碳纳米管场发射阴极阵列制备研究与进展

碳纳米管具有良好的电子发射特性,成为理想的场致发射阴极材料,碳纳米管阵列制备研究是碳纳米管平板显示应用的前提。介绍了碳纳米管阴极阵列制备技术如丝网印制法、CVD原位生长法、光刻法和自组织法等研究与进展,并从薄膜残留去除、CNTs膜微结构改变及sp3缺陷增加等方面概述了目前CNTs场发射性能优化的进展,指出了目前存在的问题并作了简单分析。     

丝网印刷制备碳纳米管场发射阴极的研究

碳纳米管(CNT)是理想的场发射阴极材料.本文分析了CNT的长度、直径以及排列密度与CNT阴极场增强因子的关系,研究了大面积CNT场发射阴极的丝网制备技术,包括CNT浆料配制、阴极电极的制作、阴极烧制方法和表面处理方法.文中实际制备了CNT阴极,利用二极管结构测试了对其表面处理前后的场发射性能.实验结果证明,采用本文所研究的制备技术能够印制高性能的场发射CNT阴极,该研究为制备大面积CNT阴极阵列提供了技术基础.     

基于碳纳米管薄膜构建场发射平面显示器的阴极结构

碳纳米管场发射平面显示器具有工作电压低、功耗低和制造成本低等优势,近年来基于碳纳米管场发射平面显示器的研究与应用研发已成为显示技术领域研究的热点之一,并已取得丰富成果。简要回顾了碳纳米管用于场发射的机理以及用于场发射平面显示器的优势,主要介绍了碳纳米管用于场发射平面显示器研究的一些进展和一些亟待解决的问题,包括碳纳米管阴极薄膜的制备、碳纳米管阴极工作稳定性与寿命的改进以及阴极结构的设计等,并展望了碳纳米管用于场发射平面显示器的发展前景。     

碳纳米管/聚四氟乙烯复合材料场发射特性研究

通过催化热解法制备了碳纳米管,采用机械共混法制作了碳纳米管/聚四氟乙烯复合材料场发射阴极,研究了不同碳纳米管质量分数对复合材料阴极场发射特性的影响,通过制作的封装结构,对比研究了真空环境下碳纳米管/聚四氟乙烯与碳纳米管/环氧树脂复合材料的场发射特性,证明碳纳米管/聚四氟乙烯复合材料更适用于场发射阴极的真空环境中,可以满足场发射显示器件的要求.     

MWCNT/ZnO纳米线复合阴极薄膜的场发射特性

实验提出以多壁碳纳米管(MWCNT)/ZnO纳米线复合材料作为场发射阴极薄膜,研究其图形化制备工艺以及其场发射特性.用丝网印刷工艺制备图形化MWCNT/ZnO纳米线复合阴极薄膜,实验获得合适的浆料配比以及适合的烘烤和烧结温度.对MWCNT/ZnO纳米线样品进行SEM分析和场发射特性测试,发现图形化阴极设计提高了场发射电流,并且改善场发射发光均匀度;材料组分的低维化明显降低场发射开启电压;加电老练处理有效改善场发射特性.     

有机质掺杂碳纳米管阵列场发射性质的研究

碳纳米管(CNT)作为理想的场发射阴极材料,在场发射阴极阵列中的密度与阴极的场发射性能有着非常密切的关系。通过解拉普拉斯方程,得到碳管阵列密度对场增强因子的影响,同时通过对不同阵列密度的碳纳米管阵列进行有机质的填充解决了碳纳米管阵列在制备过程中的定向排列问题,并对所需碳管与有机质的质量比进行了理论计算,结果表明,阵列密度和管间距对碳管与有机质的质量比有很大影响。     

电泳法制备碳纳米管场发射阴极的研究

利用传统的电泳方法,在玻璃基片上成功地制备了场发射用碳纳米管阴极薄膜.用扫描电子显微镜和拉曼光谱观察了薄膜的形貌和结构,并测试了所制备的薄膜阴极的场发射特性.实验结果表明在玻璃的银浆导电层上沉积了一层较薄而均匀的碳纳米管膜,其场发射特性与丝网印刷工艺制备的阴极有相似甚至更佳的性能,具有更好的发射均匀性.采用电泳方法制备场发射阴极具有简单易行,成本低廉等优势,可以避免丝网印刷工艺带来的有机杂质污染和发射不均匀等问题.     

碳纳米管/二氧化硅复合材料制备及场发射特性研究

采用溶胶-凝胶法制备了碳纳米管/二氧化硅复合材料,并对复合材料的场发射特性进行了研究,结果表明:复合材料有很好的场发射特性,含有10%(质量分数)CNTs的复合材料开启场较低(0.98V/μm).研究了用稀HF溶液处理复合材料表面后场发射性能,发现场发射性能明显改善,开启场由0.98V/μm下降到0.73V/μm,发射电流为1mA/cm2时的电场由2.1V/μm下降到1.0V/μm.研究表明碳纳米管/二氧化硅复合材料非常适用于场发射平面显示器中的阴极.     

碳纳米管场发射薄膜的研究现状

碳纳米管独特的物理性质、化学稳定性和高机械强度,使其成为电子发射领域最有潜力的场发射阴极材料.分析了目前国内外场发射碳纳米管薄膜的制备技术和应用中存在的问题,并讨论了解决方案.     

PBT/石墨烯/碳纳米管复合材料的制备及其导电性能研究

以膨胀石墨为基体,用硝酸铁、碳酸铵等物质对其进行修饰,结合化学气相沉积工艺,原位制备出石墨烯/碳纳米管复合粉体材料;利用扫描电镜对复合粉体进行了表征。采用熔融混炼的方法制备PBT/石墨烯/碳纳米管复合材料并测试了其表面电阻。研究结果表明:该方法可以制备出性能优异的石墨烯/碳纳米管复合粉体材料,将该复合粉体加入到PBT中所制备的复合材料具有优良的电性能;当复合粉体加入量为5%时,PBT/石墨烯/碳纳米管复合材料的表面电阻可达到106Ω。     

碳纳米管/聚合物复合材料界面结合性能的研究进展

碳纳米管(CNT)优异的力学性能使其成为复合材料优选的增强体。CNT/聚合物复合材料的力学性能主要受其界面结合性能的影响。综述了CNT/聚合物复合材料界面结合性能的研究方法和研究现状。对CNT/聚合物复合材料界面结合性能的研究,实验上采用微观表征技术、拉曼光谱分析技术和纳米力学拔出法,分子模拟方法则是通过对CNT施加位移或外力模拟CNT从聚合物基体中的抽拔过程。概述了聚合物的类型、晶态结构以及CNT的手性、功能化处理等因素对CNT/聚合物复合材料界面结合性能的影响,并展望了CNT/聚合物复合材料界面结合性能未来研究的重点方向。     

功能化碳纳米管改性热塑性复合材料研究进展

碳纳米管(CNT)具有纳米级直径、大长径比、高强度,同时又具有优异的柔韧性以及良好的化学稳定性,这使得CNT可以成为增强聚合物复合材料的理想填料。然而,由于范德华力相互作用,CNT极难在热塑性基体中形成稳定分散。将CNT表面功能化是有效改善CNT与树脂基体亲和性和实现有效分散的重要手段。综述了CNT功能化的方法,功能化CNT在热塑性基体中的分散研究进展,及其改性后对热塑性基体的电学和力学性能等的影响,最后阐述了目前CNT在聚合物中应用的关键问题。     

Recent Advances in Research on Carbon Nanotube–Polymer Composites

Carbon nanotubes (CNTs) demonstrate remarkable electrical, thermal, and mechanical properties, which allow a number of exciting potential applications. In this article, we review the most recent progress in research on the development of CNT–polymer composites, with particular attention to their mechanical and electrical (conductive) properties. Various functionalization and fabrication approaches and their role in the preparation of CNT–polymer composites with improved mechanical and electrical properties are discussed. We tabulate the most recent values of Young's modulus and electrical conductivities for various CNT–polymer composites and compare the effectiveness of different processing techniques. Finally, we give a future outlook for the development of CNT–polymer composites as potential alternative materials for various applications, including flexible electrodes in displays, electronic paper, antistatic coatings, bullet‐proof vests, protective clothing, and high‐performance composites for aircraft and automotive industries.     

Carbon nanotube reinforced polymer composites—A state of the art

Because of their high mechanical strength, carbon nanotubes (CNTs) are being considered as nanoscale fibres to enhance the performance of polymer composite materials. Novel CNT-based composites have been fabricated using different methods, expecting that the resulting composites would possess enhanced or completely new set of physical properties due to the addition of CNTs. However, the physics of interactions between CNT and its surrounding matrix material in such nano-composites has yet to be elucidated and methods for determining the parameters controlling interfacial characteristics such as interfacial shear stress, is still challenging. An improvement of the physical properties of polymer nanocomposites, based on carbon nanotubes (CNTs), is addicted to a good dispersion and strong interactions between the matrix and the filler.     

CNT reinforced light metal composites produced by melt stirring and by high pressure die casting

Light metal matrix composites are of great interest due to their potential for reducing CO₂ emission through lightweight design e.g. in the automotive sector. Carbon nanotubes can be considered as ideal reinforcements, due to their high strength, high aspect ratio and thermo-mechanic properties. In this research, CNT reinforced light metal composites were produced by melt stirring and by high pressure die casting, which can be both easily scaled up. The light metal composites showed significantly improved mechanical properties already at small CNT contents. The influence of CNT concentration on the composites was also studied.     

Effect of fibre coating and geometry on the tensile properties of hybrid carbon nanotube coated carbon fibre reinforced composite

Hierarchically structured hybrid composites are ideal engineered materials to carry loads and stresses due to their high in-plane specific mechanical properties. Growing carbon nanotubes (CNTs) on the surface of high performance carbon fibres (CFs) provides a means to tailor the mechanical properties of the fibre–resin interface of a composite. The growth of CNT on CF was conducted via floating catalyst chemical vapor deposition (CVD). The mechanical properties of the resultant fibres, carbon nanotube (CNT) density and alignment morphology were shown to depend on the CNT growth temperature, growth time, carrier gas flow rate, catalyst amount, and atmospheric conditions within the CVD chamber. Carbon nanotube coated carbon fibre reinforced polypropylene (CNT-CF/PP) composites were fabricated and characterized. A combination of Halpin–Tsai equations, Voigt–Reuss model, rule of mixture and Krenchel approach were used in hierarchy to predict the mechanical properties of randomly oriented short fibre reinforced composite. A fractographic analysis was carried out in which the fibre orientation distribution has been analyzed on the composite fracture surfaces with Scanning Electron Microscope (SEM) and image processing software. Finally, the discrepancies between the predicted and experimental values are explained.     

生物质纤维基包装复合材料的研究现状

目的综述纤维基复合材料在包装中的应用和研究现状。方法介绍国内外生物质纤维基复合材料在发泡型材料、薄膜、板材等不同种类包装材料中的应用现状,分别总结各类包装材料使用的基材及制备工艺,比较不同纤维基复合材料的性能差异,指出复合材料在制备工艺及性能上的不足,并展望纤维基包装复合材料的发展前景。结果纤维素具有天然的化学结构,使纤维基材料具有良好的力学性能、阻隔性、可降解性,较好地应用在不同包装材料中。结论纤维基复合材料具有性能优良、可生物降解、经济环保等特点,在包装领域具有较大发展潜力,在原料的选择、制备工艺绿色化及性能的可控性等方面还有较大的研究空间。     

AlN-CNTs/聚酰亚胺复合材料的制备与性能

为了研究氮化铝(AlN)和碳纳米管(CNTs)对聚酰亚胺(PI)的导热、热学、力学性能的协同效应,采用湿法球磨和热压成型法制备了AlN/PI和CNTs-AlN/PI复合材料。利用X射线衍射仪、扫描电子显微镜对复合材料进行了物相分析和断面形貌表征,分别考察了AlN及其与CNTs协同对PI复合材料的导热、热学、力学性能的影响。结果表明,AlN和CNTs在PI基体中分散均匀且接触界面良好,AlN的加入可以显著地提高复合材料的导热性能,且对复合材料的热稳定性和力学性能有一定的提高;固定AlN的含量为10%,加入少量的CNTs可以提高复合材料的导热性能,但对复合材料的力学性能有一定的负面影响。     

球磨工艺对原位合成碳纳米管增强铝基复合材料微观组织和力学性能的影响

将原位化学气相沉积法合成的碳纳米管(CNTs)与铝的复合粉末进行球磨混合,进而粉末冶金制备CNTs/Al复合材料,研究球磨工艺对复合材料的微观组织和力学性能的影响。结果表明:球磨过程中不添加过程控制剂所得到的复合材料力学性能优异;随着球磨时间的增加,CNTs逐步分散嵌入铝基体内部,复合材料的组织也变得更加致密均匀。CNTs/Al复合材料的硬度和抗拉强度均随球磨时间的延长持续增加,但是伸长率先增后减。经90min球磨的CNTs/Al复合材料展现了强韧兼备的特点,其硬度和抗拉强度较原始纯铝提高了1.4倍和1.7倍,并且具有17.9%的高伸长率。     

Assessment of carbon nanotube yarns as reinforcement for composite overwrapped pressure vessels

Carbon nanotubes (CNTs) are one-dimensional nanomaterials with outstanding electrical and thermal conductivities and mechanical properties. Recent advances in CNT manufacturing have made bulk forms such as yarns, tapes and sheets available in commercial quantities to permit the evaluation of these materials for aerospace use. The high tensile properties of CNT composites can be exploited in tension-dominated applications such as composite overwrapped pressure vessels (COPVs). To investigate their utility in this application, aluminum (Al) rings were overwrapped with thermoset/CNT yarn, thermally cured under a vacuum bag, and their mechanical properties measured. Fabrication parameters such as CNT/resin ratio, tension applied during winding, and the number of CNT yarn layers were investigated to determine their effects on the mechanical performance of overwrapped Al rings. Mechanical properties of the CNT composite overwrapped Al rings (CCOARs) were measured under static and cyclic loads at room, elevated, and cryogenic temperatures to evaluate their performance relative to bare Al rings. The ultimate load carried by the composite overwrap in the CCOARs increased with increasing number of wraps. The wet winding process for the CCOAR fabrication improved load transfer compared to the dry winding process due to enhanced interfacial adhesion between the CNT yarn and the applied resin. Wet winding Al rings with CNT yarn/thermoset overwraps resulted in ∼11% increase in weight relative to the bare ring and increased the room temperature breaking load by over 200%.