A novel sonoelectrochemical method for the size-controlled synthesis of spherical copper nanoparticles in an aqueous phase was developed. In this study, poly(N-vinylpyrrolidone) (PVP) was used as the stabilizer for the copper clusters. The copper nanoparticles were characterized by XRD, UV-vis, IR, DLS, TEM, and HRTEM. The PVP was found to greatly promote the formation rate of copper particles and to significantly reduce the copper deposition rate, thereby making monodispersed copper nanoparticles. We could control the particle size by adjusting various parameters such as current density, deposition, temperature, and sonic power, and improve the homogeneity of the copper particles. The results also showed that the transfer rate of PVP-stabilized copper clusters from the cathodic vicinity to the bulk solution played an important role in the preparation of the monodispersed nanoparticles.

Pulsed sonoelectrochemical synthesis of size-controlled copper nanoparticles stabilized by poly(N-vinylpyrrolidone)

Stabilizer‐Free Metal Nanoparticles and Metal–Metal Oxide Nanocomposites with Long‐Term Stability Prepared by Physical Vapor Deposition into Ionic Liquids

Copper nanoparticles have been prepared by electro-reduction process using plating bath containing homogeneously acidified copper sulphate solution. The nanoparticles are formed as spongy layers of ball structures on the plating electrode. The spongy layers of copper can be easily separated to give fine particles. Structural characterizations are done by using X-ray diffraction, X-ray photoelectron spectroscopy, and ultraviolet-visible spectroscopy. Morphological characterizations are done by scanning electron microscope (SEM) and transmission electron microscope (TEM).

Synthesis of Copper Nanoparticles by Electroreduction Process

Over the last 20 years or so, a variety of new technologies has been developed to produce sub-micron powders. Among the products attracting interest is nanoaluminium which is being evaluated in specialist propulsion and exothermic end-uses. This paper examines the advances made in ‘nanopowder’ production in the context of the existing aluminium powder industry where finest commercial grades have a median size of ~6 μm (one or two orders of magnitude coarser than nanopowders) and which today supplies the markets being targeted by nanopowders with coarser, but effective products. Are there genuine market opportunities for nanoaluminium and if so, how will they be produced? One the one hand there are the novel nanopowder production methods which are high yielding but generally slow and costly, while on the other, there is the very fine fraction from conventional atomising routes which generate a very low yield of sub-micron powder but which nevertheless can translate into a meaningful rate as part of the bulk production. Can conventional routes ever hope to make sufficient volumes of nanopowders cost effectively and which will be the favoured routes in future? Moreover, what of the ‘ultrafine’ size range (~0.5–5 μm) which is of more immediate potential interest to today’s powder users. This paper seeks to identify the near term opportunities for application of low volume/high value ultrafine and nano powders.

Development and applications of ultrafine aluminium powders

Oxidation of nano-sized aluminum powders

Metallic nanopowders can be produced by applying a high power electrical pulse to a wire while in argon. The electromagnetic field created by the pulse confines the plasma until the vapor pressure of the metal exceeds the ability of the field to cantain it and on explosion accurs, creating metallic clusters of spherical particles. Rapid adicbatic quenching creates defects in the particles and they behave as if they are extensively warked, with a lowering of recrystallization temperature and the release of energy when the powders reach a threshold temperature substantially below melting. The powders are highly reactive and some are pyrophoric. Applications include their use in prapellants, explosives and pyrotechnics, as chemical reactants for organic synthesis, as catalysts, as conductors in microelectronics and as a sintering aid. Kilogram quantities of the following metals have been fabricated by this technique: nickel, iron, tungsten, tin, aluminum, copper, zinc, titanium, silver and indium.

F. Tepper

Papers

Metallic nanopowders produced by the electro-exploding wire process