Papers by Keyword: Carbon Nanofiber

Abstract: This paper presents a fundamental study of processing, morphologies, properties, and applications of a novel non-woven nanopaper based on carbon nanofibers (CNFs). Unique material formulations were developed to tailor the non-woven nanopaper to specific engineering applications. The non-woven nanopaper was made from a variety of nanomaterials (e.g. carbon nanotubes, carbon nanofibers, graphene, nanoclay, nickel nanostrands, POSS, etc.) with tailored nanostructures by precisely controlling composition, dispersion, functionalization, orientation, porosity, and thickness during the vacuum infiltration, pressure infiltration, or spray/infiltration process. The polymer matrix was impregnated into the stacked nanopapers to form multi-layered laminated composites. Such non-woven nanopaper based composites were designed and fabricated to achieve high energy dissipation capability for vibrational damping, high thermal conductivity and thermal stability for fire retardancy, ultra-high electrical conductivity and current-carrying capacity for lightning strike protection, and electro-actuation of shape memory polymer composites.

Abstract: Silicon postsare fabricated by inductively coupled plasmaetching (ICP). Then, a SU-8 layer is spin-coated. During the photolithography, the opening areas of mask are aligned to the top surface of the underlying silicon posts.SU-8 fibers that interconnect the underlying silicon postsare created due to the mask-induced diffraction effect. After pyrolysis, SU-8 photoresist is transformedinto carbon, and as the results, carbon fibers that interconnect the underlying silicon postsare created.

Abstract: The incorporation of carbon nanofibers with a high aspect ratio and extremely large surface area into glass/epoxy polymers improve their mechanical properties significantly. Previously large number of efforts have been made to improve mechanical properties by mixing carbon nanofibers into resin, however, it may raise high viscosities which create difficulties during manufacturing of polymer composite samples. Presently, an attempt has been made to improve mechanical properties of nanocomposites by using, a different technique i.e spraying the Carbon nanoFibers (CNF) on glass fabric layers before impregnating it with epoxy resin. This paper presents influence of two different processing techniques used for manufacturing of polymer nanocomposites. Firstly, solution was prepared to obtain well dispersed epoxy resin filled with 1.0 wt % CNF, to impregnate carbon fabric in a vacuum assisted resin transfer molding (VARTM) setup for sampling. Secondly, the nanocomposite samples were prepared using a spraying methodology i.e dispersing the CNF solution on carbon fabric and followed by VARTM. Tensile, compression and flexural tests were performed to evaluate the effectiveness of CNF addition on the improvement of mechanical properties by using both techniques. Results indicated, CNF addition offered simultaneous increase in mechanical properties in different percentages by using both the processes respectively. SEM analysis of fractured surfaces has also been carried out to examine the micro structural details of in-depth study.

Abstract: In order to study the infrared interference characteristics of nanocarbon materials smoke, a large smoke chamber and laser test device were used to measure the attenuation characteristic of carbon nanofibers and nanographites smoke for laser. The mass concentrations were measured to obtain the rate of forming smokescreen for nanocarbon materials, and the smoke transmittance to infrared laser were measured to get attenuation characteristic of nanocarbon materials with different sizes. The test results provide the application basis of nanocarbon materials in passive interference fields.

Abstract: Carbon nanofibers is a new kind of electromagnetic wave absorbing materials and it is expected as a new kind of smoke interference agent. To study the scattering and extinction characteristics of carbon nanofibers, the electromagnetic scattering calculating model was established, and the induced current equation was solved by moment method, as well as the relationship between the infrared extinction cross section and the length of carbon nanofibers was analyzed and calculated based on MATLAB. The results show that when the conductivity of carbon nanofibers is large, the extinction cross section appears a series of resonant peaks along with the length change, and when the length of carbon nanofibers is equal to the first resonant length, the extinction cross section of unit volume will reach the maximum value, and a good extinction effect can be achieved at the same time. The contribution of scattering to extinction is enhanced with the increase of electrical conductivity.

Abstract: Ti metal matrix composites (Ti–MMCs) reinforced by vapor grown carbon nanofiber (VGCF) and graphite particle (Gr) were prepared via powder metallurgy and hot extrusion. Ti with 0~0.4wt% VGCF/Gr mixture powders were consolidated by using spark plasma sintering (SPS) at 800 °C. Hot extrusion was then performed at 1000 °C with an extrusion ratio of 37:1. Microstructures and mechanical properties of the as-extruded Ti composites were investigated. Tensile strength of Ti–VGCF/Gr composites was steadily augmented when additions of VGCF/Gr were increased from 0.1 to 0.4 wt%. YS and UTS were increased 40.2% and 11.4% for Ti–0.4wt%VGCF as compared to pure Ti, while those values were 30.5% and 2.1% for Ti–0.4wt%Gr. The strengthening mechanism including grain refinement, carbon solid solution strengthening and dispersion hardening of TiC/carbon was discussed in detail.

Abstract: Carbon nano fibers reinforced polymers have good mechanical properties but are difficult to process. In order to find out the influences of carbon nano fibers (CNF) on processing performance of epoxy resin, a series of tests on viscosity were carried out, including the influence of CNF weight fraction, CNF oxidation and temperature change. Infrared spectrum was used to detect the functional groups in CNF. The mechanism of CNF influence on viscosity of CNF reinforced epoxy resin has been discussed. The experimental results indicate that the weight fraction and oxidation of CNF enhanced viscosity of epoxy and the temperature have an inverse relationship with viscosity.

Abstract: Uniform growth of WO3 with macroscopic structures was successfully achieved by using carbon nanofibers (CNFs) as template. Field emission scanning electron microscopy (FE-SEM), coupled with X-ray diffraction (XRD) analysis confirmed the template effect and the existence of WO3 immobilized on the macroscopic silica fiber.

Abstract: A simpleand inexpensive top down approach to fabricate micropatterned carbon micro- and nano-fibers has been developed combiningCarbon-MEMS technology, Low Voltage Near-Field Electrospinning (LVNFES),and isotropic dry etching.A multitude of applications can take advantage of these patterned carbon nanofibers especially in the field of electrochemical sensors and nanoelectronics. In particular, wehave developed a novel polymeric ink that exhibits excellent electrospinning capability in a LVNFES setup and that does survive the pyrolysis process. To illustrate the potential of this new ink, we have fabricated carbon fiberssuspended on Carbon-MEMS structures.The fiber thickness can be controlled by adjusting the LVNFES voltage and using isotropic oxygen plasma based dry etching.

Abstract: Carbon nanotube (CNT) is one of the most attractive materials for the potential applications of nanotechnology due to its excellent mechanical, thermal, electrical and optical properties. We demonstrated the fabrication of carbon nanotube and carbon nanofiber (CNF) inside the pore and at the surface of anodic aluminum oxide (AAO) membrane by chemical vapor deposition method at atmospheric pressure. Ethanol was used as a hydrocarbon source and Co–Mo as catalyst. CNT was synthesized at different temperature. High graphitic multiwall carbon nanotube (MWCNT) was found at 750°C, while CNF was found at 800°C and above temperature analyzing by Raman spectroscopy.