应用聚焦离子束/电子束技术的碳纳米管探针制备工艺研究

提出利用电子束诱导铂沉积和聚焦离子束铣削技术,实现碳纳米管原子力显微镜探针针尖的制备和结构优化研究。结合高分辨率扫描电子显微镜观测和纳米操纵仪,利用电子束诱导铂沉积实现碳纳米管固定到普通原子力显微镜探针末端,可实现直径小于10nm的纳米管探针制备。提出基于聚焦离子束铣削和照射技术实现对纳米管针尖的长度、角度的精确调控优化,纳米管探针的角度调控精度优于1°。     

原子力显微镜探针表征烷烃及正烷类有机化合物的研究

原子力显微镜(AFM)作为一种重要的科研、生产工具被广泛使用,其测量精度很大程度上决定于所使用的探针针尖的尖锐度。本研究使用标准微机械加工工艺在低应力氮化硅悬臂上通过各向异性湿法刻蚀形成硅针尖。通过对三十六烷烃和正六十烷的表征测量,验证了探针针尖的纳米尺度尖锐度。     

扫描探针显微镜在纳米科技中的应用

本文在介绍了扫描探针显微镜的发展和有关纳米科技知识的基础上,论述了扫描显微镜在纳米科技中的应用。     

扫描探针显微镜在纳米材料表征中的应用

报道了扫描探针显微镜在纳米电子薄膜材料的形貌、晶界、晶粒形状与尺度、表面粗糙度和剖面分析中的具体应用实例,以及纳米磁性薄膜中的微磁畴、铁电材料的微电畴和半导体PN区像等电磁特殊性的可视分析应用。     

基于原子力显微的多模式扫描探针显微镜

扫描探针显微镜是目前世界上分辨率最高的显微镜之一,也是纳米技术研究的主要工具。本文在分析原子力显微镜工作原理的基础上,探讨多模式扫描探针显微镜的相关功能,并对扫描探针显微镜的发展前景进行展望。     

高长径比探针在高分子纳米纤维膜原子力显微镜扫描上的应用

原子力显微镜技术是用于表征表面纳米级形貌的一种重要手段,对于纳米纤维膜等聚合物表面分析具有一定的优势.本文详细叙述了原子力显微镜的基本原理及操作步骤,研究了扫描模式、测试参数、探针类型等因素对较大粗糙度的纳米纤维膜测试结果的影响.结果表明,高长径比探针比常规探针更能真实的反应表面的形貌信息.     

悬臂式光纤探针

悬臂式探针的研制是 SNOM- AFM的重要技术之一。用熔拉—腐蚀相结合的方法 ,将普通单模石英光纤制成直锥型探针。再利用自制的工具在 CO2 激光束下将针尖打弯 ,制成悬臂式探针样品。简单地讨论了此种探针的弹性常数     

双成象单元扫描探针显微镜在纳米计量中的应用

研制了用于纳米计量的双成象单元扫描隧道显微镜一原子力显微镜,由扫描隧道显微镜参考单元和原子力显微镜被测单元组合而成。两者共用同一XY扫描器,同时对参考样品石墨和被测样品扫描成象。得到的石墨原子晶格参考图象与被测样品图象横向尺度相同,计数前者的原子晶格个数,即可精确测定被测样品图象的尺寸。利用本方法可对任何样品表面的超微观结构进行严格的纳米计量。     

SPM技术在碳纤维结构研究上的应用

简单介绍了系列扫描探针显微镜（SPM）的性能、原理及其应用,重点综述了SPM尤其是扫描隧道显微镜（STM）和原子力显微镜（AFM）在碳纤维结构研究领域中的应用。     

Smith预估器在纳米操作系统中的应用

针对纳米操作系统中存在的滞后性质,提出了带Smith预估器的PID控制方法.从理论上解决了纳米操作系统中由于纯滞后性质而引起的系统超调或振荡.从而保证了纳米操作中观测的精度和准确性.     

Effect of carbon nanotube structural parameters on field emission properties

Experimental studies were devoted to the effect of structural parameters, i.e., tube diameter and density, on the field electron emission characteristics of carbon nanotubes. Thermal chemical vapor deposition system was employed to synthesize carbon nanotubes. Nanotubes with different diameters and densities were obtained by adjusting the thickness of the iron (Fe) catalyst film. The morphologies of the Fe and carbon nanotube film were characterized by scanning electron microscopy respectively. Further field emission measurement confirmed that the tube diameter and density could significantly affect the electron emission properties of the carbon nanotube. Possible physical reasons for the effect are discussed.     

Effects of mechanical properties on the tribo-electrification mechanisms of iron rubbing with carbon steels

The mechanisms of tribo-electrification and the associated wear behavior of a pair of dissimilar metals in the form of a pin and a plate rubbing against each other under dry severe wear condition were investigated using a reciprocating friction tester. The materials were iron and carbon steels of 0.2%, 0.45% and 0.7% carbon. Results showed that when an iron pin rubbed against the steel plate specimens, increasing the carbon content caused the formation mechanism of the wear particle to vary from macro-asperity removal to yielding wear. The material adhesive transfer was mainly from the pin to the plate specimen due to yielding wear. Hence, the polarity of tribo-electrification for the pin specimen varied from random to positive. Consequently, a model that described this mechanism was proposed. Now, when the materials were reversed, i.e. the three types of carbon steels were used as the pin to rub against an iron plate, increasing the carbon percentage of the pin specimen resulted in the wear mechanism to vary from macro-asperity removal to grooving wear, the latter of which resulted in material transfer mainly from the plate specimen to the pin specimen. In contrast to the previous case, the polarity of tribo-electrification for the pin specimen varied from random to negative and a model that described this mechanism was proposed. Based on the above two models, a micro-model of tribo-electrification mechanism for self-mated materials was proposed. By using this micro-model, the mechanism of tribo-electrification in same material abrasion can be reasonably explained.     

Tapping mode scanning force microscopy in water using a carbon nanotube probe

An improved technique for obtaining tapping mode scanning force microscopy (TMSFM) images of soft samples submerged in water is described. This technique makes use of a carbon nanotube several microns in length mounted on a conventional silicon cantilever as the TMSFM probe. The sample is covered by a shallow water layer and during imaging only a portion of the nanotube is submerged. This mode of operation largely eliminates the undesirable effects of hydrodynamic damping and acoustic excitation that are present during conventional tapping mode operation in liquids and leads to high-quality TMSFM images. Because of their low bending force constants, carbon nanotubes are ideal for gentle imaging of soft samples. Because of their small (5–20 nm) diameter and cylindrical shape they provide excellent lateral resolution and are ideal for scanning high aspect ratio objects.     

Influence of molecular weight on performance properties of polyethersulphone and its composites with carbon fabric

The effect of molecular weight (MW) of a polymer on the wettability of fibers and its influence on the performance properties need to be addressed in detail. Specialty polymer, viz. polyethersulphone (PES), with varying MW was selected as a matrix material to develop the composites with carbon fabric (CF). Since carbon fiber is inert towards the matrix, cold remote nitrogen–oxygen plasma (CRNOP) treatment was employed to improve its chemical reactivity, by incorporating functional groups to promote the fiber–matrix adhesion. Evaluation of mechanical and sliding wear properties of polymers and composites led to the conclusion that the CRNOP treatment was beneficial to enhance performance properties. The MW and MFI have inverse relation. MW proved to be a controlling parameter for pristine polymers while melt flow index (MFI) was the decisive parameter for the performance of composites. Perforations and increased roughness on the treated carbon fiber, as observed by the field emission scanning electron microscopy (FESEM), were responsible for the improved fiber–matrix adhesion and hence performance properties.     

Influence of the multi-walled carbon nanotube and short carbon fibre composition on tribological properties of epoxy composites

The present research work deals with the development of a novel polymer composite for brake pad applications. The composite that was used consists of epoxy resin, carbon fibre and carbon nanotubes in varying weight percentage. The tribological performance of three different samples was tested using a pin-on-disc under dry contact condition. The results indicated that the sample filled with short carbon fibres (SCF), and multi-walled carbon nanotube (MWCNT) had superior performance. Reduction in wear rate was observed due to synergism between SCF and MWCNT as compared to SCF only. Scanning electron microscopy was subsequently performed on all samples. The micrographs show changes in the structural formation after the incorporation of SCFs and MWCNT. This increased composite structural strength and explains why SCF and MWCNT’s hybrid-filled composite material has better tribological properties.     

机械密封端面宽度对密封性能的影响

这里通过试验研究了转速和密封面宽度对机械密封性能的影响。通过分析发现,转速和密封面宽度都是影响端面温升的重要因素,窄的密封面可以明显地降低端面温升。在混合摩擦条件下,密封面宽度对摩擦系数的影响很小。     

Effect of mechanical activation of ultra-high-molecular-weight polyethylene on its mechanical and triboengineering properties

The effect of mechanical activation of initial ultra-high-molecular-weight polyethylene powders on the pysicomechanical properties of the polymer is studied. Mechanical activation is found to raise the strain and strength properties, as well as the triboengineering characteristics of ultra-high-molecular-weight polyethylene. X-ray diffraction analysis, IR spectroscopy, and optical and electronic microscopy show that mechanoactivation of the initial powder defines the polymer’s structural organization.