Experimental study of metal nanoparticle synthesis by an arc evaporation/condensation process (original) (raw)

The transition from spark to arc discharge and its implications with respect to nanoparticle production

Journal of Nanoparticle Research, 2013

The synthesis of nanoparticles by means of electrical discharges between two electrodes in an inert gas at atmospheric pressure, as driven by a constant current ranging from a few milliamps to tens of amps, is investigated in this work. An extensive series of experiments are conducted with copper as a consumable electrode and pure nitrogen as the inert gas. Three different DC power supplies are used to drive electrical discharges for the entire operating current range. Then, three electrical discharge regimes (spark, glow, and arc) with distinct voltage-current characteristics and plasma emission spectra are recognized. For the first time, nanoparticles are synthesized by evaporation of an electrode by atmospheric pressure inert gas DC glow discharge of a few millimeters in size. The discharge regimes are characterized in terms of the mass output rate and the particle size distribution of the copper aerosols by means of online (tapered element oscillating microbalance, TEOM; and scanning mobility particle sizer, SPMS) and offline (gravimetric analysis; small and wide angle X-ray scattering, SWAXS; and transmission electron microscopy, TEM) techniques. The electrical power delivered to the electrode gap and the gas flow rate are two major parameters determining the aerosol mass output rate and the aerosol particle size distribution. The mass output rate of copper aerosols raises from 2 mg h -1 to 2 g h -1 when increasing the electrical power from 9 to 900 W. The particle mean size (SMPS d g ) varies between 20 and 100 nm depending upon the electrical power and the gas flow rate, whereas the particle size dispersion (SMPS r g ) ranges from 1.4 to 1.7 and is only weakly dependent on the gas flow rate.

Design of metal nanoparticle synthesis by vapor flow condensation

Chemical Engineering Science, 2002

A systematic engineering study on continuous synthesis of bismuth metal nanoparticles by vapor condensation in tube ows is presented. Simulations of aerosol nucleation, condensation and coagulation are cast in a design diagram format to guide experimental studies on the e ect of process parameters on product nanoparticle characteristics. Flow visualization, tracer gas analysis and computational uid dynamics are used to unravel the e ect of particle residence time distribution on product morphology during evaluation of alternate quenching designs for the metal vapor. Bismuth nanoparticles of average diameter 12-37 nm, as determined by nitrogen adsorption and X-ray di raction, were made by controlling the quenching gas ow rate, carrier gas ow rate and process pressure. ?

COPPER NANOPARTICLES OBTAINED BY ARC DISCHARGE METHOD: SYNTHESIS, CHARACTERIZATION, AND PROPERTIES.

Our objective in this paper is to study the effect of the current on the fabrication copper nanoparticles Cu- NPs and its effect on the yield and to investigate a new technique for plasma preparation of nanoparticles. A new instrument, which uses a three-phase current to support a double-arc discharge method for generating the plasma and evaporate the solids, is described. The crystal structure of nanoparticles, which was examined by X-ray diffraction XRD, shows that diffraction peaks for the Cu- NPs indicate that they are crystalline in nature. The morphology of the product was examined by Scanning Electron Microscope (SEM). From the micrograph, it was observed that the nanoparticles size ranges from 44 to123 nm. The particle size analyzer gives the size distributions with an overall sizing range. The particle size analyzer (PSA) constituents with SEM (the particles size ranges from 30-128 nm). The ultraviolet-visible (UV?Vis) spectrometry contributed to the analysis of size and optical properties of the nanoparticles through each current value (from 30A-110A). Fourier transform infrared (FTIR) spectroscopy analysis (4500 - 500 cm−1) confirmed the presences of Cu- NPs by an appearance of no sharp peaks for any functional group. The developed technique was shown to be suitable for the preparation of Cu- NPs of different sizes. However, a scale-up of production rate often leads to an increase in particle size and broadening of size distribution.

The influence of plasma operation parameters on synthesis process of copper particles at atmospheric pressure

Plasma Processes and Polymers, 2017

Copper particles, generated using an atmospheric pressure plasma jet (APPJ), are characterized and their generation is studied. The particle synthesis is based on the vaporization/condensation process. In our study, we used a radiofrequency (RF) plasma jet operating in an inert gas and copper bulk metal as source material. The RF power effects on the plasma characteristics are investigated. Correlating the information obtained by optical emission spectroscopy (OES), with visual investigations and with the profilometric electrode surface analyses we identify a RF power threshold when particles starts to be formed. Moreover, the metal vaporization stabilized after a couple of minutes of discharge operation. The influences of RF power over the particles shape, mean size and size distributions are studied.

Metal particle combustion and nanotechnology

Proceedings of the Combustion Institute, 2009

Metal combustion has received renewed interest largely as a result of the ability to produce and characterize metallic nanoparticles. Much of the highly desirable traits of nanosized metal powders in combustion systems have been attributed to their high specific surface area (high reactivity) and potential ability to store energy in surfaces. In addition, nanosized powders are known to display increased catalytic activity, superparamagnetic behavior, superplasticity, lower melting temperatures, lower sintering temperatures, and higher theoretical densities compared to micron and larger sized materials. The lower melting temperatures can result in lower ignition temperatures of metals. The combustion rates of materials with nanopowders have been observed to increase significantly over similar materials with micron sized particles. A lower limit in size of nanoenergetic metallic powders in some cases may result from the presence of their passivating oxide coating. Consequently, coatings, self-assembled monolayers (SAMs), and the development of composite materials that limit the volume of non-energetic material in the powders have been under development in recent years. After a brief review of the classifications of metal combustion based on thermodynamic considerations and the different types of combustion regimes of metal particles (diffusion vs. kinetic control), an overview of the combustion of aluminum nanoparticles, their applications, and their synthesis and assembly is presented.

Large scale synthesis of copper nickel alloy nanoparticles with reduced compressibility using arc thermal plasma process

Scientific Reports, 2021

Among the various methods employed in the synthesis of nanostructures, those involving high operating temperature and sharp thermal gradients often lead to the establishment of new exotic properties. Herein, we report on the formation of Cu-Ni metallic alloy nanoparticles with greatly enhanced stiffness achieved through direct-current transferred arc-thermal plasma assisted vapour-phase condensation. High pressure synchrotron X-ray powder diffraction (XRPD) at ambient temperature as well as XRPD in the temperature range 180 to 920 K, show that the thermal arc-plasma route resulted in alloy nanoparticles with much enhanced bulk modulus compared to their bulk counterparts. Such a behaviour may find an explanation in the sudden quenching assisted by the retention of a large amount of local strain due to alloying, combined with the perfect miscibility of the elemental components during the thermal plasma synthesis process.

Modeling metallic nanoparticle synthesis in a magnetron-based nanocluster source by gas condensation of a sputtered vapor

Copper nanoparticles NPs were synthesized by inert-gas condensation of a sputtered metallic vapor using a dedicated commercial reactor. By controlling the time of residence of NPs in the carrier gas phase via the tuning of the collision path length, Cu NPs were produced. They exhibit various and well controlled diameters 3–10 nm and a relatively narrow size dispersion. On the basis of these experimental results, a detailed modeling of NP nucleation and growth based on the classical nucleation theory was developed. It takes into account the peculiar geometry and thermal profile of the NP reactor. The simulated curves, calculated by a MATLAB ® program developed for that purpose, exhibit a good qualitative agreement with experiment. Moreover, they highlight the role of process parameters and the strong influence of the reactor temperature profile on the NP size distribution. In the future, such calculations could be used for the optimization of the NP source design in order to increase its efficiency and reproducibility.

Approaches to increasing yield in evaporation/condensation nanoparticle generation

Journal of Aerosol Science, 2002

With the recent interest in the chemical, electronic and optical properties of nanometer scale metal particles, there is now interest in manufacturing these materials in larger quantities. Since both small particle size and high particle number concentrations are sought, there is a need for improved particle generation reactors that can realize both goals. Here, results are presented for the synthesis of indium metal nanoparticles in an evaporation=condensation aerosol generator. Size distributions were measured for metal nanoparticles formed using a standard ow conÿguration, as well as using several variations on the standard conÿguration. The aim of the modiÿcations is to increase the cooling rate and thus, to increase the nucleation rate of the nanoparticles. An increase in the number concentration of particles and, in some cases, a signiÿcant decrease in average particle size was observed when the modiÿed reactor conÿgurations were used. These results can be explained by the changes in the time-temperature history of the nanoparticles resulting from the modiÿcations to the aerosol generator. A monodisperse model of nanoparticle formation and growth, accounting for nucleation, condensation and coagulation, was used to describe particle formation in the standard ow conÿguration, to guide the modiÿcations, and to describe particle formation in one of the modiÿed conÿgurations, with qualitative agreement seen between measured and predicted particle sizes. ?

Ambient spark generation to synthesize carbon-encapsulated metal nanoparticles in continuous aerosol manner

Nanoscale, 2009

We report the use of spark generation in an inert gas atmosphere to synthesize carbon-encapsulated metal nanoparticles (CEMNs) in a continuous aerosol manner using a metal (nickel, cobalt, iron)graphite carbon electrode configuration without the use of a vacuum. The spark-generated particles consisted of CEMNs and carbonaceous aggregated debris. The outer layer of the CEMNs showed parallel fringes (ordered graphitic nanostructures) while the debris consisted of disordered nanostructures. Electron and X-ray diffraction showed that both metal and graphite in the CEMNs were the pure elements except for iron-carbon, which contained a carbide phase. Based on the order of the activation energies for carbon diffusion into a metal: iron-carbon (10.5-16.5 kcal mol À1) < cobaltcarbon (34.7 kcal mol À1) $ nickel-carbon (33.0-34.8 kcal mol À1), it was concluded that carbide particles form more easily from elemental iron than nickel or cobalt. The metal-to-carbon mass fractions of the spark-generated particles from nickel (anode)carbon (cathode), cobalt-carbon, and iron-carbon spark configurations were 18.7, 28.3, and 11.2%, respectively, while the mass fractions for the configurations of metal (cathode)-carbon (anode) were 6.4, 9.1, and 4.3%, respectively. Similarly, the yield of CEMNs from the metal (anode)-carbon (cathode) electrodes was higher (54, 61, and 53%) than that of metal (cathode)-carbon (anode) electrodes (18, 30, and 18%).

Synthesis and coating of copper oxide nanoparticles using atmospheric pressure plasmas

Surface and Coatings Technology, 2007

Metals and metal oxides are well-known catalysts in many applications. TNO investigates metal and metal oxide nanoparticles as catalysts in rocket and gun propellants. Using nanosize particles allows to tune the curing, mechanical or ballistic properties of the propellant, but to avoid undesired chemical side-reactions a coating of these nanoparticles is sometimes desirable. As a model compound copper oxide was selected. Two atmospheric plasma techniques are presented for synthesis of nanoparticles with suitable coating layers. The first technique is based on injection of existing copper particles (30 nm) in a dielectric barrier discharge. The second technique is based on the combination of a thermal wire arc technique and a non-thermal dielectric barrier discharge. Copper nanoparticles are synthesised via evaporation of copper wire followed by nucleation. Coating takes place in the dielectric barrier discharge zone. The thermal plasma synthesised nanoparticles have been characterised by a narrow size distribution and a main size around 50 nm. For both techniques evaporation of liquid acetone and methyl methacrylate have been used to provide gas phase coating precursors. The coated particles are collected on polycarbonate membranes and TEM grids to be characterised by SEM and TEM. The results show nanoparticles coated with a 5 to 10 nm thick carbon layer.