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Author: Stephen Alan Steiner (III.) Publisher: ISBN: Category : Languages : en Pages : 315
Book Description
Nanoengineered hierarchal fiber architectures are promising approaches towards improving the inter- and intralaminar mechanical properties (e.g., toughness and strength) and non-mechanical properties of advanced fiber-reinforced composites such as graphite/epoxy. One fiber architecture of particular interest is carbon fiber coated with radially-aligned arrays of carbon nanotubes (CNTs), which can enable through-thickness and interply matrix reinforcement of carbon-fiber-reinforced composites while simultaneously providing additional multifunctional benefits such as electrical and thermal conductivity enhancement. Growth of CNTs on carbon fibers can be achieved by chemical vapor deposition (CVD) techniques, however previous processes for doing so have resulted in a significant reduction in the tensile strength and stiffness of the carbon fibers. This thesis aims to develop an understanding of catalyst-substrate and CVD environment-substrate interactions relevant to maintaining fiber mechanical properties in the growth of CNTs on carbon fibers by CVD and to use this understanding to develop practical approaches for growing CNTs on carbon fibers that simultaneously preserve fiber properties. Novel oxide-based catalysts are demonstrated for the first time to be effective for both CNT growth and graphitization of amorphous carbon and are characterized using in situ metrology. These catalysts show promise for use on substrates that exhibit sensitivity to conventional metal catalysts (such as carbon fibers). New CVD processing techniques based on materials properties unique to this class of catalysts are presented and explored. Coatings for enabling growth of aligned CNTs on carbon fibers, coatings for improving adhesion of materials to carbon fibers, and coatings for facilitating low-temperature growth of CNTs on carbon fibers are developed. The mechanochemical responses of carbon fibers to high-temperature processing, exposure to CVD gases relevant for CNT growth, and in situ tensioning during CVD growth at high temperatures are investigated. Methods for growing CNTs on carbon fibers that enable aligned CNT morphologies and that preserve fiber properties are presented. A new system for optimizing CNT growth on carbon fibers with special considerations for oxide-based catalysts is described. Finally, recommendations for manufacturing hierarchal carbon fibers for composites in an industrially practical way are made.
Author: Stephen Alan Steiner (III.) Publisher: ISBN: Category : Languages : en Pages : 315
Book Description
Nanoengineered hierarchal fiber architectures are promising approaches towards improving the inter- and intralaminar mechanical properties (e.g., toughness and strength) and non-mechanical properties of advanced fiber-reinforced composites such as graphite/epoxy. One fiber architecture of particular interest is carbon fiber coated with radially-aligned arrays of carbon nanotubes (CNTs), which can enable through-thickness and interply matrix reinforcement of carbon-fiber-reinforced composites while simultaneously providing additional multifunctional benefits such as electrical and thermal conductivity enhancement. Growth of CNTs on carbon fibers can be achieved by chemical vapor deposition (CVD) techniques, however previous processes for doing so have resulted in a significant reduction in the tensile strength and stiffness of the carbon fibers. This thesis aims to develop an understanding of catalyst-substrate and CVD environment-substrate interactions relevant to maintaining fiber mechanical properties in the growth of CNTs on carbon fibers by CVD and to use this understanding to develop practical approaches for growing CNTs on carbon fibers that simultaneously preserve fiber properties. Novel oxide-based catalysts are demonstrated for the first time to be effective for both CNT growth and graphitization of amorphous carbon and are characterized using in situ metrology. These catalysts show promise for use on substrates that exhibit sensitivity to conventional metal catalysts (such as carbon fibers). New CVD processing techniques based on materials properties unique to this class of catalysts are presented and explored. Coatings for enabling growth of aligned CNTs on carbon fibers, coatings for improving adhesion of materials to carbon fibers, and coatings for facilitating low-temperature growth of CNTs on carbon fibers are developed. The mechanochemical responses of carbon fibers to high-temperature processing, exposure to CVD gases relevant for CNT growth, and in situ tensioning during CVD growth at high temperatures are investigated. Methods for growing CNTs on carbon fibers that enable aligned CNT morphologies and that preserve fiber properties are presented. A new system for optimizing CNT growth on carbon fibers with special considerations for oxide-based catalysts is described. Finally, recommendations for manufacturing hierarchal carbon fibers for composites in an industrially practical way are made.
Author: Zhifeng Ren Publisher: Springer Science & Business Media ISBN: 3642304907 Category : Science Languages : en Pages : 310
Book Description
This book gives a survey of the physics and fabrication of carbon nanotubes and their applications in optics, electronics, chemistry and biotechnology. It focuses on the structural characterization of various carbon nanotubes, fabrication of vertically or parallel aligned carbon nanotubes on substrates or in composites, physical properties for their alignment, and applications of aligned carbon nanotubes in field emission, optical antennas, light transmission, solar cells, chemical devices, bio-devices, and many others. Major fabrication methods are illustrated in detail, particularly the most widely used PECVD growth technique on which various device integration schemes are based, followed by applications such as electrical interconnects, nanodiodes, optical antennas, and nanocoax solar cells, whereas current limitations and challenges are also be discussed to lay the foundation for future developments.
Author: Huisheng Peng Publisher: William Andrew ISBN: 0323415318 Category : Technology & Engineering Languages : en Pages : 510
Book Description
Industrial Applications of Carbon Nanotubes covers the current applications of carbon nanotubes in various industry sectors, from the military to visual display products, and energy harvesting and storage. It also assesses the opportunities and challenges for increased commercialization and manufacturing of carbon nanotubes in the years ahead. Real-life case studies illustrate how carbon nanotubes are used in each industry sector covered, providing a valuable resource for scientists and engineers who are involved and/or interested in carbon nanotubes in both academia and industry. The book serves as a comprehensive guide to the varied uses of carbon nanotubes for specialists in many related fields, including chemistry, physics, biology, and textiles. Explains how carbon nanotubes can be used to improve the efficiency and performance of industrial products Includes real-life case studies to illustrate how carbon nanotubes have been successfully employed Explores how carbon nanotubes could be mass-manufactured in the future, and outlines the challenges that need to be overcome
Author: Rita Khanna Publisher: BoD – Books on Demand ISBN: 1789235189 Category : Technology & Engineering Languages : en Pages : 148
Book Description
Carbon fibres are lightweight, chemically stable materials with high mechanical strength, and have state-of-the-art applications in aerospace, marine, construction and automotive sectors. The demand for carbon fibre?based components is expected to grow dramatically with expanding opportunities for lightweight metals and composites. Although this field has achieved a high level of maturity, nanoscale developments in carbon fibres have seen dramatic improvements in the functions of conventional biomaterials and composites. This book reveals several new developments in the field to enhance characteristics of carbon fibres and their composites, novel applications for tissue engineering, biological scaffoldings and implants, recycling and reuse of end-of-life CFRP and manufacturing waste and other issues of concern in the field of carbon fibres.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The present invention includes carbon nanotubes whose hollow cores are 100% filled with conductive filler. The carbon nanotubes are in uniform arrays on a conductive substrate and are well-aligned and can be densely packed. The uniformity of the carbon nanotube arrays is indicated by the uniform length and diameter of the carbon nanotubes, both which vary from nanotube to nanotube on a given array by no more than about 5%. The alignment of the carbon nanotubes is indicated by the perpendicular growth of the nanotubes from the substrates which is achieved in part by the simultaneous growth of the conductive filler within the hollow core of the nanotube and the densely packed growth of the nanotubes. The present invention provides a densely packed carbon nanotube growth where each nanotube is in contact with at least one nearest-neighbor nanotube. The substrate is a conductive substrate coated with a growth catalyst, and the conductive filler can be single crystals of carbide formed by a solid state reaction between the substrate material and the growth catalyst. The present invention further provides a method for making the filled carbon nanotubes on the conductive substrates. The method includes the steps of depositing a growth catalyst onto the conductive substrate as a prepared substrate, creating a vacuum within a vessel which contains the prepared substrate, flowing H2/inert (e.g. Ar) gas within the vessel to increase and maintain the pressure within the vessel, increasing the temperature of the prepared substrate, and changing the H2/Ar gas to ethylene gas such that the ethylene gas flows within the vessel. Additionally, varying the density and separation of the catalyst particles on the conductive substrate can be used to control the diameter of the nanotubes.
Author: Mildred S. Dresselhaus Publisher: Springer Science & Business Media ISBN: 3642833799 Category : Technology & Engineering Languages : en Pages : 391
Book Description
This book was begun after three of the present authors gave a series of in vited talks on the subject of the structure and properties of carbon filaments. This was at a conference on the subject of optical obscuration, for which submicrometer diameter filaments with high length-to-diameter ratios have potential applications. The audience response to these talks illustrated the need of just one scientific community for a broader knowledge of the struc ture and properties of these interesting materials. Following the conference it was decided to expand the material presented in the conference proceedings. The aim was to include in a single volume a description of the physical properties of carbon fibers and filaments. The research papers on this topic are spread widely in the literature and are found in a broad assortment of physics, chemistry, materials science and engineering and polymer science journals and conference proceedings (some of which are obscure). Accordingly, our goal was to produce a book on the subject which would enable students and other researchers working in the field to gain an overview of the subject up to about 1987.
Author: Peter J. F. Harris Publisher: Cambridge University Press ISBN: 113947815X Category : Technology & Engineering Languages : en Pages : 315
Book Description
Carbon nanotubes represent one of the most exciting research areas in modern science. These molecular-scale carbon tubes are the stiffest and strongest fibres known, with remarkable electronic properties, and potential applications in a wide range of fields. Carbon Nanotube Science is a concise, accessible book, presenting the basic knowledge that graduates and researchers need to know. Based on the successful Carbon Nanotubes and Related Structures, this book focuses solely on carbon nanotubes, covering the major advances made in recent years in this rapidly developing field. Chapters focus on electronic properties, chemical and bimolecular functionalisation, nanotube composites and nanotube-based probes and sensors. The book begins with a comprehensive discussion of synthesis, purification and processing methods. With its comprehensive coverage of this active research field, this book will appeal to researchers in a broad range of disciplines, including nanotechnology, engineering, materials science and physics.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Carbon nanotubes are promising candidates for enhancing electronic devices in the future at the nanoscale level. Their integration into todays electronics has however been challenging due to the difficulties in controlling their orientation, location, chirality and diameter during formation. This thesis investigates and develops new techniques for the controlled growth and assembly of carbon nanotubes as a way to address some of these challenges. Colloidal lithography using nanospheres of 450 nm in diameter, acting as a shadow mask during metal evaporation, has been used to pattern thin films of single-walled carbon nanotube multilayer catalysts on Si and Si/SiO2 substrates. Large areas of periodic hexagonal catalyst islands were formed and chemical vapor deposition resulted in aligned single-walled carbon nanotubes on Si substrates within the hexagonal array of catalyst islands. On silicon dioxide, single-walled carbon nanotubes connecting the hexagonal catalyst islands were observed. To help explain these observations, a growth model based on experimental data has been used. Electrostatic interaction, van der Waals interaction and gas flow appear to be the main forces contributing to single-walled carbon nanotube alignment on Si/SiO2. Although the alignment of single-walled carbon nanotubes on Si substrates is still not fully understood, it may be due to a combination of the above factors, in addition to silicide-nanotube interaction. Atomic force microscopy and Raman spectroscopy of the post-growth samples show single-walled carbon nanotubes of 1-2 nm in diameter. Based on the atomic force microscopy data and Raman spectra, a mixture of individual and bundles of metallic and semiconducting nanotubes were inferred to be present. A novel technique based on direct nanowriting of carbon nanotube catalysts in liquid form has also been developed. The reliability of this method to produce nanoscale catalyst geometries in a highly controlled manner, as required for carbo.
Author: Xu Li Publisher: ISBN: Category : Languages : en Pages :
Book Description
The first part of this research involves the growth of vertically aligned carbon nanotube (CNT) arrays (or CNT carpets) that are desired in many important applications. Growth of high-quality, dense CNT carpets via catalytic chemical vapor deposition (CCVD) has been largely limited to catalysts supported on amorphous alumina or silica. Although catalyst design and CCVD process optimization have been extensively investigated, scalable growth of CNT carpets especially on nontraditional substrates remains largely a challenge. To develop a rational basis for designing efficient CNT catalysts, a deeper understanding of the role of substrates in CNT carpet growth during CCVD is required. In this study, a fundamental investigation of the effects of substrate properties on CNT carpet growth from supported catalysts under different reaction conditions and feedstock is carried out. To illuminate the interrelationships between properties of catalyst supporting layers on CNT carpet growth behaviors, CNT growth experiments from Fe catalyst supported on a variety of nontraditional substrates including stainless steel (SS), MgO, MgAl2O4 (100, 110, and 111 crystalline phases), and ZrO2 were carried out. This study reveals that ion beam bombardment of 316 SS decreases the film thickness of AlxOy required for CNT growth to 5 nm AlxOy. The role of ion beam bombardment is to transform a highly crystalline surface into an amorphous surface, resulting in favorable catalyst-substrate interactions that enhances CNT growth. Our results reveal that Fe catalyst supported on different phases of MgAl2O4 spinel substrates show different CNT growth behaviors due to their different surface chemistries and surface energies. The second part of this research is motivated by the drive to seek new routes that yield clean fuels and chemicals via Fischer-Tropsch synthesis (FTS). FTS provides a pathway for the transformation of biomass, coal or natural gas into fuels and chemicals using a transition metal catalyst. Co-based catalysts are of interest because they exhibit relatively higher activity and selectivity to long-chain paraffins, high resistance to deactivation, and a low water-gas shift (WGS) reaction activity. Catalytic performance is sensitive to the catalyst preparation method and type of catalyst precursor. To investigate the effect of the type of catalyst precursor used during synthesis on physicochemical properties and efficiency of FTS process, SiO2-supported Co catalysts were synthesized via an incipient wetness impregnation method from four different precursors: Co(NO3)2 (Co-Nit), Co(C2H3O2)2 (Co-Ace), CoCl2 (Co-Chl), and Co(OH)2 (Co-Hyd). This study reveals the type of Co precursor used during synthesis has significant effects on catalyst dispersion, size, crystalline phase, reducibility, stability, and FTS performance (CO conversion, C5+ selectivity, turnover frequency, and catalyst lifetime). Prenatal and postmortem characterization of the catalyst reveal sintering and formation of Co2C in all catalysts except Co-Nit, which may explain the various degrees of deactivation observed. Further, XANES and EXAFS data confirm the superior structural stability of Co-Hyd and presence of hydroxyl groups even after reaction.
Author: Stephen Alan Steiner (III.)
Author: Stephen Alan Steiner (III.)
Author: Zhifeng Ren
Author: Huisheng Peng
Author: Rita Khanna
Author: 
Author: Mildred S. Dresselhaus
Author: Peter J. F. Harris
Author: Jingyu Sun
Author: 
Author: Xu Li