Production of carbon-coated aluminium nanopowders in pulsed microarc discharge

Abstract

A new technique of metal nanopowder production and in situ coating using a microarc discharge is proposed. The feasibility of this method is demonstrated and preliminary results are presented. The microarc discharge was operated at 1 atm in both pure Ar and natural gas environments. Respectively, aluminium nanoparticles without and with ∼1 nm thick carbon surface coating were obtained. The morphology and structures of the nanoparticles were studied using a transmission electron microscope (TEM), and size distribution of the coated particles was determined from the TEM image analyses. It was found that the sizes of the produced carbon-coated aluminium particles were well described by a lognormal distribution with the geometrical mean size of 22.7 nm and standard deviation of 1.35.

Metal-based reactive nanomaterials

“…In a modification of the latter approach, aluminum was used as a consumable anode of the microarc discharge operated in natural gas to produce aluminum nanoparticles coated with a thin protective layer of carbon [56]. Carbon-coated aluminum nanopowders were also obtained when aluminum nanoparticles generated by arc-or laser ablation of an aluminum target were quenched in an argon-ethylene flow [57].…”

“…Respective SEM or TEM images can be readily used for straightforward, although labor-intensive, size classification of the observed particles, e.g., Ref. [56]. In order to be representative, such measurements must consider a large number of particles.…”

A reaction model for plasma coating of nanoparticles by amorphous carbon layers

“…The surfaces of particles can be altered by coating them with other materials for improving properties such as adhesion, hydrophobicity, hydrophilicity, printability, corrosion resistance, etc. The specific and broad spectrum of applications of coated particles includes ͑but is not limited to͒ removal of metal ions from water using ZnO particles coated with an acrylic film; 1 photocatalyst for water decontamination using glass spheres coated with TiO 2 ; 2,3 reinforcing materials, e.g., SiC particles coated with metallic nickel and copper, for aluminum-based metal matrix composites; 4,5 pharmaceutical dosage, e.g., microcapsule coated with composite latex membrane; 6 field emission display technology in the area of flat-panel displays using silica particles coated with phosphor; 7 superparamagnetism application of magnemite particles coated with polymethacrylic acid; 8,9 abrasives formed by diamond growth on Si and SiO 2 particles; 10 ferromagnetic iron particles coated with aluminum for toner for color copying machines; 11 solid fuels for combustors, e.g., aluminum nanoparticles coated with carbon; 12 improving flowability and decreasing wettability of food thickening agent cornstarch and food additive microcrystalline cellulose by coating with silica; 13 increasing the humidity resistance of magnesium particles used in flares and tracer bullets by coating with silica and wax; 13 and increasing weather durability of TiO 2 pigment, in paint, by coating TiO 2 particles with silica. 14 The possibility of many techniques, combinations of particle and coating materials, and range of operating conditions make the physicochemical phenomena of coating complex.…”

A High-Temperature Reducing Jet Reactor for Flame-Based Metal Nanoparticle Production

“…They also have potential for use in thermally conductive inks and pastes and in EMI shielding applications (Luechinger et al 2008). Aerosol methods such as arc-discharge techniques (Ermoline et al 2002;Liu et al 2004) and flame-spray pyrolysis in a reducing atmosphere (Athanassiou et al 2006;Luechinger et al 2008) combine the synthesis of particles and carbon coating into one step, and provide the most economical routes to these materials. Stark and co-workers have prepared carbon-coated copper nanoparticles using a flame-spray pyrolysis approach and tested their performance in conductive inks and sensing applications (Athanassiou et al 2006;Luechinger et al 2008).…”