氮离子注入法合成CNx膜的化学键表征

采用N离子注入金刚石膜和热解石墨方法合成了CNx膜,用Raman光谱和XPS谱对合成薄膜中C、N的化学键合状态进行了研究.通过与Raman光谱的比较,我们对合成样品XPS谱中N1s的化学键合状态作出如下归属≈400.0 eV属于sp2 C-N键;≈398.5 eV则属于sp3 C-N键.结果显示碳原子、氮原子间的化学键合状态,明显地依赖于衬底材料及注入N离子的能量.     

磁控溅射非晶CNx薄膜的热稳定性研究

为了研究非晶CNx薄膜的热稳定性,采用射频磁控溅射方法沉积了非晶CNx薄膜样品,并在真空中退火至900℃,利用FTIR,Raman和XPS谱探讨了高温退火对CNx薄膜化学成分及键合结构的影响.研究表明:CNx薄膜样品中N原子分别与sp、sp2和sp3杂化状态的C原子相结合,退火处理极大地影响了CN键合结构的稳定性;当退火温度低于600℃时,膜内N含量的损失较少,CNx薄膜的热稳定性较好,退火温度超过600℃时,将导致CNx膜中大多数C、N间的键合分离,造成N大量损失,膜的热稳定性下降;退火可促使膜内sp3型键向sp2型键转变,在膜中形成大量的sp2型C键,导致CNx膜的石墨化.     

a-C:N膜的制备及结构分析

采用射频溅射法在锗衬底上沉积无定形碳氮膜 (a- C:N) ,用 X射线光电子谱 (XPS)、傅立叶变换红外光谱 (FT- IR)和喇曼光谱 (RS)分析了膜的成分与结构。结果表明 ,氮是以化学键的形式存在于膜中 ,且有三种不同的 C- N键合状态。随着反应气体中氮气分压的增加 ,a- C:N膜中氮浓度增加 ,C≡N键的含量增加。     

碳氮纳米结构材料的Raman和XPS分析

利用等离子体增强热丝化学气相沉积在不同条件下制备了不同结构的碳氮纳米结构材料。用扫描电子显微镜(SEM)、显微Raman光谱仪和X射线光电子谱(XPS)仪对它们的形貌和结构进行了分析。SEM照片表明在不同的生长条件下可制备出碳氮纳米尖锥、碳氮柱。Raman谱中位于1350和1607cm-1的D和G峰,表明制备的碳氮纳米结构材料主要由sp2碳组成。根据D和G峰的强度比,估计的sp2碳颗粒为4nm。XPS谱在398.4eV处显示出与氮有关的峰,表明制备的碳氮纳米结构材料中含有氮。对N1sXPS谱的峰进行拟合后,发现位于398.4eV的峰由位于398.3和约400.0eV的两个峰组成,分别与sp3和sp2 C—N键有关,表明材料中的部分碳原子被氮原子所替代。     

掺硼四面体非晶碳膜的微观结构及光谱表征

分别采用过滤阴极真空电弧技术制备了不同含硼量四面体非晶碳(ta-C:B)膜, 并用X射线光电子能谱(XPS)、Raman光谱对薄膜的微观结构和化学键态进行了研究. XPS分析表明薄膜中B主要以石墨结构形式存在, 随着B含量的增加, sp³杂化碳的含量逐渐减小, Ta-C:B膜的Raman谱线在含硼量较高时, 其D峰和G峰向低频区偏移, 且G峰的半峰宽变窄, 表明B的引入促进了sp²杂化碳的团簇化, 减小了原子价键之间的变形, 从而降低了薄膜的内应力．     

CNx薄膜的制备和光电性能

以单晶硅片(100)和镀Pt硅片为衬底,用电化学沉积方法在阴极制备出CNx薄膜(x接近于1),薄膜的表面平滑,颗粒均匀.热处理后得到了β-C3N4和α-C3N4多晶结构薄膜.热处理温度的提高使薄膜中的C≡N键逐渐减少而消失,氮元素的流失使薄膜中非晶碳的成分增多,但是薄膜中碳氮逐渐以sp3C-N为主.薄膜的能带在1.1～1.8 eV之间,氮含量对能带大小影响较大.热处理使薄膜的电阻率(高于108Ω@cm)变化不大.氮含量影响PL谱中3.0和3.5 eV处发射峰的峰强,不影响峰位.     

非晶碳膜中sp2和sp3相的检测方法

非晶碳薄膜由sp2和sp3杂化的碳原子组成.sp2和sp3碳原子的比例是决定非晶碳膜的结构和性能的重要参数.如何定量或定性地分析碳薄膜中sp2和sp3碳的含量一直是十分重要的问题.目前用来测定sp2和sp3碳及其比例的实验方法有13C核磁共振谱(NMR)、电子能量损失谱(EELS)、X射线光电子能谱(XPS)、椭圆偏振谱、拉曼光谱(Raman)、红外光谱(IR)等.综述了这些测定方法及其特点.     

类金刚石碳膜的组成和结构

用射频辉光放电离解烃制备了类金刚石碳膜。由IR、XPS、AES、Raman、SEM、TEM、TED和元素分析等手段,分析表征了膜的组成、碳原子化学键态和晶形结构。表明膜是sp~3C-C和C-H键为主体的非晶态,在非晶碳基质中存在一定的微晶石墨和金刚石成分。     

PAN预氧化纤维的炭化过程

采用Raman光谱、XRD、AE、XPS和TG-MS方法分析PAN预氧化纤维在连续炭化过程中纤维结构参数和C、N、O含量的变化,以及反应中小分子的释放情况.Raman光谱分析表明:在炭化过程中纤维内sp2杂化的C-C原子键距逐渐变大,晶体尺寸增大,石墨化度也随之提高,乱层石墨结构趋于完善;XRD分析结果表明:炭化过程巾纤维的择优取向性提高,微孔含量减小是炭纤维体密度增大和强度逐步提高的原因所在;从预氧化纤维、低温炭化和高温炭化纤维的表面和本体元素分析的结果发现:炭化过程中碳元素的富集和非碳元素的脱除是由外向内的过程;TG-MS分析表明:小分子的释放主要发生在低温炭化的过程中,而高温炭化过程主要是大的梯形分子链交联脱除N2的反应.     

硼碳氮薄膜的脉冲激光沉积及其光学性能

采用脉冲激光沉积技术,在Si(100)和石英基片上制备了硼碳氮薄膜(BCN)。利用X射线衍射(XRD),傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)和紫外-可见分光光度计对BCN薄膜进行了表征,研究了激光能量密度对BCN薄膜沉积速率、组分、结构和光学性能的影响。FTIR和XPS分析结果表明BCN薄膜中包含B-C,C-N和N-B化学键,说明实现了B、C和N的原子级化合。当激光能量密度从1 J/cm2增加到6 J/cm2时,BCN薄膜的沉积速率加快,N含量由7.2%增加到15%,光学禁带宽度(Eg)从4.02 eV降低到3.82 eV,Eg的降低主要与BCN薄膜中碳含量的增加有关。     

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 ...