经钨离子束处理的H13钢的表面结构和成分研究

采用由金属蒸汽真空弧离子源(MEVVA)引出的强束流脉冲钨离子对H13钢进行了离子注入表面改性研究.注入剂量为3×1017cm-2,引出电压为48kV,平均束流为15μA*cm-2.利用卢瑟福背散射谱(RBS)测量了注入表面的成分,借助X射线衍射仪(XRD)和X射线光电子能谱仪(XPS)考察了注入表面的氧化情况及微观结构.研究发现,钨离子注入H13钢能减轻其表面铁元素的氧化;钨元素在其表面的原子百分比可达28%左右,并根据能带论确定了注入样品中钨和铁元素的电子结构.     

强束流钼注入铝中的反常分布研究

利用从金属蒸汽真空弧 (简称 MEVVA)离子源引出的强束流脉冲钼离子对纯铝进行了不同束流密度的离子注入试验。钼离子的加速电压为 4 8k V,剂量为 3× 10 1 7cm- 2 ,平均束流密度为 2 5和 4 7μA· cm- 2 。透射电镜 (TEM)分析证明在注入层内可形成 Al1 2 Mo晶体 ;背散射 (RBS)分析证明 Al1 2 Mo的厚度可达 6 0 0至70 0 nm;结合强束流脉冲注入的特点 ,根据碰撞理论提出了解释钼反常分布的“蜂窝”模型。     

钼离子注入束流大小对H13钢表层结构与耐磨性能的影响

利用金属蒸汽真空弧离子源引出的强束流钼离子，对H13钢进行了高剂量的离子注入。测量了注入试样的磨损性能，发现在注入剂量为3×1017cm－2、注入束流密度低于47μA·cm－2时，其耐磨性得到不同程度的改善。分别利用卢瑟福背散射谱（RBS）、X射线衍射（XRD）和X光电子能谱（XPS）测试了注入试样的表面成分及其微观结构。讨论了H13钢耐磨性的影响因素。     

氮离子注入钨的微观分析

对不同剂量N 离子注入钨的试样进行了XRD及XPS微观分析 ,研究注入层的元素、成分、化学态以及有关的相结构。结果表明 ,注入层除了单质W外 ,还有氧化物WO3 ,氮 氧 钨的化合物 ,如Wx(N ,O)以及氮化物δ WN ,随着氮离子注入剂量的增加 ,Wx(N ,O)减少 ,而δ WN量增加 ,污染物WO3 也相应减少。文中对有关机理作了相应的探讨。     

离子注入机专利技术

离子注入机的基本原理是入射离子与半导体(靶)的原子核和电子不断发生碰撞,其方向改变,能量减少,经过一段曲折路径的运动后,因动能耗尽而停止在某处从而改变该处的电学特性以及实现掺杂。该文根据离子注入机各部分的不同作用,将离子体注入机分解为六个技术分支,具体包括离子源、离子筛选系统、加速结构(加速或减速)、束流系统(包括扫描、聚焦等调整注入前束流种类或参数的其他结构)、靶室、控制系统等,根据离子注入机领域产业的发展现状、多个关键技术领域的专利状况,分析了该领域的专利申请量和核心,同时对该领域未来发展趋势进行了预测。     

一种新型复合加速离子注入动力学研究

提出了一种基于靶台(工件)二次加速的束线离子注入的新方法,基本原理是将传统束线离子注入和等离子体离子注入有效复合。采用二维Particle-in-cell(PIC)模型对这种注入方法进行了数值仿真研究。考察了靶台加负偏压情况下靶台表面空间电势、离子密度变化以及离子的运动状态的时空演化。统计分析了不同时刻离子注入剂量、注入能量和注入角度的分布规律。结果表明:靶台施加偏压对束流离子起到了很好的二次加速效果,束线离子复合加速离子注入这种新方法理论上是切实可行的。同时发现在靶台附近空间电场的作用下,离子束会发生小角度偏转,由柱状形逐渐变成"喇叭口"形,靶台表面有效注入范围扩大。靶台表面注入剂量分布呈中心区域高边缘区域低的趋势。这种新方法有助于减缓电源硬件加工的难度,增加了工艺的灵活性。     

凹模内腔等离子体离子注入数值仿真—(Ⅰ)脉冲宽度效应

模具表面改性日益受到人们重视。本文采用二维Particle-in-cell/Monte Carlo Collision模型对等离子体浸没离子注入处理凹模型腔内表面的鞘层动力学及均匀性进行了研究。考察了电压脉宽对鞘层中电势分布、离子的运动状态以及型腔内表面离子注入剂量、能量和角度的空间分布的影响。结果表明随着电压脉宽的增加,凹模型腔内表面的注入剂量不均匀性增加,同时注入到内表面的高能离子数目也增加。脉冲宽度变化对注入角度影响不大,离子以接近垂直的入射角度注入到型腔底部,而在侧壁上离子注入角度接近45°。当脉冲宽度较大时,发现少部分注入到侧壁上的离子以一定角度从下往上注入到样品表面,这是由于碰撞效应造成的。从能量和剂量的角度,存在一个合适的脉冲宽度,过大的脉宽会引起剂量不均匀性增加,同时离子注入能量也会下降。     

凹模内腔等离子体离子注入数值仿真-(I)脉冲宽度效应

模具表面改性日益受到人们重视.本文采用二维Particle-in-cell/Monte Carlo Collision模型对等离子体浸没离子注入处理凹模型腔内表面的鞘层动力学及均匀性进行了研究.考察了电压脉宽对鞘层中电势分布、离子的运动状态以及型腔内表面离子注入剂量、能量和角度的空间分布的影响.结果表明随着电压脉宽的增加,凹模型腔内表面的注入剂量不均匀性增加,同时注入到内表面的高能离子数目也增加.脉冲宽度变化对注入角度影响不大,离子以接近垂直的入射角度注入到型腔底部,而在侧壁上离子注入角度接近45°.当脉冲宽度较大时,发现少部分注入到侧壁上的离子以一定角度从下往上注入到样品表面,这是由于碰撞效应造成的.从能量和剂量的角度,存在一个合适的脉冲宽度,过大的脉宽会引起剂量不均匀性增加,同时离子注入能量也会下降.     

强束流Ta离子注入铝的研究

利用从金属蒸汽真空弧离子源引出的强束流Ta离子 ,进行了Ta离子注入铝的研究。研究结果表明 ,在离子注入剂量为 5× 10 17cm- 2 ,平均束流密度为 4 0 μA·cm- 2 ,加速电压为 4 2kV下 ,Ta离子注入能在铝表面形成相应的合金层。借助卢瑟福背散射 (RBS)和X射线衍射 (XRD)分析 ,我们发现表面合金层中形成了Al3Ta相 ,Ta在铝中能产生 10 %以上的原子百分浓度 ,其深度高达 2 0 0nm。     

Si器件加工大束流离子注入的真空问题

本文从大束流离子注入的真空环境及对离子注入机性能影响的角度，讨论了大束流离子注入机真空系统的布置和设计。     

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.     

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.     

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.     

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 ...