KDP晶体(100)面生长台阶聚并现象的AFM研究

采用激光偏振干涉手段实时测量了KDP晶体(100)面的生长速度与过饱和度之间的关系,用AFM技术观察了KDP晶体(100)面在不同过饱和度下的基本台阶和聚并台阶形貌,并据此分析了由基本台阶到聚并台阶的过程及其与过饱和度之间的关系.研究表明:过饱和度为1.8%时,(100)面上以基本台阶为主,基本台阶的高度为0.366 nm,约为半晶胞高度;增大过饱和度,基本台阶开始聚并,聚并初期,台阶高度增加,进而台阶宽度增加;随着过饱和度的增大,台阶聚并加剧,推移速度加快,但聚并台阶的斜率基本不变.     

ZTS晶体(100)面台阶聚并现象的AFM非实时研究

通过对301 K时,不同过饱和度以及掺杂2.5%(摩尔分数)尿素(σ=0.09)条件下生长的ZTS晶体进行AFM非实时扫描,对其(100)面的基本台阶以及聚并形成宏观台阶的形貌情况进行了研究。发现ZTS晶体(100)面在低过饱和度下(σ=0.03),以基本台阶推移为主,台阶高度约为0.553nm,近似为晶格参数a值的一半;在高过饱和度下(σ=0.09),以台阶聚并后的宏观台阶推移为主。而在同样的过饱和度下掺入尿素则会加剧台阶聚并的程度,该实验结果很好地符合了杂质诱导产生非对称台阶动力学系数理论模型。     

ADP晶体的生长丘、台阶微观形貌及台阶棱边能

ADP晶体{100}面族生长的实时与非实时AFM(atomic force microscopy,AFM)研究表明,过饱和度σ处于0.005～0.04,生长温度介于293～313K之间时,晶面上观察到位错生长丘和其它晶体缺陷所形成的生长丘,晶面主要为台阶推进方式生长;位错生长丘上空洞的出现与位错弹性理论相符;随过饱和度σ降低,台阶形貌会发生相应变化;生长温度为298K时,台阶棱边能不小于6.2×10-7J/cm2.     

流动对ZTS晶体(100)面台阶生长动力学影响的研究

通过利用光学显微镜对ZTS晶体(100)面的台阶推移过程进行实时观察,对不同溶液供应速度及不同过饱和度下的台阶生长动力学进行了研究。结果表明,随着溶液供应速度S的增大,台阶平均推移速率先增大后减小。溶液供应速度S≈1.2mL/min时,台阶平均推移速率达到最大。而在静止的生长溶液中,台阶平均推移速率随着过饱和度σ的增大呈非线性增大,同时确定了生长死区σd和台阶平均推移速率急剧增大时的临界过饱和度值σ*,并计算了不同过饱和度阶段的台阶动力学系数和台阶活化能。     

ZTS晶体(100)面生长过程的实时AFM研究

利用原子力显微镜(AFM)对不同生长条件下ZTS晶体(100)面生长过程进行实时观测发现,(100)面均呈现为台阶面,台阶分单台阶、聚并台阶和准聚并台阶3种。位错、缺陷和二维成核均可形成单台阶;聚并台阶以整体推移的方式生长,而准聚并台阶内的单台阶保持单台阶推移的特点。单台阶的推移展现出明显的各向异性。聚并台阶的聚并程度随着过饱和度增大而增大;台阶簇内台阶合并和不同生长源生成的沿不同推移方向推移的台阶相互影响引起台阶运动失稳均能导致聚并台阶的形成;聚并台阶列同步向前推移体现出生长的稳定性,随着生长进行,生长台阶各个位置的过饱和度差异会导致稳定性遭到破坏。另外发现,晶体表面存在优先成核位置,优先成核位置位于台阶边缘,且成核过程遵循成核—扩展—再次成核的规律性。     

硫脲硫酸锌晶体（100）面台阶生长动力学实时研究

运用光学显微镜实时观测了硫脲硫酸锌晶体（100）面台阶推移过程。获得了不同过饱和度、不同台阶高度、不同生长时间、不同台阶边缘扭折密度下的台阶推移速率;应用＂净流量＂模型解释了不同台阶推移速率的差异与过饱和度之间的依赖关系,计算了生长单元与台阶融合活化能及单台阶的动力学系数。通过分析发现台阶推移速率随过饱和度增加而线性增加,随台阶高度增加而下降;同一台阶推移速率随时间变化的现象与台阶重组过程有关;而台阶边缘扭折密度则从根本上决定了台阶推移速率的大小和变化趋势。     

pH值对ADP晶体(100)面生长的影响

通过对40℃、不同pH值和过饱和度下ADP晶体(100)面法向生长速度的研究,发现在同一过饱和度下,改变pH值后晶面的生长速度明显加快。实验数据显示,在过饱和度较低时,(100)面的生长以螺旋位错生长机制为主;过饱和度较高时,以二维成核生长机制为主,而且pH值的改变会促使ADP晶体在较低的过饱和度下就从位错生长机制向二维成核生长机制转变。利用实验数据计算出了不同pH值下、二维成核生长机制控制晶体生长时的台阶棱边能。最后,运用原子力显微镜(AFM)非实时观察了不同过饱和度、不同pH值下生长的ADP晶体(100)面的微观形貌,发现与正常pH值相比,在较低的过饱和度下,pH=2.5和5.0的晶面上就出现了二维核。     

添加剂DTPA对KDP晶体快速生长及性能的影响研究

在添加1×10^-4 (mol/mol KDP) 二乙烯三胺五乙酸(DTPA)的溶液中, 利用“点籽晶”快速生长法生长了KDP晶体. 实验发现, 添加少量DTPA即可使不同饱和温度下的KDP生长溶液的亚稳区宽度均得到提高. 利用激光偏振干涉装置研究了不同浓度的DTPA对KDP晶体(100)面生长动力学的影响. 发现随DTPA掺杂量增加, 临界过饱和度(死区)一直降低, 生长速度则是先增加经过一个最大值后减小. 表征了晶体的光学透过率和晶体内部的杂质金属离子含量, 发现掺杂1×10^-4 (mol/mol) DTPA大幅提高了快速生长的KDP晶体在紫外区的透过率, 并有效地减少了进入晶体内部的杂质金属离子含量.     

二维平移法小尺寸KDP单晶生长溶液流动与传质模拟

二维平移法是一种新型的晶体生长方法.在该方法中,晶体不再作正反转运动,而是沿着特定轨迹作周期性的平移运动.本工作对二维平移法小尺寸磷酸二氢钾(KDP)单晶生长过程进行了数值模拟研究,获得了不同平移速度、不同平移距离以及不同迎流角度下晶体附近溶液流动与晶面过饱和度分布.结果表明:增加平移速度,晶面过饱和度随之增加,但流场结构并无明显变化;增大平移距离,晶面的过饱和度反而降低,标准差则有逐渐增大的趋势,这不利于提高过饱和度均匀性;不同迎流角度下,柱面的过饱和度分布差异较大,对流的不对称性也更加明显,当迎流角度为45°时,对晶体生长更有利.此外,台阶推移结果表明,不均匀的过饱和度会造成台阶弯曲和聚并,二维平移法更利于台阶稳定推移,有望提高形貌稳定性和晶体质量.     

磷酸二氢钾晶体薄表面层生长动力学实时显微研究

利用光学显微镜实时观测磷酸二氢钾(KDP)晶体柱面及锥面薄表面层的生长过程,测得不同过饱和度下薄表面层前端不同倾角的非正常棱边推移速度。结果表明:倾角越小,非正常棱边推移速度越慢,薄表面生长终止于其前端的正常棱边处;随着过饱和度的增大,非正常棱边推移速度线性增加。计算得到柱面及锥面薄表面层前端非正常棱边推移动力学系数,由于Eslice(010) Eslice(101),因而柱面薄表面层的生长动力学系数大于锥面。建立了基于非奇异面上台阶生长机制下的薄表面层生长体扩散模型。应用该模型解释了薄表面层生长速度随其厚度及前端非正常棱边倾角的变化关系,并讨论了溶液流动对薄表面层生长的影响。结果发现薄表面层生长存在一个使其以恒定厚度向前推移的临界厚度。     

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...     

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.     

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.……     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.     

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.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

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