Flow-levitation Method Research Articles

Characterisation of microstructure and properties of nano-copper powders prepared by flow levitation method

Nano-Cu powders were prepared by flow levitation method. The morphologies, granularities, structure and properties of nano-Cu particles were systematically investigated by transmission electron microscopy, X-ray diffraction analysis, UV visible absorption spectroscopy and X-ray photoelectron spectroscopy. The results show that the mean granularity of the almost spheric nano-Cu particles prepared in Ar is 50 nm. The maximum specific absorption appears at the wavelength of 590 nm. On the surface of the nano-Cu particles, the number of Cu atoms versus O atoms is about 94·88 : 5·12 resulting from XPS spectra.

Undercooling Solidification and Magnetic Properties of Pr<SUB>90</SUB>Fe<SUB>10</SUB> Alloy Produced by the Gas Flow Levitation Method

The magnetic properties and amorphous formation ability of Pr-based alloys have been reported and discussed. In this paper, Pr90Fe10 alloys were studied to reveal the solidification behavior associated with undercooling, magnetic properties of the metastable phase, and relation between undercooling and metastable phase formation by using the gas flow levitation method. The samples were solidified at various cooling rates from approximately 50 K/s to approximately 270 K/s. Undercooling increased with the cooling rate. According to the results of the SEM-EDS analysis, the Pr90Fe10 samples that solidified at high undercooling conditions in eutectic reactions consist of the primary α-Pr, eutectic α-Pr, and metastable phases whereas the samples that solidified at low undercooling conditions in eutectic reactions consist of the primary α-Pr, eutectic α-Pr, and Pr2Fe17 phases. Additionally, the magnetic properties changed due to the undercooling.

In situ encapsulation of copper nanoparticles by the dielectric barrier discharge

An experimental investigation is reported on in situ encapsulating copper nanoparticles with a nanolayer of hydrocarbon coating. Copper nanoparticles produced by the flow-levitation method are in situ encapsulated by the dielectric barrier discharge, which generates carbon and hydrogen plasmas for forming a polymerized nanolayer of hydrocarbon at the surface of Cu nanoparticles. The structural, chemical components and optical properties of the encapsulated Cu nanoparticles are characterized by transmission electron microscopy, energy dispersive x-ray spectra, x-ray diffraction, x-ray photoelectron spectra, and UV-visible absorption.

In situ organic coating of metal nanoparticles

A physical approach has been developed to in situ coat metal nanoparticles with a nanolayer of organic hydrocarbon film. Copper nanoparticles produced by the flow-levitation method were in situ coated with hydrocarbon films via a dielectric barrier discharge. The hydrocarbon-coated Cu nanoparticles have been analyzed by transmission electron microscopy and infrared absorption to determine the size distribution and dispersion of nanoparticles as well as the chemical components and thickness of the coatings.

Production of copper nanoparticles by the flow-levitation method

Copper nanoparticles have been synthesized by the flow-levitation method and coated withcarbon-and-hydrogen films through the hollow-cathode glow discharge. The uncoated andcoated Cu nanoparticles have been analysed by transmission electron microscopy, x-raydiffraction, and infrared absorption. Their size, dispersion, and coating thickness have beenexamined.

Theoretical simulations of preparation of nanometal Particles by Flow-levitation Method

This paper describes the principle of flow-levitation method. An analytical mode l for preparation of nanometal powders in inert gases is presented. Associated w ith the relation between dynamics of gas flow and temperature, the process of th ermal diffusion, nucleation, condensation and crystallization of powders is stud ied. The results of theoretical analysis are in agreement with the practice.It i ndicates that we can control the particle-size distribution by choosing appropri ate characteristic technological parameters.