类金刚石膜形态的分子动力学模拟研究

类金刚石膜（Diamond-like carbon，DLC）优异的性能与碳原子sp^2 sp^3杂化密切相关。本文采用分子动力学方法，分别模拟计算了以C原子和CH3原子团为主要沉积物，在不同入射能量下制备无氢DLC膜和含氢DLC膜的动力学过程。研究了所生长成的两类DLC膜的具体形态及s—p杂化特性。揭示了无氢和含氢的两类DLC膜中sp^2与sp^3键的形成与连接结构形式，模拟结果表明：合适的入射能量可获得致密的DLC膜。在中等入射能量下，得到的sp^3键含量的计算结果较好地符合实验结果，体现了理论计算与分析对实验制备的指导意义。     

PAN基炭纤维中sp2杂化的C-C原子键距与结构参数之间关系

利用Raman散射及X射线衍射方法，对不同炭化温度下制备的PAN基炭纤维样品进行了测试。根据Raman散射的测试结果，从Fitzer碳键键距出发，给出了PAN基炭纤维中sp^2杂化的C—C原子键距a0随炭化温度的变化规律。由各样品的X射线衍射测试结果，得到了各样品的结构参数（La、Lc、d002）。分析了sp^杂化的C—C原子键距a0随结构参数（La、Lc、d002）变化的原因。结果表明，C—C原子键距a0与石墨化程度有关，且随La、lc的增大及d002的减小C—C原子键距增大。     

层状结构碳材料与Ar离子束的相互作用

利用XPS分析技术原位研究了层状结构的石墨碳及碳纳米管材料与Ar离子束的相互作用机理，以及对层状碳材料电子结构的影响。研究结果表明，Ar离子束与层状碳材料作用后，构成层状结构的以sp2杂化为基础的C－C共轭π键被Ar离子束打断，形成了新的C－C键。原有的层状结构也被破坏，形成了无定形结构。Ar离子束的作用是通过与C－C共轭π键作用，促进C-C共轭π键的断裂，而不仅仅是单纯的剥离作用。     

沉积参数对含氢非晶碳膜结构及性能的影响

本文利用射频等离子体增强化学气相沉积（RF-PECVD）技术,以CH4、H2为气源,Ar-为稀释气体,通过增加过渡层和改变输入功率和气体成分比例（CH／H2）,在不锈钢基底上制备了含氢非晶碳膜（a-C：H）。利用拉曼光谱（Raman）、X射线光电子能谱（XPS）、纳米显微硬度计和摩擦磨损试验机等研究手段对含氢非晶碳膜的形貌、结构、显微硬度和耐磨性进行了表征。Ramas光谱和XPS分析表明,薄膜是由sp^2和sp^3杂化组成的非晶碳膜。显微硬度和摩擦学测试表明,在较低射频功率和富氢等离子体中沉积的a—C：H膜表面光滑、结构致密,薄膜的硬度、摩擦系数、耐磨性和结合力等性能较好。     

辅助气体压强比例对中频脉冲非平衡磁控溅射沉积类金刚石薄膜结构与性能的影响

以高纯石墨为靶材、氩气(Ar)和甲烷(CH4)为辅助气体,利用中频脉冲非平衡磁控溅射技术在不同气体压强比例下制备了类金刚石薄膜,采用原子力显微镜、拉曼光谱仪、傅立叶变换红外光谱仪、纳米压痕测试仪对所制备薄膜的表面形貌、微观结构、机械性能进行了分析.结果表明:当Ar气压强比例由17％增加到50％时,类金刚石薄膜的RMS表面粗糙度、sp3杂化键含量、纳米硬度、弹性模量随Ar气压强比例的增加而增加,当Ar气压强比例由50％增加到86％时,薄膜的RMS表面粗糙度、sp3杂化键含量、纳米硬度、弹性模量随Ar气压强比例的增加而减小.以上结果说明辅助气体压强比例对类金刚石薄膜的表面形貌、微观结构、机械性能有较大的影响.     

氟化活性炭纤维的制备及其憎水性

将活性炭纤维（ACF）和氟气反应制备了氟化活性炭纤维（FACF）。XPS的研究结果表明FACF的碳原子是以sp^3杂化轨道同氟原子形成共价键。αs图分析氮吸附等温线的结果表明，ACF氟化后其比表面积和微孔容积显著降低、微孔宽度基本不变。FACF对水的吸附量极小，微孔表面具有完美的憎水性和高稳定性。     

离子束辅助沉积制备多晶Al_2O_3薄膜

利用电子枪蒸镀 Al_2O_3,同时辅以 Ar 离子轰击的离子束辅助沉积方法(IBAD)制备 Al_2O_3薄膜,并与单纯电子枪蒸镀方法(PVD)制备的薄膜进行了结构和表面形貌的比较。IBAD 法可以得到结构均匀致密的γ-Al_2O_3晶态薄膜,而 PVD 方法仅能得到非晶态疏松的结构。分析结果表明,薄膜沉积过程中,提高离子轰击能量和增加基片加热温度在一定程度上具有相同的效果。     

C2H2／H2比率对铝合金上电弧离子镀类金刚石膜的结构和腐蚀性能的影响

本文研究了在2024铝合金衬底上，环境气氛中C2H2／H2比率对电弧离子镀沉积类金刚石膜层的结构和腐蚀性能的影响。Raman谱分析表明，随着C2H2／H2比率的降低，其D峰和G峰的强度比ID／IG值增加，这意味着膜层中sp^3／sp^2键比率减少，膜层的力学性能下降；同时，G峰的峰位向高波数方向移动，峰的半高宽变窄；D峰的峰位也在向高波数方向移动变化，但峰的半高宽变化相反，逐渐宽化。膜层可以进一步提高铝合金试样的抗腐蚀能力，从自腐蚀电位看，随着C2H2／H2比率的降低，膜层试样的抗腐蚀性能略逐渐增加。     

等离子体化学气相沉积类金刚石碳膜的特性及应用

类金刚石（DLC）膜是含有sp^3杂化态的亚稳态非晶碳膜，是具有极高的硬度、化学稳定性和光学透明性的半导体材料。这篇综述介绍了用等离子体化学气相沉积DLC膜的沉积方法、所制备薄膜的特性及应用，最后展望了DLC膜的发展趋势。     

PCEC-CaO-SiO_2-P_2O_5杂化材料

采用分子量为1 500的聚乙二醇(PEG)为大分子引发剂,引发ε-己内酯开环聚合,合成了分子量为2 900、3 400、4 700的端羟基的聚己内酯-聚乙二醇-聚己内酯(PCEC)嵌段共聚物,并用异氰酸基丙基三乙氧基硅烷(IPTS)将该共聚物端羟基修饰。红外结果表明,该聚合物在3 440、1 732、1 242、1 106cm-1等处有羟基、酯键、醚键的特征峰,与IPTS反应后在3 350cm-1、1 531cm-1处出现了N—H的伸缩振动峰和(N—H)+(C—N)的弯曲振动峰,证实了PCEC以及端基为三乙氧基硅基的PCEC结构。采用溶胶-凝胶法将该产物与生物玻璃前躯体进行反应,获得PCEC-CaO-SiO2-P2O5有机-无机杂化材料。PCEC-CaO-SiO2-P2O5杂化材料在模拟体液(SBF)中浸泡24h后,表面就开始覆盖钙磷沉淀物。XRD测试结果表明,PCEC-CaO-SiO2-P2O5杂化材料表面覆盖的沉淀物主要成分为羟基磷灰石,表面沉积物随着杂化材料中亲水性成分的增加而增加。力学性能测试表明,随着高分子中PEG含量的增加,PCEC-CaO-SiO2-P2O5有机-无机杂化材料的压缩模量从6.9 MPa上升到65 MPa。细胞毒性表明,PCEC-CaO-SiO2-P2O5杂化材料对细胞没有明显的毒性。     

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 ...