沉积温度对ZrO2薄膜结构及表面形貌的影响

采用反应磁控溅射方法,在室温～550℃的沉积温度下,在Si(100)和玻璃基片上沉积了厚度在纳米量级的ZrO2薄膜.通过高分辨电子显微镜、原子力显微镜和透射光谱分析,研究了沉积温度对ZrO2薄膜的相结构、表面形貌和折射率的影响.研究结果表明沉积温度低于250℃时,ZrO2薄膜的结构完全呈非晶态,但250℃沉积的薄膜有比较高的致密度;随着沉积温度的升高,薄膜出现了明显的结晶现象,主要为单斜ZrO2相;沉积温度为450℃时,ZrO2薄膜晶化不完全,在晶粒堆砌处有非晶ZrO2相存在;沉积温度为550℃时,ZrO2薄膜完全晶化,在晶粒堆砌处有四方ZrO2相存在.此外,根据薄膜相结构和表面形貌的研究结果,探讨了沉积温度对薄膜生长行为的影响及其物理机制.     

正交相BaSi_2薄膜的制备及结晶研究

室温下采用磁控溅射的方法在p-Si(111)衬底上沉积Ba膜,然后置入高真空退火炉中在400~850℃退火12h生成Ba的硅化物薄膜,对退火后的Ba-Si化合物进行了晶体结构、表面形貌、透射光谱及电学性质的测试分析,研究了退火温度对薄膜结晶的影响。实验结果表明,退火温度对生成Ba-Si化合物及薄膜的表面形貌影响很大,随着退火温度从400℃升高到800℃,薄膜的结晶情况逐渐改善,晶粒随着温度的升高逐渐增大;800℃对于生成多晶的BaSi2薄膜是一个比较理想的退火温度;850℃生成了多相共生的硅化物薄膜。     

TiO_2自组装膜的制备及抗菌性能研究

以TiCl4为主要原料,采用自组装工艺,在玻璃基底表面制备TiO2薄膜。考察了(NH4)2SO4的添加、热处理温度、TiCl4浓度、反应温度、反应时间等工艺参数对TiO2薄膜结构和抗菌性能的影响规律。结果表明:未添加(NH4)2SO4时生成金红石型TiO2,而添加(NH4)2SO4可生成锐钛矿型TiO2,并且有利于TiO2膜均匀沉积。升高热处理温度,提高了TiO2的结晶度和薄膜附着力。但是,晶型和结晶度对薄膜的抗菌性能没有显著影响。随着TiCl4浓度增加,反应温度提高和反应时间延长,TiO2薄膜的抗菌性能得到提高。在最佳工艺条件,热处理温度为600℃、TiCl4浓度为0.2mol/L、反应温度为80℃、反应时间为80min时,抗菌率达100%。     

SiO2光子晶体结构色薄膜的制备与光学性能研究

为了研究结构色薄膜在不同条件下的带隙性能,采用改进的St?ber法,制备不同粒径的亚微米级别单分散SiO_2微球,并利用垂直沉积自组装方法在载玻片表面制备出以SiO_2为结构基元的光子晶体结构色薄膜。采用扫描电子显微镜、红外光谱仪、紫外-可见分光光度计对微球及薄膜的形貌与光学性能进行分析。结果表明:在微球合成过程中,随着反应温度的升高,SiO_2微球粒径逐渐减小;通过自组装制备的结构色薄膜,其光子带隙随着SiO_2微球粒径的增大而发生红移。进一步研究发现,随着入射光与光子晶体结构色薄膜法线夹角的不断增大,光子带隙所对应的中心波长变短,发生蓝移。     

电子束蒸发法制备掺钇稳定氧化锆薄膜的光学特性研究

利用电子束蒸镀方法在单晶硅和石英玻璃上制备了掺不同Y_2O_3浓度的掺钇稳定ZrO_2薄膜(YSZ),用X射线衍射、原子力显微镜、扫描电子显微镜和透射光谱测定薄膜的结构、表面特性和光学性能,研究了退火对薄膜结构和光学性能的影响.结果表明:一定浓度的Y_2O_3掺杂可以使ZrO_2薄膜稳定在四方相,退火显著影响薄膜结构,随着温度的升高薄膜结构依次经历由非晶到四方相再到四方和单斜混合相转变;AFM分析显示薄膜表面YSZ颗粒随着退火温度的升高逐渐增大,表面粗糙度相应增大,晶粒大小计算表明,退火温度的提高有助于薄膜的结晶化,退火温度从400℃到1100℃变化范围内晶粒大小从15.6nm增大到46.3nm;同时利用纳秒激光对薄膜进行了破坏阈值测量,结果表明电子束蒸镀制备YSZ薄膜是一种制备高抗激光损伤镀层的有效方法.     

直流溅射沉积氧化镍薄膜及结构表征

采用直流溅射并结合热处理工艺制备氧化镍薄膜,利用X射线衍射仪(XRD)、扫描电镜(SEM)、能谱仪(EDX)考察退火温度对薄膜结构、形貌和组成的影响,并通过恒流充放电技术初步考察薄膜的电化学性能.研究结果表明,在400℃～500℃退火温度下制备了表面光滑、结构致密的NiO薄膜;随着退火温度的升高,薄膜的晶粒尺寸逐渐增大,晶形趋于完整;其中,500℃下退火2 h获得的NiO薄膜具有良好的电化学循环稳定性,有望成为高性能的全固态薄膜镡电池阳极材料.     

沉积工艺对高 k栅介质 ZrO2薄膜生长行为的影响

采用反应射频磁控溅射法在Si（100）基片上制备了ZrO2薄膜，通过高分辨电子显微镜、原子力显微镜，研究了沉积工艺参数（主要包括氧分压和沉积温度）对ZrO2薄膜的表面形貌和微结构的影响．研究结果显示；氧分压和沉积温度是影响ZrO2薄膜生长行为的重要因素．随氧分压的增大，ZrO2薄膜的表面粗糙度近乎呈线形增加的趋势，ZrO2薄膜微结构演化过程是a-ZrO2（非晶）→a-ZrO2和少量m-ZrO2（单斜）→m-ZrO2和少量t-ZrO2（四方）→m-ZrO2；随沉积温度从室温升高到550℃，ZrO2薄膜微结构演化过程是a-ZrO2（〈250℃）→m-zrO2和少量a-ZrO2（450℃）→m-ZrO2和少量t-ZrO2（550℃）；此外，根据薄膜微结构和表面形貌的研究结果，探讨了沉积温度对薄膜生长行为的影响及其物理机制．     

退火温度对溶胶-凝胶法制备TiO2薄膜的结构和光学特性的影响

采用溶胶-凝胶浸渍提拉法分别在氧化硅和石英衬底上制备TiO2薄膜,并以不同的退火温度保温30min。通过采用X射线衍射仪(XRD)、扫描电镜(SEM)及紫外-可见分光光度计,对TiO2薄膜的结构和光学性能进行了详细分析,并且进行了对甲基橙的降解实验。研究结果表明,随着退火温度的升高,薄膜的晶相由锐钛矿向金红石转变,转变温度在700～800℃之间。在该转变过程中,薄膜结晶程度良好,800℃时薄膜表面平整无开裂;随着热处理温度的升高,TiO2薄膜的吸收峰蓝移,紫外区吸收范围扩大。在800℃退火时,薄膜中所含锐钛矿TiO2为31.4%(质量分数)。此时薄膜表现出最高的甲基橙降解率。     

调控CN_x薄膜的紫外可见波段光学性能研究北大核心CSCD

采用等离子体增强化学气相沉积(PECVD)在不同衬底温度(常温、50、100、150、200℃)下制备了碳氮(CNx)薄膜,并对其形貌、结构及光学性能进行了研究。通过扫描电镜得出随着衬底温度的升高,薄膜由疏松逐渐变得致密。X射线光电子能谱分析表明:薄膜的结合健有sp^2C=C、sp^3C-C、sp^2C=N和sp^3C-N。随着衬底温度的升高,sp^2C=C的比例没有明显变化,sp3C-C比例逐渐增大(28.6%~36.4%),sp^3C-N的比例也逐渐增大(21.4%~33.4%),而sp^2C=N的比例减小(40.2%~21%)。反射光谱和吸收光谱显示:随着衬底温度的升高,薄膜在200~800 nm波段内的反射率增大(8%~40%),吸收率减小(92%~60%)。进一步推导得到薄膜的光学带隙随着衬底温度的升高而增大(2.5~3.57 e V),主要由薄膜中sp^2C=N减少导致的。本文实现了对CN_x薄膜在紫外可见波段范围内的光学带隙的调控。     

调控CN_x薄膜的紫外可见波段光学性能研究

采用等离子体增强化学气相沉积(PECVD)在不同衬底温度(常温、50、100、150、200℃)下制备了碳氮(CNx)薄膜,并对其形貌、结构及光学性能进行了研究。通过扫描电镜得出随着衬底温度的升高,薄膜由疏松逐渐变得致密。X射线光电子能谱分析表明:薄膜的结合健有sp~2C=C、sp~3C-C、sp~2C=N和sp~3C-N。随着衬底温度的升高,sp~2C=C的比例没有明显变化,sp3C-C比例逐渐增大(28.6%~36.4%),sp~3C-N的比例也逐渐增大(21.4%~33.4%),而sp~2C=N的比例减小(40.2%~21%)。反射光谱和吸收光谱显示:随着衬底温度的升高,薄膜在200~800 nm波段内的反射率增大(8%~40%),吸收率减小(92%~60%)。进一步推导得到薄膜的光学带隙随着衬底温度的升高而增大(2.5~3.57 e V),主要由薄膜中sp~2C=N减少导致的。本文实现了对CN_x薄膜在紫外可见波段范围内的光学带隙的调控。     

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 ...