共查询到20条相似文献,搜索用时 62 毫秒
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本文采用VHF-PECVD技术制备了系列硅薄膜,通过椭圆偏振技术及拉曼测试手段研究了衬底表面预处理时间对微晶硅薄膜的微结构及其生长的影响.实验结果表明:随衬底预处理时间(0~10 min)的延长,薄膜的晶化率从14%提高到44%;薄膜表面的硅团簇尺寸减小,在衬底预处理10 min时,薄膜表面的粗糙度较小.在衬底未预处理与预处理10 min时,在相同的沉积参数下,沉积两系列不同生长阶段硅薄膜的生长指数接近.原因是H等离子体预处理使衬底表面的原子氢增多,有利于成膜先驱物在衬底表面的迁移,影响薄膜的初期成核,使薄膜易于晶化. 相似文献
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本文综述了纳米硅薄膜制备新技术的进展。着重介绍了高氢稀释硅烷蚀刻法,微波氢基团增强化学气相沉积,逐层法和高频数值等离子体化学气相沉积技术制备纳米硅薄膜的沉积过程和生长机制.本文指出氢基团为各项新技术发展的关键并将在今后纳米硅薄膜制备技术发展中起重要作用。 相似文献
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采用PECVD技术,在玻璃衬底上低温沉积了优质本征纳米硅薄膜,并利用Raman光谱对其微结构作了表征。研究结果表明,硅烷浓度、衬底温度Ts对表征纳米硅薄膜微结构的晶化率和平均晶粒尺寸参数影响很大。SiH4浓度越低,越有利于晶化,对应的晶化率拐点温度越低。平均晶粒尺寸、晶化率随衬底温度的升高具有相似的变化规律,谱中出现的拐点温度一致,暗示它们之间存在紧密的联系。从薄膜生长角度对该实验结果作了合理解释。 相似文献
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通过改变氢气对硅烷的稀释比R, 采用等离子体增强化学气相沉积(PECVD)方法制备出具有非晶/微晶相变过渡区的氢化硅薄膜, 并研究了所得硅膜在不同沉积阶段的微观结构和形貌、晶化效果和电学性能。研究结果表明, 当R=10时, 样品呈典型的非晶特性; 随着氢稀释比的增大, 薄膜表现出两相结构, 且衬底表面处的非晶过渡层逐渐减薄, 也即非晶向微晶的转变提前。但XRD结果显示, 硅膜的晶化率和平均晶粒尺寸随着R的增加呈先增后减的趋势, 在R=28.6时达到最大值。另外, 暗电导率和载流子浓度表现出了与晶化率一样的变化趋势, 显示出硅膜的电学性能与微观结构的高度正相关性。 相似文献
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采用等离子体化学气相沉积(PECVD)技术在不同N_2O流量条件下制备了镶嵌有纳米晶硅(nc-Si)的富硅氧化硅(SiOx)薄膜,利用透射电镜(TEM),X射线衍射分析(XRD),傅里叶变换红外(FTIR)和透射光谱技术研究了薄膜中的氢含量和氧含量变化及其对薄膜晶化度、薄膜键合结构和光吸收特性的影响。结果表明,薄膜由nc-Si粒子和非晶SiOx组成,为混合相结构。nc-Si的生长与氧化反应的竞争决定了薄膜微观结构、键合特性以及光吸收特性。随着N_2O流量的增加,薄膜的晶粒尺寸逐渐减小。晶界区过渡晶硅的比例减少,晶粒界面随之消失,带隙呈持续增加趋势。该实验结果为ncSi/SiOx薄膜在新型太阳电池中的应用提供了基础数据。 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
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. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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Steffen Müller-Probandt 《材料科学与工程:中英文B版...》2018,(4):161-177
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... 相似文献
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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. 相似文献
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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.…… 相似文献
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Janet Lang 《Materials and Manufacturing Processes》2017,32(7-8):857-866
ABSTRACTThe 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. 相似文献
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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. 相似文献
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C. Qihong W. Zhan‐Wen J. Yi J. Yehua L. Fei F. Hanguang 《Materialwissenschaft und Werkstofftechnik》2014,45(7):582-590
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. 相似文献
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Dimiter Hadjistamov 《材料科学与工程:中英文B版...》2019,(2):56-65
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 ... 相似文献