不同基底上碳纳米管的制备及生长机理

以二茂铁为催化前驱物,C2H2为碳源,N2为载气,采用浮动催化法,在蓝宝石、单晶硅、石英、玻璃以及碳纤维基底上制备了不同形貌和结构的碳纳米管.利用扫描电子显微镜和Raman光谱对碳纳米管的形貌和微结构进行了表征.结果表明在蓝宝石和石英基底上所生长的碳纳米管薄膜具有较好的定向性和较高的石墨化程度;单晶硅基底上碳纳米管薄膜呈"底疏顶密"分布;而玻璃和碳纤维基底上所生长的碳纳米管不具有定向性.最后,对不同基底对碳纳米管生长的影响进行了分析和讨论.     

改变基底合成不同形貌碳纳米管宏观结构

采用化学气相沉积法,选用不同基底和表面涂层合成了碳纳米管垂直阵列薄膜、管束和条带三种碳纳米管宏观结构,并用扫描电镜（SEM）和透射电镜（TEM）进行了表征。结果表明：在石英涂层上合成的定向碳纳米管薄膜厚度达毫米级;在表面有Al2O3涂层的不锈钢基底上可合成碳纳米管垂直阵列薄膜和不同尺寸宏观管束结构;在表面有SiO2涂层...     

定向碳纳米管的化学气相沉积制备法

报道了一种简便有效的合成定向碳纳米管 (CNTs)的化学气相沉积 (CVD)制备方法。以铁为催化剂 ,乙炔为碳源 ,采用单一反应炉 ,直接在石英基底上沉积催化剂颗粒薄膜 ,成功合成了定向性好、管径均匀的高质量大密度的碳纳米管     

定向碳纳米管薄膜的制备

以二茂铁为催化剂前驱体,氢气为载气,乙炔为碳源,硅片作衬底,用化学气相沉积法,采用不同的催化剂引入方式,在700℃下分别制备出定向碳纳米管薄膜及非定向碳纳米管薄膜.并基于实验结果对影响生长定向碳纳米管的因素进行分析,表明催化剂颗粒的诱导作用是导致生长定向碳纳米管的重要原因.     

定向碳纳米管阵列在石英玻璃基底上的模板化生长研究

分别以带有刻痕的石英玻璃和溅射过Au膜的石英玻璃为生长基底,通过催化裂解二茂铁和二甲苯混合物的方法,在基底上制备出了模板化的定向碳纳米管(CNT)阵列,扫描电镜(SEM)和透射电镜(TEM)观察表明:在这两种基底上生长的定向碳纳米管阵列的模板化程度都很高,其中的碳纳米管多为直径在20～50nm的多壁管(MWNT),且具有很好的定向性。本文还分析、对比了基底材料对定向碳纳米管生长的影响,初步探讨了定向碳纳米管模板化生长的形成机制。     

辅助气体对RF-PECVD制备碳纳米管薄膜形貌的影响

采用射频等离子体增强化学气相沉积(RF-PECVD)技术,以Ni为催化剂,经600℃裂解C2H2在Si基底上制备出定向碳纳米管薄膜。采用扫描电子显微镜(SEM)表征了刻蚀后Ni颗粒与沉积的碳纳米管薄膜的形貌。研究了辅助气体对等离子体预处理催化剂与碳纳米管生长的影响。结果表明:辅助气体(H2与N2)流量比对催化剂颗粒尺寸、分布以及碳纳米管生长有显著影响;合适的气体流量比有利于减少碳纳米管薄膜的杂质颗粒,促进其定向生长。预处理过程中气体流量比H2:N2=20:5时,预处理后催化剂Ni颗粒分布密度大、粒径小且分布范围窄,适合碳纳米管均匀着床;沉积生长碳纳米管薄膜时,H2:N2=20:15可得到纯度高、定向性好的碳纳米管。     

聚乙烯醇增强碳纳米管薄膜的表面粘附性能研究

采用抽滤法在碳纳米管薄膜中引入聚乙烯醇构筑复合网络结构,并利用聚乙烯醇的官能团增强薄膜与基底间的范德华作用力,实现强粘附效果。通过选择聚合物的平均聚合度,可实现在玻璃基底上最高达到550kPa的粘附强度,是未经聚乙烯醇处理的6~10倍。这种复合结构也可以显著提高对铜片、硅片、镍箔的粘附效果,其平均粘附强度可分别达到172.6,305.7,335.5kPa。     

H2O2原位净化定向碳纳米管阵列的研究

采用无模板的化学气相沉积法(CVD)，在石英衬底上制备了大面积、高定向性、自支撑的定向碳纳米管阵列。对此阵列采用原位H2O2氧化，可以有效地达到净化定向碳纳米管阵列的目的。扫描电镜(SEM)检测表明净化碳纳米管的过程并不会破坏其定向性。此种方法可以获得不同厚度的、多数碳管端帽打开、非晶碳、缺陷碳管和杂质较少的定向碳纳米管阵列，此种阵列在场发射等方面具有应用价值。Raman光谱和热失重分析(TGA)表明经过净化的碳纳米管的晶化程度和热稳定性都有所提高。     

定向碳纳米管薄膜的制备研究

采用化学气相沉积法制备了定向碳纳米管薄膜,研究了向反应室载入水、氨水对定向碳纳米管薄膜的影响,并用SEM、TEM、XRD对碳纳米管进行了表征。结果表明：向反应室载入水的量增大,定向碳纳米管的长度先增加后减小。载入水的氩气流量为400ml／min,定向碳纳米管的长度1750μm;向反应室载入氨水,得到疏密相间排列的定向碳纳米管薄膜,氨水量增加,定向碳纳米管薄膜的厚度减小。     

电泳沉积碳纳米管场发射阴极研究进展

电泳法是一种工艺简洁、低能耗、低成本的薄膜制备工艺.基于电泳技术的碳纳米管薄膜具有对基底类型和形状要求低、常温操作等优势,尤其适宜于在复杂不规则基底和低熔点材料上的应用.在阐述了电泳法的工艺特点的基础上,本文总结了应用电泳技术制备碳纳米管薄膜的方法,讨论了丰富多样的碳纳米管电泳液制备工艺,介绍了碳纳米管薄膜作为场发射阴极在真空电子领域的应用开发新进展.     

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.……     

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.     

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 ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.