共查询到20条相似文献,搜索用时 156 毫秒
1.
《真空科学与技术学报》2017,(6)
采用脉冲激光沉积技术,在c面蓝宝石衬底上制备出了VO_2薄膜。利用X射线衍射、Raman光谱、原子力显微镜对生长的样品的结构和表面形貌进行了表征;利用霍尔效应测试仪和紫外-可见-红外光分光光度计分别测试薄膜的方块电阻和透过率。结果表明:在蓝宝石衬底上生长出了结晶性能良好的VO_2薄膜;相变前后其方块电阻变化高达4个数量级,红外透过率的变化高达56%。VO_2薄膜表现出了良好的金属-绝缘转变特性。 相似文献
2.
采用射频磁控溅射方法和热处理工艺制备了二氧化钒(VO2)薄膜,并制作了金属钨/VO2/金属钨三明治结构,通过改变金属钨/VO2/金属钨三明治结构中VO2薄膜与金属钨电极的接触面积,研究了VO2薄膜的电致相变特性.采用x射线衍射仪(XRD)、扫描电子显微镜(SEM)、四探针和半导体参数测试仪对VO2薄膜的结晶取向、表面形貌、方块电阻和,I-V特性进行了测试.实验结果表明,所制备的VO2薄膜为具有热致相变特性的单一组分VO2纳米薄膜,在热激励下,薄膜的方块电阻相变幅度达到2个数量级;在电压的激励下,VO2薄膜与金属钨的接触面积为12μm×12um时,电流发生跳变的阁值电压为9.4V,随着接触面积的减小,闽值电压也逐渐降低. 相似文献
3.
4.
采用微波加热Polyol法以PVP作为稳定剂,首先快速合成了晶粒尺寸为2~6nm具有不同长宽比的各向异性的单分散金属钌胶体颗粒.以单分散胶体颗粒为晶种,获得不同团聚程度的纳米金属钌颗粒.高分辨电子显微镜(HRTEM)研究表明,树枝状纳米金属钌是由随机取向的金属钌单晶颗粒组成的. 相似文献
5.
6.
7.
电磁干扰、电磁辐射对人类生产生活的影响越来越严重,电磁屏蔽材料因而应运而生。目前的电磁屏蔽材料中,金属纳米线具有较高的电导率和可弯折性能,其中银纳米线因具有化学稳定性好、制备成本较低、成膜后易修复、可大批量生产等优势,成为新一代电磁屏蔽材料。以溴化钠和氯化铁为原料制备银纳米线并将其半嵌入到聚氨酯膜形成屏蔽材料。制备的银纳米线@聚氨酯薄膜无需后期热处理,方块电阻达到10Ω/sq,当薄膜厚度达到5μm时,其电磁屏蔽效能超过40dB。与此同时,制备的半嵌入式结构银纳米线@聚氨酯薄膜具有优良的耐弯折性能(弯折500次方块电阻变化率0.5,电磁屏蔽效能变化率为3%)和力学稳定性能(粘接200次方块电阻变化率0.35)。 相似文献
8.
9.
柔性衬底ITO薄膜的制备及其光电性能研究 总被引:5,自引:3,他引:2
在室温下,采用直流反应磁控溅射法,在聚酯薄膜(PEP)衬底上镀制了高性能的ITO薄膜。为了提高薄膜与基底的结合力,溅射前采用多弧离子源对PEP表面进行了等离子体清洗。研究了溅射工艺参数对ITO薄膜的光电性能和红外发射率的影响规律,探讨了ITO膜的透光和导电机理,并分析了方块电阻与红外发射率的相互关系。实验结果表明,通过等离子体清洗,ITO薄膜的结合力和光电性能都得到了改善。ITO薄膜的红外发射率和方块电阻受制备条件的影响规律具有相似之处,红外发射率随薄膜方块电阻的增大而呈增加的趋势。 相似文献
10.
11.
《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
12.
13.
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
14.
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
15.
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
16.
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
17.
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
18.
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
19.
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
20.
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