Laser Induced Modifications of Carbon Nanotube Composite Surfaces (original) (raw)
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Abstract: The synthesis of the single-walled carbon nanotubes (SWCNTs) by laser ablation process (LA) is catalyst-dependent. In this work, two targets techniques were used instead of one target. The two targets used are nickel sheet (as catalyst) and graphite (as carbon source) next to each other. The laser used is Q-switched Nd:YAG of wavelength 1064nm hits the two targets simultaneously at the interface between them. Different parameters of LA process were studied: furnace temperature 750ºC -1000ºC, Ar flow rates and different laser fluenes. The prepared CNTs were then used to prepare polymer/CNTs nano-composite. Scanning electron microscope and Raman spectroscopy were used to characterize the produced CNTs. The results showed that during laser ablation, the diameter of the prepared carbon nanotubes will decrease with increasing temperature from 750ºC to 1000ºC . The yield of the SWCNTs will increase with temperature from 850ºC to 1000ºC. The production of SWCNTs and MWCNTs are possible by controlling the furnace temperature. At Ar flow rates of 2 L/min, the SWCNTs yield is maximum. The polymer/CNTs nanocomposite prepared showed some improvement in the mechanical properties i.e. ultimate strength and Young's modulus. Keywords: Carbon nano-tubes; Laser ablation; Electron microscopy; Raman spectroscopy; Nano-composites
Journal of Laser Applications, 2016
This study attempts to investigate different CO 2 laser conditions on electrical conductivity and surface properties of multiwalled carbon nanotubes/poly methyl methacrylate (MWCNT/PMMA) nanocomposite. In order to reach this aim, outputs like morphology of surface, electrical conductivity of laser cut surface, heat affected zone (HAZ), burr, and surface roughness were studied. The nanocomposite, which contains carbon nanotubes, exhibits anisotropic behavior, therefore, the laser cutting outputs are investigated within the inflow direction and perpendicular to the flow direction. Morphology of the nanocomposites and cut surfaces are investigated using scanning electron microscopy that showed the contacts between nanotubes are increased after laser cutting. Findings obviously show increasing the laser power and decreasing the feed rate improve the electrical conductivity. As a prominent result, the minimum surface electrical resistivity was obtained from over 2 Â 10 14 to 886 X by using a power of 120 W, a cutting velocity of 0.3 m/min for 1.5 wt. % MWCNT into PMMA matrix. In the case of laser cutting outputs, the presence of MWCNTs increased HAZ, surface roughness in two directions, and burr in perpendicular to flow direction, but it decreases the burr in the inflow directions. By increasing the cutting velocity, HAZ and burr decrease in two studied directions, but it has partial effect on surface roughness.
Journal of Laser Micro/Nanoengineering, 2016
Thermal spread pattern is an effective parameter on laser workability of materials. The thermal behavior pattern of nanocomposites containing carbon nanotubes (CNTs) mostly depends on CNTs alignment and their dispersion within the polymer matrix. This phenomenon makes different their laser workability. The present work is trying to investigate experimentally the influence of alignment and dispersion pattern of CNTs within the polycarbonate (PC) and polystyrene (PS) matrixes on laser cutting workability. In order to reach this purpose, in the first step, the injection and compression molded nanocomposites by different CNT loadings were produced, and then they were cut by laser in different conditions. The transmission electron microscope (TEM) was used to explore the CNTs structure with in the polymer. The results show that the CNTs loading, alignment and dispersion are the effective parameters on outputs. The minimum amounts of kerf width, heat affected zone, burr and kerf taper angle were obtained for compression molded samples. The findings also reveal the CNTs alignment and dispersion pattern are more effective than the CNT loading on kerf width and burr for both of PS and PC polymers matrix. Improving the conditions in lower power and higher cutting velocity is another important finding.
Raman and electron microscopy analysis of carbon nanotubes exposed to high power laser irradiance
Journal of Applied Physics, 2009
High power laser radiometry requires efficient and damage-resistant detectors. The current study explores the evolving nature of carbon nanotube coatings for such detectors upon their exposure to incrementally increasing laser power levels. Electron microscopy images along with the D-band to G-band intensity ratios from the Raman spectra from eight irradiance levels are used to evaluate changes before and after the exposure. Electron microscopy images of the exposed multiwalled carbon nanotubes revealed the formation of intermittent pockets of moundlike structures at high power densities exceeding 11 kW/ cm 2. Raman spectroscopy measurements also demonstrated higher values for the ratio of the D-band intensity to that of the G-band, suggesting the possible transformation of nanotubes into structurally different forms of carbon. Exposure to a sample of single-walled nanotubes did not demonstrate the evolution of structural changes, which could be due in part to the higher irradiance levels relative to the damage threshold, employed in the experiment.
Brittle and ductile removal modes observed during diamond turning of carbon nanotube composites
Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 2009
Surface heat treatment in glasses and ceramics, using CO 2 lasers, has attracted the attention of several researchers around the world due to its impact in technological applications, such as lab-on-a-chip devices, diffraction gratings and microlenses. Microlens fabrication on a glass surface has been studied mainly due to its importance in optical devices (fiber coupling, CCD signal enhancement, etc). The goal of this work is to present a systematic study of the conditions for microlens fabrications, along with the viability of using microlens arrays, recorded on the glass surface, as bidimensional codes for product identification. This would allow the production of codes without any residues (like the fine powder generated by laser ablation) and resistance to an aggressive environment, such as sterilization processes. The microlens arrays were fabricated using a continuous wave CO 2 laser, focused on the surface of flat commercial soda-lime silicate glass substrates. The fabrication conditions were studied based on laser power, heating time and microlens profiles. A He-Ne laser was used as a light source in a qualitative experiment to test the viability of using the microlenses as bidimensional codes.
Nanostructured diamond-like carbon by dual pulsed laser ablation-pulsed gas feeding
2007
Diamond-like carbon films is a metastable form of carbon containing mixture of Sp3 and Sp2 hybridization. In the previous decades Diamond-like carbon has been studying widely due to its unique properties resembling those of diamond. These properties exhibit the high hardness, high wear resistance, low friction coefficient, chemical inertness, high electrical resistance, and optical transparency in the IR region. These properties make DLC films a good candidate in various applications such as the mechanical, optical, coating magnetic hard dicks, and biocompatibility in the replacement of hip joints, heart valves, stents, as well as zinc sulphide for IR windows. In the present work nano-structure diamond-like carbon was deposited at room temperature by Pulsed Laser Ablation in a methane atmosphere on corning glass and silicon substrate. The structures of Diamondlike carbon film such the surface morphology and the composition has been studied by the scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The structural properties of DLC films have been studying by were investigated by Raman spectroscopy. The vibrational mode of C-H molecules and the composition of carbon, oxygen and hydrogen have been investigated \ by Fourier transformations Infrared Absorption, Rutherford backscattering, Elastic Recoil Detector. The optical and the surface topography of the films have been studied by Ultraviolet Visible spectrophotometer, Zygo interferometer, and Stylus Profiler. SEM shows that DLC films deposited in a high vacuum peel out of the silicon substrate whereas the films deposited on glass shows the dark yellow color depending on the thickness of the films. Raman results indicate the depended of DLC films on deposition time, the Sp3 fraction increase from 21% to 97.1% and the peak position changes with respect to time. XPS result shows excellent films produced by pulsed laser ablation with C1s in the range 81.5%-88.8 % with the surface roughness less 30nm. These smooth film shows promise applications on hard and medical biocompatibility. DLC films deposited on have refractive (n) in range of 1.7 to 2.2 suitable for optical applications.
Synthesis of carbon nanotubes by the laser ablation method: Effect of laser wavelength
Physica Status Solidi B-basic Solid State Physics, 2015
The effect of laser wavelength on single-wall carbon nanotubes synthesis yield and their properties was studied. A doublepulse Nd:YAG laser, working at a wavelength of 355 or 1064 nm, was used for carbon nanotubes production. The synthesized carbon nanotubes (CNTs) were investigated using the SEM/STEM microscopy and Raman spectroscopy. The results show that the useful range of UV laser radiation fluence is narrower and the properties of synthesized CNTs depend much more on the laser fluence than in the case of infrared laser radiation.
Characterization of a Pure Diamond-Like Carbon Film Deposited by Nanosecond Pulsed Laser Deposition
2019
This work aims to investigate the properties and microstructure of diamond-like carbon film deposited by pulsed laser deposition by ablation of a graphite target in a vacuum chamber on a steel substrate. The equipment was mounted to provide one laser beam. The target of high purity graphite and the steel substrate were polished. The mechanical and tribological properties of the film were characterized using Raman spectroscopy, nanoindentation test, scratch test, roughness profile, tribometer, optical microscopy and SEM images. It was concluded that the pulsed laser deposition (PLD) technique associated with the low-pressure chamber and a graphite target provides a good fraction of sp3 bonding, that the process variable as surface polishing and laser parameter have great influence in tribological properties and in adherence tests performance. The optical microscopy images are efficient to identify the metallurgical bond.
Femtosecond laser ablation of diamond-like carbon films
Applied Surface Science, 2004
Diamond-like carbon (DLC) coatings were deposited on Si substrates using a hot filament diode discharge and they were irradiated with ultrashort laser pulses (800 nm, 150 fs, <4 J/cm 2 ). The laser-treated films were examined using optical microscopy, Raman spectroscopy, SEM, AFM and white-light interferometery. Damage threshold of 0.16 J/cm 2 and ablation rates below 110 nm/pulse were determined. Changes in the structure of the laser-irradiated films were showed by means of Raman investigations. The laser-treated samples were etched and the depths of modified material layers were determined. Ablation experiments with longer laser pulses (1064 nm, 100 ns, <3 J/cm 2 ) were also performed and the irradiated DLC films were afterwards analyzed using the same procedures. Dissimilarities in the structure changes induced by fs-and ns-laser irradiation were observed and comments are given. #
Synthesis of carbon nanotubes by laser ablation in graphite substrate of industrial arc electrodes
Physica Scripta, 2008
The effect of laser wavelength on single-wall carbon nanotubes synthesis yield and their properties was studied. A doublepulse Nd:YAG laser, working at a wavelength of 355 or 1064 nm, was used for carbon nanotubes production. The synthesized carbon nanotubes (CNTs) were investigated using the SEM/STEM microscopy and Raman spectroscopy. The results show that the useful range of UV laser radiation fluence is narrower and the properties of synthesized CNTs depend much more on the laser fluence than in the case of infrared laser radiation.