻和气敏性能影响.实验证明:退火处理对于薄膜的O/Sn影响不大.经过退火处理的薄膜样品,基本具有完整的金红石结构,随着退火温度的增加,薄膜表面孔隙增加,表面电阻和对氢气的敏感性都显著提高.     

氧化锌薄膜的拉曼光谱研究

利用拉曼光谱结合X射线衍射分析对未掺杂和掺杂的ZnO薄膜，陶瓷薄膜进行了研究，ZnO薄膜及ZnO陶瓷薄膜均由sol-gel法制备，掺杂组份有Bi2O3,Sb2O3,MnO和Cr2O3等。结果表明，未掺杂的薄膜的ZnO主晶相均表现出显著的定向生长特征，其拉曼光谱特征谱峰为437cm^-1，谱峰强度随薄膜退火温度的提高略有增强，掺杂后ZnO的拉曼谱峰发生了红移，掺Bi2O3后ZnO的拉曼谱峰由347cm^-1移质移至434cm^-1，掺Sb2O3后ZnO的拉曼谱峰移至435cm^-1，而掺杂Bi2O3,Sb2O3,MnO和Cr2O3等组份的ZnO陶瓷薄膜的ZnO拉曼谱峰则移至434cm^-1，说明掺杂元素进入了ZnO晶格，引起了晶格的变化，ZnO薄膜性能不仅受次晶相组成的影响，而且受因掺杂元素进入而引起的ZnO晶格畸变的影响。     

机械球磨-热压法制备Bio.5Sb1.5Te3热电材料

用机械球磨-热压法制备了Bi0.5Sb1.5Te3热电材料,分别研究了机械球磨时间对合成Bi0.5Sb1.5Te3合金相的影响和烧结温度对其热电性能的影响.结果表明Bi、Sb、、Te原始混合粉末高能球磨10 h以后,就可以完全合金化,生成Bi0.5Sb1.5Te3相.球磨10h的粉末分别在400、450和520℃下热压烧结成型,烧结样品的密度随烧结温度的增大而增加,Seebeck系数和电阻率随烧结温度的升高而降低     

基于磁控溅射的金属氧化物气敏薄膜的研究进展

气体传感器的应用越来越广泛,对气敏材料的研究也越来越深入。磁控溅射法是生产气敏薄膜的一种主要方法,本文重点介绍了用磁控溅射法制备的几种金属氧化物薄膜(SnO2、WO3、ZnO、TiO2、In2O3和NiO等)的气敏性能及其研究进展,对其它薄膜做了简要概述,并提出了目前在气敏薄膜研究中存在的问题。     

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.……     

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...     

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.     

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 ...