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The flame temperature distribution at different heights of the alcohol burner. The abscissa denotes the vertical height relative to the flame nozzle and the ordinate denotes the corresponding temperature of the symmetrical core of the flame.
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In this article, we demonstrate that carbon nanostructures could be synthesized on the Ni-plated YG6 (WC-6 wt% Co) hardmetal substrate by a simple ethanol diffusion flame method. The morphologies and microstructures of the Ni-plated layer and the carbon nanostructures were examined by various techniques including scanning electron microscopy, X-ray...
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... the factors such as the flame size, temperature, and the unavoidable flame instability in the combustion process, the Ni-plated hardmetal substrates were inserted in the flame at 5 cm above the fuel nozzle. To make it clear, Figure 1 shows the position of the substrates in the flame, and the flame temperature distribution at different heights of the alcohol burner was shown in Figure 2. The flame temperature at 5 cm was measured about 800°C by a K-type thermocouple with a diameter of 1 mm. ...Similar publications
Pt/C, Bi/C and PtBi/C (Pt:Bi atomic ratios of 90:10, 70:30 and 50:50) electrocatalysts were prepared by borohydride reduction using H2PtCl6·6H2O and Bi(NO3)3·5H2O as metal sources and Vulcan XC72 as carbon support. The obtained electrocatalysts were characterized by energy-dispersive X-ray analysis, X-ray diffraction, transmission electron microsco...
Citations
... The D-band arises due to scattering from a defect, which breaks the basic symmetry of the graphene sheet whereas the Gband corresponds to the perfect sp 2 graphitic structure. 19,20 The position of D and G-bands remains almost same, however, the intensity ratio (I D =I G ) between these bands varies with variation in fuel to oxidizer°o w rate ratio, indicating more disordering of clusters at Q F =Q O 2 ¼ 0:7 and least disordering at Q F =Q O 2 ¼ 0:14. This is reasonable as particle size is more at Q F =Q O 2 ¼ 0:7 as compared to that at 0.14. ...
Aggregates of spherical carbon nanostructures were grown directly on stainless steel substrate in a controllable co-flow diffusion flame. The flow rates of fuel and oxidizer were found to have a key influence on the size of the synthesized particles. At fuel to oxidizer flow rate ratio of 0.7, carbon nanostructures with diameter range of 24–46[Formula: see text]nm were obtained. However, the diameter was reduced to 6–15[Formula: see text]nm as we decrease the flow rate ratio to 0.14. Apart from decrease in crystallite and particle size revealed by XRD spectra and HRTEM images, respectively, the Raman spectra showed the decrease in disorder-induced features at lower flow rate ratio.
... As a part of ongoing studies on oxy-fuel diffusion flames, the correlation of yield of carbon nanostructures formed in flame environment with flue gas emissions has been investigated in the present work. In comparison to other synthesis methods, flames can naturally provide both a hydrocarbon-rich and high-temperature environment, essential for the growth of carbon nanostructures [1]. The carbon atoms present in the hydrocarbon fuel serve as a source to form graphite layers with catalyst helping in the transformation of gas-phase carbon atoms into solid graphite layers and high-temperature serving as an activation source of catalyst particles [2]. ...
This paper investigates the relationship between yield of carbon nanostructures produced in flame environment and flue gas emissions for an axisymmetric co-flow diffusion flame. Simulation has been carried out at four different equivalence ratios to scrutinize the optimum ratio at which maximum carbon nanostructures can be obtained with minimum hazardous emissions. Numerical model solves the time-independent Navier-Stokes equation coupled with the equations for energy and species conservation to compute the temperature and species distributions inside the flame. A simple one-step soot model has been used to model the soot formation process. The computed species concentrations are compared with the experimental values and are found to show less than 10% variation. The results indicate that the level of emission of NO
X
decreases appreciably at higher equivalence ratios. The percentage emission of CO and CO2however is not affected significantly. Furthermore, HRTEM and EDX analysis has been conducted on collected carbon material to determine its internal structure and elemental composition. HRTEM indicates the formation of spherical nanoparticles having an average diameter of 30 nm and EDX spectrum reveals that the synthesized sample consists of 99.35 weight% carbon.
... On the other hand, the occurrence of D-band at 1342 cm −1 corresponded to the disordered or sp 3 -like carbon atoms [27][28][29][30][31], and was rather intense, broad, and asymmetric. Our Raman results are compatible with those reported by Hurtado et al. [27], Zhu et al. [32], Gentoiu et al. [33], and Nasri-Nasrabadi et al. [34], regarding systems containing micro/nano structured carbon. More specifically, Zhu et al. [32] synthesized carbon nanostructures on Ni-plated commercial hard metal YG6 (WC-6 wt% Co) using a simple ethanol diffusion flame technique. ...
... Carbon tubes obtained by this method can be helpful when producing composite solutions of high rheological stability that allows for the omission of time requirements during the extrusion procedure. Our Raman results are compatible with those reported by Hurtado et al. [27], Zhu et al. [32], Gentoiu et al. [33], and Nasri-Nasrabadi et al. [34], regarding systems containing micro/nano structured carbon. More specifically, Zhu et al. [32] synthesized carbon nanostructures on Ni-plated commercial hard metal YG6 (WC-6 wt% Co) using a simple ethanol diffusion flame technique. ...
... Our Raman results are compatible with those reported by Hurtado et al. [27], Zhu et al. [32], Gentoiu et al. [33], and Nasri-Nasrabadi et al. [34], regarding systems containing micro/nano structured carbon. More specifically, Zhu et al. [32] synthesized carbon nanostructures on Ni-plated commercial hard metal YG6 (WC-6 wt% Co) using a simple ethanol diffusion flame technique. It was found that the deposition duration caused both a higher quality and degree of graphitization of flame deposited carbon nanostructures. ...
In this study, we examined the influence of microstructured charcoal (MC) when added to ammonium nitrate fuel oil (ANFO) samples. We performed a study that investigated ANFOs structure, crystallinity, and morphology by utilizing infrared spectroscopy (IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM), respectively. MC characteristics were probed by Raman spectroscopy and SEM analysis. SEM analysis indicated how fuel oil (FO) covered ammonium nitrate prill. Moreover, the surface of the MC was covered by specific microfibers and microtubes. The disordered graphitic structure of the MC was also confirmed by Raman spectroscopy. Simulation of blasting properties revealed that the addition of MC should decrease blasting parameters like heat explosion, detonation pressure, and detonation temperature. However, the obtained differences are negligible in comparison with the regular ANFO. All analyses indicated that MC was a good candidate as an additive to ANFO.
... However, these methods are difficult to control, very expensive, non-continuous, non-scalable and require a lot of energy consumption. Recently, new synthetic methods such as microwave-assisted and flame synthesis have been proposed [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. ...
... Other study has found that the CNS formation in IDF besides depending on the O 2 concentration and temperature also depends on the catalytic precursor and the fuel type used [12]. Among the most commonly, used catalytic systems for CNS synthesis are those based on transition metals such as Ni, Fe, Co, Zn and Cu [12,[23][24][25]; while the most widely used fuels in the IDF configuration are ethylene and methane. With these precursors, several authors have synthesized several CNS at temperatures ranging between 673 K and 1920 K [12,18,23,25]. ...
... Among the most commonly, used catalytic systems for CNS synthesis are those based on transition metals such as Ni, Fe, Co, Zn and Cu [12,[23][24][25]; while the most widely used fuels in the IDF configuration are ethylene and methane. With these precursors, several authors have synthesized several CNS at temperatures ranging between 673 K and 1920 K [12,18,23,25]. What is common in these studies regardless of the flame-formed CNS is that the major precursor species found in the flame environment are CO, C 2 H 2 and H 2 which have even been used as test molecules to understand the growth mechanisms of these carbonaceous structures. ...
The synthesis of carbon nanostructures, (CNS), with tubular-like morphology were carried out over Ni and NiFe catalysts introduced into different inverse diffusion flames environments fueled with ethylene, ethylene-benzene and benzene. In general, only the ethylene and benzene-doped ethylene flames could produce CNS since the pure benzene flame favored the soot formation path. Although the addition of benzene into the flame favored the CNS production in mass and particle dimensions, a loss of quality of the internal structure of the tube walls was seen particularly when the NiFe catalyst was used. Three types of tubular structures were obtained depending of flame and catalytic system. The multi-walled carbon nanotubes were only observed in the ethylene flame (800 K–1400 K) over the Ni catalyst, while the hollowed and solid carbon nanofibers were observed in the ethylene-benzene flame (800 K–1200 K) over both the Ni-based and NiFe catalysts. Also, a small amount of carbon nano-onions were seen at the tip of the ethylene-benzene flame where temperature was closer to 1400 K. In all cases, the base-growth model was the dominant mechanism for the tubular CNS found at the periphery of the flame, a place where the most important chemical species concentration (CO, C2H2 C6H6 and H2) was higher enough for catalyst activation.
... Among the well known methods for synthesis of diamond and graphite, such as detonation of carbon-based explosives [3], plasma-enhanced chemical vapor deposition [4], pulsed laser deposition [5,6], ion beam/magnetron sputtering [7][8][9], etc., the combustion flame synthesis at atmospheric pressure offers overwhelming simplicity and several advantages [10][11][12][13][14]. For instance, the chemically reactive environment of the flame ensures high deposition rates of over 0.028 μm/s and~1.5-2 ...
Historically, the synthesis of diamond and graphite via combustion flames stands out as a simplified, scalable and inexpensive approach. Unfortunately, this method is not beneficial for industrial applications in coatings due to limitations related with the high flame and substrate temperatures. Here, we report novel findings about the formation mechanism of graphite-like and diamond-like supported nanostructures in low temperature laminar diffusion flames. Both materials are formed upon controllable combustion at atmospheric pressure of a cylindrical paper wick immersed in rapeseed oil. An accurate adjustment of the incident air flow and the amount of available fuel allow deposition of carbon soot or diamond-like carbon (DLC). The DLC formation is favorable in a narrow stoichiometric range at flame temperatures within ~ 210–260 °C and beyond this range the particles precipitate as soot. The comparative structural analysis using scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy, along with the full thermal and stoichiometric profiles for the chosen combustion conditions, suggest a kinetically driven graphite-to-diamond transformation rather than a thermodynamically induced phase transition. Our results reveal a new direction in the principles of graphite and diamond formation in flames that could be applied to surmount the existing shortcomings in flame synthesis.
... Introducing intermediate layer between the cemented carbide substrate and the diamond coating is a way for this purpose. The use of electroplated nickel as the interlayer is of interest in this study considering nickel's thermal expansion coefficient which is close to that of hard metal, and that diamond can deposit and grow on nickel substrate [3,5,6]. The Scientific World Journal Electroplating for nickel deposition uses an electrolytic path. ...
Electroplated nickel coating on cemented carbide is a potential pretreatment technique for providing an interlayer prior to diamond deposition on the hard metal substrate. The electroplated nickel coating is expected to be of high quality, for example, indicated by having adequate thickness and uniformity. Electroplating parameters should be set accordingly for this purpose. In this study, the gap distances between the electrodes and duration of electroplating process are the investigated variables. Their effect on the coating thickness and uniformity was analyzed and quantified using design of experiment. The nickel deposition was carried out by electroplating in a standard Watt's solution keeping other plating parameters (current: 0.1 Amp, electric potential: 1.0 V, and pH: 3.5) constant. The gap distance between anode and cathode varied at 5, 10, and 15 mm, while the plating time was 10, 20, and 30 minutes. Coating thickness was found to be proportional to the plating time and inversely proportional to the electrode gap distance, while the uniformity tends to improve at a large electrode gap. Empirical models of both coating thickness and uniformity were developed within the ranges of the gap distance and plating time settings, and an optimized solution was determined using these models.
... In γ-(Fe, Ni) solid solution matrix, the hard phases of CrB, Fe 2 B and Cr 23 C 6 is identified in the coating. Zhu et al. (2011) demonstrated that carbon nanostructures could be synthesized on the Ni-plated YG6 (WC-6 wt% Co) hardmetal substrate by a simple ethanol diffusion flame method. The morphologies and microstructures of the Ni-plated layer and the carbon nanostructures were examined by various techniques including scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. ...
The energy required in an electroplating process and the material costs are important considerations in product manufacturing. The most important plating criteria, however, are quality and the uniformity of the deposited metals. The nickel plating process is used extensively for decorative, engineering, and electroforming purposes. Because of the appearance and other properties of the electrodeposited material, nickel deposition can be varied, over a wide range, by controlling the composition and the operating parameters of the plating solution. Decorative applications account for about 80% of the nickel consumed in plating; 20% is consumed for engineering and electroforming purposes. Autocatalytic (electroless) nickel plating processes are commercially important but are outside the scope of this review. In this review, the basic facts of nickel electroplating processes, thickness test and methods, are discussed. The properties of nickel and the different effects of the operating parameters on nickel plating, together with the simulation and design tools, are also reviewed. Simulation tools can help to obtain better plating results. Non-destructive techniques to evaluate the coatings on a microstructural and the technical evaluation with TEM, SEM, XRD and other techniques were also reviewed.
Flame‐retardant coatings are widely used in a variety of personnel or product protection, and many applications would benefit from film stretchability if suitable materials are available. It is challenging to develop flame‐retardant coatings that are stretchable, eco‐friendly, and capable of being integrated on mechanically dynamic devices. Here, a concept is reported that uses pretextured montmorillonite (MMT) hybrid nanocoatings that can undergo programed unfolding to mimic the stretchability of elastomeric materials. These textured MMT coatings can be transferred onto an elastomeric substrate to achieve an MMT/elastomer bilayer device with high stretchability (225% areal strain) and effective flame retardancy. The bilayer composite is utilized as flame‐retardant skin for a soft robotic gripper, and it is demonstrated that the actuated response can manipulate and rescue irregularly shaped objects from a fire scene. Furthermore, by depositing the conformal MMT nanocoatings on nitrile gloves, the firefree gloves can endure direct flame contact without ignition. Montmorillonite–elastomer bilayer architectures with high stretchability and effective flame retardancy can be applied as flame‐retardant protective skins for soft robotic grippers and nitrile gloves. With the stretchable and flame‐retardant barriers, the soft pneumatic actuator is capable of continuous inflation/deflation within flames and can act as a compliant gripper for manipulating and rescuing irregular objects from a fire scene.
A novel method for the flame synthesis of carbon nanoparticles with controllable fraction of amorphous, graphitic-like and diamond-like phases is reported. The structure of nanoparticles was tailored using a conical chimney with an adjustable air-inlet opening. The opening was used to manipulate the combustion of an inflamed wick soaked in rapeseed oil, establishing three distinct combustion regimes at fully-open, half-open and fully-closed opening. Each regime led to the formation of carbon coatings with diverse structure and chemical reactivity through a facile, single-step process. In particular, the fully-closed opening suppressed most of the inlet air, causing an increased fuel/oxygen ratio and decreased flame temperature. In turn, the nucleation rate of soot nanoparticles was enhanced, triggering the precipitation of some of them as diamond-like carbon (DLC). Surface characterization analyses using Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron spectroscopy confirmed this hypothesis, indicating a short-range ordered nanocrystalline structure and ∼80% sp3 bonds in the coatings deposited at fully-closed opening. Furthermore, three groups of 5 MHz Quartz Crystal Microbalances (QCMs) coated with soot and DLC, corresponding to each of the three combustion regimes, showed different frequency responses to aqueous ethanol and isopropanol solutions in the concentration range of 0-12.5 wt%. The DLC coated QCMs exhibited relatively constant frequency shift of ∼2250 Hz regardless of the chemical, while the response of soot coated counterparts was influenced by the quantity of heteroatoms in the film. Our method can be applied in chemical sensing for the development of piezoresonance liquid sensors with tunable sensitivity.
CuO nanocrystals with as-designed morphologies such as uniform quasi-spherical nanoparticles and high-purity nanoleaves were synthesized by adjusting the addition of sodium hydroxide and hydrazine hydrate in aqueous solution at room temperature (25 °C). The increase of sodium hydroxide would accelerate the reaction rate and favor the nucleation of CuO nanocrystals. The decrease of the surface energy will promote the oriented attachment of nanocrystallites along the [−111] direction into nanowires and the final formation of two dimensional (2D) nanoleaves. Increasing the quantity of hydrazine hydrate could decrease the solution system energy and promote the aggregation of CuO nanocrystals from 2D nanoleaves into 3D quasi-spherical nanoparticles. All the CuO nanocrystals with different morphologies were characterized via transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The CuO nanoleaves exhibit excellent gas sensing performance in response to ethanol, showing the strongest response value of 8.22 at 1500 ppm ethanol for 260 °C.
